WorldWideScience

Sample records for ferrite superparamagnetic nano

  1. Superparamagnetic behavior of indium substituted NiCuZn nano ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Hashim, Mohd, E-mail: md.hashim09@gmail.com [Department of Physics, Aligarh Muslim University, Aligarh 202002 (India); Shirsath, Sagar E. [Spin Device Technology Centre, Faculty of Engineering, Shinshu University, Nagano 380-8553 (Japan); Meena, S.S. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Kotnala, R.K. [National Physical Laboratory (CSIR), Dr. K.S. Krishnan Road, New Delhi 110012 (India); Kumar, Shalendra [Department of Applied Physics, Aligarh Muslim University, Aligarh 202002 (India); School of Materials Science and Engineering, Changwon National University, Changwon, Gyeongnam 641-773 (Korea, Republic of); Ravinder, D. [Department of Physics, Osmania University, Hyderabad 500007, AP (India); Raghasudha, M. [Department of Chemistry, Jayaprakash Narayan College of Engineering, Mahabubnagar 509001, AP (India); Bhatt, Pramod [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Şentürk, Erdoğan [Department of Physics, Sakarya University, Esentepe 54187, Sakarya (Turkey); Alimuddin [Department of Physics, Aligarh Muslim University, Aligarh 202002 (India); Kumar, Ravi [Centre for Material Science Engineering, National Institute of Technology, Hamirpur 177005, HP (India)

    2015-05-01

    Nano structured indium substituted NiCuZn ferrites with chemical composition Ni{sub 0.5}Cu{sub 0.25}Zn{sub 0.25}Fe{sub 2−x}In{sub x}O{sub 4} (0.0≤x≤0.4) were prepared using citrate-gel method. The XRD analysis confirmed the formation of single phased cubic spinel structure with a crystallite size ranging from 25 to 34 nm. The morphology of the prepared samples was studied using transmission electron microscopy and the thermal growth of the samples was analyzed by thermo gravimetric analysis and differential thermal analysis. Magnetic properties such as the Curie temperature and the temperature dependence magnetization studies of the samples were carried out using vibrating sample magnetometer. From the temperature dependence of both the field cooled and Zero field cooled magnetization measurements in the temperature range 50–350 K under an applied field of 500 Oe, the blocking temperature (T{sub b}) was estimated to be 325 K. Above T{sub b} the material shows superparamagnetic behavior which makes the material desirable for biomedical applications. - Highlights: • Crystallite size of Ni{sub 0.5}Cu{sub 0.25}Zn{sub 0.25}Fe{sub 2−x}In{sub x}O{sub 4} ranges from 25 to 34 nm. • T{sub c} of the ferrites has decreased from 698 K to 653 K with increase in In content. • Ferrites with x=0.0, 0.2 and 0.4 show superparamagnetic nature with T{sub c} of 325 K. • Hence the materials are desirable for biomedical applications and show excellent application in hyperthermia cancer therapy.

  2. Superparamagnetic La doped Mn-Zn nano ferrites: dependence on dopant content and crystallite size

    Science.gov (United States)

    Thakur, Prashant; Sharma, Rohit; Kumar, Manoj; Katyal, S. C.; Negi, N. S.; Thakur, Nagesh; Sharma, Vineet; Sharma, Pankaj

    2016-07-01

    Magnetic nanoparticles are found to exhibit exciting and substantially distinct magnetic properties due to high surface-to-volume ratio and several crystal structures in comparison to those discovered in their bulk counterparts. The properties of nanoparticles also largely depend on the route of their synthesis. In the present work, we report the synthesis of superparamagnetic nanoparticles of Mn0.5Zn0.5La x Fe2-x O4 (x = 0, 0.025, 0.050, 0.075, 0.1) ferrites by co-precipitation method. Structural, morphological and elemental study has been performed using x-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), FESEM and EDS. Different structural parameters (crystallite size, interplanar spacing and lattice constant) have been calculated from XRD. Formation of cubical spinel structure has been confirmed from XRD and FTIR. Cation distribution for all the samples has been proposed and used for calculation of various theoretical parameters. Magnetic properties have been investigated using vibrating sample magnetometer at room temperature and show transition between paramagnetic and superparamagnetic behavior. Maximum saturation magnetization and magnetic moment have been obtained at x = 0.050. The results are attributed to the solubility of La in Mn-Zn ferrite and the size of nanoparticles. The samples have also been analyzed for dielectric, electric and optical properties. For x ≤ 0.050, a blue shift in absorbance and photoluminescence measurements has been observed due to quantum confinement.

  3. Investigations of superparamagnetism in magnesium ferrite nano-sphere synthesized by ultrasonic spray pyrolysis technique for hyperthermia application

    Science.gov (United States)

    Das, Harinarayan; Sakamoto, Naonori; Aono, Hiromichi; Shinozaki, Kazuo; Suzuki, Hisao; Wakiya, Naoki

    2015-10-01

    In this paper, we present the synthesized of magnesium ferrite (MgFe2O4) nano-spheres by a single-step ultrasonic spray pyrolysis (USP) technique from the aqueous metal nitrate precursor solution without any organic additives or post-annealing processes. The effects of different pyrolysis temperatures on the particles size, morphology and their superparamagnetic behavior have been investigated to evaluate the heat generation efficiency in an AC magnetic field. The X-ray powder diffraction spectra of MgFe2O4 nano-spheres synthesized at the pyrolysis temperatures of 600, 700, 800 and 900 °C exhibited single phase cubic structure and obtained mean crystallite size (primary particles) of 4.05, 9.6, 15.97 and 31.48 nm, respectively. Transmission electron microscopy (TEM) confirms that the particles consisted of aggregates of the primary crystallite had densely congested spherical morphology with extremely smooth surface appearance. Field emission electron microscopy (FESEM) reveals that the shape and size of the nano-spheres (secondary particles) does not change significantly but the degree of agglomeration between the secondary particles was reduced with increasing the pyrolysis temperature. The average size and size distribution of nano-spheres measured using electrophoretic scattering photometer have found very low polydispersity index (PDI) for all samples. The field dependent magnetization studies indicated superparamagnetic nature for the particles having crystallite size i.e. 4.05 and 9.6 nm and exhibited ferromagnetic nature for 15.97 and 31.48 nm. It is also demonstrated that, as the pyrolysis temperature increases, the saturation magnetization of the MgFe2O4 nanopowders increases due to enhancement of crystallites. The shift in Curie temperature is well described by the finite-size scaling formula. The magnetically loss heating values of selected samples in crystallite size of 9.6 and 15.97 nm were investigated by measuring the time dependent temperature

  4. Investigations of superparamagnetism in magnesium ferrite nano-sphere synthesized by ultrasonic spray pyrolysis technique for hyperthermia application

    Energy Technology Data Exchange (ETDEWEB)

    Das, Harinarayan, E-mail: hn_das@yahoo.com [Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johoku Naka-ku, Hamamatsu 432-8561 (Japan); Materials Science Division, Atomic Energy Centre, Bangladesh Atomic Energy Commission, Dhaka 1000, Bangladesh (Bangladesh); Sakamoto, Naonori [Department of Electronics and Materials Science, Shizuoka University, 3-5-1 Johoku Naka-ku, Hamamatsu 432-8561 (Japan); Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku Naka-ku, Hamamatsu 432-8561 (Japan); Aono, Hiromichi [Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama 790-85770 (Japan); Shinozaki, Kazuo [Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, 2-12-1 O-okayama Meguro-ku, Tokyo 152-8550 (Japan); Suzuki, Hisao; Wakiya, Naoki [Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johoku Naka-ku, Hamamatsu 432-8561 (Japan); Department of Electronics and Materials Science, Shizuoka University, 3-5-1 Johoku Naka-ku, Hamamatsu 432-8561 (Japan); Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku Naka-ku, Hamamatsu 432-8561 (Japan)

    2015-10-15

    In this paper, we present the synthesized of magnesium ferrite (MgFe{sub 2}O{sub 4}) nano-spheres by a single-step ultrasonic spray pyrolysis (USP) technique from the aqueous metal nitrate precursor solution without any organic additives or post-annealing processes. The effects of different pyrolysis temperatures on the particles size, morphology and their superparamagnetic behavior have been investigated to evaluate the heat generation efficiency in an AC magnetic field. The X-ray powder diffraction spectra of MgFe{sub 2}O{sub 4} nano-spheres synthesized at the pyrolysis temperatures of 600, 700, 800 and 900 °C exhibited single phase cubic structure and obtained mean crystallite size (primary particles) of 4.05, 9.6, 15.97 and 31.48 nm, respectively. Transmission electron microscopy (TEM) confirms that the particles consisted of aggregates of the primary crystallite had densely congested spherical morphology with extremely smooth surface appearance. Field emission electron microscopy (FESEM) reveals that the shape and size of the nano-spheres (secondary particles) does not change significantly but the degree of agglomeration between the secondary particles was reduced with increasing the pyrolysis temperature. The average size and size distribution of nano-spheres measured using electrophoretic scattering photometer have found very low polydispersity index (PDI) for all samples. The field dependent magnetization studies indicated superparamagnetic nature for the particles having crystallite size i.e. 4.05 and 9.6 nm and exhibited ferromagnetic nature for 15.97 and 31.48 nm. It is also demonstrated that, as the pyrolysis temperature increases, the saturation magnetization of the MgFe{sub 2}O{sub 4} nanopowders increases due to enhancement of crystallites. The shift in Curie temperature is well described by the finite-size scaling formula. The magnetically loss heating values of selected samples in crystallite size of 9.6 and 15.97 nm were investigated by measuring

  5. Superparamagnetic response of zinc ferrite incrusted nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Maldonado, K.L., E-mail: liliana.lopez.maldonado@gmail.com [Instituto de Ingeniería y Tecnología, Universidad Autónoma de Ciudad Juárez, Av. Del Charro 450 norte, 32310 Ciudad Juárez (Mexico); Presa, P. de la, E-mail: pmpresa@ucm.es [Instituto de Magnetismo Aplicado (UCM-ADIF-CSIC), PO Box 155, 28230 Las Rozas (Spain); Dpto. Física de Materiales, Univ. Complutense de Madrid, Madrid (Spain); Betancourt, I., E-mail: israelb@unam.mx [Departamento de Materiales Metálicos y Cerámicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México, D.F. 04510 (Mexico); Farias Mancilla, J.R., E-mail: rurik.farias@uacj.mx [Instituto de Ingeniería y Tecnología, Universidad Autónoma de Ciudad Juárez, Av. Del Charro 450 norte, 32310 Ciudad Juárez (Mexico); Matutes Aquino, J.A., E-mail: jose.matutes@cimav.edu.mx [Centro de Investigación en Materiales Avanzados, Miguel de Cervantes 120, 31109 Chihuahua (Mexico); Hernando, A., E-mail: antonio.hernando@externos.adif.es [Instituto de Magnetismo Aplicado (UCM-ADIF-CSIC), PO Box 155, 28230 Las Rozas (Spain); Dpto. Física de Materiales, Univ. Complutense de Madrid, Madrid (Spain); and others

    2015-07-15

    Highlights: • Incrusted nanoparticles are found at the surface of ZnFe{sub 2}O{sub 4} microparticles. • Magnetic contribution of nano and microparticles are analyzed by different models. • Langevin model is used to calculate the nanoparticles-superparamagnetic diameter. • Susceptibility and Langevin analysis and calculations agree with experimental data. - Abstract: Zinc ferrite is synthesized via mechano-activation, followed by thermal treatment. Spinel ZnFe{sub 2}O{sub 4} single phase is confirmed by X-ray diffraction. SEM micrographs show large particles with average particle size 〈D{sub part}〉 = 1 μm, with particles in intimate contact. However, TEM micrographs show incrusted nanocrystallites at the particles surface, with average nanocrystallite size calculated as 〈D{sub inc}〉 ≈ 5 nm. The blocking temperature at 118 K in the ZFC–FC curves indicates the presence of a superparamagnetic response which is attributable to the incrusted nanocrystallites. Moreover, the hysteresis loops show the coexistence of superpara- and paramagnetic responses. The former is observable at the low field region; meanwhile, the second one is responsible of the lack of saturation at high field region. This last behavior is related to a paramagnetic contribution coming from well-ordered crystalline microdomains. The hysteresis loops are analyzed by means of two different models. The first one is the susceptibility model used to examine separately the para- and superparamagnetic contributions. The fittings with the theoretical model confirm the presence of the above mentioned magnetic contributions. Finally, using the Langevin-based model, the average superparamagnetic diameter 〈D{sub SPM}〉 is calculated. The obtained value 〈D{sub SPM}〉 = 4.7 nm (∼5 nm) is consistent with the average nanocrystallite size observed by TEM.

  6. Study of Mössbauer and magnetic properties of Al{sup 3+} ions doped superparamagnetic nano ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Satish, E-mail: apusaan@gmail.com; Chand, Jagdish; Sarveena,; Singh, M. [Department of Physics Himachal Pradesh University Summer-Hill Shimla-171005 (India)

    2015-06-24

    Nanocrystalline Al{sup 3+} ions doped Mg{sub 0.2}Mn{sub 0.5}Ni{sub 0.3}Al{sub y}Fe{sub 2-y}O{sub 4} compositions, where y=0.0 and 0.10 have been synthesized by citrate precursor method. Crystal structure and magnetic properties have been investigated at room temperature by means of X-ray diffraction, TEM, LCR meter, VSM and Mössbauer spectroscopy. Particle size and lattice parameter has been found to decrease as non-magnetic Al content increased. Relative loss factor has very low value in range of 10{sup −6}–10{sup −5} which is three orders of magnitude less than samples prepared by conventional method. The Mössbauer spectroscopy results shows superparamagnetism. The isomer shift corresponding to Fe{sup 3+} ions do not show any significant variation which indicates that replacement of Fe{sup 3+} ions do not affect significantly the d-electrons density which in turn affects the s-electrons density around Fe{sup 3+} nuclei. The nuclear hyperfine magnetic fields have been found to decrease at A-site and B-site with increasing substitution of Al{sup 3+} ions in Mg-Mn-Ni ferrite.

  7. Magnetic resonance in superparamagnetic zinc ferrite

    Indian Academy of Sciences (India)

    Jitendra Pal Singh; Gagan Dixit; R C Srivastava; Hemant Kumar; H M Agrawal; Prem Chand

    2013-08-01

    In the present work, we have synthesized zinc ferrite nanoparticles by nitrate method. Presence of almost zero value of coercivity and remanence in the hysteresis of these samples shows the superparamagnetic nature at room temperature. Electron paramagnetic resonance spectroscopy performed on these samples in the temperature range 120–300 K indicates the systematic variation of the line-shapes of the spectra with temperature. Both gvalue and peak-to-peak linewidth decrease with increase in temperature. The variation of g-values and peak-topeak linewidth with temperature has been fitted with existing models and we observed different values of activation energies of the spins for both the samples.

  8. Superparamagnetic calcium ferrite nanoparticles synthesized using a simple sol-gel method for targeted drug delivery.

    Science.gov (United States)

    Sulaiman, N H; Ghazali, M J; Majlis, B Y; Yunas, J; Razali, M

    2015-01-01

    The calcium ferrite nano-particles (CaFe2O4 NPs) were synthesized using a sol-gel method for targeted drug delivery application. The proposed nano-particles were initially prepared by mixing calcium and iron nitrates that were added with citric acid in order to prevent agglomeration and subsequently calcined at a temperature of 550°C to obtain small particle size. The prepared nanoparticles were characterized by using an XRD (X-ray diffraction), which revealed the configuration of orthorhombic structures of the CaFe2O4 nano-particles. A crystallite size of ~13.59 nm was obtained using a Scherer's formula. Magnetic analysis using a VSM (Vibrating Sample Magnetometer analysis), revealed that the synthesized particles exhibited super-paramagnetic behavior having magnetization saturation of approximately 88.3emu/g. Detailed observation via the scanning electron microscopy (SEM) showed the calcium ferrite nano-particles were spherical in shape.

  9. Superparamagnetism in Zn Substituted Copper-gallate Ferrite

    Institute of Scientific and Technical Information of China (English)

    N.N. Nikitenkov; A.M. Hashhash; I.P. Chernov; Yu.I. Tyurin

    2010-01-01

    Solid solution of spinel ferrite Cu1-xZnxFe2-yGayO4 with (0.0≤x≤0.5 and y=0.1) are synthesized. XRD measurements confirm the presence of single-phase tetragonal structure with c/a>1 for CuFe2O4 and samples with (x=0.0 and 0.1). The tetragonal phase is attributed to the presence of the cooperative Jahn-Teller Cu ions in the octahedral B-site in the spinel lattice. Tetragonal-to-cubic transformation is occurred at the compositional parameter x≥0.2 and the lattice parameter a is found to decrease with increasing Zn content x. 57Fe M(o)ssbauer measurements at 293K for these compounds reveal superparamagnetic phase for samples with (0.0≤x≤0.2). In contrast, M(o)ssbauer spectra at 12K for these materials show well ordered spectra where, the cation distribution and the hyperfine parameters are determined.

  10. Hydrothermal synthesis of fine stabilized superparamagnetic nanoparticles of Zn{sup 2+} substituted manganese ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Zahraei, Maryam, E-mail: zahraee_maryam@yahoo.com [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Monshi, Ahmad [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Morales, Maria del Puerto [Instituto de Ciencia de Materiales de Madrid, ICMM/CSIC, Cantoblanco, 28049 Madrid (Spain); Shahbazi-Gahrouei, Daryoush [Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan 81746-734615 (Iran, Islamic Republic of); Amirnasr, Mehdi [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Behdadfar, Behshid [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2015-11-01

    Superparamagnetic Zn{sup 2+} substituted manganese ferrite Mn{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} (x=0.3, 0.35, 0.4 and 0.45) nanoparticles (NPs) were synthesized via a direct, efficient and environmental friendly hydrothermal method. The synthesized NPs were characterized by X-ray powder diffractometry (XRD), transmission electron microscopy (TEM), thermo-gravimetry (TG) and vibrating sample magnetometry (VSM). The effects of various parameters such as the pH of reaction mixture, time and temperature of hydrothermal treatment and Zn substitution on the spinel phase formation, the magnetization, and the size of resulting NPs are discussed. The Zn{sup 2+} substituted manganese ferrite NPs obtained from hydrothermal process crystallized mainly in the spinel phase. Nevertheless, without citrate ions, the hematite phase appeared in the product. The monophase Zn{sup 2+} substituted manganese ferrite NPs hydrothermally prepared in the presence of citric acid had mean particle size of 7 nm and a narrow size distribution. Furthermore, the synthesized NPs can be used to prepare ferrofluids for biomedical applications due to their small size, good stability in aqueous medium (pH 7) and also high magnetization value. - Highlights: • Single phase Mn–Zn ferrite NPs were synthesized by hydrothermal method. • Substitution of Zn in Mn-ferrite increased Ms. • These Mn–Zn ferrite NPs can be used for biomedical applications.

  11. Gd3+ doped Mn-Zn soft ferrite nanoparticles: Superparamagnetism and its correlation with other physical properties

    Science.gov (United States)

    Thakur, Prashant; Sharma, Rohit; Sharma, Vineet; Barman, P. B.; Kumar, Manoj; Barman, Dipto; Katyal, S. C.; Sharma, Pankaj

    2017-06-01

    Superparamagnetic nanoparticles are very important in biomedicine due to their various applications like drug delivery, gene delivery in the body and also used for hyperthermia. In the present work, superparamagnetic nanoparticles of Mn0.5Zn0.5GdxFe2-xO4 (x = 0, 0.025, 0.050, 0.075, 0.1) ferrites have been prepared by co-precipitation method. Thorough characterizations (XRD, FTIR, FE-SEM, EDS, VSM and fluorescence spectroscopy) have proved the formation of cubical spinel superparamagnetic nanoparticles of soft ferrites. A cation distribution has been proposed for the determination of various important theoretical parameters for these samples. With the addition of Gd3+ nanoparticles have shown the superparamagnetism at room temperature confirmed by VSM analysis. Photoluminescence (PL) spectra shows a blue shift (for x = 0.025, 0.075) which may be due to quantum confinement.

  12. Superparamagnetic nano-immunobeads toward food safety insurance

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xuefeng [National Center for Nanoscience and Technology (China); Zhang, Lei; Zeng, Jing, E-mail: zengj@bjciq.gov.cn [Beijing Entry-Exit Inspection and Quarantine Bureau (China); Gao, Yan, E-mail: gaoyan@nanoctr.cn; Tang, Zhiyong [National Center for Nanoscience and Technology (China)

    2013-07-15

    In this work, superparamagnetic nano-immunobeads (SPM-NIBs) based on conjugation of superparamagnetic Fe{sub 3}O{sub 4} nanoparticles with specific antibodies have been developed toward food safety insurance. The resultant SPM-NIBs exhibits excellent colloidal stability and reversible magnetic response. Vibrio parahaemolyticus, which is a main foodborne pathogenes from contaminated seafood, can be separated specifically and efficiently by the resultant SPM-NIBs. The results of bacteria separation demonstrate that the SPM-NIBs have a higher specific activity and sensitivity toward V. parahaemolyticus. About 80 % of V. parahaemolyticus cells can be captured when the concentration of the broth reaches 10{sup 3} CFU/mL. Thus, the SPM-NIBs can effectively enhance the efficiency for target bacteria inspections by shortening the period of culture time. This work holds the promise of development of general technique to prepare effective SPM-NIBs toward food safety inspections and other bio-related applications for target analyte separation and collection.

  13. Synthesis, characterization and FC–ZFC magnetization studies of cobalt substituted lithium nano ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Aravind, G. [Department of Physics, Osmania University, Hyderabad 500007, Telangana (India); Raghasudha, M., E-mail: raghasudha_m@yahoo.co.in [Department of Chemistry, Jayaprakash Narayan College of Engineering, Mahabubnagar 509001, Telangana (India); Ravinder, D., E-mail: ravindergupta28@rediffmail.com [Department of Physics, Osmania University, Hyderabad 500007, Telangana (India)

    2015-03-15

    Cobalt substituted Lithium Nano ferrites with the chemical composition [Li{sub 0.5}Fe{sub 0.5}]{sub 1−x}Co{sub x}Fe{sub 2}O{sub 4} (where x=0.0, 0.2, 0.4, 0.6, 0.8, 1.0) were synthesized through Citrate-Gel auto combustion technique. Structural characterization of the prepared ferrites was carried by X-ray diffraction analysis (XRD) and Scanning Electron Microscopy (SEM). XRD analysis has confirmed the formation cubic spinel structure of the ferrite compositions with a particle size ranging from 37 nm to 42 nm. The SEM images represent large agglomeration of the nano particles of the ferrite samples with broader grain size distribution. Temperature dependent magnetic properties of [Li{sub 0.5}Fe{sub 0.5}]{sub 1−x}Co{sub x}Fe{sub 2}O{sub 4} for two compositions with cobalt content x=0.8 and x=1.0 were carried out using Vibrating sample magnetometer (VSM). The magnetization as a function of an applied field ±10 T was carried out at temperatures 5 K and 310 K. Field cooled (FC) and Zero field cooled (ZFC) magnetization measurements under an applied field of 100 Oe and 1 KOe in the temperature range of 5–375 K were performed. These measurements have resulted the blocking temperature (T{sub b}) at around 350 K i.e. above room temperature for both the ferrites. Below this temperature the ferrites show ferromagnetic behavior and above which superparamagnetic behavior where the coercivity and remanence magnetization are almost zero. Such behavior makes the ferrites to be desirable for biomedical applications. - Highlights: • Crystallite size of [Li{sub 0.5}Fe{sub 0.5}]{sub 1−x}Co{sub x}Fe{sub 2}O{sub 4}, 0≤x≤1.0 ranges from 37 nm to 42 nm. • Blocking temperature (T{sub b}) of Li{sub 0.1}Co{sub 0.8} Fe{sub 2.1}O{sub 4} and CoFe{sub 2}O{sub 4} is at around 350 K. • These two ferrites show superparamagnetic behavior above 350 K. • These ferrites are desirable for bio-medical applications.

  14. HYDROTHERMAL SYNTHESIS OF NANO-METER MICROPOROUS ZINC FERRITE

    Institute of Scientific and Technical Information of China (English)

    Xiaoling Hu; Ping Guan; Xin Yan

    2004-01-01

    Nano-meter microporous zinc ferrite was prepared by a hydrothermal method, using triethylamine as a template. Adsorption curves showed that the product had a microporous structure. The effects of precursor pH, reaction temperature and reaction time on the preparation were studied, yielding optimal conditions: pH=11,448 K, 360 min. The morphology of zinc ferrite as observed by TEM, showed that zinc ferrite was well-crystallized and well-dispersed with little conglomeration.

  15. Size controlled sonochemical synthesis of highly crystalline superparamagnetic Mn–Zn ferrite nanoparticles in aqueous medium

    Energy Technology Data Exchange (ETDEWEB)

    Abbas, Mohamed [Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 711-873 Daegu (Korea, Republic of); Ceramics Department, National Research Centre, El-Bohous Street, 12622 Cairo (Egypt); Torati, Sri Ramulu [Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 711-873 Daegu (Korea, Republic of); Rao, B. Parvatheeswara [Department of Physics, Andhra University, Visakhapatnam 530003 (India); Abdel-Hamed, M.O. [Physics Department, Faculty of Science, El-Minia University (Egypt); Kim, CheolGi, E-mail: cgkim@dgist.ac.kr [Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 711-873 Daegu (Korea, Republic of)

    2015-09-25

    Highlights: • Mn–Zn ferrite NPs were synthesized by two different methods are polyol and sonochemical. • The sonochemical method produced NPs with high crystallinity than polyol method. • The ferrite samples synthesized by sonochemical method showed high magnetization values and superparamagnetic properties. • XRD, TEM, EDS, TGA, FTIR, and VSM techniques used to characterize the samples. - Abstract: Monodisperse Mn{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4} (x = 0.2, 0.5 and 0.8) nanoparticles have been synthesized using two different routes namely sonochemical and polyol methods, and the shape and size along with physiochemical properties of the nanoparticles were compared in detail. In both the routes, the synthesis was performed in a single reaction without the use of any surfactant and deoxygenated conditions. The reaction kinetics and surface adsorption characteristics of nanoparticles were observed by thermogravimetric analysis and Fourier transform infrared spectroscopy measurements. X-ray diffraction patterns confirmed the formation of a pure ferrite phase with cubic spinel structure, and the patterns further clearly indicate that the sonochemical method produces highly crystalline particles without any post calcination reaction, comparing with the polyol process. Transmission electron microscopy results reveal that the nanoparticles synthesized by polyol method are mostly aggregated and spherical in nature whereas the nanoparticles produced by sonochemical method are monodisperse large particles with cubic like shapes. The overall studies demonstrated that the sonochemical method is facile, reliable, rapid and very attractive for the aqueous synthesis of highly crystalline and high magnetic moment (84.5 emu/g) monodisperse superparamagnetic Mn–Zn ferrite nanoparticles which considered as potential materials for various applications.

  16. [Superparamagnetic Cobalt Ferrite Nanoparticles "Blow up" Spatial Ordering of Double-stranded DNA Molecules].

    Science.gov (United States)

    Yevdokimov, Yu M; Pershina, A G; Salyanov, V I; Magaeva, A A; Popenko, V I; Shtykova, E V; Dadinova, L A; Skuridin, S G

    2015-01-01

    The formation of cholesteric liquid-crystalline dispersions formed by double-stranded DNA molecules, handled by positively charged superparamagnetic cobalt ferrite nanoparticles, as well as action of these nanoparticles on DNA dispersion, are considered. The binding of magnetic nanoparticles to the linear double-stranded DNA in solution of high ionic strength (0.3 M NaCl) and subsequent phase exclusion of these complexes from polyethylene glycol-containing solutions lead to their inability to form dispersions, whose particles do possess the spatially twisted arrangement of neighboring double-stranded DNA molecules. The action of magnetic nanoparticles on DNA dispersion (one magnetic nanoparticle per one double-stranded DNA molecule) results in such "perturbation" of DNA structure at sites of magnetic nanoparticles binding that the regular spatial structure of DNA dispersion particles "blows up"; this process is accompanied by disappearance of both abnormal optical activity and characteristic Bragg maximum on the small-angle X-ray scattering curve. Allowing with the fact that the physicochemical properties of the DNA liquid-crystalline dispersion particles reflect features of spatial organization of these molecules in chromosomes of primitive organisms, it is possible, that the found effect can have the relevant biological consequences.

  17. X-ray diffraction and Moessbauer studies on superparamagnetic nickel ferrite (NiFe{sub 2}O{sub 4}) obtained by the proteic sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, N.A.S. [Departamento de Engenharia Metalúrgica e de Materiais, Centro de Tecnologia, Campus do Pici, Universidade Federal do Ceará – UFC, 60455-760 Fortaleza, CE (Brazil); Utuni, V.H.S.; Silva, Y.C. [Departamento de Física, Universidade Federal do Ceará – UFC, Campus do Pici, 60440-970 Fortaleza, CE (Brazil); Kiyohara, P.K. [Instituto de Física, Universidade de São Paulo – USP, 05315-970 São Paulo, SP (Brazil); Vasconcelos, I.F. [Departamento de Engenharia Metalúrgica e de Materiais, Centro de Tecnologia, Campus do Pici, Universidade Federal do Ceará – UFC, 60455-760 Fortaleza, CE (Brazil); Miranda, M.A.R., E-mail: marcus.a.r.miranda@gmail.com [Departamento de Física, Universidade Federal do Ceará – UFC, Campus do Pici, 60440-970 Fortaleza, CE (Brazil); Sasaki, J.M. [Departamento de Física, Universidade Federal do Ceará – UFC, Campus do Pici, 60440-970 Fortaleza, CE (Brazil)

    2015-08-01

    Nickel ferrite (NiFe{sub 2}O{sub 4}) nanoparticles were synthesized by the proteic sol–gel method at synthesis temperature of 250 °C, 300 °C and 400 °C, with the objective of obtaining superparamagnetic nanoparticles. Thermogravimetric analysis (TGA) and temperature-programed oxidation (TPO) presented peaks around 290 °C indicating that nickel ferrite was forming at this temperature. X-ray powder diffraction (XRPD) confirmed that the polycrystalline sample was single phased NiFe{sub 2}O{sub 4} with space group Fd3m. Scherrer equation applied to the diffraction patterns and transmission electron microscopy (TEM) images showed that the size of the nanoparticles ranged from 9 nm to 13 nm. TEM images also revealed that the nanoparticles were agglomerated, which was supported by the low values of surface area provided by the Brunauer-Emmet-Teller (BET) method. Moessbauer spectroscopy presented spectra composed of a superposition of three components: a sextet, a doublet and a broad singlet pattern. The sample synthetized at 300 °C had the most pronounced doublet pattern characteristic of superparamagnetic nanoparticles. In conclusion, this method was partially successful in obtaining superparamagnetic nickel ferrite nanoparticles, in which the synthetized samples were a mixture of nanoparticles with blocking temperature above and below room temperature. Magnetization curves revealed a small hysteresis, supporting the Moessbauer results. The sample with the higher concentration of superparamagnetic nanoparticles being the one synthetized at 300 °C. - Highlights: • Superparamagnetic nickel ferrite nanoparticles were grown by the proteic sol–gel method. • The proteic sol–gel method provided superparamagnetic nickel ferrite nanoparticles with sizes in the range of 9–13 nm. • Nickel ferrite nanoparticles were prepared at temperatures as low as 250 °C. • The nickel ferrite nanoparticles were studied by x-ray diffraction and Moessbauer.

  18. Synthesis and characterization of nano silver ferrite composite

    Science.gov (United States)

    Murthy, Y. L. N.; Kondala Rao, T.; Kasi viswanath, I. V.; Singh, Rajendra

    2010-07-01

    We report the synthesis of nano sized silver ferrite composite having the empirical formula AgFeO 2 by a co-precipitation method. The resulting powders are thin platelets, transparent and a rich ruby red in color in transmission. The X-ray diffraction (XRD) powder data consisted of only nine reflections, and the analysis showed the unit cell to be rhombohedral. The powders showed extensive XRD line broadening and the sizes of the crystals are calculated to be in the range 4-36.5 nm. The morphology of the silver ferrite composite studied using scanning electron microscope showed nano sized particles. The particle size is found to increase with increase in annealing temperature. The magnetic behavior, measured using a vibrating sample magnetometer, indicated a change from paramagnetic to ferromagnetic with increase in particle size.

  19. Studies on structural properties of clay magnesium ferrite nano composite

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Manpreet, E-mail: manpreetchem@pau.edu; Singh, Mandeep [Department of Chemistry, Punjab Agricultural University, Ludhiana-141004 (India); Jeet, Kiran, E-mail: kiranjeet@pau.edu; Kaur, Rajdeep [Electron Microscopy and Nanoscience Laboratory, Punjab Agricultural University, Ludhiana-141004 (India)

    2015-08-28

    Magnesium ferrite-bentonite clay composite was prepared by sol-gel combustion method employing citric acid as complexing agent and fuel. The effect of clay on the structural properties was studied with X-ray diffraction (XRD), Fourier transform infrared (FT-IR) Spectroscopy, Scanning electron microscopy (SEM), SEM- Energy dispersive Spectroscope (EDS) and BET surface area analyzer. Decrease in particle size and density was observed on addition of bentonite clay. The BET surface area of nano composite containing just 5 percent clay was 74.86 m{sup 2}/g. Whereas porosity increased from 40.5 per cent for the pure magnesium ferrite to 81.0 percent in the composite showing that nano-composite has potential application as an adsorbent.

  20. The metamorphosis of heterometallic trinuclear antiferromagnetic complexes into nano-sized superparamagnetic spinels.

    Science.gov (United States)

    Vasylenko, Inna V; Gavrylenko, Konstiantyn S; Il'yin, Vladimir G; Golub, Vladimir; Goloverda, Galina; Kolesnichenko, Vladimir; Addison, Anthony W; Pavlishchuk, Vitaly V

    2010-05-15

    Thermal decomposition of the trinuclear heterometallic oxoacetates [Fe(2)M(μ(3)-O)(CH(3)COO)(6)(H(2)O)(3)] has been used as a single-precursor method for synthesis of the spinel-structured ternary oxides MFe(2)O(4) (M = Mn(II), Co(II), and Ni(II)). This facile process occurring at 320 °C results in the formation of nanocrystalline, (7-20 nm) highly pure stoichiometric ferrites in quantitative yield. The magnetic properties of these nanoparticulate ferrites were studied in the 10-300 K temperature range, revealing superparamagnetic behaviour for the Ni and Mn particles and ferromagnetic behavior for the Co ones at room temperature. Their blocking temperatures follow the order: CoFe(2)O(4) > MnFe(2)O(4) > NiFe(2)O(4).

  1. Preparation and Characterization of Super-paramagnetic Nano-beads for DNA Isolation

    Institute of Scientific and Technical Information of China (English)

    Xin XIE; Xu ZHANG; Bing Bin YU; wei Yang FE

    2004-01-01

    Unique coupling reagent, bis-(2-hydroxyethyl methacrylate) phosphate was used to prepare coated and functionalized superparamagnetic nanobeads, leading to a simple, effective method for coating the nanobeads. With this method, the thickness of the coating layer and the functional group contents on the nano-beads could be controlled by changing the quantity of the coated monomers. The nanobeads were characterized by means of transmission electron microscopy (TEM) and Fourier transformation infrared spectroscopy (FTIR). The carboxyl-modified magnetic nano-beads were employed to streamline the protocol of isolation of genomic DNA from the human whole blood.

  2. Biopolymers coated superparamagnetic Nickel Ferrites: Enhanced biocompatibility and MR imaging probe for breast cancer

    Science.gov (United States)

    Bano, Shazia; Zafar, Tayyaba; Akhtar, Shahnaz; Buzdar, Saeed Ahmed; Waraich, Mustansar Mahmood; Afzal, Muhammad

    2016-11-01

    We report evidence for the promising application of bovine serum albumin (BSA), chitosan (CS) or carboxymethyl cellulose (CMC) coated NiFe2O4 cores for improved biocompatibility and enhanced T2 relaxivity, through a single combinatorial approach. Pure nickel-ferrite nano cores (NFs) successfully synthesized by thermolysis, were immobilize with BSA, CS or CMC layer employing a simple cross linking procedure to avoid any significant influence of these biopolymers on the morphology and crystal structure of the cores. Phase, morphology, magnetic hysteresis and surface chemistry were characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), vibrating sample magnetometer (VSM) and Fourier transform infrared (FTIR) spectroscopy. The preliminary haemolysis and cell viability experiments show that biopolymers conjugation mitigates the haemolytic effect of the NFs on erythrocytes as the haemolytic index is less than 2% and cell viability is up to 100%, when normalized with the nontreated cells. The relaxivity value of coated NFs is 351±2.6 when compared to 84±0.22 of NFs without biopolymer conjugation. The results demonstrate that BSA, CS or CMC covering on NFs provide a single combinatorial approach to improve the biocompatibility and enhance the relaxivity value. Thus addressing the current challenge of the same with very good contrast for targeting MCF-7 without any further vectorization.

  3. Biopolymers coated superparamagnetic Nickel Ferrites: Enhanced biocompatibility and MR imaging probe for breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Bano, Shazia, E-mail: shaziaphy@gmail.com [Department of Physics, The Islamia University of Bahawalpur (Pakistan); Zafar, Tayyaba [Department of Physics, The Islamia University of Bahawalpur (Pakistan); Akhtar, Shahnaz [Department of Pharmacy, The Islamia University of Bahawalpur (Pakistan); Buzdar, Saeed Ahmed [Department of Physics, The Islamia University of Bahawalpur (Pakistan); Waraich, Mustansar Mahmood, E-mail: mustansarwaraich@gmail.com [Quaid-e-Azam Medical College B.V. Hospital, Bahawalpur (Pakistan); Afzal, Muhammad [Department of Physics, The Islamia University of Bahawalpur (Pakistan)

    2016-11-01

    We report evidence for the promising application of bovine serum albumin (BSA), chitosan (CS) or carboxymethyl cellulose (CMC) coated NiFe{sub 2}O{sub 4} cores for improved biocompatibility and enhanced T2 relaxivity, through a single combinatorial approach. Pure nickel-ferrite nano cores (NFs) successfully synthesized by thermolysis, were immobilize with BSA, CS or CMC layer employing a simple cross linking procedure to avoid any significant influence of these biopolymers on the morphology and crystal structure of the cores. Phase, morphology, magnetic hysteresis and surface chemistry were characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), vibrating sample magnetometer (VSM) and Fourier transform infrared (FTIR) spectroscopy. The preliminary haemolysis and cell viability experiments show that biopolymers conjugation mitigates the haemolytic effect of the NFs on erythrocytes as the haemolytic index is less than 2% and cell viability is up to 100%, when normalized with the nontreated cells. The relaxivity value of coated NFs is 351±2.6 when compared to 84±0.22 of NFs without biopolymer conjugation. The results demonstrate that BSA, CS or CMC covering on NFs provide a single combinatorial approach to improve the biocompatibility and enhance the relaxivity value. Thus addressing the current challenge of the same with very good contrast for targeting MCF-7 without any further vectorization. - Highlights: • A single combinatorial system for the promising application of biopolymers coated NiFe{sub 2}O{sub 4} cores. • Immobilization of a thin layer of three different biopolymers via a simple approach. • Excellent MR contrast enhancement and targeting of MCF-7 without any further vectorization.

  4. Direct characterization of the superparamagnetic-ferromagnetic transition of single nano-islands

    Energy Technology Data Exchange (ETDEWEB)

    Rodary, Guillemin; Wedekind, Sebastian; Oka, Hirofumi; Sander, Dirk; Kirschner, Juergen [Max-Planck-Institut fuer Mikrostrukturphysik, Halle (Germany)

    2009-07-01

    The transition from a superparamagnetic to a ferromagnetic state is studied on single Co nano-islands by spin-polarized scanning tunneling spectroscopy. Magnetic hysteresis loops of the local differential conductance on individual island are measured as a function of the size of the nanostructure and of the temperature. A clear transition of magnetic response from a hysteresis free to a hysteretic behavior due to magnetization direction switching is observed when increasing the island size. This is ascribed to the superparamagnetic to ferromagnetic transition. The same transition is demonstrated to be also accessible by decreasing the temperature and crossing the blocking temperature. We find a blocking temperature of 10 K for an island of 1010 atoms. We discuss these experimental results in the perspective of a simple model of thermally activated magnetization switching that allows quantitative finding of local magnetic anisotropy.

  5. Nano copper ferrite: A reusable catalyst for the synthesis of , -unsaturated ketones

    Indian Academy of Sciences (India)

    Y L N Murthy; B S Diwakar; B Govindh; K Nagalakshmi; I V Kasi Viswanath; Rajendra Singh

    2012-05-01

    Copper ferrite nano material as reusable heterogeneous initiator in the synthesis of , -unsaturated ketones and allylation to acid chlorides are presented. The reaction of allylichalides with various acid chlorides is achieved in the presence of copper ferrite nano powders at room temperature in tetrahydrofuran (THF). The present method is first of its kind in the synthesis of title compounds without any additive/co-catalyst. The nano catalyst is easily recovered and its reusability is recorded.

  6. Ferroelectric and photocatalytic behavior of bismuth ferrite nano wire

    Energy Technology Data Exchange (ETDEWEB)

    William, R. V.; Marikani, A., E-mail: amari@mepcoeng.ac.in [Department of Physics, Mepco Schlenk Engineering College, Sivakasi – 626 005, Tamil Nadu (India); Madhavan, D. [Department of Chemistry, Mepco Schlenk Engineering College, Sivakasi – 626 005, Tamil Nadu (India)

    2016-05-23

    Multiferroic bismuth ferrite nanowires are prepared through polyol method with an average diameter of 35 nm with a narrow size distribution. The band gap was determined to be 2.10 eV, indicating their potential application as visible-light-response photo catalyst. The magnificent photocatalytic behaviors of BiFeO{sub 3} nanowires are understood from the methyl violet degradation under visible light irradiation. Moreover, the nano-wire takes only a lesser time for the diffusion of electron-hole pair from the surface of the sample. Further the BiFeO{sub 3} nano-wire was characterized using XRD, SEM, and U-V. The ferroelectric studies of BiFeO{sub 3} nano-wire show a frequency dependent property and maximum coercivity of 2.7 V/cm were achieved with a remanent polarization at 0.5 µC/cm{sup 2} at the frequency 4 kHz. The coercivity of BiFeO{sub 3} nano wire changes with variation of frequency from 1 kHz to 4 kHz.

  7. A comparison study of polymer/cobalt ferrite nano-composites synthesized by mechanical alloying route

    Directory of Open Access Journals (Sweden)

    Sedigheh Rashidi

    2015-12-01

    Full Text Available In this research, the effect of different biopolymers such as polyethylene glycol (PEG and polyvinylalcohol (PVA on synthesis and characterization of polymer/cobalt ferrite (CF nano-composites bymechanical alloying method has been systematically investigated. The structural, morphological andmagnetic properties changes during mechanical milling were investigated by X-ray diffraction (XRD,Fourier transform infrared spectroscopy (FTIR, transmission electron microscopy (TEM, fieldemission scanning electron microscopy (FESEM, and vibrating sample magnetometer techniques(VSM, respectively. The polymeric cobalt ferrite nano-composites were obtained by employing atwo-step procedure: the cobalt ferrite of 20 nm mean particle size was first synthesized by mechanicalalloying route and then was embedded in PEG or PVA biopolymer matrix by milling process. Theresults revealed that PEG melted due to the local temperature raise during milling. Despite thisphenomenon, cobalt ferrite nano-particles were entirely embedded in PEG matrix. It seems, PAV is anappropriate candidate for producing nano-composite samples due to its high melting point. InPVA/CF nano-composites, the mean crystallite size and milling induced strain decreased to 13 nm and0.48, respectively. Moreover, milling process resulted in well distribution of CF in PVA matrix eventhough the mean particle size of cobalt ferrite has not been significantly affecetd. FTIR resultconfirmed the attachment of PVA to the surface of nano-particles. Magnetic properties evaluationshowed that saturation magnetization and coercivity values decreased in nano-composite samplecomparing the pure cobalt ferrite.

  8. Enhanced nonlinear optical absorption and optical limiting properties of superparamagnetic spinel zinc ferrite decorated reduced graphene oxide nanostructures

    Science.gov (United States)

    Saravanan, M.; T. C., Sabari Girisun

    2017-01-01

    Nonlinear absorption and optical limiting properties of ZnFe2O4-rGO magnetic nanostructures was investigated by the Z-scan technique using Q-switched Nd:YAG laser (5 ns, 532 nm, 10 Hz) as an excitation source. Excited state absorption was the dominant process responsible for the observed nonlinearity in ZnFe2O4 decorated rGO which arises due to photo-generated charge carriers in the conduction band of zinc ferrite and increases in defects at the surface of rGO due to the incorporation of ZnFe2O4. The magnitude of the nonlinear absorption co-efficient was found to be in the order of 10-10 m/W. A noteworthy enhancement in the third-order NLO properties in ZnFe2O4-(15 wt%) rGO with those of individual counter parts and well known graphene composites was reported. Role of induced defects states (sp3) arising from the functionalization of rGO in the enhancement of NLO response was explained through Raman studies. Earlier incorporation and distribution of ZnFe2O4 upon GO through one-step hydrothermal method was analyzed by XRD and FTIR. Formation of (nanospheres/nanospindles) ZnFe2O4 along with reduction of graphene oxide was confirmed through TEM analysis. VSM studies showed zinc ferrite decorated rGO posseses superparamagnetic behavior. The tuning of nonlinear optical and magnetic behavior with variation in the content of spinel ferrites upon reduced graphene oxide provides an easy way to attain tunable properties which are exceedingly required in both optoelectronics and photothermal therapy applications.

  9. Nano-ferrites for water splitting: Unprecedented high photocatalytic hydrogen production under visible light

    KAUST Repository

    Mangrulkar, Priti A.

    2012-01-01

    In the present investigation, hydrogen production via water splitting by nano-ferrites was studied using ethanol as the sacrificial donor and Pt as co-catalyst. Nano-ferrite is emerging as a promising photocatalyst with a hydrogen evolution rate of 8.275 μmol h -1 and a hydrogen yield of 8275 μmol h -1 g -1 under visible light compared to 0.0046 μmol h -1 for commercial iron oxide (tested under similar experimental conditions). Nano-ferrites were tested in three different photoreactor configurations. The rate of hydrogen evolution by nano-ferrite was significantly influenced by the photoreactor configuration. Altering the reactor configuration led to sevenfold (59.55 μmol h -1) increase in the hydrogen evolution rate. Nano-ferrites have shown remarkable stability in hydrogen production up to 30 h and the cumulative hydrogen evolution rate was observed to be 98.79 μmol h -1. The hydrogen yield was seen to be influenced by several factors like photocatalyst dose, illumination intensity, irradiation time, sacrificial donor and presence of co-catalyst. These were then investigated in detail. It was evident from the experimental data that nano-ferrites under optimized reaction conditions and photoreactor configuration could lead to remarkable hydrogen evolution activity under visible light. Temperature had a significant role in enhancing the hydrogen yield. © 2012 The Royal Society of Chemistry.

  10. Preparation of Dy-ferrite Ferrofluids and Magnetochemical Studies on the Superparamagnetism

    Institute of Scientific and Technical Information of China (English)

    HU,Xian-Luo(胡先罗); XU,Chao(徐超); SHEN,Qin(沈骎); CHEN,Yi-Wei(陈奕卫); ZHAO,Hong(赵泓); ZHU,Chuan-Zheng(朱传征)

    2001-01-01

    This paper reports unprecedented preparation of Dy-ferrite water-based ferrofiuids stabilized by polymeric surfactant PMAA. The stability of ferrofluids was characterized in terms of the equation of criterion for the stability of ferrofluids. Magnetic susceptibility was measured with a Faraday-type magnetic balance at different temperature and with different magnetic field intensity. According to the Langevin function,superparamagtism of Dy-ferrite ferrofiuids has been confirmed by the curves of saturation magnetization σ versus H/T, and the blocking temperature is between 160 and 200 K.In terms of the simplified Langevin function in the low magnefic field, the average particle size is 20 nm that coincides with the result evaluated by FHMW. In addition, chemical analysis, infi-ared spect-a and Mosslauer spectroscopy were utilized to analyze the main components of the ferrofiuids.

  11. Dielectric behaviour of Zn substituted Cu nano-ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Parashar, Jyoti, E-mail: phyjyoti.2@gmail.com [Department of Physics, University of Rajasthan, Jaipur 302055 (India); Saxena, V.K.; Jyoti; Bhatnagar, Deepak [Department of Physics, University of Rajasthan, Jaipur 302055 (India); Sharma, K.B. [Department of Physics, S.S. Jain Subodh P.G. College, Jaipur 302004 (India)

    2015-11-15

    Herein, the dielectric properties such as permittivity (real part ε′ and imaginary part ε′′) and dielectric loss tangent (tan δ) are reported for Zn substituted Cu ferrites (Cu{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4}; 0≤x≤1) composite using the sol–gel auto-combustion method. The variations of real and imaginary part of dielectric constant, tan δ and AC conductivity (σ{sub ac}) are studied at room temperature in the frequency range of 100 Hz–120 MHz. The real part of dielectric constant decrease with increasing frequency and the imaginary part (ε′′) varies with frequency showing the characteristic peak for each sample. The relation of tan δ with frequency shows relaxation spectra. Further, the σ{sub ac} tended to increase with increase in frequency. The variation in dielectric constant may be explained on the basis of space charge polarization, according to Maxwell and Wagner two-layer model. The dielectric constant and tan δ as a function of temperature are also studied with different temperatures ranging from 323 K to 583 K. - Highlights: • Zn substituted Cu nano-ferrite samples bearing formula Cu{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4}(0≤x≤1) are synthesized by the sol–gel auto combustion method. • The variation of real and imaginary parts of dielectric constant, dielectric loss tangent (tan δ) and AC conductivity with frequency are reported in the frequency range from 100 Hz to 120 MHz at room temperature. • The real part of dielectric constant (ε′) decreases with increasing frequency where as the AC conductivity (σ{sub ac}) increases with increase in frequency. The relation of tan δ with frequency shows relaxation spectra. • The variation in dielectric constant may be explained on the basis of space charge polarization, according to Maxwell and Wagner two-layer model. • Dielectric constant as a function of temperature is studied at different temperatures ranging from 323 K to 583 K.

  12. Room temperature magnetism in zinc nano ferrite synthesized by a novel oxalate-ceramic method

    Energy Technology Data Exchange (ETDEWEB)

    Bhatt, Kapil K., E-mail: getdrkapil@yahoo.com [Department of Physics, Wilson College, Chowpatty, Mumbai 400 007 (India); Department of Physics and National Centre for Nanosciences and Nanotechnology, University of Mumbai, Santacruz (E), Mumbai 400 098 (India); Niwate, Yogesh S.; Garje, Shivram S. [Department of Chemistry, University of Mumbai, Santacruz (E), Mumbai 400 098 (India); Kothari, D.C. [Department of Physics and National Centre for Nanosciences and Nanotechnology, University of Mumbai, Santacruz (E), Mumbai 400 098 (India)

    2015-07-01

    Zinc nano-ferrite has been synthesized using a novel oxalate-ceramic method and its magnetic properties are reported in this paper. The hysteresis loop recorded at 300 K exhibits ferrimagnetic behavior. The Neel temperature was found to be 557 K. The AC susceptibility curve also indicates ferrimagnetic behavior. The temperature dependent magnetization curves, obtained in the temperature range of 4–300 K, show spin glass behavior. Using this method of synthesis large quantity of ferrite can be synthesized therefore this method can become useful technique for industrial scale production. - Highlights: • Oxalate-ceramic method is a novel technique to synthesize spinel ferrites. • Zinc ferrite synthesized by this technique are in nanocrystalline form with average crystallite size of 32 nm. • Neel temperature of zinc ferrite is found to be 557 K. • Different magnetic behavior in different temperature regime.

  13. Microstructure and Superparamagnetic Properties of Mg-Ni-Cd Ferrites Nanoparticles

    Directory of Open Access Journals (Sweden)

    M. M. Eltabey

    2014-01-01

    Full Text Available Magnesium substituted nickel cadmium ferrite nanoparticles MgxNi0.6−xCd0.4Fe2O4 (from x = 0 to 0.6 with step 0.1 have been synthesized by the chemical coprecipitation route. X-ray diffraction (XRD and infrared spectroscopy (FTIR revealed that the obtained powders have a single phase of cubic spinel structure. The crystallite sizes calculated from XRD data have been confirmed using transmission electron microscopy (TEM showing that the powders are consisting of nanosized grains with an average size range 5–1.5 nm. Magnetic hysteresis loops were traced at 6.5 K as well as at room temperature using VSM. It was found that, due to the Mg2+-ions substitution, the values of saturation magnetization Ms for the investigated samples were decreased, whereas the coercive field Hc increased. Both zero field cooling (ZFC and field cooling (FC curves are measured in the temperature range (6.5–350 K and the values of blocking temperature TB were determined. No considerable variation in the values of TB was observed with increasing Mg-content, whereas the values of the effective anisotropy constant Keff were increased.

  14. Magnetic separation of encapsulated islet cells labeled with superparamagnetic iron oxide nano particles.

    Science.gov (United States)

    Mettler, Esther; Trenkler, Anja; Feilen, Peter J; Wiegand, Frederik; Fottner, Christian; Ehrhart, Friederike; Zimmermann, Heiko; Hwang, Yong Hwa; Lee, Dong Yun; Fischer, Stefan; Schreiber, Laura M; Weber, Matthias M

    2013-01-01

    Islet cell transplantation is a promising option for the restoration of normal glucose homeostasis in patients with type 1 diabetes. Because graft volume is a crucial issue in islet transplantations for patients with diabetes, we evaluated a new method for increasing functional tissue yield in xenogeneic grafts of encapsulated islets. Islets were labeled with three different superparamagnetic iron oxide nano particles (SPIONs; dextran-coated SPION, siloxane-coated SPION, and heparin-coated SPION). Magnetic separation was performed to separate encapsulated islets from the empty capsules, and cell viability and function were tested. Islets labeled with 1000 μg Fe/ml dextran-coated SPIONs experienced a 69.9% reduction in graft volume, with a 33.2% loss of islet-containing capsules. Islets labeled with 100 μg Fe/ml heparin-coated SPIONs showed a 46.4% reduction in graft volume, with a 4.5% loss of capsules containing islets. No purification could be achieved using siloxane-coated SPIONs due to its toxicity to the primary islets. SPION labeling of islets is useful for transplant purification during islet separation as well as in vivo imaging after transplantation. Furthermore, purification of encapsulated islets can also reduce the volume of the encapsulated islets without impairing their function by removing empty capsules.

  15. Boron effects on the ductility of a nano-cluster-strengthened ferritic steel

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Z.W. [Engineering Research Center of Materials Behavior and Design, Ministry of Education, Nanjing University of Science and Technology, Nanjing 210094 (China); Materials Research and Education Center, Auburn University, 275 Wilmore Labs, Auburn, AL 36849 (United States); Liu, C.T., E-mail: mmct8tc@inet.polyu.edu.hk [Materials Research and Education Center, Auburn University, 275 Wilmore Labs, Auburn, AL 36849 (United States); Department of Mechanical Engineering, the Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Guo, S. [Department of Mechanical Engineering, the Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Cheng, J.L.; Chen, G. [Engineering Research Center of Materials Behavior and Design, Ministry of Education, Nanjing University of Science and Technology, Nanjing 210094 (China); Fujita, Takeshi; Chen, M.W. [Institute for Materials Research, and World Premier International Research Center for Atoms, Molecules and Materials, Tohoku University, Sendai 980-8577 (Japan); Chung, Yip-Wah; Vaynman, Semyon; Fine, Morris E. [Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208-3108 (United States); Chin, Bryan A. [Materials Research and Education Center, Auburn University, 275 Wilmore Labs, Auburn, AL 36849 (United States)

    2011-01-25

    Research highlights: {yields} Cu-rich nano-particle precipitation strengthens the ferritic steels. {yields} Boron doping suppresses brittle intergranular fracture. {yields} Moisture-induced environmental embrittlement can be alleviated by surface coating. - Abstract: The mechanical properties of Cu-rich nano-cluster-strengthened ferritic steels with and without boron doping were investigated. Tensile tests at room temperature in air showed that the B-doped ferritic steel has similar yield strength but a larger elongation than that without boron doping after extended aging at 500 deg. C. There are three mechanisms affecting the ductility and fracture of these steels: brittle cleavage fracture, week grain boundaries, and moisture-induced hydrogen embrittlement. Our study reveals that boron strengthens the grain boundary and suppresses the intergranular fracture. Furthermore, the moisture-induced embrittlement can be alleviated by surface coating with vacuum oil.

  16. NanoFerrite particle based radioimmunonanoparticles: binding affinity and in vivo pharmacokinetics.

    Science.gov (United States)

    Natarajan, A; Gruettner, C; Ivkov, R; DeNardo, G L; Mirick, G; Yuan, A; Foreman, A; DeNardo, S J

    2008-06-01

    Dextran and PEG-coated iron oxide nanoparticles (NP), when suitably modified to enable conjugation with molecular targeting agents, provide opportunities to target cancer cells. Monoclonal antibodies, scFv, and peptides conjugated to 20 nm NP have been reported to target cancer for imaging and alternating magnetic field (AMF) therapy. The physical characteristics of NPs can affect their in vivo performance. Surface morphology, surface charge density, and particle size are considered important factors that determine pharmacokinetics, toxicity, and biodistribution. New NanoFerrite (NF) particles having improved specific AMF absorption rates and diameters of 30 and 100 nm were studied to evaluate the variation in their in vitro and in vivo characteristics in comparison to the previously studied 20 nm superparamagnetic iron oxide (SPIO) NP. SPIO NP 20 nm and NF NP 30 and 100 nm were conjugated to (111)In-DOTA-ChL6, a radioimmunoconjugate. Radioimmunoconjugates were conjugated to NPs using 25 microg of RIC/mg of NP by carbodiimide chemistry. The radioimmunonanoparticles (RINP) were purified and characterized by PAGE, cellulose acetate electrophoresis (CAE), live cell binding assays, and pharmacokinetics in athymic mice bearing human breast cancer (HBT 3477) xenografts. RINP (2.2 mg) were injected iv and whole body; blood and tissue data were collected at 4, 24, and 48 h. The preparations used for animal study were >90% monomeric by PAGE and CAE. The immunoreactivity of the RINP was 40-60% compared to (111)In-ChL6. Specific activities of the doses were 20-25 microCi/2.2 mg and 6-11 microg of mAb/2.2 mg of NP. Mean tumor uptakes (% ID/g +/- SD) of each SPIO 20 nm, NF 30 nm, and 100 nm RINP at 48 h were 9.00 +/- 0.8 (20 nm), 3.0 +/- 0.3 (30 nm), and 4.5 +/- 0.8 (100 nm), respectively; the ranges of tissue uptakes were liver (16-32 +/- 1-8), kidney (7.0-15 +/- 1), spleen (8-17 +/- 3-8), lymph nodes 5-6 +/- 1-2), and lung (2.0-4 +/- 0.1-2). In conclusion, this study

  17. Room temperature ferromagnetic ordering in indium substituted nano-nickel-zinc ferrite

    Science.gov (United States)

    Thakur, Sangeeta; Katyal, S. C.; Gupta, A.; Reddy, V. R.; Singh, M.

    2009-04-01

    Nano-nickel-zinc-indium ferrite (NZIFO)(Ni0.58Zn0.42InxFe2-xO4) with varied quantities of indium (x =0,0.1,0.2) have been synthesized via reverse micelle technique. X-ray diffraction and transmission electron microscopy confirmed the size, structure, and morphology of the nanoferrites. The addition of indium in nickel-zinc ferrite (NZFO) has been shown to play a crucial role in enhancing the magnetic properties. Room temperature Mössbauer spectra revealed that the nano-NZFO ferrite exhibit collective magnetic excitations, while indium doped NZFO samples have the ferromagnetic phase. The dependence of Mössbauer parameters, viz. isomer shift, quadrupole splitting, linewidth, and hyperfine magnetic field, on In3+ concentration has been studied. Mössbauer study on these nanosystems shows that the cation distribution not only depends on the particle size but also on the preparation route. Mössbauer results are also supported by magnetization data. Well defined sextets and appearance of hysteresis at room temperature indicate the existence of ferromagnetic couplings which makes nano-NZIFO ferrite suitable for magnetic storage data.

  18. Sol-Gel Synthesis and Characterization of Selected Transition Metal Nano-Ferrites

    Directory of Open Access Journals (Sweden)

    Aurelija GATELYTĖ

    2011-09-01

    Full Text Available In the present work, the sinterability and formation of nanosized yttrium iron garnet (Y3Fe5O12, yttrium perovskite ferrite (YFeO3, cobalt, nickel and zinc iron spinel (CoFe2O4, NiFe2O4 and ZnFe2O4, respectively powders by an aqueous sol-gel processes are investigated. The metal ions, generated by dissolving starting materials of transition metals in the diluted acetic acid were complexed by 1,2-ethanediol to obtain the precursors for the transition metal ferrite ceramics. The phase purity of synthesized nano-compounds was characterized by infrared spectroscopy (IR and powder X-ray diffraction analysis (XRD. The microstructural evolution and morphological features of obtained transition metal ferrites were studied by scanning electron microscopy (SEM.http://dx.doi.org/10.5755/j01.ms.17.3.598

  19. Study of magnesium ferrite nano particles with excess iron content

    Energy Technology Data Exchange (ETDEWEB)

    Sumangala, T.P., E-mail: sumampoornima@gmail.com [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Mahender, C. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Sahu, B.N. [Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Venkataramani, N. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Prasad, Shiva [Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India)

    2014-09-01

    Stoichiometric and non stoichiometric magnesium ferrite (MgFe{sub 2+δ}O{sub 4}, δ=0.0, 0.1) were synthesized by the sol gel combustion method resulting in nanocrystalline powders with size ranging from 10 to 100 nm. These powders were calcined at various temperatures (300–800 °C). One part of the calcined powder was quenched in liquid nitrogen and the other part furnace cooled. α-Fe{sub 2}O{sub 3} was observed in all calcined samples by XRD and this was also reflected in the magnetization data. Electrical response of MgFe{sub 2.1}O{sub 4+δ} spinel phase to 75 ppm ethanol was found to be greater than that for a stoichiometric magnesium ferrite.

  20. Development of new ferritic alloys reinforced by nano titanium nitrides

    Energy Technology Data Exchange (ETDEWEB)

    Mathon, M.H., E-mail: marie-helene.mathon@cea.fr [Laboratoire Léon Brillouin, CEA-CNRS, CEA/Saclay, 91191 Gif-sur-Yvette (France); Perrut, M., E-mail: mikael.perrut@onera.fr [Laboratoire Léon Brillouin, CEA-CNRS, CEA/Saclay, 91191 Gif-sur-Yvette (France); Poirier, L., E-mail: poirier@nitruvid.com [Bodycote France and Belgium, 9 r Jean Poulmarch, 95100 Argenteuil (France); Ratti, M., E-mail: mathieu.ratti@snecma.fr [CEA, DEN, Service de Recherches Métallurgiques Appliquées, F91191 Gif-sur-Yvette (France); Hervé, N., E-mail: nicolas.herve@cea.fr [CEA, DRT, LITEN, F38054 Grenoble (France); Carlan, Y. de, E-mail: yann.decarlan@cea.fr [CEA, DEN, Service de Recherches Métallurgiques Appliquées, F91191 Gif-sur-Yvette (France)

    2015-01-15

    Nano-reinforced steels are considered for future nuclear reactors or for application at high temperature like the heat exchangers tubes or plates. Oxide Dispersion Strengthened (ODS) alloys are the most known of the nano-reinforced alloys. They exhibit high creep strength as well as high resistance to radiation damage. This article deals with the development of new nano reinforced alloys called Nitride Dispersed Strengthened (NDS). Those are also considered for nuclear applications and could exhibit higher ductility with a simplest fabrication way. Two main fabrication routes were studied: the co-milling of Fe–18Cr1W0.008N and TiH{sub 2} powders and the plasma nitration at low temperature of a Fe–18Cr1W0.8Ti powder. The materials were studied mainly by Small Angle Neutron Scattering. The feasibility of the reinforcement by nano-nitride particles is demonstrated. The final size of the nitrides can be similar (few nanometers) to the nano-oxides observed in ODS alloys. The mechanical properties of the new NDS show an amazing ductility at high temperature for a nano-reinforced alloy.

  1. Efficient gas sensitivity in mixed bismuth ferrite micro (cubes) and nano (plates) structures

    Energy Technology Data Exchange (ETDEWEB)

    Waghmare, Shivaji D.; Jadhav, Vijaykumar V.; Gore, Shaym K. [Center for Nanomaterials and Energy Devices, School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, Maharashtra (India); Yoon, Seog-Joon; Ambade, Swapnil B. [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Seoul 133-1791 (Korea, Republic of); Lokhande, B.J. [Department of Physics, Solapur University, Solapur (India); Mane, Rajaram S., E-mail: rsmane_2000@yahoo.com [Center for Nanomaterials and Energy Devices, School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, Maharashtra (India); Han, Sung-Hwan, E-mail: shhan@hanyang.ac.kr [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Seoul 133-1791 (Korea, Republic of)

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► Micro (cubes) structure embedded in nano (plates) of bismuth ferrite was prepared by a chemical method. ► These structures were characterized by XRD and SEM. ► LPG, CO{sub 2} and NH{sub 4} gases were exposed. ► Properties related to gas sensors were measured and reported. -- Abstract: Mixed micro (cubes) and nano (plates) structures of bismuth ferrite (BFO) have been synthesized by a simple and cost-effective wet-chemical method. Structural, morphological and phase confirmation characteristics are measured using X-ray diffraction, field-emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis techniques. The digital FE-SEM photo-images of BFO sample confirmed an incubation of discrete micro-cubes into thin and regularly placed large number of nano-plates. The bismuth ferrite, with mixed structures, films show considerable performance when used in liquefied petroleum (LPG), carbon dioxide (CO{sub 2}) and ammonium (NH{sub 3}) gas sensors application. Different chemical entities in LPG have made it more efficient with higher sensitivity, recovery and response times compared to CO{sub 2} and NH{sub 3} gases. Furthermore, effect of palladium surface treatment on the gas sensitivity and the charge transfer resistances of BFO mixed structures is investigated and reported.

  2. Superparamagnetic behavior of heat treated Mg0.5Zn0.5Fe2O4 ferrite nanoparticles studied by Mössbauer spectroscopy

    Science.gov (United States)

    Srinivas, Ch.; Singh, S. B.; Tirupanyam, B. V.; Meena, S. S.; Yusuf, S. M.; Prasad, S. A. V.; Krishna, K. S. Rama; Sastry, D. L.

    2016-05-01

    Nanoparticles of Mg0.5Zn0.5Fe2O4 ferrite have been synthesized by co-precipitation method. XRD and Mössbauer spectroscopic results of Mg0.5Zn0.5Fe2O4 annealed at 200 °C, 500 °C and 800 °C are reported. It was observed that the crystallite size increases and the lattice parameter decreases with increase in annealing temperature. The observed decrease in lattice strain supports the increase in crystallite size. The Mössbauer spectra of the samples annealed at 200 °C and 500 °C exhibits superparamagnetic doublets whereas the Mössbauer spectrum of the sample annealed at 800 °C exhibits paramagnetic doublet along with weak sextet of hyperfine interaction. The values of isomer shift resemble the presence of high spin iron ions. The studied ferrite nanoparticles are suitable for biomedical applications. The results are incorporated employing core-shell model and cation redistribution.

  3. Structural, magnetic and dielectric studies of copper substituted nano-crystalline spinel magnesium zinc ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Zaki, H.M., E-mail: dakdik2001@yahoo.com [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); Department of Physics, Faculty of Science, Zagazig University, Zagazig (Egypt); Al-Heniti, S.H. [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); Elmosalami, T.A. [Department of Physics, Faculty of Science, Zagazig University, Zagazig (Egypt)

    2015-06-05

    Highlights: • Nano ferrite Mg{sub 0.5}Zn{sub 0.5−x}Cu{sub x}Fe{sub 2}O{sub 4} were prepared through co-precipitation route. • Structural investigations of XRD and FTIR revealed formation of spinel structure. • Lattice constant decrease while saturation magnetization increase. • Correlated barrier-hopping (CBH) is the dominant conduction mechanism. • Dielectric properties make sample appropriate for multilayer inductor applications. - Abstract: Nano-crystalline Mg{sub 0.5}Zn{sub 0.5−x}Cu{sub x}Fe{sub 2}O{sub 4} (x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) ferrite powders were synthesized using co-precipitation method. The influence of Cu{sup 2+} ions substitution on the structural and magnetic properties was investigated. X-ray diffraction measurements revealed the formation of nano-crystalline ferrite with single cubic spinel phase. The lattice constant was found to decrease with increasing Cu{sup 2+} ions content. Infrared spectral analysis confirmed formation of the spinel structure for the respective ferrite system. Magnetic data showed that the saturation magnetization (M{sub s}) increases with Cu{sup 2+} concentration up to x = 0.2 and then decreases with further increase of Cu{sup 2+} ions in this ferrite system. The proposed cation distribution deduced from X-ray diffraction, infrared spectra and magnetization data indicated mixed ferrite type. Dielectric constants ε′, dielectric loss ε′′, dielectric loss tangent tan δ and ac conductivity, σ{sub ac}, were investigated as a function of frequency and temperature. Influence of Cu{sup 2+} substation on the ac conductivity exhibited significant behavior at low frequencies and low temperatures, T ⩽ 100 °C. Both dielectric constants (ε′, ε″) found to increase with the increase of the temperature. At low temperatures, dielectric loss tan δ indicated a decrease with frequency with slight change at high temperatures.

  4. Structural and magnetic properties of nano nickel-zinc ferrite synthesized by reverse micelle technique

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Sangeeta [Jaypee University of Information Technology, Waknaghat, District Solan 173215 (India)], E-mail: megha2k5@rediffmail.com; Katyal, S.C. [Jaypee University of Information Technology, Waknaghat, District Solan 173215 (India); Singh, M. [Department of Physics, Himachal Pradesh University, Shimla 171005 (India)

    2009-01-15

    Nanocrystalline nickel-zinc ferrites (Ni{sub 0.58}Zn{sub 0.42}Fe{sub 2}O{sub 4}) at different pH values (less than 9.6, 9.6, 10.96, and 11.40) for the alkali-precipitating reaction were synthesized by reverse micelle technique. X-ray diffraction reveals a well-defined nickel-zinc ferrite crystal phase at pH=9.6. Increase in pH value obstructs pure-phase formation and results in partial formation of {alpha}-Fe{sub 2}O{sub 3}. The magnetic behaviour of the samples was studied by superconducting quantum interference device. All the samples show superparamagnetic behaviour at room temperature (300 K) and negligible hysteresis at low temperature (5 K). The low value of saturation magnetization is explained on the basis of spin canting. The high-field irreversibility and shifting of the hysteresis loop detected in single-phase sample has been assigned to a spin-disordered phase, which has a spin-freezing temperature of approximately 42 K and other two samples have an antiferromagnetic phase ({alpha}-Fe{sub 2}O{sub 3}) coupled to the ferromagnetic phase.

  5. Structural and magnetic properties of nano nickel zinc ferrite synthesized by reverse micelle technique

    Science.gov (United States)

    Thakur, Sangeeta; Katyal, S. C.; Singh, M.

    2009-01-01

    Nanocrystalline nickel-zinc ferrites (Ni 0.58Zn 0.42Fe 2O 4) at different pH values (less than 9.6, 9.6, 10.96, and 11.40) for the alkali-precipitating reaction were synthesized by reverse micelle technique. X-ray diffraction reveals a well-defined nickel-zinc ferrite crystal phase at pH=9.6. Increase in pH value obstructs pure-phase formation and results in partial formation of α-Fe 2O 3. The magnetic behaviour of the samples was studied by superconducting quantum interference device. All the samples show superparamagnetic behaviour at room temperature (300 K) and negligible hysteresis at low temperature (5 K). The low value of saturation magnetization is explained on the basis of spin canting. The high-field irreversibility and shifting of the hysteresis loop detected in single-phase sample has been assigned to a spin-disordered phase, which has a spin-freezing temperature of approximately 42 K and other two samples have an antiferromagnetic phase (α-Fe 2O 3) coupled to the ferromagnetic phase.

  6. Preparation and magnetic properties of nano size nickel ferrite particles using hydrothermal method

    Directory of Open Access Journals (Sweden)

    Nejati Kamellia

    2012-03-01

    Full Text Available Abstract Background Nickel ferrite, a kind of soft magnetic materials is one of the most attracting class of materials due to its interesting and important properties and has many technical applications, such as in catalysis, sensors and so on. In this paper the synthesis of NiFe2O4 nanoparticles by the hydrothermal method is reported and the inhibition of surfactant (Glycerol or Sodium dodecyl sulfate on the particles growth is investigated. Methods For investigation of the inhibition effect of surfactant on NiFe2O4 particles growth, the samples were prepared in presence of Glycerol and Sodium dodecyl sulfate. The X-ray powder diffraction (XRD, transmission electron microscopy (TEM, Fourier transform infrared spectroscopy (FT-IR, vibrating sample magnetometer (VSM and inductively coupled plasma atomic emission spectrometer (ICP-AES techniques were used to characterize the samples. Results The results of XRD and ICP-AES show that the products were pure NiFe2O4 and also nanoparticles grow with increasing the temperature, while surfactant prevents the particle growth under the same condition. The average particle size was determined from the Scherrer's equation and TEM micrographs and found to be in the range of 50-60 nm that decreased up to 10-15 nm in presence of surfactant. The FT-IR results show two absorption bands near to 603 and 490 cm-1 for the tetrahedral and octahedral sites respectively. Furthermore, the saturated magnetization and coercivity of NiFe2O4 nanoparticles were in the range of 39.60 emu/g and 15.67 Qe that decreased for samples prepared in presence of surfactant. As well as, the nanoparticles exhibited a superparamagnetic behavior at room temperature. Conclusions Nanosized nickel ferrite particles were synthesized with and without surfactant assisted hydrothermal methods. The results show that with increasing of temperature, the crystallinity of nanoparticles is increased. In the presence of surfactants, the crystallinity of

  7. Structure dependent electrical properties of Ni-Mg-Cu nano ferrites

    Science.gov (United States)

    Choudhari, Nagabhushan J.; Kakati, Sushanth S.; Hiremath, Chidanandayya S.; Pujar, Rangappa B.

    2016-05-01

    Nano ferrites with the general chemical formula Ni0.5MgxCu1-x Fe2O4 were synthesized by chemical route. They were characterized by x-ray diffraction by powder method. The diffraction patterns confirm the formation of single phase ferrites. The particle size is calculated by Scherrer formula which varies between 20nm to 60nm. DC resistivity was measured as a function of composition from room temperature to 700o C by two probe method. These ferrites show higher resistivity than those synthesized by ceramic method, due to control over composition and morphology. This leads to the elimination of domain wall resonance so that the materials can work at higher frequencies. AC resistivity was measured as a function of frequency at room temperature. Dielectric dispersion obeys Maxwell - Wagner model, in accordance with Koop's phenomenological theory. The variation of loss angle follows the variation of ac resistivity with frequency and composition. The change in ac conductivity with frequency obeys the power law σa = B.ωn. Such a behavior suggests that conductivity is due to polarons in all the samples.

  8. Synthesis, structural, dielectric and magnetic properties of polyol assisted copper ferrite nano particles

    Science.gov (United States)

    Pavithradevi, S.; Suriyanarayanan, N.; Boobalan, T.

    2017-03-01

    Nanocrystalline copper ferrite CuFe2O4 is synthesized by co-precipitation method in ethylene glycol as chelating agent, using sodium Hydroxide as precipitator at pH 8. The as synthesized CuFe2O4 is annealed at temperatures of 350 °C, 700 °C, and 1050 °C for 2 h respectively. The thermal analysis of the synthesized sample is done by TG technique. It is shown that at 260 °C ethylene glycol has evaporated completely and after 715 °C, spinel ferrite is formed with a cubic structure. The calculated lattice parameters are in agreement with the reported values. FTIR spectra of CuFe2O4 nano particles are as synthesized and annealed at 1050 °C and recorded between 400 cm-1 and 4000 cm-1. It shows that when the temperature increases ethylene glycol gradually evaporates. Finally, nano crystalline single phase spinel ferrite is obtained. X-ray diffraction (XRD) and electron diffraction (EDS) studies show that the sample is indexed as the face centered cubic spinel structure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that the particles are flaky and spherical with the crystallite size in the range of 25-34 nm. From the dielectric studies, the dielectric constant decreases as the frequency increases. Low value of dielectric loss at higher frequencies suggests that the material is suitable for high frequency applications. AC conductivity increases with frequency. The magnetic properties of the samples are measured using a vibrating sample magnetometer (VSM) at room temperature, which shows that the sample exhibited a typical super paramagnetic behavior at low temperature. The saturation magnetization, remanant magnetism, and coercivity increases with applied field.

  9. Structural, morphological, magnetic and dielectric characterization of nano-phased antimony doped manganese zinc ferrites

    Science.gov (United States)

    Sridhar, Ch. S. L. N.; Lakshmi, Ch. S.; Govindraj, G.; Bangarraju, S.; Satyanarayana, L.; Potukuchi, D. M.

    2016-05-01

    Nano-phased doped Mn-Zn ferrites, viz., Mn0.5-x/2Zn0.5-x/2SbXFe2O4 for x=0 to 0.3 (in steps of 0.05) prepared by hydrothermal method are characterized by X-ray diffraction, Infrared and scanning electron microscopy. XRD and SEM infer the growth of nano-crystalline cubic and hematite (α-Fe2O3) phase structures. IR reveals the ferrite phase abundance and metal ion replacement with dopant. Decreasing trend of lattice constant with dopant reflects the preferential replacement of Fe3+ions by Sb5+ion. Doping is found to cause for the decrease (i.e., 46-14 nm) of grain size. An overall trend of decreasing saturation magnetization is observed with doping. Low magnetization is attributed to the diamagnetic nature of dopant, abundance of hematite (α-Fe2O3) phase, non-stoichiometry and low temperature (800 °C) sintering conditions. Increasing Yafet-Kittel angle reflects surface spin canting to pronounce lower Ms. Lower coercivity is observed for x≤0.1, while a large Hc results for higher concentrations. High ac resistivity (~106 ohm-cm) and low dielectric loss factor (tan δ~10-2-10-3) are witnessed. Resistivity is explained on the base of a transformation in the Metal Cation-to-Oxide anion bond configuration and blockade of conductivity path. Retarded hopping (between adjacent B-sites) of carriers across the grain boundaries is addressed. Relatively higher resistivity and low dielectric loss in Sbdoped Mn-Zn ferrite systems pronounce their utility in high frequency applications.

  10. Structural, electrical and magnetic characteristics of nickel substituted cobalt ferrite nano particles, synthesized by self combustion method

    Energy Technology Data Exchange (ETDEWEB)

    Sontu, Uday Bhasker, E-mail: sontuudaybhasker@yahoo.co.in; Yelasani, Vijayakumar; Musugu, Venkata Ramana Reddy

    2015-01-15

    Nickel-substituted cobalt ferrite nano-particles are synthesized using a self-combustion method. Aqueous metal nitrates and citric acid form the precursors. No external oxidizing agents are used to change the pH of the precursors; this resulted in a more environment friendly synthesis. Structural, magnetic and electrical characteristics of the nano ferrites are verified using X-ray diffractometer (XRD), VSM and impedance analyzer respectively. Phase formation, particle size, lattice parameter, X-ray density, saturation magnetization, coercivity, dielectric constant and electrical activation energy as function of nickel substitution in cobalt ferrite are studied. It is shown here that the magnetic and electrical properties can be tuned by varying the nickel concentration. - Highlights: • Environmentally less polluting and simple, industrially scalable method of nano-ferrite synthesis. • Repeatability of the method is self-evident from consistent particle size. • Electrical and magnetic properties are tunable due to nickel substitution. • Nickel substitution increases dielectric constant value and also improves electrical resistivity. • Higher concentration of Ni introduces phase impurity into the cubic spinel ferrite.

  11. Structural, electrical and magnetic characteristics of nickel substituted cobalt ferrite nano particles, synthesized by self combustion method

    Science.gov (United States)

    Sontu, Uday Bhasker; Yelasani, Vijayakumar; Musugu, Venkata Ramana Reddy

    2015-01-01

    Nickel-substituted cobalt ferrite nano-particles are synthesized using a self-combustion method. Aqueous metal nitrates and citric acid form the precursors. No external oxidizing agents are used to change the pH of the precursors; this resulted in a more environment friendly synthesis. Structural, magnetic and electrical characteristics of the nano ferrites are verified using X-ray diffractometer (XRD), VSM and impedance analyzer respectively. Phase formation, particle size, lattice parameter, X-ray density, saturation magnetization, coercivity, dielectric constant and electrical activation energy as function of nickel substitution in cobalt ferrite are studied. It is shown here that the magnetic and electrical properties can be tuned by varying the nickel concentration.

  12. Improved electrical properties of cadmium substituted cobalt ferrites nano-particles for microwave application

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Rabia [Institute of Chemical Sciences, Gomal University, D. I. Khan (Pakistan); Hussain Gul, Iftikhar, E-mail: iftikhar.gul@scme.nust.edu.pk [Thermal Transport Laboratory (TTL), Materials Engineering Department, School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology - NUST, H-12 Campus, Islamabad (Pakistan); Zarrar, Muhammad [Thermal Transport Laboratory (TTL), Materials Engineering Department, School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology - NUST, H-12 Campus, Islamabad (Pakistan); Anwar, Humaira [Islamabad Model College for Girls G-10/2, Islamabad (Pakistan); Khan Niazi, Muhammad Bilal [Department of Chemicals Engineering, SCME, NUST, H-12 Campus, Islamabad (Pakistan); Khan, Azim [Institute of Chemical Sciences, Gomal University, D. I. Khan (Pakistan)

    2016-05-01

    Cadmium substituted cobalt ferrites with formula Cd{sub x}Co{sub 1−x}Fe{sub 2}O{sub 4} (x=0.0, 0.2, 0.35, 0.5), have been synthesized by wet chemical co-precipitation technique. Electrical, morphological and Structural properties of the samples have been studied using DC electrical resistivity and Impedance analyzer, Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD), respectively. XRD, SEM and AFM have been used to study the structural parameters such as measured density, lattice constant, X-ray density, crystallite size and morphology of the synthesized nano-particles. Debye–Scherrer formula has been used for the estimation of crystallite sizes. The estimated crystallite sizes were to be 15–19±2 nm. Hopping length of octahedral and tetrahedral sites have been calculated using indexed XRD data. The porosity and lattice constant increased as Cd{sup 2+}concentration increases. DC electrical resistivity was performed using two probe technique. The decrease of resistivity with temperature confirms the semiconducting nature of the samples. The dielectric properties variation has been studied at room temperature as a function of frequency. Variation of dielectric properties from 100 Hz to 5 MHz has been explained on the basis of Maxwell and Wagner’s model and hoping of electrons on octahedral sites. To separates the grains boundary and grains of the system Cd{sub x}Co{sub 1−x}Fe{sub 2}O{sub 4} the impedance analysis were performed. - Highlights: • Preparation of homogeneous, spherical and single phase well crystallized cobalt ferrites. • A simple and economical PEG assisted wet chemical co-precipitation method has been used. • Increased in DC electrical resistivity and activation energy. • Decease in dielectric constant used for microwave absorber. • AC conductivity of Cd{sup 2+} substituted Co-ferrites increases.

  13. Influence of fuel ratios on auto combustion synthesis of barium ferrite nano particles

    Indian Academy of Sciences (India)

    D Bahadur; S Rajakumar; Ankit Kumar

    2006-01-01

    Single-domain barium ferrite nano particles have been synthesized with narrow particle-size distribution using an auto combustion technique. In this process, citric acid was used as a fuel. Ratios of cation to fuel were maintained variously at 1 : 1, 1 : 2 and 1 : 3. The pH was 7 in all cases. Of all three cases, a cation to citric acid ratio of 1 : 2 gives better yield in the formation of crystalline and single domain particles with a narrow range of size distribution. Most particles are in the range of 80 to 100 nm. Maximum magnetization and coercivity values are also greater for 1 : 2 ratios. These values measured at room temperature are found to be 55 emu/gram and 5000 Oe respectively. XPS and ESR studies support the results.

  14. Microstructure Evolution in Nano-reinforced Ferritic Steel Processed By Mechanical Alloying and Spark Plasma Sintering

    Science.gov (United States)

    Boulnat, Xavier; Perez, Michel; Fabregue, Damien; Douillard, Thierry; Mathon, Marie-Hélène; de Carlan, Yann

    2013-11-01

    Oxide-dispersion strengthened ferritic steel was produced by high-energy attrition, leading to a complex nanostructure with deformed ferritic grains. After mechanical alloying, the powder was then consolidated by spark plasma sintering (SPS) using various thermo-mechanical treatments. Hot isostatic pressing (HIP) was also performed on the same powder for comparison. Above 1123 K (850 °C), SPS consolidation-induced heterogeneous microstructure composed of ultra-fine-grained regions surrounded by larger grains. Spatial distribution of the stored energy was measured in the bimodal microstructure using the Kernel average misorientation. In contrary to large recrystallized grains, ultra-fine grains are still substructured with low-angle grain boundaries. The precipitation kinetics of the nano-oxides during consolidation was determined by small-angle neutron scattering. Precipitation mainly occurred during the heating stage, leading to a high density of nanoclusters that are of prime importance for the mechanical properties. Other coarser titanium-enriched oxides were also detected. The multiscale characterization allowed us to understand and model the evolution of the complex microstructure. An analytical evaluation of the contributing mechanisms explains the appearance of the complex grain structure and its thermal stability during further heat treatments. Inhomogeneous distribution of plastic deformation in the powder is the major cause of heterogeneous recrystallization and further grain growth during hot consolidation. Then, the thermal stability of coherent nano-oxides is responsible for effective grain boundary pinning in recovered regions where the driving pressure for recrystallization is lowered. This scenario is confirmed in both SPSed and HIPed materials.

  15. Structure and magnetic properties of Co and Ni nano-ferrites prepared by a two step direct microemulsions synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Pulišová, P., E-mail: pulisovap@yahoo.com [Faculty of Metallurgy, Technical University of Košice, Park Komenského 3, 04200 Košice (Slovakia); Institute of Inorganic Chemistry of the AS CR, v.v.i., Husinec-Řež 1001, 25068 Řež (Czech Republic); Kováč, J. [Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 04001 Košice (Slovakia); Voigt, A. [Process Systems Engineering, Otto-von-Guericke Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg (Germany); Raschman, P. [Faculty of Metallurgy, Technical University of Košice, Park Komenského 3, 04200 Košice (Slovakia)

    2013-09-15

    Nano-particles of CoFe{sub 2}O{sub 4}, NiFe{sub 2}O{sub 4} and Co{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4} were synthesized by a two step microemulsion precipitation where inverse micelles of water in hexanol were stabilized using cetyltrimethylammonium bromide. Powder X-ray diffraction analysis and Transmission electron microscopy measurements provided data to clarify the crystal structure and size of the produced nano-particles. Different measurements of magnetic properties at low temperatures of 2 K revealed that nano-particles of NiFe{sub 2}O{sub 4} represent magnetically soft ferrite with a coercivity ∼40 kA/m, whereas nano-particles of CoFe{sub 2}O{sub 4} and Co{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4} were magnetically harder with a coercivity of 815 and 947 kA/m, respectively. Additionally zero field cooling and field cooling measurements provided data for estimating the blocking temperature of the materials produced. For NiFe{sub 2}O{sub 4} this temperature is lower, 23 K. The blocking temperature of CoFe{sub 2}O{sub 4} of 238 K and Co{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4} of 268 K are higher in comparison with NiFe{sub 2}O{sub 4}. - Highlights: • Nano-scale ferrites prepared by precipitation in microemulsions show magnetic behavior. • XRD and TEM found that particle size of prepared magnetic nano-ferrites is in range from 5 to 10 nm. • Prepared CoFe{sub 2}O{sub 4} and Co{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4} ferrites are magnetically harder than NiFe{sub 2}O{sub 4} ferrite. • Precipitation in microemulsions offers preparation at low temperature as cost effective method.

  16. Characterization of Nano-Structured Nickel-Cobalt Ferrites Synthesized By Citrate-Gel Auto Combustion Method

    Directory of Open Access Journals (Sweden)

    Abdul Gaffoor

    2014-04-01

    Full Text Available Nano-ferrites of the composition Ni1-xCoxFe2O4(where x=0.0,0.2,0.4,0.6,0.80 and 1.0 were synthesized at a very low temperature (180°C by Citrate-gel auto combustion method The synthesized powders were sintered at 5000C for four hours in an air and were characterized by X-ray diffraction (XRD which confirmed the formation of cubic spinel structure of ferrites. The crystallite size was in the range of 20nm to 31 nm. Such low nano sized ferrites are desirable for variety of applications like, in magnetic data storage and in etc. Morphological studies by Scanning Electron Microscopy (SEM revealed formation of largely agglomerated, well defined nano particles of the sample. Elemental composition characterizations of the prepared samples were performed by Energy Dispersive Spectroscopy (EDS which shows the presence of Ni, CO, Fe and O without precipitating cations.

  17. Electrical and morphological properties of magnetocaloric nano ZnNi ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Hemeda, O.M., E-mail: omhemeda@yahoo.co.uk [Physics Department, Faculty of Science, Tanta University, Tanta (Egypt); Mostafa, Nasser Y. [Materials and Corrosion Group, Department of Chemistry, Faculty of Science, Taif University (Saudi Arabia); Chemistry Department, Faculty of Science, Suez Canal University, Ismailia 41522 (Egypt); Abd Elkader, Omar H. [Electron Microscope & Thin Films Department, Physics Division, National Research Center, Dokki 12622, Cairo (Egypt); Electron Microscope Unit, Zoology Department, College of Science, King Saud University, Riyadh (Saudi Arabia); Hemeda, D.M.; Tawfik, A.; Mostafa, M. [Physics Department, Faculty of Science, Tanta University, Tanta (Egypt)

    2015-11-15

    A series of Zn{sub 1–x}Ni{sub x}Fe{sub 2}O{sub 4} nano ferrite (with x=0, 0.2, 0.4, 0.6, 0.8, and 1) compositions were synthesized using the combustion technique. The powder samples were characterized by XRD. The X-ray analysis showed that the samples were single phase spinel cubic structure. The AC resistivity decreases by increasing the frequency from 1 kHz to 10 kHz. As the frequency of the applied field increases the hopping of charge carrier also increase, thereby decreasing the resistivity. A shift in dielectric maximum is observed toward higher temperature with increasing the Ni content from 536 K to 560 K at 1 kHz. The HRTEM (high resolution TEM) images of four compositions have lattice spacing which confirms the crystalline nature of the samples. The surface morphology SEM of the sample consists of some grains with relatively homogenies distribution with an average size varying from 0.85 to 0.92 μm. The values for entropy change in this work are still small but are significally higher than the values that have been reported for iron oxide nanoparticle. The magnetic entropy change was calculated from measurements of M (H, T) where H is the magnetic field and T is the temperature. The maximum value of entropy change (∆S) obtained near Curie temperature which makes these material candidates for magnetocaloric applications. - Highlights: • Nanoparticles of Ni–Zn ferrite were prepared by solution combustion method. • A shift in dielectric maximum is observed toward high temperature with increasing the Ni content. • The inter planner distance obtained from HRTEM coincide with the f XRD results. • The entropy change vs. temperature shows a broad maximum near Curie temperature. • This results are useful for the operation of cooling devices.

  18. Electrical and morphological properties of magnetocaloric nano ZnNi ferrite

    Science.gov (United States)

    Hemeda, O. M.; Mostafa, Nasser Y.; Abd Elkader, Omar H.; Hemeda, D. M.; Tawfik, A.; Mostafa, M.

    2015-11-01

    A series of Zn1-xNixFe2O4 nano ferrite (with x=0, 0.2, 0.4, 0.6, 0.8, and 1) compositions were synthesized using the combustion technique. The powder samples were characterized by XRD. The X-ray analysis showed that the samples were single phase spinel cubic structure. The AC resistivity decreases by increasing the frequency from 1 kHz to 10 kHz. As the frequency of the applied field increases the hopping of charge carrier also increase, thereby decreasing the resistivity. A shift in dielectric maximum is observed toward higher temperature with increasing the Ni content from 536 K to 560 K at 1 kHz. The HRTEM (high resolution TEM) images of four compositions have lattice spacing which confirms the crystalline nature of the samples. The surface morphology SEM of the sample consists of some grains with relatively homogenies distribution with an average size varying from 0.85 to 0.92 μm. The values for entropy change in this work are still small but are significally higher than the values that have been reported for iron oxide nanoparticle. The magnetic entropy change was calculated from measurements of M (H, T) where H is the magnetic field and T is the temperature. The maximum value of entropy change (∆S) obtained near Curie temperature which makes these material candidates for magnetocaloric applications.

  19. Synthesis and characterization of nano crystalline nickel zinc ferrite for chlorine gas sensor at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Pawar, C. S., E-mail: charudutta-p@yahoo.com [Material Science and Thin Film Research Laboratory, Department of Physics,Shankarrao Mohite Mahavidyalaya, Akluj India (India); Gujar, M. P. [Shri. Shivaji Junior College, Bawada, Dist: Pune (India); Mathe, V. L. [Department of Physics, University of Pune, Pune – 411 007 India (India)

    2015-06-24

    Nano crystalline Nickel Zinc ferrite (Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4}) thin films were synthesized by Sol Gel method for gas response. The phase and microstructure of the obtained Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4} thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). The nanostructured Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4} thin film shows single spinel phase. Magnetic study was obtained with the help of VSM. The effects of working temperature on the gas response were studied. The results reveal that the Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4} thin film gas sensor shows good selectivity to chlorine gas at room temperature. The sensor shows highest sensitivity (∼50%) at room temperature, indicating its application in detecting chlorine gas at room temperature in the future.

  20. Microwave processed bulk and nano NiMg ferrites: A comparative study on X-band electromagnetic interference shielding properties

    Energy Technology Data Exchange (ETDEWEB)

    Chandra Babu Naidu, K., E-mail: chandrababu954@gmail.com [Ceramic Composite Laboratory, Centre for Crystal Growth, SAS, VIT University, Vellore 632014, Tamilnadu (India); Madhuri, W., E-mail: madhuriw12@gmail.com [Ceramic Composite Laboratory, Centre for Crystal Growth, SAS, VIT University, Vellore 632014, Tamilnadu (India); IFW, Leibniz Institute for Solid State and Materials Research, Technische Universität Dresden, 01069 Dresden (Germany)

    2017-02-01

    Bulk and nano Ni{sub 1-x}Mg{sub x}Fe{sub 2}O{sub 4} (x = 0–1) samples were synthesized via microwave double sintering and microwave assisted hydrothermal techniques respectively. The diffraction pattern confirmed the formation of cubic spinel phases in case of both the ferrites. The larger bulk densities were achieved to the bulk than that of nano. In addition, a comparative study on X-band (8.4–12 GHz) electromagnetic interference shielding properties of current bulk and nanomaterials was elucidated. The results showed that the bulk Ni{sub 0.6}Mg{sub 0.4}Fe{sub 2}O{sub 4} composition revealed the highest total shielding efficiency (SE{sub T}) of ∼17 dB. In comparison, the shielding efficiency values of all bulk contents were higher than that of nano because of larger bulk densities. Moreover, the ac-electromagnetic parameters such as electrical conductivity (σ{sub ac}), the respective real (ε′ & μ′) and imaginary parts (ε″ & μ″) of complex permittivity and permeability were investigated as a function of gigahertz frequency. The bulk ferrites of x = 0.4 & 0.6 showed the high ε″ of 10.26 & 6.71 and μ″ of 3.65 & 3.09 respectively at 12 GHz which can work as promising microwave absorber materials. Interestingly, nanoferrites exhibited negative μ″ values at few frequencies due to geometrical effects which improves the microwave absorption. - Highlights: • Bulk and nano NiMg ferrites are prepared by microwave and hydrothermal method. • X-band EMI shielding properties are studied for both bulk and nano ferrites. • Bulk Ni{sub 0.6}Mg{sub 0.4}Fe{sub 2}O{sub 4} revealed the highest SE{sub T} of ∼17 dB at 8.4 GHz. • Bulk x = 0.4 & 0.6 showed the high ε″ and μ″ at 12 GHz for absorber applications.

  1. High-Performance Flexible Organic Nano-Floating Gate Memory Devices Functionalized with Cobalt Ferrite Nanoparticles.

    Science.gov (United States)

    Jung, Ji Hyung; Kim, Sunghwan; Kim, Hyeonjung; Park, Jongnam; Oh, Joon Hak

    2015-10-07

    Nano-floating gate memory (NFGM) devices are transistor-type memory devices that use nanostructured materials as charge trap sites. They have recently attracted a great deal of attention due to their excellent performance, capability for multilevel programming, and suitability as platforms for integrated circuits. Herein, novel NFGM devices have been fabricated using semiconducting cobalt ferrite (CoFe2O4) nanoparticles (NPs) as charge trap sites and pentacene as a p-type semiconductor. Monodisperse CoFe2O4 NPs with different diameters have been synthesized by thermal decomposition and embedded in NFGM devices. The particle size effects on the memory performance have been investigated in terms of energy levels and particle-particle interactions. CoFe2O4 NP-based memory devices exhibit a large memory window (≈73.84 V), a high read current on/off ratio (read I(on)/I(off)) of ≈2.98 × 10(3), and excellent data retention. Fast switching behaviors are observed due to the exceptional charge trapping/release capability of CoFe2O4 NPs surrounded by the oleate layer, which acts as an alternative tunneling dielectric layer and simplifies the device fabrication process. Furthermore, the NFGM devices show excellent thermal stability, and flexible memory devices fabricated on plastic substrates exhibit remarkable mechanical and electrical stability. This study demonstrates a viable means of fabricating highly flexible, high-performance organic memory devices. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Synthesis and characterization of nano-sized cobalt ferrite prepared via polyol method using conventional and microwave heating techniques

    Energy Technology Data Exchange (ETDEWEB)

    Ibrahim, Amal M., E-mail: amozarei@yahoo.co [Surface Chemistry and Catalysis Laboratory, Physical Chemistry Department, National Research Center, Al Buhouth St., Cairo (Egypt); El-Latif, M.M. Abd; Mahmoud, Morsi M. [Fabrication Technology Department, Advanced Technology and New Materials Research Institute, Mubarak City for Scientific Research and Technology Applications, Alexandria (Egypt)

    2010-09-10

    Nano-sized single-phase cobalt ferrite samples were prepared via polyol method using ethylene glycol as a high boiling point solvent as well as a reducing agent. These samples were prepared by two different heating techniques; conventional heating technique and microwave assisting technique using a 2.45 GHz multimode microwave synthesis unit. The crystallite size of the obtained samples was found to be in the range from 10 nm to 12 nm. The obtained samples were characterized using transmission electron microscope (TEM) and X-ray diffraction (XRD). Quantum design SQUID magnetometer was used to study the magnetic measurement.

  3. Superparamagnetic behavior of heat treated Mg{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} ferrite nanoparticles studied by Mössbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Srinivas, Ch., E-mail: srinivas.chintoju75@gmail.com; Prasad, S. A. V. [Department of Physics, Sasi Institute of Technology and Engineering, Tadepalligudem 534101 (India); Singh, S. B. [Department of Physics, Government Polytechnic, Tadepalligudem 534101 (India); Tirupanyam, B. V. [Department of Physics, Government College (Autonomous), Rajahmundry 533401 (India); Meena, S. S., E-mail: ssingh@barc.gov.in; Yusuf, S. M. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Krishna, K. S. Rama [Department of Physics, Srinivasa Institute of Eneering technologyy, Amalapuram, 533222 (India); Sastry, D. L. [Department of Physics, Andhra University, Visakhapatnam 530003 (India)

    2016-05-23

    Nanoparticles of Mg{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} ferrite have been synthesized by co-precipitation method. XRD and Mössbauer spectroscopic results of Mg{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} annealed at 200 °C, 500 °C and 800 °C are reported. It was observed that the crystallite size increases and the lattice parameter decreases with increase in annealing temperature. The observed decrease in lattice strain supports the increase in crystallite size. The Mössbauer spectra of the samples annealed at 200 °C and 500 °C exhibits superparamagnetic doublets whereas the Mössbauer spectrum of the sample annealed at 800 °C exhibits paramagnetic doublet along with weak sextet of hyperfine interaction. The values of isomer shift resemble the presence of high spin iron ions. The studied ferrite nanoparticles are suitable for biomedical applications. The results are incorporated employing core-shell model and cation redistribution.

  4. Low dielectric loss in nano-Li-ferrite spinels prepared by sol–gel auto-combustion technique

    Indian Academy of Sciences (India)

    Mamata Maisnam; Nandeibam Nilima; Maisnam Victory; Sumitra Phanjoubam

    2016-02-01

    Pure and doped nano-Li-ferrite spinels were prepared by the sol–gel auto-combustion technique. The prepared ferrites were pelleted and heat treated at different temperatures. Structural characterization was carried out on the as-prepared samples and also on the heat-treated samples using X-ray diffraction (XRD). The studies confirmed the formation of single phase with spinel structures in all the samples. The crystallite size of the samples evaluated from XRD data was found to be 17–24 nm. Scanning electron microscopic photomicrographs revealed the microstructures and the grain size of these nanoferrites. The room-temperature dielectric constant and dielectric loss tangent, tan δ were measured as a function of frequency in the range 100 Hz–1 MHz. These nanoferrites showed the normal dielectric dispersion behaviour. The observed dielectric constant and dielectric loss tangent were found to be much lower than those measured on substituted Li-ferrites prepared by the conventional ceramic method. The results obtained were discussed in the paper.

  5. A comparative study on the optical limiting properties of different nano spinel ferrites with Z-scan technique

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Jeevan Job; Krishnan, Shiji [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam, Kerala 686560 (India); Sridharan, K.; Philip, Reji [Light and Matter Physics Group, Raman Research Institute, C.V. Raman Avenue, Sadashivanagar, Bangalore 560080 (India); Kalarikkal, Nandakumar, E-mail: nkkalarikkal@mgu.ac.in [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam, Kerala 686560 (India); Centre for Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam, Kerala 686560 (India)

    2012-08-15

    Highlights: ► First report in which the optical limiting properties of five different nano spinel ferrites are compared. ► The obtained nonlinearity fits to a two-photon like absorption process. ► Except for NiFe{sub 2}O{sub 4}, the observed nonlinearity has contributions from excited state absorption. ► A size dependent optical limiting response is obtained. ► Among the investigated ferrites, ZnFe{sub 2}O{sub 4} is found to be a better candidate for the optical limiting applications. -- Abstract: We report the optical limiting properties of five different spinel ferrites, NiFe{sub 2}O{sub 4}, Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}, ZnFe{sub 2}O{sub 4}, Ni{sub 0.5}Co{sub 0.5}Fe{sub 2}O{sub 4}, and CoFe{sub 2}O{sub 4} with an average particle grain size of 8 nm. The optical limiting properties are investigated using the open aperture Z-scan technique. The obtained nonlinearity fits to a two-photon like absorption process. Except for NiFe{sub 2}O{sub 4}, the observed nonlinearity has contributions from excited state absorption. The optical limiting response is also studied against particle size and the nonlinearity is found to increase with increasing particle size within the range of our investigations. On comparing the optical limiting properties, ZnFe{sub 2}O{sub 4} is found to be a better candidate for the optical limiting applications. To the best of our knowledge, this is the first report where the optical limiting properties of spinel ferrites are compared.

  6. Superparamagnetic state by linear and non-linear AC magnetic susceptibility in Mn0.5Zn0.5Fe2O4 ferrites nanoparticles.

    Science.gov (United States)

    Suneetha, T; Kundu, S; Kashyap, Subhash C; Gupta, H C; Nath, T K

    2013-01-01

    The Mn0.5Zn0.5Fe2O4 nanoparticles has been synthesized using citrate-gel-precursor method. The direct mixing of nitrates and acetates yields homogeneous nanoparticles. Phase formation and crystal structure of the synthesized powder were examined through the X-ray diffraction (XRD). Fourier transform infrared (FTIR) spectra of the sample confirm the spinel structure. The average particle size was determined by transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). The average particle size is found to be about 13 nm. Superparamagnetic-like nature of the nanoparticles of Mn0.5Zn0.5Fe2O4 has been revealed through various dc and linear and non-linear ac magnetization measurements. However, the nanoparticles do not behave like ideal non-interacting superparamagnets. The magnetic particle size is found to be about 8 nm with saturation magnetization about 18.1 emu/g. The blocking temperature (T(B)) of the nanoparticle assembly is found to be about 150 K as observed from dc and ac magnetization measurements. The frequency dependence of the blocking temperature (T(B)) is found to follow Vogel-Fulcher law. The associated characteristic time tau0 is found to be 10(-5) s. This value is different from that generally found for non-interacting superparamagnetic (SPM) systems (tau0 = 10(-9)-10(-10) s).

  7. Transition from Superparamagnetism to Ferromagnetic Single-Domain in a Heisenberg Model for Nano-cluster Magnetic System

    Institute of Scientific and Technical Information of China (English)

    SHAO Yuan-Zhi; HE Zhen-Hui

    2000-01-01

    By considering a magnetic system of an ensemble of nanometer clusters without any external magnetic field, the Monte Carlo simulation of the Heisenberg model is used to investigate the transition from a superparamagnetism to a ferromagnetic single-domain state, which is caused by the growth of the clusters. We studied the variation of the dynamic growth exponent P and the transition critical size of the cluster Nc against the reduced temperature t and the uniaxial anisotropy constant A. We found that the growth exponent maximized at a certain temperature,other than being taken as a universal constant as some researchers suggested previously.

  8. Influence of Inter-Particle Interactions on the Superparamagnetic Relaxation Time in a Sample of Nano-Sized Feroxyhyte Particles

    DEFF Research Database (Denmark)

    Meaz, T; Koch, C. Bender; Mørup, Steen

    1996-01-01

    Ultrafine particles of feroxyhyte (delta-FeOOH) have been studied by Mossbauer spectroscopy. Coating of the particles with oleic acid results in a decrease of the superparamagnetic blocking temperature, whereas pressing the particles with a uniaxial pressure of 1.3 GPa leads to an increase...... of the blocking temperature. The results suggest that the interaction between the ferrimagnetic particles leads to ordering of the magnetic moments below a critical temperature, which depends on the strength of the interaction. Measurements at 5 K in a large magnetic field show that the particles have a non...

  9. Role of intensive milling in the processing of barium ferrite/magnetite/iron hybrid magnetic nano-composites via partial reduction of barium ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Molaei, M.J., E-mail: mj.molaee@merc.ac.ir [Materials and Energy Research Center, P.O. Box: 31787-316, Karaj (Iran, Islamic Republic of); Delft Chem Tech, Faculty of Applied Sciences, Delft University of Technology, Julianalaan 136, 2628 BL Delft (Netherlands); Ataie, A.; Raygan, S. [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box: 14395-553, Tehran (Iran, Islamic Republic of); Picken, S.J. [Delft Chem Tech, Faculty of Applied Sciences, Delft University of Technology, Julianalaan 136, 2628 BL Delft (Netherlands)

    2015-03-15

    In this research a mixture of barium ferrite and graphite was milled for different periods of time and then heat treated at different temperatures. The effects of milling time and heat treatment temperature on the phase composition, thermal behavior, morphology and magnetic properties of the samples have been investigated using X-ray diffraction, differential thermal analysis, high resolution transmission electron microscopy and vibrating sample magnetometer techniques, respectively. X-ray diffraction results revealed that BaFe{sub 12}O{sub 19}/Fe{sub 3}O{sub 4} nanocomposites form after a 20 h milling due to the partial reduction of BaFe{sub 12}O{sub 19}. High resolution transmission electron microscope images of a 40 h milled sample showed agglomerated structure consisting of nanoparticles with a mean particle size of 30 nm. Thermal analysis of the samples via differential thermal analysis indicated that for un-milled samples, heat treatment up to 900 °C did not result in α-Fe formation, while for a 20 h milled sample heat treatment at 700 °C resulted in reduction process progress to the formation of α-Fe. Wustite was disappeared in an X-ray diffraction pattern of a heat treated sample at 850 °C, by increasing the milling time from 20 to 40 h. By increasing the milling time, the structure of heat treated samples becomes magnetically softer due to an increase in saturation magnetization and a decrease in coercivity. Saturation magnetization and coercivity of a sample milled for 20 h and heat treated at 850 °C were 126.3 emu/g and 149.5 Oe which by increasing the milling time to 40 h, alter to 169.1 emu/g and 24.3 Oe, respectively. High coercivity values of milled and heat treated samples were attributed to the nano-scale formed iron particles. - Graphical abstract: Display Omitted - Highlights: • Barium ferrite and graphite were treated mechano-thermally. • Increasing milling time increases reduction progress after heat treatment. • Composites

  10. Effect of Ca substitution on some physical properties of nano-structured and bulk Ni-ferrite samples

    Energy Technology Data Exchange (ETDEWEB)

    Assar, S.T., E-mail: soha_talaat@yahoo.com; Abosheiasha, H.F.

    2015-01-15

    Nanoparticles of Ni{sub 1−x}Ca{sub x}Fe{sub 2}O{sub 4} (x=0.0, 0.02, 0.04, 0.06 and 0.10) were prepared by citrate precursor method. A part of these samples was sintered at 600 °C for 2 h in order to keep the particles within the nano-size while the other part was sintered at 1000 °C to let the particles to grow to the bulk size. The effect of Ca{sup 2+} ion substitution in nickel ferrite on some structural, magnetic, electrical and thermal properties was investigated. All samples were characterized by using X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM). A two probe method was used to measure the dc electrical conductivity whereas the photoacoustic (PA) technique was used to determine the thermal diffusivity of the samples. To interpret different experimental results for nano and bulk samples some cation distributions were assumed based on the VSM and XRD data. These suggested cation distributions give logical explanations for other experimental results such as the observed values of the absorption bands in FTIR spectra and the dc conductivity results. Finally, in the thermal measurements it was found that increasing the Ca{sup 2+} ion content causes a decrease in the thermal diffusivity of both nano and bulk samples. The explanation of this behavior is ascribed to the phonon-phonon scattering. - Highlights: • The physical properties of both nano and bulk samples of Ni-Ca ferrites were investigated. • Cation distribution plays a vital role in tailoring the physical properties of all the samples. • The dc conductivity of the nanosamples is higher than their bulk counterparts. • Increasing Ca{sup 2+} content enhances M{sub s}, M{sub r}, and σ{sub dc} of the bulk samples over their nanocounterparts. • The behavior of thermal diffusivity of the samples attributed to the phonon-phonon scattering.

  11. Solvothermal synthesis and characterization of monodisperse superparamagnetic iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shichuan; Zhang, Tonglai; Tang, Runze; Qiu, Hao [State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China); Wang, Caiqin [Shandong Special Industry Group Co., Ltd, Shandong 255201 (China); Zhou, Zunning [State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China)

    2015-04-01

    A series of magnetic iron oxide nanoparticle clusters with different structure guide agents were synthesized by a modified solvothermal method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analyses (TG), a vibrating sample magnetometer (VSM) and Fourier transform infrared spectroscopy (FTIR). It is found that the superparamagnetic nanoparticles guided by NaCit (sodium citrate) have high saturation magnetization (M{sub s}) of 69.641 emu/g and low retentivity (M{sub r}) of 0.8 emu/g. Guiding to form superparamagnetic clusters with size range of 80–110 nm, the adherent small-molecule citrate groups on the surface prevent the prefabricated ferrite crystals growing further. In contrast, the primary small crystal guided and stabilized by the PVP long-chain molecules assemble freely to larger ones and stop growing in size range of 100–150 nm, which has saturation magnetization (M{sub s}) of 97.979 emu/g and retentivity (M{sub r}) of 46.323 emu/g. The relevant formation mechanisms of the two types of samples are proposed at the end. The superparamagnetic ferrite clusters guided by sodium citrate are expected to be used for movement controlling of passive interference particles to avoid aggregation and the sample guided by PVP will be a candidate of nanometer wave absorbing material. - Highlights: • A facile synthesis of two kinds of monodisperse iron oxide nano-particle clusters was performed via a modified one-step solvothermal method in this work. • The NaCit and PVP as different guiding agents are used to control the formation and aggregation of nano-crystals during reacting and the ripening processes. • The superparamagnetic NaCit–Fe{sub 3}O{sub 4} samples have high saturation magnetization (M{sub s}) of 69.641 emu/g and low retentivity (M{sub r}) of 0.8 emu/g. • The relevant formation mechanisms of the two types of samples are proposed.

  12. Study of cation distribution of spinel zinc nano-ferrite by X-ray

    Science.gov (United States)

    Najafi Birgani, Azadeh; Niyaifar, Mohammad; Hasanpour, Ahmad

    2015-01-01

    A set of zinc ferrite samples with ZnFe2O4 chemical composition were synthesized in 400, 500, and 1100 °C using conventional solid state synthesis method. The X-ray diffraction pattern of all the three samples was studied at room temperature. This diffraction pattern confirmed the existence of a single-phase cubic spinel structure with lattice parameters of 8.451, 8.448, and 8.437 Å, respectively. Oxygen position and cation distribution of the samples between the tetrahedral site, A and the octahedral site, B were examined using R-Factor method. The results showed that cation distribution of zinc ferrite samples changes from a normal spinel mode into a mixed spinel mode with the decrease of particle size. Moreover, the ratio of zinc divalent cations migrating from the tetrahedral site to the octahedral site was calculated.

  13. Swift heavy ion induced surface modifications in nano-crystalline Li-Mg ferrite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Sanjukta [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India) and Department of Physics, University of Calcutta, 92 A.P.C. Road, Kolkata 700009 (India)]. E-mail: sanjukta@iopb.res.in; Ganesan, V. [Inter University Consortium for DAE facilities, Khandwa Road, Indore 452017 (India); Khan, S.A. [Nuclear Science Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Ayyub, Pushan [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Kumar, Nitendar [Solid State Physics Laboratory, DRDO, Lucknow Road, Delhi 110054 (India)

    2006-09-30

    The swift heavy ion (190 MeV Au{sup 14+}) induced modifications in surface morphologies of the nanocrystals of ferrite thin films have been extensively studied through the images of atomic force microscopy (AFM). In most of the irradiated films significant features like, the ditch and dike structures, have been observed through out the surface. We try to explain the observed changes on the basis of thermal spike model followed by momentum transfer induced lateral mass transport. In addition to these changes some new and interesting features have been noticed after irradiation in 8F and 9F ferrite thin films. These new features are attributed to sputtering phenomenon due to the presence of defects like latent tracks.

  14. Refinement of atomic and magnetic structures using neutron diffraction for synthesized bulk and nano-nickel zinc gallate ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Ata-Allah, S.S. [Reactor Physics Department, NRC, Atomic Energy Authority, P.O. Box 13759, Cairo (Egypt); Balagurov, A.M. [Frank Laboratory of Neutron Physics, JINR, 141980 Dubna, Moscow region (Russian Federation); Hashhash, A. [Reactor Physics Department, NRC, Atomic Energy Authority, P.O. Box 13759, Cairo (Egypt); Bobrikov, I.A. [Frank Laboratory of Neutron Physics, JINR, 141980 Dubna, Moscow region (Russian Federation); Hamdy, Sh. [Reactor Physics Department, NRC, Atomic Energy Authority, P.O. Box 13759, Cairo (Egypt)

    2016-01-15

    The parent NiFe{sub 2}O{sub 4} and Zn/Ga substituted spinel ferrite powders have been prepared by solid state reaction technique. As a typical example, the Ni{sub 0.7}Zn{sub 0.3}Fe{sub 1.5}Ga{sub 0.5}O{sub 4} sample has been prepared by sol–gel auto combustion method with the nano-scale crystallites size. X-ray and Mössbauer studies were carried out for the prepared samples. Structure and microstructure properties were investigated using the time-of-flight HRFD instrument at the IBR-2 pulsed reactor, at a temperatures range 15–473 K. The Rietveld refinement of the neutron diffraction data revealed that all samples possess cubic symmetry corresponding to the space group Fd3m. Cations distribution show that Ni{sup 2+} is a complete inverse spinel ion, while Ga{sup 3+} equally distributed between the two A and B-sublattices. The level of microstrains in bulk samples was estimated as very small while the size of coherently scattered domains is quite large. For nano-structured sample the domain size is around 120 Å.

  15. Study of cation distribution of spinel zinc nano-ferrite by X-ray

    Energy Technology Data Exchange (ETDEWEB)

    Najafi Birgani, Azadeh, E-mail: a.najafibirgani@gmail.com; Niyaifar, Mohammad; Hasanpour, Ahmad

    2015-01-15

    A set of zinc ferrite samples with ZnFe{sub 2}O{sub 4} chemical composition were synthesized in 400, 500, and 1100 °C using conventional solid state synthesis method. The X-ray diffraction pattern of all the three samples was studied at room temperature. This diffraction pattern confirmed the existence of a single-phase cubic spinel structure with lattice parameters of 8.451, 8.448, and 8.437 Å, respectively. Oxygen position and cation distribution of the samples between the tetrahedral site, A and the octahedral site, B were examined using R-Factor method. The results showed that cation distribution of zinc ferrite samples changes from a normal spinel mode into a mixed spinel mode with the decrease of particle size. Moreover, the ratio of zinc divalent cations migrating from the tetrahedral site to the octahedral site was calculated. - Highlights: • The average crystallite size of a set of zinc ferrite samples compared. • The cation distribution of the samples were studied. • A fraction of zinc ions migrated to the octahedral site. • This migration due to reduced power of ligands. • Their spinel structure of samples change by this migration.

  16. Enhanced electrical properties in Nd doped cobalt ferrite nano-particles

    Science.gov (United States)

    Abbas, S.; Munir, A.; Zahra, F.; Rehman, M. A.

    2016-08-01

    Spinel ferrites are important class of compounds which has variety of electrical, magnetic and catalytic applications. A small amount of rare earth element causes modification in structural, electrical and magnetic properties of ferrite materials for practical applications. Neodymium doped cobalt ferrites with composition CoNdxFe2-xO4 where x is 0.1 has been synthesized by sol-gel method. Sol-gel method was preferred because it has good control over stoichiometry, crystallite size and particle size distribution. Characterization was done by using X-Ray Diffraction (XRD) technique for structural analysis and crystal structure was found to be spinel. Particles like morphology was observed in micrographs obtained by Scanning Electron Microscopy (SEM). Thermal analysis of sample has been done which includes Thermogravimetric analysis (TGA) and Differential Scanning calorimetry (DSC). Fourier transform infra-red spectroscopy (FT-IR) of samples was also performed. DC resistivity as a function of temperature has been studied and its shows direct dependence on temperature and inverse dependence on the concentration of Nd dopant. The studied material is a potential candidate for resistive random access memory application.

  17. Structure, Morphology and Chemical Synthesis of Mg1-xZnxFe2O4 Nano-Ferrites Prepared by Citrate-Gel Auto Combustion Method

    Directory of Open Access Journals (Sweden)

    D.Ravikumar

    2014-04-01

    Full Text Available Mg-Zn Nano ferrites having chemical formula Mg1-xZnxFe2O4(where x=0.0, 0.2, 0.4, 0.6, 0.8, 1.0 were synthesized by the citrate-gel auto combustion method. Synthesized powders were sintered at 500oC for four hours in air and characterized by XRD, SEM and EDS.XRD analysis shows that cubic spinal structure of the ferrites and the crystalline sizes (D were found in the range 25-35 nm. The values of the lattice parameter (a increases and X-ray density (dx increases with doping of Zn content. Scanning Electron Microscopy (SEM studies revealed Nano nature of the samples. An elemental composition of the samples was studied by using Energy Dispersive Spectroscopy (EDS. The observed results can be explained on the basis of composition and crystallite size.

  18. Influencing factors in the CO-precipitation process of superparamagnetic iron oxide nano particles: A model based study

    Energy Technology Data Exchange (ETDEWEB)

    Roth, Hans-Christian; Schwaminger, Sebastian P.; Schindler, Michael [Bioseparation Engineering Group, Technische Universität München, Boltzmannstraße 15, Garching d-85748 (Germany); Wagner, Friedrich E. [Technische Universität München, Physics Department El5, Garching d-85748 (Germany); Berensmeier, Sonja, E-mail: s.berensmeier@tum.de [Bioseparation Engineering Group, Technische Universität München, Boltzmannstraße 15, Garching d-85748 (Germany)

    2015-03-01

    The study, presented here, focuses on the impact of synthesis parameters on the co-precipitation process of superparamagnetic iron oxide nanoparticles. Particle diameters between 3 and 17 nm and saturation magnetizations from 26 to 89 Am{sup 2} kg{sup −1} were achieved by variation of iron salt concentration, reaction temperature, ratio of hydroxide ions to iron ions and ratio of Fe{sup 3+}/Fe{sup 2+}. All synthesis assays were conceived according to the “design of experiments” method. The results were fitted to significant models. Subsequent validation experiments could confirm the models with an accuracy>95%. The characterization of the chemical composition, as well as structural and magnetic properties was carried out using powder X-ray diffraction, transmission electron microscopy, Raman and Mössbauer spectroscopy and superconducting quantum interference device magnetometry. The results reveal that the particles' saturation magnetization can be enhanced by the employment of high iron salt concentrations and a molar ratio of Fe{sup 3+}/Fe{sup 2+} below 2:1. Furthermore, the particle size can be increased by higher iron salt concentrations and a hyperstoichiometric normal ratio of hydroxide ions to iron ions of 1.4:1. Overall results indicate that the saturation magnetization is directly related to the particle size. - Highlights: • We model the impact of synthesis parameters in the Massart process. • Optimization of synthesis parameters according to particle size and magnetization. • Particles are fully characterized with XRD, TEM and SQUID magnetometry.

  19. Nano copper and cobalt ferrites as heterogeneous catalysts for the one-pot synthesis of 2,4,5-tri substituted imidazoles

    Indian Academy of Sciences (India)

    Paul Douglas Sanasi; D Santhipriya; Y Ramesh; M Ravi Kumar; B Swathi; K Jaya Rao

    2014-11-01

    A simple one-pot synthesis has been developed for the synthesis of 2,4,5-trisubstituted imidazoles using magnetic recyclable spinel nano copper and cobalt ferrites by the condensation of benzil, aromatic aldehyde and ammonium acetate in ethanol as solvent. The reaction, with these catalysts was carried out under mild reaction conditions with very good yields of substituted imidazoles. These catalysts can be recycled very easily and reused, which makes this methodology environmentally benign.

  20. Synthesis and properties of single domain sphere-shaped barium hexa-ferrite nano powders via an ultrasonic-assisted co-precipitation route.

    Science.gov (United States)

    Liu, Junliang; Liu, Ping; Zhang, Xingkai; Pan, Dongjun; Zhang, Peng; Zhang, Ming

    2015-03-01

    To synthesize high quality barium hexa-ferrite nano powders, an ultrasonic-assisted co-precipitation method has been used and the influences of the ultrasonic technique on the particle morphologies and magnetic properties of the synthesized barium hexa-ferrite nano powders have been investigated. The results indicated that the introduction of ultrasonic energy into the co-precipitation process promoted the composition homogeneities of the co-precipitated precursors, minished their particle sizes, and exerted the additional surface barriers between the particles, which influenced both the phase formation and particle growth-up processes during the subsequent heating treatment and altered the particle sizes, size distributions and particle shapes of the final synthesized powders. The average particle sizes of the synthesized nano powders dramatically decreased from 210 nm to about 100 nm as the inputting ultrasonic power increased, while the size distribution became increasingly uniform except for a few of large particles existed as the inputting power approached to a high value. The magnetization at 1.4 T of the as-synthesized barium hexa-ferrite dramatically increased and approached to the highest value of 57.9 emu/g due to the elimination of multi-domain particles, the alleviation of particle adhesion and the evolution of particle shape from flake to quasi-sphere as well as the uniform particle size distribution as the ultrasonic assistance was employed, and slightly decreased because of the coarsening in particle sizes.

  1. Investigation on different oxides as candidates for nano-sized ODS particles in reduced-activation ferritic (RAF) steels

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, Jan, E-mail: j.hoffmann@kit.edu [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM-AWP), Karlsruhe (Germany); Rieth, Michael; Lindau, Rainer; Klimenkov, Michael; Möslang, Anton [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM-AWP), Karlsruhe (Germany); Sandim, Hugo Ricardo Zschommler [Department of Materials Engineering, EEL, University of São Paulo, 12600-970 Lorena (Brazil)

    2013-11-15

    Future generation reactor concepts are based on materials that can stand higher temperatures and higher neutron doses in corrosive environments. Oxide dispersion strengthened steels with chromium contents ranging from 9 to 14 wt.% – produced by mechanical alloying – are typical candidate materials for future structural materials in fission and fusion power plants. Y{sub 2}O{sub 3} has proven to be a good candidate for addition to ferritic steels during mechanical alloying to form nano-sized dispersion oxide particles during compacting of the material. These oxide particles have many positive effects on the material such as improved high-temperature properties and higher corrosion resistance. However, there is potential for improvements by choosing different oxides. In this present work, four different oxides (MgO, La{sub 2}O{sub 3}, Ce{sub 2}O{sub 3} and ZrO{sub 2}) are selected by looking at their thermal stabilities and Gibbs free enthalpies of various chemical compositions. These oxides are mixed and mechanically alloyed with ferritic steel powder (Fe13Cr1W0.3Ti) and compared to a reference material produced with Y{sub 2}O{sub 3} (Fe13Cr1W0.3Ti + Y{sub 2}O{sub 3}). The materials were characterized in terms of their mechanical properties and detailed microstructural investigations by transmission electron microscopy and electron backscatter diffraction. All further results of the mechanical testing and microstructural characterizations are analyzed, compared, and discussed in this paper.

  2. Synthesis of Ferrite Nickel Nano-particles and Its Role as a p-Dopant in the Improvement of Hole Injection of an Organic Light-Emitting Diode

    Science.gov (United States)

    Noori, Maryam; Jafari, Mohammad Reza; Hosseini, Sayed Mohsen; Shahedi, Zahra

    2017-07-01

    We fabricated an organometallic complex based on zinc ions using zinc complex as a fluorescent in organic light-emitting diodes (OLEDs). Also, the nano-particles of ferrite nickel were produced in a simple aqueous system prepared by mixing Ni (NO3)2, Fe (NO3)3 and deionized water solutions. The synthesized zinc bis (8-hydroxyquinoline) (Znq2) complex and NiFe2O4 nano-particles were characterized by using x-ray diffraction (XRD), ultraviolet-visible (UV-Vis), Fourier transform infrared spectroscopy (FT-IR) as well as photoluminescence spectroscopy analysis. Their energy level was also determined by some cyclic voltammetry (CV) measurements. The maximum green photoluminescence was observed at 565 nm. The nano-particles of ferrite nickel were utilized in preparation of OLEDs by blending of the magnetic nano-particles with PEDOT:PSS and Zn-complex solutions. The electrical and optical performance of prepared OLEDs with/without doped nano-particle was studied. The samples were configured into two structures: (1) Indium Tin Oxide (ITO)/ poly(3,4-ethylenedi-oxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/Znq2/(2-4-biphenylyl)-5-phenyl-oxadiazole (PBD)/aluminum (Al) and (2) ITO/PEDOT:PSS:NiFe2O4(NPs)/Znq2/PBD/Al. Obtained results showed that the current density and electroluminescence efficiency were increased and the turn-on voltage decreased (about 3 V) by using nano-particles into a PEDOT:PSS layer (Hole transport layer). Also, the electroluminescence efficiency was decreased by incorporating magnetic nano-particles into a Zn-complex layer (emissive layer). It was found that utilizing NiFe2O4 nano-particles caused an increase of hole-injection layer conductivity effectively and a decrease of the turn-on voltage.

  3. Synthesis of Ferrite Nickel Nano-particles and Its Role as a p-Dopant in the Improvement of Hole Injection of an Organic Light-Emitting Diode

    Science.gov (United States)

    Noori, Maryam; Jafari, Mohammad Reza; Hosseini, Sayed Mohsen; Shahedi, Zahra

    2017-02-01

    We fabricated an organometallic complex based on zinc ions using zinc complex as a fluorescent in organic light-emitting diodes (OLEDs). Also, the nano-particles of ferrite nickel were produced in a simple aqueous system prepared by mixing Ni (NO3)2, Fe (NO3)3 and deionized water solutions. The synthesized zinc bis (8-hydroxyquinoline) (Znq2) complex and NiFe2O4 nano-particles were characterized by using x-ray diffraction (XRD), ultraviolet-visible (UV-Vis), Fourier transform infrared spectroscopy (FT-IR) as well as photoluminescence spectroscopy analysis. Their energy level was also determined by some cyclic voltammetry (CV) measurements. The maximum green photoluminescence was observed at 565 nm. The nano-particles of ferrite nickel were utilized in preparation of OLEDs by blending of the magnetic nano-particles with PEDOT:PSS and Zn-complex solutions. The electrical and optical performance of prepared OLEDs with/without doped nano-particle was studied. The samples were configured into two structures: (1) Indium Tin Oxide (ITO)/ poly(3,4-ethylenedi-oxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/Znq2/(2-4-biphenylyl)-5-phenyl-oxadiazole (PBD)/aluminum (Al) and (2) ITO/PEDOT:PSS:NiFe2O4(NPs)/Znq2/PBD/Al. Obtained results showed that the current density and electroluminescence efficiency were increased and the turn-on voltage decreased (about 3 V) by using nano-particles into a PEDOT:PSS layer (Hole transport layer). Also, the electroluminescence efficiency was decreased by incorporating magnetic nano-particles into a Zn-complex layer (emissive layer). It was found that utilizing NiFe2O4 nano-particles caused an increase of hole-injection layer conductivity effectively and a decrease of the turn-on voltage.

  4. Synthesis of zinc substituted cobalt ferrites via reverse micelle technique involving in situ template formation: A study on their structural, magnetic, optical and catalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Charanjit; Jauhar, Sheenu [Department of Chemistry, Panjab University, Chandigarh 160014 (India); Kumar, Vinod [ICON Analytical Equipment (P) Ltd., Mumbai 400018 (India); Singh, Jagdish [Institute Instrumentation Centre, Indian Institute of Technology–Roorkee (India); Singhal, Sonal, E-mail: sonal1174@gmail.com [Department of Chemistry, Panjab University, Chandigarh 160014 (India)

    2015-04-15

    Nano-crystalline particles of visible light responsive Zn–Co ferrites having formula Zn{sub x}Co{sub 1-x}Fe{sub 2}O{sub 4} (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) were successfully synthesized via reverse micelle technique. Sodium dodecyl sulfate was used as a surfactant/templating agent. The ferrite formation was confirmed using powder X-Ray Diffraction (XRD) and Fourier Transform Infrared (FT-IR) spectroscopy. The spherical shape of the ferrite particles was established by High Resolution Transmission Electron Microscope (HR-TEM) analysis. From the magnetic studies, the ferromagnetic nature of CoFe{sub 2}O{sub 4} was known. However, the nano-particles exhibited a transition from ferromagnetic to super-paramagnetic upon increasing the zinc concentration. In addition, the photo-Fenton activity of ferrites was also studied by carrying out degradation of Rhodamine B (RhB) dye under visible light irradiation. The catalytic activity increased with increase in zinc ion concentration. - Highlights: • Controlled dimensions of Zn–Co ferrite nanoparticles by microemulsion technique. • Spherical shape with uniform size distribution of ∼5 nm was achieved. • Significant shift from ferromagnetic to superparamagnetic with Zn{sup 2+} ion doping. • Improved photocatalytic activity with Zn{sup 2+} ion doping.

  5. Preparation and properties of a nano TiO2/Fe3O4 composite superparamagnetic photocatalyst

    Institute of Scientific and Technical Information of China (English)

    LI Yuxiang; ZHANG Mei; GUO Min; WANG Xidong

    2009-01-01

    Nano TiO2/Fe3O4 composite particles with different molar ratios of TiO2 to Fe3O4 wefe prepared via sol-gel method. X-ray diffraction, transmission electron microscopy, and vibration sample magnetometry were used to characterize the TiO2/Fe3O4 particles. The photocatalytic activity of the particles was tested by degrading methyl blue solution under UV illumination (254 nm). The results indicate that with the con-tent of TiO2 increasing, the photocatalytic activity of the composite particles enhances, while the magnetism of the particles decreases. When the molar ratio of TiO2 to Fe3O4 is about 8, both the photocatalytic activity and magnetism of the TiO2/Fe3O4 particles are relatively high, and their photocatalytic activity remains well after repeated use.

  6. Bio-inspired synthesis and characterization of superparamagnetic particles; Sintese e caracterizacao bioinspirada de particulas superparamagneticas

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Vinicius F., E-mail: vfc_mg@yahoo.com.br [Universidade Federal de Itajuba (UNIFEI), MG (Brazil); Queiroz, Alvaro A.A. [Universidade Federal de Itajuba (UNIFEI), MG (Brazil). Centro de Estudos e Inovacao em Materiais Biofuncionais Avancados

    2012-08-15

    This paper discusses the bio-inspired synthesis of type YFeAl ferrites encapsulated into polyglycerol dendrimers (PGLD) generation 3. The structure and morphological properties of the system YFeAl/PGLD was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The magnetic properties were studied through the techniques of Moessbauer spectroscopy and magnetization. The cytotoxicity of the nanoparticles encapsulated in dendrimers PGLD G3 at the cell membrane was studied against mammalian cell line CHO.K1 measuring the amount of lactate dehydrogenase (LDH) released by the cell damage. Microscopy TEM and XRD analysis indicate that spherical nanoparticles were obtained highly crystalline and monodisperse with size 20 nmsuperparamagnetic behavior of the system YFeAl/PGLD. The cytotoxicity results indicated that YFeAl / PGLD nano system is suitable for use in nano medicine. (author)

  7. Surface modification of Cobalt ferrite nano-hollowspheres for inherent multiple photoluminescence and enhanced photocatalytic activities

    Science.gov (United States)

    Talukdar, Souvanik; Mandal, Dipika; Mandal, Kalyan

    2017-03-01

    Nano-hollow spheres (NHSs) are the new drift in magnetic nanostructures as they provide more surface area at nano length scale with enhanced magnetic properties compared to their nanoparticle counterpart. Here we reported the synthesis of biocompatible CoFe2O4 NHSs of diameter around 250 nm and emergence of intrinsic multiple photoluminescence from blue, green to red on modifying their surface with small organic ligands like tartrate. The surface modified NHSs also showed notable photocatalytic activity towards the degradation of environmentally malefic dyes like Methylene Blue and Rhodamine B. The surface modified NHSs are found to exhibit superior magnetic properties.

  8. Impacts of Ni–Co substitution on the structural, magnetic and dielectric properties of magnesium nano-ferrites fabricated by micro-emulsion method

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Rajjab; Mahmood, Azhar [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Khan, Muhammad Azhar [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Chughtai, Adeel Hussain [Institute of Chemical Sciences, Bahauddin Zakaryia University, Multan 6100 (Pakistan); Shahid, Muhammad [BK 21 Physics Research Division, Institute of Basic Sciences, SKKU Advanced Institute of Nanotechnology, Department of Energy Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Shakir, Imran [Deanship of Scientific Research, College of Engineering, King Saud University, PO Box 800, Riyadh 11421 (Saudi Arabia); Warsi, Muhammad Farooq, E-mail: farooqsi_warsi@yahoo.com [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan)

    2014-01-25

    Graphical abstract: Ni–Co substituted magnesium ferrite (Mg{sub 1−x} Ni{sub y} Fe{sub 2−y} Co{sub y} O{sub 4}) nano-structures were successfully fabricated by a cheap route. The Mg{sub 0.6} Ni{sub 0.4} Co{sub 0.4} Fe{sub 1.6}O{sub 4} (x, y = 0.4) nano-ferrite exhibited the maximum magnetic behavior and minimum dielectric behavior, that suggested their applications in devices working at GHz frequencies. Highlights: • Mg{sub 1-x}Ni{sub x}Co{sub y}Fe{sub 2-y}O{sub 4} nano ferrites were successfully fabricated by cheap route. • The magnetic behavior was increased up to x = 0.4. • Mg{sub 0.6} Ni{sub 0.4} Co{sub 0.4} Fe{sub 1.6}O{sub 4} nano-ferrite can be used in high frequency devices. -- Abstract: Magnesium ferrite (MgFe{sub 2}O{sub 4}) nano-structures doped with Ni–Co at magnesium and iron sites respectively were fabricated by the micro-emulsion method and characterized by the X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM) and dielectric measurements. The analysis of XRD patterns confirm the single phase spinel structure and the crystallite size calculated by Scherer’s formula lies in the range of 15–26 nm. The spectral studies elucidate the characteristic feature of spinel phase. The real and imaginary parts of dielectric constant and dielectric loss exhibit peaking behavior. The dielectric properties have been explained on the basis of Debye-type relaxation phenomenon in accordance with Koop’s phenomenological theory. The increase in the tendency of saturation magnetization is consistent with the enhancement of crystallinity. The crystallite size is small enough to obtain considerable signal to noise ratio in the recording media. The optimized dielectric and magnetic parameters suggest that the material with composition Mg{sub 0.6} Ni{sub 0.4} Co{sub 0.4} Fe{sub 1.6}O{sub 4} may be used for applications in recording media and microwave devices.

  9. An in situ powder neutron diffraction study of nano-precipitate formation during processing of oxide-dispersion-strengthened ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hongtao, E-mail: hongtao.zhang@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Gorley, Michael J. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Chong, Kok Boon; Fitzpatrick, Michael E. [Materials Engineering, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Roberts, Steve G.; Grant, Patrick S. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom)

    2014-01-05

    Highlights: • In situ powder neutron diffraction to study precipitate formation in ODS steel. • First real time observation of nano-precipitate formation during processing. • Y{sub 2}O{sub 3} particles were fully dissolved into steel matrix during mechanical alloy. • The precipitation occurred during annealing of as-milled powder above 900 °C. -- Abstract: The evolution of phases in a Fe–14Cr–10Y{sub 2}O{sub 3} (wt%) oxide-dispersion-strengthened ferritic steel during mechanical alloying (MA) and subsequent annealing was studied by high resolution powder neutron diffraction, with emphasis on the kinetics of oxide-based nano-precipitate formation. Y{sub 2}O{sub 3} particles were completely dissolved into the ferritic matrix during MA. The formation of nano-precipitates was then observed by in situ thermo-diffraction experiments during annealing of as-milled powder above 900 °C, supported by scanning electron microscopy. This revealed nano-precipitate coarsening with increasing annealing temperature. Powder microhardness was measured at various processing stages, and hardness changes are discussed in terms of the measured phase fractions, crystallite size and lattice strain at different temperatures and times.

  10. Preparation and characterization chemistry of nano-crystalline Ni-Cu-Zn ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Hashim, Mohd, E-mail: md.hashim09@gmail.com [Department of Applied Physics, Aligarh Muslim University, Aligarh 202002 (India); Alimuddin [Department of Applied Physics, Aligarh Muslim University, Aligarh 202002 (India); Shirsath, Sagar E. [Spin Device Technology Centre, Faculty of Engineering, Shinshu University, Nagano 380-8553 (Japan); Kumar, Shalendra [Department of Physics, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Kumar, Ravi [Centre for Material Science Engineering, National Institute of Technology, Hamirpur, HP (India); Roy, Aashis S. [Department of Materials Engineering, Indian Institute of Science, Bangalore, Karnataka (India); Shah, Jyoti; Kotnala, R.K. [National Physical Laboratory (CSIR), Dr. K.S. Krishnan Road, New Delhi 110012 (India)

    2013-02-05

    Highlights: Black-Right-Pointing-Pointer Single phase Ni{sub 0.5}Cu{sub 0.25}Zn{sub 0.25}Fe{sub 2-x}In{sub x}O{sub 4} ferrites were synthesized by citrate-nitrate precursor auto combustion. Black-Right-Pointing-Pointer Magnetic properties decreased due to the substitution of In{sup 3+} ions. Black-Right-Pointing-Pointer Dielectric properties decreased with increase in frequency. Black-Right-Pointing-Pointer This composition can be used for multilayer chip inductor (MLCI) applications. - Abstract: In submitted research; nanocrystalline powders having elements Ni{sub 0.5}Cu{sub 0.25}Zn{sub 0.25}Fe{sub 2-x}In{sub x}O{sub 4} with varied amounts of indium (x = 0.0, 0.1, 0.2, 0.3 and 0.4) were grown-up by modified citrate to nitrate alchemy. The realism of single phase cubic spinel creation of the synthesized ferrite samples was studied by the DTA-TGA, XRD, SEM, EDX, FT-IR, VSM and dielectric measurements. SEM was applied to inspect the morphological variations and EDX was used to determine the compositional mass ratios. The studies on the dielectric constant ({epsilon} Prime ), dielectric loss ({epsilon} Double-Prime ), loss tangent (tan {delta}), ac conductivity ({sigma}{sub ac}), resistive and reactive parts of the impedance analysis (Z' and Z') at room temperature were also carried out. The saturation magnetizations (Ms) were determined using the vibrating sample magnetometer (VSM). Ms. decreased with the increase In{sup 3+} doping content, as Fe{sup 3+} of 5{mu}{sub B} ions are replaced by In{sup 3+} of 0 {mu}{sub B} ions.

  11. Design and Fabrication of Millimeter Wave Hexagonal Nano-Ferrite Circulator on Silicon CMOS Substrate

    Science.gov (United States)

    Oukacha, Hassan

    The rapid advancement of Complementary Metal Oxide Semiconductor (CMOS) technology has formed the backbone of the modern computing revolution enabling the development of computationally intensive electronic devices that are smaller, faster, less expensive, and consume less power. This well-established technology has transformed the mobile computing and communications industries by providing high levels of system integration on a single substrate, high reliability and low manufacturing cost. The driving force behind this computing revolution is the scaling of semiconductor devices to smaller geometries which has resulted in faster switching speeds and the promise of replacing traditional, bulky radio frequency (RF) components with miniaturized devices. Such devices play an important role in our society enabling ubiquitous computing and on-demand data access. This thesis presents the design and development of a magnetic circulator component in a standard 180 nm CMOS process. The design approach involves integration of nanoscale ferrite materials on a CMOS chip to avoid using bulky magnetic materials employed in conventional circulators. This device constitutes the next generation broadband millimeter-wave circulator integrated in CMOS using ferrite materials operating in the 60GHz frequency band. The unlicensed ultra-high frequency spectrum around 60GHz offers many benefits: very high immunity to interference, high security, and frequency re-use. Results of both simulations and measurements are presented in this thesis. The presented results show the benefits of this technique and the potential that it has in incorporating a complete system-on-chip (SoC) that includes low noise amplifier, power amplier, and antenna. This system-on-chip can be used in the same applications where the conventional circulator has been employed, including communication systems, radar systems, navigation and air traffic control, and military equipment. This set of applications of

  12. The comparative study of the structural and the electrical properties of the nano spinel ferrites prepared by the soft mehanochemical synthesis

    Directory of Open Access Journals (Sweden)

    Sekulić D.L.

    2014-01-01

    Full Text Available Nano spinel ferrites MFe2O4 (M=Ni, Mn, Zn were obtained by soft mechanochemical synthesis in a planetary ball mill. The appropriate mixture of oxide and hydroxide powders was used as initial compounds. All of this mixture of powders was mechanically activated, uniaxial pressed and sintered at 1100°C/2h. The phase composition of the powders and sintered samples were analyzed by XRD and Raman spectroscopy. Morphologies were examined by SEM. In this study, the AC-conductivity and DC-resistivity of sintered samples of MFe2O4 (M= Ni, Mn, Zn ferrites were measured at different frequencies and at room temperature. The values of the electrical conductivities show an increase with increasing temperature, which indicated the semiconducting behavior of the studied ferrites. The conduction phenomenon of the investigated samples could be explained on the basis of hopping model. The complex impedance spectroscopy analysis was used to study the effect of grain and grain boundary on the electrical properties of all three obtained ferrites [Projekat Ministarstva nauke Republike Srbije, br. III 45003

  13. Copper doped nickel ferrite nano-crystalline thin films: A potential gas sensor towards reducing gases

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Pratibha; Godbole, R.V.; Bhagwat, Sunita, E-mail: smb.agc@gmail.com

    2016-03-01

    NiFe{sub 2}O{sub 4} and (1 wt% and 3 wt%) Cu:NiFe{sub 2}O{sub 4} thin films have been fabricated using spray pyrolysis deposition technique at 350 °C and then sintered at 650 °C for 3 h. X-ray diffraction, SEM, EDAX, UV-VIS spectroscopy, SQUID VSM were carried out to investigate phase formation, microstructural and influence of Cu doping on magnetic properties of NiFe{sub 2}O{sub 4} thin films. The gas response towards various gases viz. ethanol, Liquid Petroleum Gas (LPG), methanol and hydrogen sulfide (H{sub 2}S) is investigated. The results of XRD revealed that all samples had shown the principal phase of nickel ferrite and the lattice parameter was found to vary from 8.294 Å to 8.314 Å on an incorporation of Cu, and the crystalline sizes were about 40–45 nm. The effect of Cu concentration on saturation magnetization and coercive force were studied. The maximum value of saturation magnetization calculated from hysteresis loop was 89.16 emu/g at room temperature and 96.88 emu/g at 50 K. Cu content on the film surface was found to be maximum for 1 wt% Cu:NiFe{sub 2}O{sub 4} thin film and this film showed an improved response towards all gases. Response of ethanol for NiFe{sub 2}O{sub 4} thin film was found to be higher as compared to all the other gases. The lowering of the optimum operating temperature is observed in 1 wt% Cu:NiFe{sub 2}O{sub 4} thin film with higher selectivity towards ethanol than other gases. All results indicated that the Cu doping in nickel ferrite thin films has a significant influence on the properties. - Highlights: • Cu:NiFe{sub 2}O{sub 4} thin films are synthesized by low cost spray pyrolysis technique. • Addition of Cu content improves magnetic properties. • Cu content on the surface of the film enhances the gas response. • NiFe{sub 2}O{sub 4} thin films exhibit predominant selectivity towards ethanol. • 1 wt% Cu:NiFe{sub 2}O{sub 4} film responses towards ethanol at lower optimum temperature.

  14. Transport properties of nano manganese ferrite-propylene glycol dispersion (nanofluids): new observations and discussion

    Science.gov (United States)

    Aishwarya, V.; Suganthi, K. S.; Rajan, K. S.

    2013-07-01

    Experiments were conducted on the preparation of manganese ferrite nanoparticles and their surface modification for dispersion in propylene glycol. The appropriate concentrations of ferrous sulphate and manganese sulphate (precursors) for synthesis of uniform Mn0.43Fe2.57O4 nanoparticles (size range 20-25 nm) were found to be 0.05 and 0.025 M, respectively. These nanoparticles were coated with citric acid and dispersed in propylene glycol for the preparation of nanofluids. The effects of temperature and nanoparticle concentration on nanofluid viscosity and thermal conductivity have been studied. Our study on the influence of nanoparticle concentration on viscosity reveals the existence of a viscosity minimum for 0.25 vol% of citric acid-modified Mn0.43Fe2.57O4-propylene glycol nanofluid. A thermal conductivity enhancement of 68 % was observed for 2 vol% nanofluid. Correlating viscosity and thermal conductivity measurements, particle clustering seems to be the major factor responsible for thermal conductivity enhancement.

  15. Structural and magnetic properties of nano-sized NiCuZn ferrites synthesized by co-precipitation method with ultrasound irradiation

    Science.gov (United States)

    Harzali, Hassen; Saida, Fairouz; Marzouki, Arij; Megriche, Adel; Baillon, Fabien; Espitalier, Fabienne; Mgaidi, Arbi

    2016-12-01

    Sonochemically assisted co-precipitation has been used to prepare nano-sized Ni-Cu-Zn-ferrite powders. A suspension of constituent hydroxides was ultrasonically irradiated for various times at different temperatures with high intensity ultrasound radiation using a direct immersion titanium horn. Structural and magnetic properties were investigated using X-diffraction (XRD), FT-IR spectroscopy, transmission electron microscopy (TEM), Nitrogen adsorption at 77 K (BET) and Vibrating sample magnetometer (VSM). Preliminary experimental results relative to optimal parameters showed that reaction time t=2 h, temperature θ=90 °C and dissipated Power Pdiss=46.27 W. At these conditions, this work shows the formation of nanocrystalline single-phase structure with particle size 10-25 nm. Also, ours magnetic measurements proved that the sonochemistry method has a great influence on enhancing the magnetic properties of the ferrite.

  16. Preparation, characterization and application of nanosized copper ferrite photocatalysts for dye degradation under UV irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Zaharieva, Katerina, E-mail: zaharieva@ic.bas.bg [Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Block 11, 1113 Sofia (Bulgaria); Rives, Vicente, E-mail: vrives@usal.es [GIR-QUESCAT, Dpto. Química Inorgánica, Universidad de Salamanca, 37008 Salamanca (Spain); Tsvetkov, Martin, E-mail: mptsvetkov@gmail.com [Faculty of Chemistry and Pharmacy, St. Kliment Ohridski University of Sofia, 1 J. Bourchier Blvd., 1164 Sofia (Bulgaria); Cherkezova-Zheleva, Zara, E-mail: zzhel@ic.bas.bg [Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Block 11, 1113 Sofia (Bulgaria); Kunev, Boris, E-mail: bkunev@ic.bas.bg [Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Block 11, 1113 Sofia (Bulgaria); Trujillano, Raquel, E-mail: rakel@usal.es [GIR-QUESCAT, Dpto. Química Inorgánica, Universidad de Salamanca, 37008 Salamanca (Spain); Mitov, Ivan, E-mail: mitov@ic.bas.bg [Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Block 11, 1113 Sofia (Bulgaria); Milanova, Maria, E-mail: nhmm@wmail.chem.uni-sofia.bg [Faculty of Chemistry and Pharmacy, St. Kliment Ohridski University of Sofia, 1 J. Bourchier Blvd., 1164 Sofia (Bulgaria)

    2015-06-15

    {sup −3} min{sup −1}) for degradation of organic dye Malachite green under UV irradiation. - Highlights: • Copper ferrites via co-precipitation, mechanochemical and/or thermal treatment. • Nano ferrites show a superparamagnetic and collective magnetic excitations nature. • The co-precipitated Cu{sub 0.25}Fe{sub 2.75}O{sub 4} posses the highest photocatalytic activity. • The amount adsorbed Malachite Green by catalyst depends on the preparation method. • The prepared copper ferrites can be applicable as cheap adsorbents and catalysts.

  17. Structural and physical properties of the nano-crystalline Al-substituted Cr–Cu ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Amer, M.A., E-mail: moazamer@hotmail.com [Physics Department, Faculty of Science, Tanta university, 31527, Tanta (Egypt); Meaz, T.M. [Physics Department, Faculty of Science, Tanta university, 31527, Tanta (Egypt); Mostafa, A.G. [Physics Department, Faculty of Science, Tanta university, 31527, Tanta (Egypt); ME Lab, Physics Department, Faculty of Science, Al-azhar University, Cairo (Egypt); El-Ghazally, H.F. [Physics Department, Faculty of Science, Tanta university, 31527, Tanta (Egypt)

    2013-10-15

    Ferrite nanoparticles are promising future materials for applications in medicine, ferrofluids, technical designing and other fields. The as-prepared CuAl{sub x}Cr{sub 0.8−x}Fe{sub 1.2}O{sub 4} nanoparticles (0≤x≤0.8) have been prepared by the chemical co-precipitation method. A study of the structure and other physical properties of the samples was carried out by using X-ray, infrared, Mössbauer and vibrating sample magnetometer (VSM) patterns and particle size distributions. The results revealed the ultrafine nature of the particles, where the crystallite size and the average particle size have been deduced. The values of the lattice parameters and crystallite size were dependent on the substitution factor x, while the oxygen parameter was higher than the standard value and independent on x. In addition to six absorption bands, a triple band attributed to the retained water in the samples was observed in the infrared spectra. The absorption bands indicated the existence of Fe{sup 2+} ions in the sample sublattices. The Mössbauer and VSM patterns proved the presence of small magnetic field in the samples, where the saturation magnetization, coercivity, hyperfine interaction parameters, cation distributions and magnetization were dependent on x. - Highlights: • CuAl{sub x}Cr{sub 0.8−x}Fe{sub 1.2}O{sub 4} nanoparticles are prepared by the co-precipitation method. • X-ray, infrared, Mössbauer and VSM patterns and particle size distributions were used. • X-ray parameters, IR band properties and particle size are dependent on x. • Mössbauer and VSM patterns indicated the presence of a small magnetic filed. • Saturation magnetization, coercivity and Mössbauer parameters are x dependent.

  18. A fully printed ferrite nano-particle ink based tunable antenna

    KAUST Repository

    Ghaffar, Farhan A.

    2016-11-02

    Inkjet printing or printing in general has emerged as a very attractive method for the fabrication of low cost and large size electronic systems. However, most of the printed designs rely on nano-particle based metallic inks which are printed on conventional microwave substrates. In order to have a fully printed fabrication process, the substrate also need to be printed. In this paper, a fully printed multi-layer process utilizing custom Fe2O3 based magnetic ink and a silver organic complex (SOC) ink is demonstrated for tunable antennas applications. The ink has been characterized for high frequency and magnetostatic properties. Finally as a proof of concept, a microstrip patch antenna is realized using the proposed fabrication technique which shows a tuning range of 12.5 %.

  19. Structural and Magnetic Characterizations of Nano Sized Grain Zinc Ferrite/Hydroxyapatite Ceramic Prepared by Solid State Reaction Route.

    Science.gov (United States)

    Pankaew, Piyapong; Klumdoung, Pattarinee

    2015-11-01

    A promising composite of bioactive hydroxyapatite (HAp) and zinc ferrite (ZnFe2O4) has potentials for future bone reinforcing formation. In present study, HAp and ZnFe2O4 composite ceramic was prepared by solid state reaction route for easier control of structural and magnetic characteristics and with low cost. HAp powder was synthesized by precipitation method from chicken eggshell. Mixed powders with varying ZnFe2O4/HAp weight ratios from 2-10 wt% were milled together and uniaxially pressed and then sintered at 1200 degrees C for 3 hours. The XRD results showing no other phases of composite ceramics with only HAp and ZnFe2O4 phases were identified, indicating high stability of HAp property. Phase fractions of ZnFe2O4 were found to increase from 10.8 to 18.73 wt% with increasing content of ZnFe2O4. FT-IR results were only revealed vibration bands of standard HAp phase. SEM results revealed primary grains sizes of the prepared ceramics in nano scale. The BET surface area and pore volume increased with increasing content of ZnFe2O4 in composite ceramics. The VSM results of composites with increasing ZnFe2O4 content had been shown with increasing magnetization from 0.05 to 1.85 emu/g while their coercivities were decreased from 44 to 24 Oe. Higher magnetization as well as higher super paramagnetic behavior could be achieved with increasing the studied ZnFe2O4 weight ratios in ZnFe2O4/HAp composite ceramics, which can be tailored for specific applications.

  20. A ferrite nano-particles based fully printed process for tunable microwave components

    KAUST Repository

    Ghaffar, Farhan A.

    2016-08-15

    With the advent of nano-particles based metallic inks, inkjet printing emerged as an attractive medium for fast prototyping as well as for low cost and flexible electronics. However, at present, it is limited to printing of metallic inks on conventional microwave substrates. For fully printed designs, ideally, the substrate must also be printed. In this work, we demonstrate a fully printed process utilizing a custom Fe2O3 based magnetic ink for functional substrate printing and a custom silver-organo-complex (SOC) ink for metal traces printing. Due to the magnetic nature of the ink, this process is highly suitable for tunable microwave components. The printed magnetic substrate is characterized for the magnetostatic as well as microwave properties. The measured B(H) curve shows a saturation magnetization and remanence of 1560 and 350 Gauss respectively. As a proof of concept, a patch antenna is implemented in the proposed stack up which shows a tuning range of 4 % around the center frequency. © 2016 IEEE.

  1. Structural and magnetic properties of nano-sized NiCuZn ferrites synthesized by co-precipitation method with ultrasound irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Harzali, Hassen, E-mail: harzali@mines-albi.fr [Laboratory of Applied Mineral Chemistry, Faculty of Sciences, University Tunis ElManar, Campus University, Farhat Hached El-Manar, 2092 Tunis (Tunisia); Saida, Fairouz; Marzouki, Arij; Megriche, Adel [Laboratory of Applied Mineral Chemistry, Faculty of Sciences, University Tunis ElManar, Campus University, Farhat Hached El-Manar, 2092 Tunis (Tunisia); Baillon, Fabien; Espitalier, Fabienne [Université de Toulouse, Mines Albi, CNRS, Centre RAPSODEE, Campus Jarlard, F-81013 Albi CT cedex 09 (France); Mgaidi, Arbi [Laboratory of Applied Mineral Chemistry, Faculty of Sciences, University Tunis ElManar, Campus University, Farhat Hached El-Manar, 2092 Tunis (Tunisia); Taibah University, Faculty of Sciences & art, Al Ula (Saudi Arabia)

    2016-12-01

    Sonochemically assisted co-precipitation has been used to prepare nano-sized Ni–Cu–Zn-ferrite powders. A suspension of constituent hydroxides was ultrasonically irradiated for various times at different temperatures with high intensity ultrasound radiation using a direct immersion titanium horn. Structural and magnetic properties were investigated using X-diffraction (XRD), FT-IR spectroscopy, transmission electron microscopy (TEM), Nitrogen adsorption at 77 K (BET) and Vibrating sample magnetometer (VSM). Preliminary experimental results relative to optimal parameters showed that reaction time t=2 h, temperature θ=90 °C and dissipated Power P{sub diss}=46.27 W. At these conditions, this work shows the formation of nanocrystalline single-phase structure with particle size 10–25 nm. Also, ours magnetic measurements proved that the sonochemistry method has a great influence on enhancing the magnetic properties of the ferrite. - Highlights: • Coprecipitation experiments were carried out with ultrasound. • The spinel ferrite NiCuZn was perfectly synthesized by ultrasound. • The saturation magnetization and crystals size are found to be correlated as the dissipated power was varied.

  2. Structural elucidation and magnetic behavior evaluation of rare earth (La, Nd, Gd, Tb, Dy) doped BaCoNi-X hexagonal nano-sized ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Majeed, Abdul, E-mail: abdulmajeed2276@gmail.com [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Khan, Muhammad Azhar, E-mail: azhar.khan@iub.edu.pk [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Raheem, Faseeh ur; Hussain, Altaf; Iqbal, F. [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Murtaza, Ghulam [Centre for Advanced Studies in Physics, Government College University, Lahore 54000 (Pakistan); Akhtar, Majid Niaz [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Shakir, Imran [Deanship of Scientific Research, College of Engineering, King Saud University, PO Box 800, Riyadh 11421 (Saudi Arabia); Warsi, Muhammad Farooq [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan)

    2016-06-15

    Rare-earth (RE=La{sup 3+}, Nd{sup 3+}, Gd{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) doped Ba{sub 2}NiCoRE{sub x}Fe{sub 28−x}O{sub 46} (x=0.25) hexagonal ferrites were synthesized for the first time via micro-emulsion route, which is a fast chemistry route for obtaining nano-sized ferrite powders. These nanomaterials were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), as well as vibrating sample magnetometer (VSM). The XRD analysis exhibited that all the samples crystallized into single X-type hexagonal phase. The crystalline size calculated by Scherrer's formula was found in the range 7–19 nm. The variations in lattice parameters elucidated the incorporation of rare-earth cations in these nanomaterials. FTIR absorption spectra of these X-type ferrites were investigated in the wave number range 500–2400 cm{sup −1.} Each spectrum exhibited absorption bands in the low wave number range, thereby confirming the X-type hexagonal structure. The enhancement in the coercivity was observed with the doping of rare-earth cations. The saturation magnetization was lowered owing to the redistribution of rare-earth cations on the octahedral site (3b{sub VI}). The higher values of coercivity (664–926 Oe) of these nanomaterials suggest their use in longitudinal recording media. - Graphical abstract: Nano-sized rare-earth (RE=La{sup 3+}, Nd{sup 3+}, Gd{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) doped Ba{sub 2}NiCoRE{sub x}Fe{sub 28−x}O{sub 46} (x=0.25) hexagonal ferrites were synthesized for the first time via micro-emulsion route and the crystallite size was found in the range 7–19 nm. The enhancement in the coercivity was observed with the doping of rare-earth cations. The higher values of coercivity (664–926 Oe) of these nanomaterials suggest their use in longitudinal recording media. - Highlights: • Micro-emulsion route was used to synthesize Ba{sub 2}NiCoRE{sub x}Fe{sub 28−x}O{sub 46} ferrites. • The crystallite size was found

  3. Structural, spectral, dielectric and magnetic properties of Tb-Dy doped Li-Ni nano-ferrites synthesized via micro-emulsion route

    Science.gov (United States)

    Junaid, Muhammad; Khan, Muhammad Azhar; Iqbal, F.; Murtaza, Ghulam; Akhtar, Majid Niaz; Ahmad, Mukhtar; Shakir, Imran; Warsi, Muhammad Farooq

    2016-12-01

    Terbium (Tb) and dysprosium (Dy) doped lithium-nickel nano-sized ferrites (Li0.2Ni0.8Tb0.5xDy0.5xFe2-xO4 where x=0.00-0.08) were prepared by micro-emulsion technique. The X-ray diffraction (XRD) patterns confirmed the single phase cubic spinel structure. The lattice constant was increased due to larger ionic radii of Tb3+ and Dy3+ cations. The crystallite size was found in the range 30-42 nm. The FTIR (Fourier transform infrared spectroscopy) spectra revealed two significant absorption bands (~400-600 cm-1) which indicate the formation of cubic spinel structure. The peaking behavior of dielectric parameters was observed beyond 1.5 GHz. The dielectric constant and dielectric loss were found to decrease by the increase of Tb-Dy contents and frequency. The doping of Tb and Dy in Li-Ni ferrites led to increase the coercive field (120-156 Oe). The smaller magnetic and dielectric parameters suggested the possible utility of these nano-materials in switching and microwave devices applications.

  4. Structural, spectral, dielectric and magnetic properties of Tb–Dy doped Li-Ni nano-ferrites synthesized via micro-emulsion route

    Energy Technology Data Exchange (ETDEWEB)

    Junaid, Muhammad, E-mail: junaid.malik95@yahoo.com [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Khan, Muhammad Azhar, E-mail: azhar.khan@iub.edu.pk [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Iqbal, F. [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Murtaza, Ghulam [Centre for Advanced Studies in Physics, Government College University, Lahore 54000 (Pakistan); Akhtar, Majid Niaz; Ahmad, Mukhtar [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Shakir, Imran [Deanship of scientific research, College of Engineering, King Saud University, PO Box 800, Riyadh 11421 (Saudi Arabia); Warsi, Muhammad Farooq [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan)

    2016-12-01

    Terbium (Tb) and dysprosium (Dy) doped lithium-nickel nano-sized ferrites (Li{sub 0.2}Ni{sub 0.8}Tb{sub 0.5x}Dy{sub 0.5x}Fe{sub 2−x}O{sub 4} where x=0.00−0.08) were prepared by micro-emulsion technique. The X-ray diffraction (XRD) patterns confirmed the single phase cubic spinel structure. The lattice constant was increased due to larger ionic radii of Tb{sup 3+} and Dy{sup 3+} cations. The crystallite size was found in the range 30–42 nm. The FTIR (Fourier transform infrared spectroscopy) spectra revealed two significant absorption bands (~400–600 cm{sup −1}) which indicate the formation of cubic spinel structure. The peaking behavior of dielectric parameters was observed beyond 1.5 GHz. The dielectric constant and dielectric loss were found to decrease by the increase of Tb–Dy contents and frequency. The doping of Tb and Dy in Li–Ni ferrites led to increase the coercive field (120–156 Oe). The smaller magnetic and dielectric parameters suggested the possible utility of these nano-materials in switching and microwave devices applications. - Highlights: • Li{sub 0.2}Ni{sub 0.8}Tb{sub 0.5x}Dy{sub 0.5x}Fe{sub 2-x}O{sub 4} ferrites were synthesized by micro-emulsion route. • Tb and Dy addition improves coercivity while decreased saturation magnetization. • These nanomaterials can be useful in microwave and switching devices applications.

  5. Biological synthesis of cobalt ferrite nanoparticles

    Directory of Open Access Journals (Sweden)

    Anal K. Jha

    2012-01-01

    Full Text Available A low-cost green and reproducible yeast (Saccharomyces cerevisiae mediated biosynthesis of cobalt ferrite nanoparticles is reported. The synthesis is performed at close to room temperature in the laboratory. X-ray, Fourier transform infrared spectroscopy and high resolution transmission electron microscopy analyses are performed to ascertain the formation of cobalt ferrite nanoparticles. Individual nanoparticles, as well as a very few aggregate having the size of 3-15 nm, were found. The vibrating sample magnetometer measurement showed superparamagnetic behavior in cobalt ferrite nanoparticles. The mechanism involved in the biosynthesis of cobalt ferrite nanoparticles has also been discussed.

  6. Evaluation of Microstructure and Mechanical Properties of Nano-Y2O3-Dispersed Ferritic Alloy Synthesized by Mechanical Alloying and Consolidated by High-Pressure Sintering

    Science.gov (United States)

    Karak, Swapan Kumar; Dutta Majumdar, J.; Witczak, Zbigniew; Lojkowski, Witold; Ciupiński, Łukasz; Kurzydłowski, K. J.; Manna, Indranil

    2013-06-01

    In this study, an attempt has been made to synthesize 1.0 wt pct nano-Y2O3-dispersed ferritic alloys with nominal compositions: 83.0 Fe-13.5 Cr-2.0 Al-0.5 Ti (alloy A), 79.0 Fe-17.5 Cr-2.0 Al-0.5 Ti (alloy B), 75.0 Fe-21.5 Cr-2.0 Al-0.5 Ti (alloy C), and 71.0 Fe-25.5 Cr-2.0 Al-0.5 Ti (alloy D) steels (all in wt pct) by solid-state mechanical alloying route and consolidation the milled powder by high-pressure sintering at 873 K, 1073 K, and 1273 K (600°C, 800°C, and 1000°C) using 8 GPa uniaxial pressure for 3 minutes. Subsequently, an extensive effort has been undertaken to characterize the microstructural and phase evolution by X-ray diffraction, scanning and transmission electron microscopy, and energy dispersive spectroscopy. Mechanical properties including hardness, compressive strength, Young's modulus, and fracture toughness were determined using micro/nano-indentation unit and universal testing machine. The present ferritic alloys record extraordinary levels of compressive strength (from 1150 to 2550 MPa), Young's modulus (from 200 to 240 GPa), indentation fracture toughness (from 3.6 to 15.4 MPa√m), and hardness (from13.5 to 18.5 GPa) and measure up to 1.5 through 2 times greater strength but with a lower density (~7.4 Mg/m3) than other oxide dispersion-strengthened ferritic steels (tungsten-based alloys (<2200 MPa). Besides superior mechanical strength, the novelty of these alloys lies in the unique microstructure comprising uniform distribution of either nanometric (~10 nm) oxide (Y2Ti2O7/Y2TiO5 or un-reacted Y2O3) or intermetallic (Fe11TiY and Al9.22Cr2.78Y) particles' ferritic matrix useful for grain boundary pinning and creep resistance.

  7. Oil/water nano-emulsion loaded with cobalt ferrite oxide nanocubes for photo-acoustic and magnetic resonance dual imaging in cancer: in vitro and preclinical studies.

    Science.gov (United States)

    Vecchione, Raffaele; Quagliariello, Vincenzo; Giustetto, Pierangela; Calabria, Dominic; Sathya, Ayyappan; Marotta, Roberto; Profeta, Martina; Nitti, Simone; Silvestri, Niccolò; Pellegrino, Teresa; Iaffaioli, Rosario V; Netti, Paolo Antonio

    2017-01-01

    Dual imaging dramatically improves detection and early diagnosis of cancer. In this work we present an oil in water (O/W) nano-emulsion stabilized with lecithin and loaded with cobalt ferrite oxide (Co0.5Fe2.5O4) nanocubes for photo-acoustic and magnetic resonance dual imaging. The nanocarrier is responsive in in vitro photo-acoustic and magnetic resonance imaging (MRI) tests. A clear and significant time-dependent accumulation in tumor tissue is shown in in vivo photo-acoustic studies on a murine melanoma xenograft model. The proposed O/W nano-emulsion exhibits also high values of r2/r1 (ranging from 45 to 85, depending on the magnetic field) suggesting a possible use as T2 weighted image contrast agents. In addition, viability and cellular uptake studies show no significant cytotoxicity on the fibroblast cell line. We also tested the O/W nano-emulsion loaded with curcumin against melanoma cancer cells demonstrating a significant cytotoxicity and thus showing possible therapeutic effects in addition to the in vivo imaging. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Sintering effect on structural, magnetic and optical properties of Ni0.5Zn0.5Fe2O4 ferrite nano particles

    Science.gov (United States)

    Kannan, Y. B.; Saravanan, R.; Srinivasan, N.; Ismail, I.

    2017-02-01

    Ni0.5Zn0.5Fe2O4 nano ferrite particles have been prepared by mechanical alloying via high energy ball milling and sintered at different temperatures from 700 °C to 1000 °C. Spinel structure is confirmed from the analysis of XRD data. Rietveld refinement method is employed to refine the XRD powder data and the structural parameters are calculated from the refinement. Small amount of hematite phase is found in all samples. The SEM, EDAX and XRF analysis reveals respectively the morphology, stoichiometric composition and purity of the powder samples. Using Maximum Entropy Method (MEM) the values of the bond strength between various sites interactions in ferrites are evaluated and compared with theoretical predictions of strengthening/weakening of various sites interactions from the values of interionic distances and interionic bond angles. Ferromagnetic nature of the samples is confirmed from the vibrating sample magnetometer study. The obtained low saturation magnetization values are attributed to presence of second phase. The optical band gap energy of the samples was determined by using UV-VIS techniques.

  9. Synthesis and Structural Characterization of Cu Substituted Ni-Zn Nano-Ferrites Prepared By Citrate-Gel Auto Combustion Technique

    Directory of Open Access Journals (Sweden)

    N. Hari Kumar

    2014-07-01

    Full Text Available The ferrite nano particles having chemical formula Ni0.2CuxZn0.8-xFe2O4 (where x=0.0 to 0.8 with step of 0.2 were synthesized by Citrate-Gel Auto Combustion method at low temperature. The synthesized powders were sintered at 500oC for 4 hours in air and characterised by XRD, SEM with EDS. XRD analysis of prepared samples were confirmed the single phase cubic spinel Structure. The crystallite size (D of prepared ferrites were in the range of 24-73nm. The values of lattice parameter (a decreased and X-ray density (dx were increased with the increasing of Cu substitution. The surface morphology of the prepared samples was investigated by Scanning Electron Microscope(SEM. An elemental composition of the samples was studied by Energy Dispersive Spectroscopy(EDS. The observed results can be explained on the basis of composition and crystal size.

  10. Effect of nano-sized precipitates on the crystallography of ferrite in high-strength strip steel

    Science.gov (United States)

    Yang, Jing-jing; Wu, Run; Liang, Wen; Tang, Meng-xia

    2014-05-01

    For strip steel with the thickness of 1.6 mm, the yield and tensile strengths as high as 760 and 850 MPa, respectively, were achieved using the compact strip production technology. Precipitates in the steel were characterized by scanning and transmission electron microscopy to elucidate the strengthening mechanism. In addition, intragranular misorientation, Kernel average misorientation, and stored energy were measured using electron backscatter diffraction for crystallographic analysis of ferrite grains containing precipitates and their neighbors without precipitates. It is found that precipitates in specimens primarily consist of TiC and Ti4C2S2. Ferrite grains containing precipitates exhibit the high Taylor factor as well as the crystallographic orientations with {012}, {011}, {112}, or {221} plane parallel to the rolling plane. Compared with the intragranular orientation of adjoining grains, the intragranular misorientation of grains containing precipitates fluctuates more frequently and more mildly as a function of distance. Moreover, the precipitates can induce ferrite grains to store a relatively large amount of energy. These results suggest that a correlation exists between precipitation in ferrite grains and grain crystallographic properties.

  11. Effect of nano-sized precipitates on the crystallography of ferrite in high-strength strip steel

    Institute of Scientific and Technical Information of China (English)

    Jing-jing Yang; Run Wu; Wen Liang; Meng-xia Tang

    2014-01-01

    For strip steel with the thickness of 1.6 mm, the yield and tensile strengths as high as 760 and 850 MPa, respectively, were achieved using the compact strip production technology. Precipitates in the steel were characterized by scanning and transmission electron microscopy to elucidate the strengthening mechanism. In addition, intragranular misorientation, Kernel average misorientation, and stored energy were measured using electron backscatter diffraction for crystallographic analysis of ferrite grains containing precipitates and their neighbors without precipitates. It is found that precipitates in specimens primarily consist of TiC and Ti4C2S2. Ferrite grains containing pre-cipitates exhibit the high Taylor factor as well as the crystallographic orientations with{012},{011},{112}, or{221}plane parallel to the rolling plane. Compared with the intragranular orientation of adjoining grains, the intragranular misorientation of grains containing precipi-tates fluctuates more frequently and more mildly as a function of distance. Moreover, the precipitates can induce ferrite grains to store a rela-tively large amount of energy. These results suggest that a correlation exists between precipitation in ferrite grains and grain crystallographic properties.

  12. Magnetic and structural properties of nano sized Dy-doped cobalt ferrite synthesized by co-precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Karimi, Z., E-mail: Zahra_kr64@yahoo.com [Department of Materials Engineering, Institute of Mechanical Engineering, University of Tabriz, Tabriz 51666-16471 (Iran, Islamic Republic of); Mohammadifar, Y.; Shokrollahi, H. [Electroceramics Group, Department of Materials Science and Engineering, Shiraz University of Technology, Shiraz (Iran, Islamic Republic of); Asl, Sh. Khameneh [Department of Materials Engineering, Institute of Mechanical Engineering, University of Tabriz, Tabriz 51666-16471 (Iran, Islamic Republic of); Yousefi, Gh. [Center for Pharmaceutical Nanotechnology and Biomaterials, Pharmaceutical Sciences Research Center, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz (Iran, Islamic Republic of); Department of Pharmaceutics, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz (Iran, Islamic Republic of); Karimi, L. [Materials Science and Engineering Department, Islamic Azad University Ahvaz Branch, Ahvaz (Iran, Islamic Republic of)

    2014-06-01

    Regarding the various applications of cobalt ferrite as a magnetic ceramic in various scientific and industrial categories, it is essential to modify and optimize its microstructural and magnetic features. Chemical composition (doped elements and their quantities) is a determining factor which has been studied in this research. For this purpose, cobalt-dysprosium ferrite ceramic nanoparticles with the chemical formula Co{sub 1−x}Dy{sub x}Fe{sub 2}O{sub 4} (x=0, 0.01, 0.03, 0.05, 0.1) were synthesized by the co-precipitation chemical method and then analyzed from the structural and magnetic perspectives. The desirable spinel phase formation was confirmed via x-ray diffractometry, and the other crystallographic parameters and cation distribution were calculated. The microscopic image of the samples showed 15 nm particles. The type and strength of the interionic bonds were determined by infrared spectroscopy. The hysteresis loop of the material was affected noticeably by doped elements as the room temperature saturation magnetization was decreased, but the residual magnetization and coercivity of ferrite were promoted by 50 and 150% after adding dysprosium, respectively. The maximum anisotropy constant, which is equal to 19.1 erg/g for undoped cobalt ferrite, was increased to 45.2 erg/g by doping 0.05 dysprosium. It is worth mentioning that introducing dopants into the lattice led to a great decrease in Curie temperature. - Highlights: • Magnetic and structural studies of Dy{sup 3+}–Co–ferrite are investigated. • Simple co-precipitation method involving less energy and low-cost is used. • The nanoparticles with high coercivity, magnetization and loop area are obtained. • The composition Co{sub 0.95}Dy{sub 0.05}Fe{sub 2}O{sub 4} has the maximum coercivity and high residual magnetization.

  13. Synthesis and characterization of magnetic cobalt ferrite nanoparticles covered with 3-aminopropyltriethoxysilane for use as hybrid material in nano technology; Sintese e caracterizacao de nanoparticulas magneticas de ferrita de cobalto recobertas por 3-aminopropiltrietoxissilano para uso como material hibrido em nanotecnologia

    Energy Technology Data Exchange (ETDEWEB)

    Camilo, Ruth Luqueze

    2006-07-01

    Nowadays with the appear of nano science and nano technology, magnetic nanoparticles have been finding a variety of applications in the fields of biomedicine, diagnosis, molecular biology, biochemistry, catalysis, etc. The magnetic functionalized nanoparticles are constituted of a magnetic nucleus, involved by a polymeric layer with active sites, which ones could anchor metals or selective organic compounds. These nanoparticles are considered organic inorganic hybrid materials and have great interest as materials for commercial applications due to the specific properties. Among the important applications it can be mentioned: magneto hyperthermia treatment, drugs delivery in specific local of the body, molecular recognition, biosensors, enhancement of nuclear magnetic resonance images quality, etc. This work was developed in two parts: 1) the synthesis of the nucleus composed by superparamagnetic nanoparticles of cobalt ferrite and, 2) the recovering of nucleus by a polymeric bifunctional 3-aminopropyltriethoxysilane. The parameters studied in the first part of the research were: pH, hydroxide molar concentration, hydroxide type, reagent order of addition, reagent way of addition, speed of shake, metals initial concentrations, molar fraction of cobalt and thermal treatment. In the second part it was studied: pH, temperature, catalyst type, catalyst concentration, time of reaction, relation ratios of H{sub 2}O/silane, type of medium and the efficiency of the recovering regarding to pH. The products obtained were characterized using the following techniques X-ray powder diffraction (DRX), transmission electronic microscopy (TEM), scanning electronic microscopy (SEM), spectroscopy of scatterbrained energy spectroscopy (DES), atomic emission spectroscopy (ICP-AES), thermogravimetric analysis (TGA/DTGA), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and magnetization curves (VSM). (author)

  14. Structural and magnetic Properties of TbZn-substituted calcium barium M-type nano-structured hexa-ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Hasan M. [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Department of Electronics, University of York, York YO10 5DD (United Kingdom); Islam, M.U., E-mail: dr.misbahulislam@bzu.edu.pk [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Xu, Yongbing [Department of Electronics, University of York, York YO10 5DD (United Kingdom); Nanjing–York International Centre of Spintronics and Nano-Engineering, Nanjing University, Nanjing 210093 (China); Asif Iqbal, M. [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); National University of Science and Technology, College of E and ME, Islamabad (Pakistan); Ali, Irshad [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan)

    2014-03-15

    Highlights: • Tb–Zn substituted Ca{sub 0.5}Ba{sub 0.5}Fe{sub 12}O{sub 19} samples exhibit single magnetoplumbite phase. • Lattice parameters a and c have increasing values. • Coercivity can be tuned at lower substitution level • Crystallites size was found in the range 18–25 nm by TEM and by Scherrer formula. • These hexa-ferrites are suitable for microwave devices and magnetic recording media. -- Abstract: Effect of TbZn substitution on the structural and magnetic properties of Ca{sub 0.5}Ba{sub 0.5−x}Tb{sub x}Zn{sub y}Fe{sub 12−y}O{sub 19}, (x = 0.00–0.10; y = 0.00–1.00) ferrites prepared by sol–gel auto combustion is reported. The synthesized samples were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Vibrating Sample magnetometery. The X-ray diffraction analysis confirmed single phase M-type hexa-ferrite structure. The lattice parameters were found to increase as TbZn contents increases, which is attributed to the ionic sizes of the implicated cations. The TbZn seems to be completely soluble in the lattice. The results of scanning electron microscopy and transmission electron microscopy shows that the grain size decreases with increase of TbZn substitution. The coercivity values (1277–2025 Oe) of all samples lies in the range of M-type hexa-ferrite and indicate that an increase of anisotropy was achieved by substitution of TbZn, while the size of nanoparticles was drastically reduced between 18 and 25 nm. The increased anisotropy and fine particle size are useful for many applications, such as improving signal noise ratio of recording devices.

  15. Combustion synthesis by reaction and characterization of nano ferrites: study of fuel aniline, citric and its mixture; Sintese por reacao de combustao e caracterizacao de nanoferritas Ni-Zn: estudo dos combustiveis anilina, acido citrico e sua mistura

    Energy Technology Data Exchange (ETDEWEB)

    Silva, M.C. da; Coutinho, J.P.; Costa, A.C.F.M., E-mail: normanda@ufcg.edu.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais; Kiminami, R.H.G.A. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Engenharia de Materiais; Freitas, N.L. de [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Tecnologia do Desenvolvimento

    2012-07-01

    The present study aims to evaluate the influence of aniline and citric acid used alone and combined in a ratio of 50% each in the characterization of NiZn ferrite synthesized by combustion reaction method in a muffle furnace. Measurements were made of temperature and reaction time. The nano-powders were characterized by XRD, EDX, textural analysis and SEM. The highest temperature was achieved by the reaction using the mixture of fuel and increased reaction time using citric acid. The nano ferrites using different fuels, and the mixture changed phases, the crystallite size and decreased surface area of the samples with aniline, citric acid and a mixture of both, respectively. The powder morphology ranged from presenting the formation of irregular blocks for the use of citric agglomerated in the form of skeins with aniline and a mixture to agglomerate larger particles. (author)

  16. Structural, Optical and EXAFS Studies of Nickel Substituted Copper Ferrites Nano-Particle by Sol-Gel Auto Combustion Method

    Science.gov (United States)

    Mishra, Ashutosh; khan, Mehjabeen; Jarabana, Kanaka M.; Bisen, Supriya

    2016-10-01

    The Cu-Ni ferrites with general formula Cu1-xNixFe2O4 (where x=0.0, 0.1, 0.2, 0.3) were prepared by sol gel method. The Extended X-ray absorption fine structure (EXAFS), X- ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) measurements were carried out. EXAFS spectra have been recorded at the k edge of Iron using the dispersive EXAFS (DEXAFS) beam line at 2.5 GeV at Indus -2 synchrotron radiation source RRCAT, Indore, India. The EXAFS data have been analyzed using the computer software Athena. These have been used to determine the bond lengths in these ferrites with the help of three different methods, namely, Levy's, Lytle's and Lytle, Sayers and Stern's (LSS) methods. The phase uncorrected bond lengths have also been obtained from Fourier transformation method and the results obtained have been compared with the results obtained from LSS method, which also gives phase uncorrected bond lengths. XRD shows the structure is the tetragonal, and FTIR was used to determine the nature of the vibrational modes present in the system.

  17. Effect of cobalt substitution on structural and magnetic properties and chromium adsorption of manganese ferrite nano particles

    Science.gov (United States)

    Ahalya, K.; Suriyanarayanan, N.; Ranjithkumar, V.

    2014-12-01

    Manganese ferrite (MnFe2O4) and cobalt doped manganese ferrite (Mn1-xCoxFe2O4) with x=0, 0.2, 0.4, 0.6, and 0.8 are synthesized at pH 11 and an annealing temperature of 900 °C, through co-precipitation technique. The particle sizes are found to be in the range of 30-35 nm. The varying dopant concentrations influence the crystalline edges, surface morphology and magnetic properties of the samples. Particle size initially increases for the incorporation of cobalt up to x=0.6 and then decreases. As cobalt concentration increases, the saturation magnetization increases up to x=0.6 and then decreases. Stretching and bending of bonds at tetrahedral and octahedral sites respectively are noticed and they shift towards the longer wavelengths. The samples are tested for their application as adsorbents of toxic heavy metal Cr(VI). The adsorption efficiency variations with dopant concentrations of samples, quantity of adsorbent and concentrations of chromium are studied.

  18. 锰锌铁氧体纳米粉体及其制备方法研究进展%Progress on preparation methods of nano-sized powders for Mn-Zn ferrites

    Institute of Scientific and Technical Information of China (English)

    徐海霞; 孙玉坤; 李冬云; 颜冲

    2016-01-01

    Mn-Zn ferrite is one of the most widely used soft ferrites in electronic industry. With the rapid development of miniaturization, lighter weight and energy saving of magnetic power electronic devices, higher demands were proposed for Mn-Zn power ferrites so nano-sized powder of Mn-Zn ferrite attracts extensive researches. The synthesis method of nano-sized powder of Mn-Zn ferrite has been reviewed in this paper, mainly including high-energy ball milling, sol-gel, co-precipitation, microemulsion and hydrothermal processing. The principle and applications of these methods have been discussed.%锰锌(Mn-Zn)铁氧体是应用最广泛的软磁铁氧体材料。随着电子器件及产品逐渐向小型化、轻量化和节能化方向发展,对其中使用的磁性元件及材料如锰锌铁氧体提出了更高的要求,因此具有更优性能的Mn-Zn 铁氧体纳米粉体得到广泛研究。作为一种新材料,纳米Mn-Zn 铁氧体的研究已经成为磁性材料研究的热点领域。阐述了制备Mn-Zn铁氧体纳米粉体的合成方法,包括高效球磨法、溶胶-凝胶法、化学共沉淀法、微乳液法和水热法。介绍了各种方法的原理与应用。

  19. Magnetic properties of nanostructured spinel ferrites and nanocomposite Nd2Fe14B/-Fe permanent magnets

    Indian Academy of Sciences (India)

    A Narayanaswamy

    2005-11-01

    This paper presents some of the important magnetic properties of the nano-structured spinel ferrites such as Ni0.5Zn0.5Fe2O4 and Mn0.67Zn0.33Fe2O4 and also that of the nanocomposite Nd2Fe14B/-Fe permanent magnetic material. The increase in the magnetic transition temperature of Ni-Zn ferrite from 538 K in the bulk state to 592 K when the grain size is reduced to 16 nm is correlated to the enhancement in the AB super-exchange interaction strength because of an increase in the magnetic ion concentration in the A-site on milling, as shown by the EXAFS and in-field Mössbauer studies. The particle size has been tailor-made by varying the concentration of the oxidant in the case of Mn-Zn ferrite. The critical particle size for the superparamagnetic limit has been found to be 25 nm with an effective magnetic anisotropy constant of 7.78 kJ m-3 which is about an order of magnitude higher than that of the bulk ferrite. The exchange coupling is found to be strengthened in the nanocomposite magnet Nd2Fe14B/-Fe, when the grain boundary anisotropy is removed by thermal annealing and thus facilitating the enhancement of the energy product.

  20. Effect of Ni{sup 2+} substitution on structural and magnetic properties of Ni–Zn ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Srinivas, Ch., E-mail: srinivas.chintoju75@gmail.com [Department of physics, Sasi Institute of Technology and Engineering, 534101 Tadepalligudem (India); Tirupanyam, B.V. [Department of physics, Government Degree College, 533211 Rajahmundry (India); Satish, A. [Department of physics, RGUKT, 521201 Nuzividu (India); Seshubai, V. [Department of physics, University of Hyderabad, 500046 Hyderabad (India); Sastry, D.L., E-mail: dl_sastry@gmail.com [Department of physics, Andhra University, 530003 Visakhapatnam (India); Caltun, O.F. [Faculty of physics, A.I.Cuza University, Iasi 700506 Romania (Romania)

    2015-05-15

    A series of co-precipitated Ni{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4} (x=0.5, 0.6, 0.7) ferrite nanoparticles heat treated at 200 °C were produced in order to understand the influence of substitution level on structural and magnetic properties including magnetocrystalline anisotropy. The XRD, FE-SEM, VSM and FC–ZFC techniques were used to characterize the samples. It is observed that as Ni{sup 2+} concentration increases crystallite size (D), saturation magnetization (M{sub s}) and blocking temperature (T{sub B}) and decreases coercive field (H{sub c}). All particles exhibit superparamagnetism at room temperature and hence lie in the single domain range. The magnetic anisotropy constant (K) is estimated to be maximum for Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} sample, whose particle size is the smallest. The results are interpreted presuming the presence of core shell interactions and/or cation redistribution that influence the magnetic properties of these ferrite nano particles. - Highlights: • The co-precipitation method support to prepare ultrafine ferrite nanoparticles. • The excellent magnetic properties obtained at low annealing temperatures. • Ni{sup 2+} substitution affect magnetic anisotropy in Ni–Zn ferrite nanoparticles.

  1. Low temperature synthesis of Mn{0.4}Zn{0.6}In{0.5}Al{0.1}Fe{1.4}O{4} nano-ferrite and characterization for high frequency applications

    Science.gov (United States)

    Mathur, P.; Thakur, A.; Singh, M.

    2008-02-01

    In the present study, nano-ferrite of composition Mn{0.4}Zn{0.6}In{0.5}Al{0.1}Fe{1.4}O{4} has been synthesized by co-precipitation method. Decomposition of residue at a temperature as low as 200 °C, gives the ferrite powder. The ferrite has been, finally, sintered at 500 °C. The structural studies have been made by using X-ray diffraction (XRD) technique and scanning electron microscopy (SEM), which confirms the formation of single spinel phase and nanostructure. The dc resistivity is studied as a function of temperature and values are found more than twice than those for the samples prepared by the other chemical methods ... It is found that the resistivity decreases with an increase in temperature. The initial permeability value is found to be higher as compared to the other chemical routes. The initial permeability value is found to increase with an increase in temperature. At a certain temperature called Curie temperature, it attains a maximum value, after which the initial permeability decreases sharply. Even at nanolevel, appreciable value of initial permeability is obtained and low magnetic losses make these ferrites especially suitable for high frequency applications. The particle size is calculated using Scherrer's equation for Lorentzian peak, which comes out between 55 nm 69 nm. Possible mechanisms contributing to these processes have been discussed.

  2. Synthesis and magnetic investigation of cobalt ferrite nanoparticles prepared via a simple chemical precipitation method

    Directory of Open Access Journals (Sweden)

    Kambiz Hedayati

    2016-04-01

    Full Text Available In this research cobalt ferrite (CoFe2O4 nano-crystalline powders were prepared by simple chemical precipitation method using cobalt sulfate. The CoFe2O4 nanoparticles were characterized by X-ray diffraction, scanning electron microscopy  and Fourier transform infra-red spectroscopy. The crystallite size of CoFe2O4 nanoparticles was calculated by Debye–Scherrer formula. The effect of precursor, capping agent, temperature and concentration on the morphology and particle size of the products was investigated. Starch and gelatin as green, safe, water-soluble and cost-effective capping agents were used. Alternative gradient field magnetometer  confirms dominant influence of temperature on the morphology and magnetic domains. Results approve magnetic samples exhibit either ferromagnetic or super-paramagnetic behavior.

  3. Superparamagnetic bead interactions with functionalized surfaces characterized by an immunomicroarray

    DEFF Research Database (Denmark)

    Skottrup, Peter Durand; Hansen, Mikkel Fougt; Moresco, Jacob Lange

    2010-01-01

    Magneto-resistive sensors capable of detecting superparamagnetic micro-/nano-sized beads are promising alternatives to standard diagnostic assays based on absorbance or fluorescence and streptavidin-functionalized beads are widely used as an integral part of these sensors. Here we have developed ...

  4. Ferrite Nanoparticles in Pharmacological Modulation of Angiogenesis

    Science.gov (United States)

    Deshmukh, Aparna; Radha, S.; Khan, Y.; Tilak, Priya

    2011-07-01

    Nanoparticles are being explored in the targeted drug delivery of pharmacological agents : angiogenesis being one such novel application which involves formation of new blood vessels or branching of existing ones. The present study involves the use of ferrite nanoparticles for precise therapeutic modulation of angiogenesis. The ferrite nanoparticles synthesized by co-precipitation of ferrous and ferric salts by a suitable base, were found to be 10-20 nm from X-ray diffraction and TEM measurements. The magnetization measurements showed superparamagnetic behavior of the uncoated nanoparticles. These ferrite nanoparticles were found to be bio-compatible with lymphocytes and neural cell lines from the biochemical assays. The chick chorioallantoic membrane(CAM) from the shell of fertile white Leghorn eggs was chosen as a model to study angiogenic activity. An enhancement in the angiogenic activity in the CAM due to addition of uncoated ferrite nanoparticles was observed.

  5. Magnetic properties of cobalt ferrite-silica nanocomposites prepared by a sol-gel autocombustion technique

    DEFF Research Database (Denmark)

    Cannas, C.; Musinu, A.; Piccaluga, G.

    2006-01-01

    The magnetic properties of cobalt ferrite-silica nanocomposites with different concentrations (15, 30, and 50 wt %) and sizes (7, 16, and 28 nm) of ferrite particles have been studied by static magnetization measurements and Mossbauer spectroscopy. The results indicate a superparamagnetic behavio...

  6. Sonochemical Synthesis of Cobalt Ferrite Nanoparticles

    Directory of Open Access Journals (Sweden)

    Partha P. Goswami

    2013-01-01

    Full Text Available Cobalt ferrite being a hard magnetic material with high coercivity and moderate magnetization has found wide-spread applications. In this paper, we have reported the sonochemical synthesis of cobalt ferrite nanoparticles using metal acetate precursors. The ferrite synthesis occurs in three steps (hydrolysis of acetates, oxidation of hydroxides, and in situ microcalcination of metal oxides that are facilitated by physical and chemical effects of cavitation bubbles. The physical and magnetic properties of the ferrite nano-particles thus synthesized have been found to be comparable with those reported in the literature using other synthesis techniques.

  7. Cation distribution correlated with magnetic properties of nanocrystalline gadolinium substituted nickel ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Heiba, Zein K. [Taif university, Faculty of Science, Physics Department, Al-Haweiah, Taif (Saudi Arabia); Ain shams university, Faculty of science, Physics Department, Cairo (Egypt); Bakr Mohamed, Mohamed, E-mail: mbm1977@yahoo.com [Physics Department, Taibah University, Al-Madinah Al-Munawara (Saudi Arabia); Ain shams university, Faculty of science, Physics Department, Cairo (Egypt); Arda, L. [Bahcesehir University, Faculty of Arts and Sciences, Ciragan Cad., Osmanpasa Mektebi Sok., No. 4, 34349 Besiktas, Istanbul (Turkey); Dogan, N. [Gebze Institute of Technology, Department of Physics, 41400 Gebze/Kocaeli (Turkey)

    2015-10-01

    Nano crystalline NiFe{sub 2−x}Gd{sub x}O{sub 4} (0.0≤x≤0.4) ferrite was prepared by citrate method. The samples were characterized with X-ray diffraction, FT-IR spectroscopy, TEM and magnetic measurements. The effect of Gd{sup 3+} cations substitution on structural, microstructural and magnetic properties of prepared nanoparticles was investigated. From Rietveld analysis, the system was found to be inverse spinel structure with Gd{sup 3+} residing on octahedral B-site 16c and the grain boundary, while Ni{sup 2+} occupying the B-site at both 16c and 16d. The lattice parameter (a) changes nonmonotonically, first increases then decreases with Gd doping content. The M–H and M–T relations had demonstrated a change in the magnetic moment and a ferrimagnetic–superparamagnetic transition in the ferrite system. For low temperature measurements, an increase in gadolinium content resulted in increasing the coercive field while the saturation of magnetization (M{sub s}), first deceases then increases with Gd doping content. At room temperature M{sub s} decreases with increasing Gd substitution. - Highlights: • NiFe{sub 2-x}Gd{sub x}O{sub 4} (0.0≤x≤0.4) nano ferrite was prepared by citrate method. • NiFe{sub 2-x}Gd{sub x}O{sub 4} has an inverse spinal structure. • At low temperature H{sub c} increases M{sub s} deceases then increases with Gd. • At room temperature M{sub s} decreases with increasing Gd substitution increases.

  8. Nano

    DEFF Research Database (Denmark)

    Nørgaard, Bent; Engel, Lars Romann

    2007-01-01

    Gennem de sidste par år har et lille ord med et meget stort potentiale gentagende trængt sig på i den offentlige bevidsthed, det er ordet "nano". Nanovidenskab og nanoteknologi er lige nu to af de "hotteste" forskningsområder og betragtes af mange som porten til en helt ny verden af muligheder....... Muligheder, vi endnu ikke kender konsekvenserne af. Center for Kunst og Videnskabs forestilling NANO giver dig chancen for at blive bekendt med verdens mindste byggesten og idégrundlaget for nanoforskningen. Vi har skabt et rum, som på mange måder minder om et laboratorium. Rummet er forsynet med storskærme......, kolber, væsker og nanopartikler. Her vil du f.eks. opleve, hvordan forskere tilfører guld helt nye egenskaber. Forestillingen veksler mellem kemiske arbejdsdemonstrationer, stemningsskabende musik og livlig debat på storskærme mellem eksperter. NANO opfordrer publikum til at tage stilling til forskningen...

  9. Effect of Ni2+ substitution on structural and magnetic properties of Ni-Zn ferrite nanoparticles

    Science.gov (United States)

    Srinivas, Ch.; Tirupanyam, B. V.; Satish, A.; Seshubai, V.; Sastry, D. L.; Caltun, O. F.

    2015-05-01

    A series of co-precipitated NixZn1-xFe2O4 (x=0.5, 0.6, 0.7) ferrite nanoparticles heat treated at 200 °C were produced in order to understand the influence of substitution level on structural and magnetic properties including magnetocrystalline anisotropy. The XRD, FE-SEM, VSM and FC-ZFC techniques were used to characterize the samples. It is observed that as Ni2+ concentration increases crystallite size (D), saturation magnetization (Ms) and blocking temperature (TB) and decreases coercive field (Hc). All particles exhibit superparamagnetism at room temperature and hence lie in the single domain range. The magnetic anisotropy constant (K) is estimated to be maximum for Ni0.5Zn0.5Fe2O4 sample, whose particle size is the smallest. The results are interpreted presuming the presence of core shell interactions and/or cation redistribution that influence the magnetic properties of these ferrite nano particles.

  10. Ultrafine grained high density manganese zinc ferrite produced using polyol process assisted by Spark Plasma Sintering

    Energy Technology Data Exchange (ETDEWEB)

    Gaudisson, T.; Beji, Z.; Herbst, F.; Nowak, S. [ITODYS, Université Paris Diderot, Sorbonne Paris Cité, CNRS UMR-7086, 75205 Paris (France); Ammar, S., E-mail: ammarmer@univ-paris-diderot.fr [ITODYS, Université Paris Diderot, Sorbonne Paris Cité, CNRS UMR-7086, 75205 Paris (France); Valenzuela, R. [D2MC, Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, 04510 Ciudad de Mexico (Mexico)

    2015-08-01

    We report the synthesis of Mn–Zn ferrite (MZFO) nanoparticles (NPs) by the polyol process and their consolidation by Spark Plasma Sintering (SPS) technique at relatively low temperature and short time, namely 500 °C for 10 min. NPs were obtained as perfectly epitaxied aggregated nanoclusters forming a kind of spherical pseudo-single-crystals of about 40 nm in size. The results on NPs consolidation by SPS underlined the importance of this clustering on the grain growth mechanism. Grain growth proceeds by coalescing nanocrystalline aggregates into single grain of almost the same average size, thus leading to a high density ceramic. Due to magnetic exchange interactions between grains, the produced ceramic does not exhibit thermal relaxation whereas their precursor polyol-made NPs are superparamagnetic. - Highlights: • Textured Mn–Zn ferrite nano-aggregates were produced in polyol. • Dense ceramic was obtained by SPS starting from these particles at 500 °C for 10 min. • The grain growth was driven by coalescence leading to nanometer-sized grains. • The 300 K-magnetic properties of the ceramic are typical of a soft magnet. • Its magnetization is very close to that of bulk despite its ultrafine grain size.

  11. Effects of La3+ doping on MnZn ferrite nanoscale particles synthesized by hydrothermal method

    Institute of Scientific and Technical Information of China (English)

    古映莹; 谭小平; 梁叔全; 桑商斌

    2004-01-01

    MnZn ferrite nanoscale particles were synthesized by hydrothermal method. The effects of amount of addition La3+ on the products were discussed. The product was characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). The results show that the sample with 0.2% La3+(mass fraction) or without La3+ has only spinel phase, but the sample with mass fraction of La3+ exceeding 0.4% posses second phase besides the spinel one; and the nano-MnZn ferrites change from cube to hexagon when the mass fractions of La3+ is up to 1.2%. TEM image of the sample with 1.2% La3+ indicates that the homogeneous hexagonal crystal is obtained and the particles are larger than those of undoped; the addition of La3+ has great influence on the crystallization of hydrothermal process and can change the shape of particles and improve their growth. The saturation magnetization of the sample with 1.2% La3+ (2.64 A·m2·kg-1) is lower than that of undoped (17.54 A·m2·kg-1) and it behaves superparamagnetically.

  12. Cation distribution and micro level magnetic alignments in the nanosized nickel zinc ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Jeevan Job [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam, Kerala 686 560 (India); Shinde, A.B.; Krishna, P.S.R. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Kalarikkal, Nandakumar, E-mail: nkkalarikkal@mgu.ac.in [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam, Kerala 686 560 (India); Centre for Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam, Kerala 686 560 (India)

    2013-01-05

    Highlights: Black-Right-Pointing-Pointer Presence of noncollinear magnetic alignments in Ni-Zn ferrite nano systems. Black-Right-Pointing-Pointer Population of the octahedral and tetrahedral sites unchanged with particle size. Black-Right-Pointing-Pointer Coercivity and saturation magnetization values decreasing with particle size. Black-Right-Pointing-Pointer Superparamagnetic behaviour found to decreases with increase in particle size. Black-Right-Pointing-Pointer Bond lengths vary with temperature and affect the magnetic moment values. - Abstract: Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} nanoparticles were synthesized through sol-gel synthesis method. Sintering at elevated temperatures was employed to obtain samples with higher particle sizes. The structural characterization using X-ray diffraction suggests that the three samples possess uniformal cation distribution. The variation of magnetization as a function of applied magnetic field at room temperature is studied using a vibrating sample magnetometer and all the samples found to exhibit nearly zero remanence and zero coercivity suggesting a superparamagnetic behaviour. The variation of magnetizations of the three different samples with temperature was studied by ZFC-FC technique at two different applied fields of 10 Oe and 1000 Oe. In order to study the possibility of structural changes, chemical and coordination differences of iron in the nanocrystalline Ni-Zn ferrite particles, room temperature {sup 57}Fe Moessbauer spectroscopy study was used. The application of 5 T magnetic field at 5 K temperature resolves the two sub spectra and canting angle of 27{sup o} and 12{sup o} were observed which clearly indicates the noncollinear magnetic alignment in nano crystallites of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}. The neutron diffraction study was performed at seven different temperatures 20, 50, 100, 150, 200, 250 and 300 K. Rietveld refinement of the neutron diffraction data was performed to deduce the basic

  13. Effects of magnetic pre-alignment of nano-powders on formation of high textured barium hexa-ferrite quasi-single crystals via a magnetic forming and liquid participation sintering route

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Junliang, E-mail: liujunliang@yzu.edu.cn [Key Laboratory of Environmental Materials and Engineering of Jiangsu Province, School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002 (China); Zeng, Yanwei [State Key Laboratory of Materials-Oriented Chemical Engineering, School of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009 (China); Zhang, Xingkai [Key Laboratory of Environmental Materials and Engineering of Jiangsu Province, School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002 (China); Zhang, Ming [Key Laboratory of Environmental Materials and Engineering of Jiangsu Province, School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002 (China); Testing Center of Yangzhou University, Yangzhou 225002 (China)

    2015-05-15

    Highly textured barium hexa-ferrite quasi-single crystal with narrow ferromagnetic resonance line-width is believed to be a potential gyromagnetic material for self-biased microwave devices. To fabricate barium hexa-ferrite quasi-single crystal with a high grain orientation degree, a magnetic forming and liquid participation sintering route has been developed. In this paper, the effects of the pre-alignment of the starting nano-powders on the formation of barium quasi-single crystal structures have been investigated. The results indicated that: the crystallites with large sizes and small specific surfaces were easily aligned for they got higher driving forces and lower resistances during magnetic forming. The average restricting magnetic field was about 4.647 kOe to overcome the average friction barrier between crystallites. The pre-aligned crystallites in magnetic forming acted as the “crystal seeds” for oriented growth of the un-aligned crystallites during liquid participation sintering to achieve a high grain orientation. To effectively promote the grain orientation degrees of the sintered pellets, the grain orientation degrees of the green compacts must be higher than a limited value of 15.0%. Barium hexa-ferrite quasi-single crystal with a high grain orientation degree of 98.6% was successfully fabricated after sintering the green compact with its grain orientation degree of 51.1%. - Highlights: • Aligned particles acted as “crystal seeds” for un-aligned ones' oriented growth. • Magnetic field of 4.647 kOe was needed to overcome crystallites' friction barrier. • GOD dramatically increased after sintering if starting GOD exceeded to 15.0%. • Quasi-single crystal was prepared by sintering green compact with GOD of 51.1%.

  14. Magnetic properties of Sn-substituted Ni-Zn ferrites synthesized from nano-sized powders of NiO, ZnO, Fe2O3, and SnO2

    Science.gov (United States)

    Ali, MA; Uddin, MM; Khan, MNI; Chowdhury, FUZ; Hoque, SM; Liba, SI

    2017-06-01

    A series of Ni0.6-x/2Zn0.4-x/2Sn x Fe2O4 (x = 0.0, 0.05, 0.1, 0.15, 0.2, and 0.3) (NZSFO) ferrite composities have been synthesized from nano powders using a standard solid state reaction technique. The spinel cubic structure of the investigated samples has been confirmed by x-ray diffraction (XRD). The magnetic properties such as saturation magnetization ({M}{{s}}), remanent magnetization ({M}{{r}}), coercive field ({H}{{c}}), and Bohr magneton (μ) are calculated from the hysteresis loops. The value of {M}{{s}} is found to decrease with increasing Sn content in the samples. This change is successfully explained by the variation of A-B interaction strength due to Sn substitution in different sites. The compositional stability and quality of the prepared ferrite composites have also been endorsed by the fairly constant initial permeability ({μ }^{\\prime }) over a wide range of frequency. The decreasing trend of {μ }^{\\prime } with increasing Sn content has been observed. Curie temperature {T}{{C}} has been found to increase with the increase in Sn content. A wide spread frequency utility zone indicates that the NZSFO can be considered as a good candidate for use in broadband pulse transformers and wide band read-write heads for video recording. The composition of x = 0.05 shows unusual results and the possible reason is also mentioned with the established formalism.

  15. Spin canting in ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Marx, J., E-mail: jmarx@physik.uni-kl.de; Huang, H.; Salih, K. S. M.; Thiel, W. R.; Schünemann, V. [University of Kaiserslautern, Department of Physics (Germany)

    2016-12-15

    Recently, an easily scalable process for the production of small (3 −7 nm) monodisperse superparamagnetic ferrite nanoparticles MeFe{sub 2}O{sub 4} (Me = Zn, Mn, Co) from iron metal and octanoic acid has been reported (Salih et al., Chem. Mater. 25 1430–1435 2013). Here we present a Mössbauer spectroscopic study of these ferrite nanoparticles in external magnetic fields of up to B = 5 T at liquid helium temperatures. Our analysis shows that all three systems show a comparable inversion degree and the cationic distribution for the tetrahedral A and the octahedral B sites has been determined to (Zn{sub 0.19}Fe{sub 0.81}){sup A}[Zn{sub 0.81}Fe{sub 1.19}] {sup B}O{sub 4}, (Mn{sub 0.15}Fe{sub 0.85}){sup A}[Mn{sub 0.85}Fe{sub 1.15}] {sup B}O{sub 4} and (Co{sub 0.27}Fe{sub 0.73}){sup A}[Co{sub 0.73}Fe{sub 1.27}] {sup B}O{sub 4}. Spin canting occurs presumably in the B-sites and spin canting angles of 33°, 51° and 59° have been determined for the zinc, the manganese, and the cobalt ferrite nanoparticles.

  16. Magnetic properties of MnFe{sub 2}O{sub 4} nano-aggregates dispersed in paraffin wax

    Energy Technology Data Exchange (ETDEWEB)

    Aslibeiki, B., E-mail: b.aslibeiki@tabrizu.ac.ir [Department of Solid State Physics, Faculty of Physics, University of Tabriz, Tabriz 51666-16471 (Iran, Islamic Republic of); Kameli, P. [Department of Physics, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2015-07-01

    Manganese ferrite, MnFe{sub 2}O{sub 4} nanoparticles with average size of ∼6.5 nm were synthesized by using a thermal decomposition method. The nanoparticles were aggregated which was confirmed by FESEM and TEM images. The aggregates with a diameter of ∼50 nm showed interacting superspin glass (SSG) behavior. The powders were dispersed in the molten paraffin wax by using ultrasonic bath. Samples with different paraffin/ferrite weight ratios of P/F= 0, 1, 5, 10 and 20 were prepared. M–H curves of the samples revealed presence of superparamagnetic state at 300 K. Saturation magnetization (M{sub s}) decreased from 26.6 to 1.3 emu/g by increasing the P/F value from 0 to 20, respectively. Furthermore, the VSM measurements showed a decrease in surface spin disorder of paraffin-embedded nanoparticles in comparison with bare particles. The AC magnetic susceptibility peak temperature, T{sub P} increased from 230 to >300 K with increasing the paraffin content in the samples. The present study showed that by dispersing the particles in a non-magnetic matrix, the blocking temperature could be increased. - Highlights: ●MnFe{sub 2}O{sub 4}/paraffin nano-sized samples with different paraffin/ferrite ratios were prepared. ●The samples were superparamagnetic at room temperature. ●Bonding between paraffin molecules and surface atoms of ferrite particles reduced the surface spin disorder of nanoparticles. ●The blocking temperature increased with increasing the paraffin concentration is the samples.

  17. Emergent nanoscale superparamagnetism at oxide interfaces

    Science.gov (United States)

    Anahory, Y.; Embon, L.; Li, C. J.; Banerjee, S.; Meltzer, A.; Naren, H. R.; Yakovenko, A.; Cuppens, J.; Myasoedov, Y.; Rappaport, M. L.; Huber, M. E.; Michaeli, K.; Venkatesan, T.; Ariando; Zeldov, E.

    2016-08-01

    Atomically sharp oxide heterostructures exhibit a range of novel physical phenomena that are absent in the parent compounds. A prominent example is the appearance of highly conducting and superconducting states at the interface between LaAlO3 and SrTiO3. Here we report an emergent phenomenon at the LaMnO3/SrTiO3 interface where an antiferromagnetic Mott insulator abruptly transforms into a nanoscale inhomogeneous magnetic state. Upon increasing the thickness of LaMnO3, our scanning nanoSQUID-on-tip microscopy shows spontaneous formation of isolated magnetic nanoislands, which display thermally activated moment reversals in response to an in-plane magnetic field. The observed superparamagnetic state manifests the emergence of thermodynamic electronic phase separation in which metallic ferromagnetic islands nucleate in an insulating antiferromagnetic matrix. We derive a model that captures the sharp onset and the thickness dependence of the magnetization. Our model suggests that a nearby superparamagnetic-ferromagnetic transition can be gate tuned, holding potential for applications in magnetic storage and spintronics.

  18. Emergent nanoscale superparamagnetism at oxide interfaces.

    Science.gov (United States)

    Anahory, Y; Embon, L; Li, C J; Banerjee, S; Meltzer, A; Naren, H R; Yakovenko, A; Cuppens, J; Myasoedov, Y; Rappaport, M L; Huber, M E; Michaeli, K; Venkatesan, T; Ariando; Zeldov, E

    2016-08-25

    Atomically sharp oxide heterostructures exhibit a range of novel physical phenomena that are absent in the parent compounds. A prominent example is the appearance of highly conducting and superconducting states at the interface between LaAlO3 and SrTiO3. Here we report an emergent phenomenon at the LaMnO3/SrTiO3 interface where an antiferromagnetic Mott insulator abruptly transforms into a nanoscale inhomogeneous magnetic state. Upon increasing the thickness of LaMnO3, our scanning nanoSQUID-on-tip microscopy shows spontaneous formation of isolated magnetic nanoislands, which display thermally activated moment reversals in response to an in-plane magnetic field. The observed superparamagnetic state manifests the emergence of thermodynamic electronic phase separation in which metallic ferromagnetic islands nucleate in an insulating antiferromagnetic matrix. We derive a model that captures the sharp onset and the thickness dependence of the magnetization. Our model suggests that a nearby superparamagnetic-ferromagnetic transition can be gate tuned, holding potential for applications in magnetic storage and spintronics.

  19. Structure and electromagnetic properties of NiZn spinel ferrite with nano-sized ZnAl{sub 2}O{sub 4} additions

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Zongliang, E-mail: zzlma@163.com; Zhang, Huaiwu; Yang, Qinghui; Jia, Lijun

    2015-11-05

    In this study, nanocrystalline ZnAl{sub 2}O{sub 4} (ZA) (x = 0–20 wt%) were introduced into Ni{sub 0.4}Zn{sub 0.6}Fe{sub 2}O{sub 4} ferrite (NZ) by a solid-state reaction method combining a sol–gel auto-combustion method. The effects of ZA addition on the crystalline phase formation, microstructures, magnetic and dielectric properties were systematically investigated. X-ray diffraction and scanning electron microscope results reveal that the added ZA can fully solve into the NZ to form a ceramic with single-phase cubic spinel structure, and the grain size decreases obviously as x > 5 wt%. Meanwhile, the magnetic and dielectric properties exhibit significantly dependent on the ZA addition content. With the increasing addition level of ZA from 0 to 20 wt%, the initial permeability μ{sub i} is found increased initially and then decreased with the maximum 679 at x = 0.5 wt%. For the samples with x ≤ 5 wt%, permittivity ε′ is relatively higher at low frequencies (ε′ = 91–138 at 1 MHz) and dielectric loss tan δ{sub ε} shows distinct peak behavior. When x reaches 10 wt%, however, the ε′ and tan δ{sub ε} show very stable spectra from 1 MHz to 1 GHz. - Highlights: • Various amount of nanocrystalline ZnAl{sub 2}O{sub 4} (ZA) were introduced into NiZn ferrite. • NiZn ferrite can form single-phase spinel ceramic materials with ZA additives. • ZA has significant effects on magnetic and dielectric properties of the ceramics. • It provides a new method for fabricating NiZn ferrite with tunable properties.

  20. Cobalt ferrite nano-composite coated on glass by Doctor Blade method for photo-catalytic degradation of an azo textile dye Reactive Red 4: XRD, FESEM and DRS investigations.

    Science.gov (United States)

    Habibi, Mohammad Hossein; Parhizkar, Janan

    2015-11-05

    Cobalt ferrite nano-composite was prepared by hydrothermal route using cobalt nitrate, iron nitrate and ethylene glycol as chelating agent. The nano-composite was coated on glass by Doctor Blade method and annealed at 300 °C. The structural, optical, and photocatalytic properties have been studied by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and UV-visible spectroscopy (UV-Vis DRS). Powder XRD analysis confirmed formation of CoFe2O4 spinel phase. The estimated particle size from FESEM data was 50 nm. The calculated energy band gaps, obtained by Tauc relation from UV-Vis absorption spectra was 1.3 eV. Photocatalytic degradation of Reactive Red 4 as an azo textile was investigated in aqueous solution under irradiation showed 68.0% degradation of the dye within 100 min. The experimental enhanced activity compare to pure Fe2O3 can be ascribed to the formation of composite, which was mainly attributable to the transfer of electron and hole to the surface of composite and hinder the electron hole recombination. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Permanent magnet system to guide superparamagnetic particles

    Science.gov (United States)

    Baun, Olga; Blümler, Peter

    2017-10-01

    A new concept of using permanent magnet systems for guiding superparamagnetic nano-particles on arbitrary trajectories over a large volume is proposed. The basic idea is to use one magnet system which provides a strong, homogeneous, dipolar magnetic field to magnetize and orient the particles, and a second constantly graded, quadrupolar field, superimposed on the first, to generate a force on the oriented particles. In this configuration the motion of the particles is driven predominantly by the component of the gradient field which is parallel to the direction of the homogeneous field. As a result, particles are guided with constant force and in a single direction over the entire volume. The direction is simply adjusted by varying the angle between quadrupole and dipole. Since a single gradient is impossible due to Gauß' law, the other gradient component of the quadrupole determines the angular deviation of the force. However, the latter can be neglected if the homogeneous field is stronger than the local contribution of the quadrupole field. A possible realization of this idea is a coaxial arrangement of two Halbach cylinders. A dipole to evenly magnetize and orient the particles, and a quadrupole to generate the force. The local force was calculated analytically for this particular geometry and the directional limits were analyzed and discussed. A simple prototype was constructed to demonstrate the principle in two dimensions on several nano-particles of different size, which were moved along a rough square by manual adjustment of the force angle. The observed velocities of superparamagnetic particles in this prototype were always several orders of magnitude higher than the theoretically expected value. This discrepancy is attributed to the observed formation of long particle chains as a result of their polarization by the homogeneous field. The magnetic moment of such a chain is then the combination of that of its constituents, while its hydrodynamic radius

  2. Nano-organocatalyst: magnetically retrievable ferrite-anchored glutathione for microwave-assisted Paal–Knorr reaction, aza-Michael addition, and pyrazole synthesis

    KAUST Repository

    Polshettiwar, Vivek

    2010-01-01

    Postsynthetic Surface modification of magnetic nanoparticles by glutathione imparts desirable chemical functionality and enables the generation of catalytic sites on the surfaces of ensuing organocatalysts. In this article, we discuss the developments, unique activity, and high selectivity of nano-organocatalysts for microwave-assisted Paal-Knorr reaction, aza-Michael addition, and pyrazole synthesis. Their insoluble character Coupled with paramagnetic nature enables easy separation of these nano-catalysts from the reaction mixture using external magnet, which eliminates the requirement of catalyst filtration. Published by Elsevier Ltd.

  3. Effect of sintering temperature on micro structural and impedance spectroscopic properties of Ni0.5Zn0.5Fe2O4 nano ferrite

    Science.gov (United States)

    Venkatesh, Davuluri; Ramesh, K. V.; Sastry, C. V. S. S.

    2017-07-01

    Ni-Zn nanoferrite Ni0.5Zn0.5Fe2O4 is prepared by citrate gel auto combustion method and sintered at various temperatures 800, 900, 1000, 1100 and 1200°C. The room temperature x-ray diffraction conforms that the single phase spinel structure is formed. Crystallite size and density were increased with increasing of sintering temperature. From Raman spectroscopy all sintered samples are single phase with cubic spinel structure belong to Fd3m space group. From surface morphology studies it is clearly observed that the particle size increased with increasing of sintering temperature. Impedance spectroscopy revel that increasing of conductivity is due to grain resistance is decreased with increasing of sintering temperature. Cole-Cole plots are studied from impedance data. The electrical modulus analysis shows that non-Debye nature of Ni0.5Zn0.5Fe2O4 ferrite.

  4. Fabrication, magnetic and microwave absorbing properties of Ba{sub 2}Co{sub 2}Cr{sub 2}Fe{sub 12}O{sub 22} hexagonal ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Bayrakdar, Harun, E-mail: h.bayrakdar@comu.edu.tr

    2016-07-25

    We have investigated the magnetic and microwave absorbing behavior of Ba{sub 2}Co{sub 2}Cr{sub 2}Fe{sub 12}O{sub 22} Nano Particles (NPs)/polyaniline (PANI) and polyacrylonitrile (PAN) nanocomposite materials. Particles showed phase purity and crystallinity in powder X ray diffraction (XRD) analysis. Temperature dependence of magnetic parameters was observed. Microwave absorbing showed very broad and high reflection loss. - Highlights: • Ba{sub 2}Co{sub 2}Cr{sub 2}Fe{sub 12}O{sub 22} NPs were investigated magnetic and absorbing behavior. • VSM measurements of NPs were showed the existence of superparamagnetism with very small coercivity and soft ferrite materials. • Nanocomposites showed higher EM absorption frequency and wider absorption bandwidth.

  5. Ferrites – what is new?

    Indian Academy of Sciences (India)

    R Ranganathan; Anindita Ray

    2002-05-01

    Ferrites, combining insulating and ferrimagnetic properties, have long been used in technology. The aim of this paper is to focus on new features in these materials. In the classical theory of ferrimagnets, Neel had predicted the unusual thermal variation of the spontaneous magnetization, such as, the disappearance of the magnetization at a temperature which was not the Curie temperature but at a point where there was compensation of the spontaneous magnetization of the two sublattices. We show experimentally that temperature (K) in spinel oxide is different under the ZFC and FC magnetization method. To our knowledge, only limited attempt has been made to study K as very few systems exhibit such behavior. In general, some of the ferrites have specific semiconducting properties, e.g., a very low carrier mobility. We discuss the anomalies of the magneto-resistance in ferrites that occur at order–disorder and order–order magnetic phase transition along with our ac and dc conductivity data near the spin compensation temperature. Another notable feature of the ferrites is that, upon irradiation of heavy ions, one can tune the magnetic ordering on bulk sample without destructive effects, i.e., irradiation-induced magnetization. It is interesting to note that spinel ferrite (nano) particle is an ideal small particle magnetic system as the crystal chemistry issue can be controlled, unlike pure metal particle systems where the crystal chemistry issues are basically fixed. In relevance to this, we will also discuss the future prospects, namely, the effect of irradiation on small particle magnetism, as, so far, only a limited attempt has been made in this field.

  6. Influence of Zr and nano-Y{sub 2}O{sub 3} additions on thermal stability and improved hardness in mechanically alloyed Fe base ferritic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kotan, Hasan, E-mail: hkotan@konya.edu.tr [Department of Metallurgical Engineering and Materials Science, Necmettin Erbakan University, Dere Aşıklar Mah. Demet Sokak, Meram, Konya 42140 (Turkey); Darling, Kris A. [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, RDRL-WMM-F, Aberdeen Proving Ground, MD 21005-5069 (United States); Scattergood, Ronald O.; Koch, Carl C. [Department of Materials Science and Engineering, NC State University, 911 Partners Way, Room 3078, Raleigh, NC 27695-7907 (United States)

    2014-12-05

    The motivation of this work was driven to improve the thermal stability in systems where polymorphic transformations can result in an additional driving force, upsetting the expected thermodynamic stability. In this study, Fe{sub 92}Ni{sub 8} alloys with Zr and nano-Y{sub 2}O{sub 3} additions were produced by ball milling and then annealed at high temperatures. Emphasis was placed on understanding the effects of dispersed nano-Y{sub 2}O{sub 3} particle additions and their effect on microstructural stability at and above the bcc-to-fcc transformation occurring at 700 °C in Fe–Ni systems. Results reveal that microstructural stability and hardness can be promoted by a combination of Zr and Y{sub 2}O{sub 3} additions, that being mostly effective for stability before and after phase transition, respectively. The mechanical strength of these alloys is achieved by a unique microstructure comprised a ultra-fine grain Fe base matrix, which contains dispersions of both nano-scale in-situ formed Zr base intermetallics and ex-situ added Y{sub 2}O{sub 3} secondary oxide phases. Both of these were found to be essential for a combination of high thermal stability and high mechanical strength properties. - Highlights: • Polymorphic transformations can limit the processing of nanostructured powders. • It causes a rapid grain growth and impairs the improved mechanical properties. • We aim to improve the hardness and thermal stability above the phase transformation. • Thermal stability is achieved by a combination of Zr and Y{sub 2}O{sub 3} additions. • Hardness is promoted by in-situ formed and ex-situ added secondary nano phases.

  7. Heat generation ability in AC magnetic field of nano MgFe{sub 2}O{sub 4}-based ferrite powder prepared by bead milling

    Energy Technology Data Exchange (ETDEWEB)

    Hirazawa, Hideyuki, E-mail: hirazawa@mat.niihama-nct.ac.j [Department of Environmental Materials Engineering, Niihama National College of Technology, Niihama 792-8580 (Japan); Aono, Hiromichi; Naohara, Takashi; Maehara, Tsunehiro [Graduate School of Science and Engineering, Ehime University, Matsuyama 790-8577 (Japan); Sato, Mitsunori [AdMeTech Co. Ltd., 2821-4, Minami-yoshida-cyo, Matsuyama 791-8042 (Japan); Watanabe, Yuji [Department of Surgery, Graduate School of Medicine, Ehime University, Toon 791-0295 (Japan)

    2011-03-15

    Nanosized MgFe{sub 2}O{sub 4}-based ferrite powder having heat generation ability in an AC magnetic field was prepared by bead milling and studied for thermal coagulation therapy applications. The crystal size and the particle size significantly decreased by bead milling. The heat generation ability in an AC magnetic field improved with the milling time, i.e. a decrease in crystal size. However, the heat generation ability decreased for excessively milled samples with crystal sizes of less than 5.5 nm. The highest heat ability ({Delta}T=34 {sup o}C) in the AC magnetic field (370 kHz, 1.77 kA/m) was obtained for fine MgFe{sub 2}O{sub 4} powder having a ca. 6 nm crystal size (the samples were milled for 6-8 h using 0.1 mm {phi} beads). The heat generation of the samples was closely related to hysteresis loss, a B-H magnetic property. The reason for the high heat generation properties of the samples milled for 6-8 h using 0.1 mm {phi} beads was ascribed to the increase in hysteresis loss by the formation of a single domain. Moreover, the improvement in heating ability was obtained by calcination of the bead-milled sample at low temperature. In this case, the maximum heat generation ({Delta}T=41 {sup o}C) ability was obtained for a ca. 11 nm crystal size sample was prepared by crystal growth during the sample calcination. On the other hand, the {Delta}T value for Mg{sub 0.5}Ca{sub 0.5}Fe{sub 2}O{sub 4} was synthesized using a reverse precipitation method decreased by bead milling. - Research highlights: > The crystal and particle size for MgFe{sub 2}O{sub 4} based ferrite were decreased by bead milling. > The highest heat ability was obtained for MgFe{sub 2}O{sub 4} having a ca. 6 nm crystal size. > This high heat generation ability was ascribed to the increase in hysteresis loss. > Hysteresis loss was increased by the formation of a single domain.

  8. Chemical and physical characterizations of spinel ferrite nanoparticles containing Nd and B elements.

    Science.gov (United States)

    Iwamoto, Takashi; Komorida, Yuki; Mito, Masaki; Takahara, Atsushi

    2010-05-15

    We first succeeded in synthesizing ferrite nanoparticles containing Nd and B elements by a chemical route using a polyol process. The lattice constants of the ferrite nanoparticles were equivalent to 8.39Å of the lattice constant for Fe(3)O(4) with the spinel structure in a bulk state independently of the size in diameter and composition (Fe:Nd:B). The size in diameter was actually dominated by the amount of ligands (oleic acid and oleylamine) coating the nanoparticles and easily tuned by changing refluxing-time under reaction. The spinel-structured ferrite nanoparticles containing Nd and B elements showed large coercivity as compared to Fe(3)O(4) nanoparticles with the spinel structure, which were prepared by the same chemical method. By doping Nd and B elements into the spinel structure of ferrite, magnetic anisotropy increased in comparison with Fe(3)O(4) nanoparticles. According to the analysis of magnetization curve using the modified Langevin function, the ferrite nanoparticles displayed the coexistence of superparamagnetic and antiferromagnetic phases. The ferrite nanoparticles containing Nd and B elements exhibited magnetic core/shell structure on the basis of various magnetic properties. The interface effect between the superparamagnetic core and antiferromagnetic shell might enhance the effective magnetic anisotropy of the ferrite nanoparticles containing Nd and B elements.

  9. Aluminum Substituted Cobalt Ferrite (Co-Al-Fe) Nano Adsorbent for Arsenic Adsorption in Aqueous Systems and Detailed Redox Behavior Study with XPS.

    Science.gov (United States)

    Penke, Yaswanth K; Anantharaman, Ganapathi; Ramkumar, Janakarajan; Kar, Kamal K

    2017-04-05

    Arsenic [As(III) and As(V)] adsorption on aluminum substituted cobalt ferrite (Co-Al-Fe) ternary metal oxide adsorbent is reported by means of qualitative and quantitative spectroscopy tools. IR and Raman active signals were observed around 810-920 cm(-1) band indicate different As-OHcomplexed and As-Ouncomplexed stretching vibrations on to the adsorbent. The adsorption behavior of arsenic (III and V) onto these adsorbents is studied as a function of contact time, different concentrations, and pH conditions. The kinetics study on adsorption were performed to understand nature of adsorption which supports the Pseudo Second Order (PSO) model. The adsorption isotherms study indicates Freundlich type of adsorption. The maximum adsorption capacity of Co-Al-Fe adsorbent is observed around 130 and 76 mg g(-1) for As(III) and As(V) systems, respectively. Detailed XPS study of As 3d, Fe 2p, Co 2p, and O 1s spectra has been reported in explaining the redox behavior and ligand exchange reactions in supporting arsenic adsorption mechanism.

  10. Synthesis and magnetic properties of a novel ferrite organogel

    Science.gov (United States)

    Li, Sichu; John, Vijay T.; Irvin, Glen C.; Rachakonda, Suguna H.; McPherson, Gary L.; O'Connor, Charles J.

    1999-04-01

    A novel magnetic organogel that can be considered a precursor example of a magnetoresponsive gel is reported. The gel is formed by the bridging of ferrite containing anionic bis(2-ethlhexyl) sodium sulfosuccinate reverse micelles with 2,6-dihydroxynaphthalene (2,6-DHN). The addition of 2,6-DHN leads to a room temperature quotes "freezing in" of the liquid solution to a clear organogel. Ferrite particles in the size range 10-15 nm are doped into the gel network and are thus suspended in the optically clear gel media. The magnetic properties of the gel were measured using a superconducting quantum interference device magnetometer. The results reveal that the gel exhibits superparamagnetic behavior with a blocking temperature of 6 K (at an applied field of 1000 G), and a coercivity of 850 G at 2 K. The ferrites introduced into the gel serve the function of magnetic "seeds" via which magnetic properties are acquired by the gel.

  11. Zinc substituted ferrite nanoparticles with Zn0.9Fe2.1O4 formula used as heating agents for in vitro hyperthermia assay on glioma cells

    Science.gov (United States)

    Hanini, Amel; Lartigue, Lenaic; Gavard, Julie; Kacem, Kamel; Wilhelm, Claire; Gazeau, Florence; Chau, François; Ammar, Souad

    2016-10-01

    In this paper we investigate the ability of zinc rich ferrite nanoparticles to induce hyperthermia on cancer cells using an alternating magnetic field (AMF). First, we synthesized ferrites and then we analyzed their physico-chemical properties by transmission electron microscopy, X-ray diffraction and magnetic and magnetocalorimetric measurements. We found that the polyol-made magnetically diluted particles are of 11 nm in size. They are superparamagnetic at body temperature (310 K) with a low but non-negligible magnetization. Interestingly, as nano-ferrimagnets they exhibit a Curie temperature of 366 K, close to the therapeutic temperature range. Their effect on human healthy endothelial (HUVEC) and malignant glioma (U87-MG) cells was also evaluated using MTT viability assays. Incubated with the two cell lines, at doses ≤100 μg mL-1 and contact times ≤4 h, they exhibit a mild in vitro toxicity. In these same operating biological conditions and coupled to AMF (700 kHz and 34.4 Oe) for 1 h, they rapidly induce a net temperature increase. In the case of tumor cells it reaches 4 K, making the produced particles particularly promising for self-regulated magnetically-induced heating in local glioma therapy.

  12. Synthesis, microstructure, and magnetic properties of monosized MnxZnyFe3 - x - yO4 ferrite nanocrystals.

    Science.gov (United States)

    Yoon, Hayoung; Lee, Ji Sung; Min, Ji Hyun; Wu, Junhua; Kim, Young Keun

    2013-12-17

    We report the synthesis and characterization of ferrite nanocrystals which exhibit high crystallinity and narrow size distributions. The three types of samples including Zn ferrite, Mn ferrite, and Mn-Zn ferrite were prepared via a non-aqueous nanoemulsion method. The structural, chemical, and magnetic properties of the nanocrystals are analyzed by transmission electron microscopy, X-ray diffraction, X-ray fluorescence, and physical property measurement system. The characterization indicates that the three types of ferrite nanocrystals were successfully produced, which show well-behaved magnetic properties, ferrimagnetism at 5 K and superparamagnetism at 300 K, respectively. In addition, the magnetization value of the ferrites increases with the increasing concentration of Mn.

  13. Heat generation ability in AC magnetic field of nano MgFe2O4-based ferrite powder prepared by bead milling

    Science.gov (United States)

    Hirazawa, Hideyuki; Aono, Hiromichi; Naohara, Takashi; Maehara, Tsunehiro; Sato, Mitsunori; Watanabe, Yuji

    2011-03-01

    Nanosized MgFe2O4-based ferrite powder having heat generation ability in an AC magnetic field was prepared by bead milling and studied for thermal coagulation therapy applications. The crystal size and the particle size significantly decreased by bead milling. The heat generation ability in an AC magnetic field improved with the milling time, i.e. a decrease in crystal size. However, the heat generation ability decreased for excessively milled samples with crystal sizes of less than 5.5 nm. The highest heat ability (ΔT=34 °C) in the AC magnetic field (370 kHz, 1.77 kA/m) was obtained for fine MgFe2O4 powder having a ca. 6 nm crystal size (the samples were milled for 6-8 h using 0.1 mm ϕ beads). The heat generation of the samples was closely related to hysteresis loss, a B-H magnetic property. The reason for the high heat generation properties of the samples milled for 6-8 h using 0.1 mm ϕ beads was ascribed to the increase in hysteresis loss by the formation of a single domain. Moreover, the improvement in heating ability was obtained by calcination of the bead-milled sample at low temperature. In this case, the maximum heat generation (ΔT=41 °C) ability was obtained for a ca. 11 nm crystal size sample was prepared by crystal growth during the sample calcination. On the other hand, the ΔT value for Mg0.5Ca0.5Fe2O4 was synthesized using a reverse precipitation method decreased by bead milling.

  14. Effect of synthesis methods with different annealing temperatures on micro structure, cations distribution and magnetic properties of nano-nickel ferrite

    Science.gov (United States)

    El-Sayed, Karimat; Mohamed, Mohamed Bakr; Hamdy, Sh.; Ata-Allah, S. S.

    2017-02-01

    Nano-crystalline NiFe2O4 was synthesized by citrate and sol-gel methods at different annealing temperatures and the results were compared with a bulk sample prepared by ceramic method. The effect of methods of preparation and different annealing temperatures on the crystallize size, strain, bond lengths, bond angles, cations distribution and degree of inversions were investigated by X-ray powder diffraction, high resolution transmission electron microscope, Mössbauer effect spectrometer and vibrating sample magnetometer. The cations distributions were determined at both octahedral and tetrahedral sites using both Mössbauer effect spectroscopy and a modified Bertaut method using Rietveld method. The Mössbauer effect spectra showed a regular decrease in the hyperfine field with decreasing particle size. Saturation magnetization and coercivity are found to be affected by the particle size and the cations distribution.

  15. Use of Specific Properties of Zinc Ferrite in Innovative Technologies

    Directory of Open Access Journals (Sweden)

    Kmita A.

    2016-12-01

    Full Text Available Zinc ferrite ZnFe2O4 both in the micro and nano scale is widely used in various fields. The article discusses the structure of this compound and its properties in the nanoscale, which is clearly different from those which the ferrite shows in the microscale. The properties of dust generated electric arc furnace, which can contain up to 40% zinc, substantially in the form of ZnFe2O4 are disscused here. Specific properties (electric, magnetic, thermal of zinc ferrite nanoparticles determine the very wide possibilities of their use, inter alia as catalysts, absorbents, gas sensors, and a tool to combat cancer.

  16. Investigation of superparamagnetism in pure and chromium substituted cobalt nanoferrite

    Science.gov (United States)

    Raghasudha, M.; Ravinder, D.; Veerasomaiah, P.

    2016-12-01

    Nanostructured magnetic materials with the chemical composition CoFe2O4 and CoCr0.9Fe1.1O4 were synthesized through Citrate-gel chemical synthesis with a crystallite size of 6.5 nm and 10.7 nm respectively. Structural characterization of the samples was performed by X-ray diffraction analysis and magnetic properties were studied using Vibrating Sample Magnetometer (VSM). Magnetization measurements as a function of applied magnetic field ±10 T at various temperatures 5 K, 25 K, 310 K and 355 K were carried out. Field cooled (FC) and Zero field cooled (ZFC) magnetization measurements under a magnetic field of 100 Oe for temperature ranging from 5-400 K were studied. The blocking temperature (Tb) for both the ferrites was observed to be around 355 K. Below blocking temperature they showed ferromagnetic behavior and above which they are superparamagnetic in nature that favors their application in the biomedical field. The substitution of paramagnetic Cr3+ ions for magnetic Fe3+ ion in cobalt ferrite has resulted in a decrease in magnetization and the coercivity of the samples. CoCr0.9Fe1.1O4 nanoferrites with observed low coercivity of 338 Oe make them desirable in high frequency transformers due to their very soft magnetic behavior.

  17. Ferrites and ceramic composites

    CERN Document Server

    Jotania, Rajshree B

    2013-01-01

    The Ferrite term is used to refer to all magnetic oxides containing iron as major metallic component. Ferrites are very attractive materials because they simultaneously show high resistivity and high saturation magnetization, and attract now considerable attention, because of the interesting physics involved. Typical ferrite material possesses excellent chemical stability, high corrosion resistivity, magneto-crystalline anisotropy, magneto-striction, and magneto-optical properties. Ferrites belong to the group of ferrimagnetic oxides, and include rare-earth garnets and ortho-ferrites. Several

  18. Study of the Structure, Composition, and Stability of Yttrium-Ti-Oxygen nm-Scale Features in Nano-Structured Ferritic Alloys

    Science.gov (United States)

    Cunningham, Nicholas John

    This work advances the understanding of the Y-Ti-O nanofeatures (NFs) in nanostructured ferritic alloys (NFAs); a class of high temperature, oxide dispersion strengthened iron alloys with applications in both advanced fission and fusion reactors. NFAs exhibit high creep strength up to 800ºC and a remarkable radiation damage tolerance and He management. However, the NFs, which are responsible for these properties, are not fully understood. This work addresses key questions including: a) what is the NF structure and composition and how are they affected by alloy composition and processing; b) what is the NFA long-term thermal stability; c) and what alternative processing paths are available to reduce costs and produce more uniform NF distributions? A detailed study using small angle neutron scattering (SANS), transmission electron microscopy (TEM-group member Y. Wu), and atom probe tomography (APT) evaluated the NF average size (), number density (N), volume fraction (f), composition, and structure in two heats of the commercial NFA MA957. The and N were ≈2.6 nm and ≈5x1023 m-3 , respectively, for both heats, with TEM indicating the NF are Y 2Ti2O7. However, SANS indicates a mixture of NF compositions or atomic densities with a difference between the heats, while APT shows compositions with ≈ 10% Cr and a Y/Ti ratio long times at temperatures up to 900ºC. Notably, Ti in the matrix and some from the NFs migrates to large, Ti-rich phases. Aging at higher temperatures up to 1000ºC for 19.5 kh produced modest coarsening for ≈ 3.8 nm and ≈30% increase in grain size for a corresponding 13% reduction in microhardness. A coarsening model shows no significant NF coarsening will occur at temperatures less than 900ºC. A number of 14YWT NFAs with different Y, Ti, and O content showed that increases in Y and Ti produce higher N and f, but the and the compositions are fairly insensitive. The O content has a more dramatic affect with low O (0.065 wt.%) producing low

  19. Nanocrystalline spinel ferrites by solid state reaction route

    Indian Academy of Sciences (India)

    T K Kundu; S Mishra

    2008-06-01

    Nanostructured NiFe2O4, MnFe2O4 and (NiZn)Fe2O4 were synthesized by aliovalent ion doping using conventional solid-state reaction route. With the doping of Nb2O5, the size of NiFe2O4 is reduced down to 33 nm. Similarly, nanostructured manganese ferrites (MnFe2O4) with diameters in the range of 45–30 nm were synthesized by Ti4+ ion doping. Particle diameters in all the specimens are found to decrease with increasing dopant content. The substitution of Nb5+ or Ti3+ ions essentially breaks up the ferrimagnetically active oxygen polyhedra. This created nanoscale regions of ferrites. Saturation magnetization and coercive field show a strong dependence on the size of the ferrite grains. Superparamagnetic behaviour is observed from the Mössbauer spectra of nanostructured NiFe2O4, if the particle size is reduced to 30 nm. Zero field cooled and field cooled curves from 30 nm sized MnFe2O4 particles showed a peak at B (∼ 125 K), typical of superparamagnetic blocking temperature. These results are explained in terms of core/shell structure of the materials. The d.c. resistivity of the doped specimens decreases by atleast five orders of magnitude compared to pure sample. This is ascribed to the presence of an interfacial amorphous phase between the sites.

  20. Annealing effect on the structural and magnetic properties of the CuAl{sub 0.6}Cr{sub 0.2}Fe{sub 1.2}O{sub 4} nano-ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Amer, M.A., E-mail: moazamer@hotmail.com [Physics Department, Faculty of Science, Tanta university, Tanta (Egypt); Meaz, T.M. [Physics Department, Faculty of Science, Tanta university, Tanta (Egypt); Mostafa, A.G. [ME. Lab., Physics Department, Faculty of Science, Al-Azhar University, Cairo (Egypt); El-Ghazally, H.F. [Physics Department, Faculty of Science, Tanta university, Tanta (Egypt)

    2015-07-15

    Graphical abstract: Mössbauer spectra of the as-prepared (AP) and annealed CuAl{sub 0.6}Cr{sub 0.2}Fe{sub 1.2}O{sub 4} samples. - Highlights: • As-prepared Cu–Al–Cr nano-ferrite samples were annealed at different temperatures T{sub A}. • Sample structure was transformed from cubic to tetragonal by JTE at 1000 °C. • Spontaneous and saturation magnetizations showed similar behavior against T{sub A}. • The deduced parameters showed dependence on T{sub A} and proved their affect by JTE. • Spontaneous magnetization proved dependence on crystallite size. - Abstract: Amounts of the as-synthesized CuAl{sub 0.6}Cr{sub 0.2}Fe{sub 1.2}O{sub 4} nanoparticles by the chemical co-precipitation method were annealed for 4 h at one of the temperatures T{sub A} = 300, 500, 600, 800 and 1000 °C for each. The techniques used for characterizing the samples were X-ray diffractions, infrared (IR) and Mössbauer spectroscopy and vibrating sample magnetometer. This study proved single-phase cubic structure of the samples annealed at T{sub A} ≤ 800 °C and tetragonal structure of the sample annealed at 1000 °C. The cubic-to-tetragonal structure transformation was attributed to the tetragonal distortion by Jahn–Teller effect (JTE) of Cu{sup 2+} ions. This study revealed that all deduced parameters were affected by JTE, whereas the crystallite size, lattice parameters, strain, threshold frequency, force constants, Debye temperature and stiffness constant were dependent on T{sub A}. IR absorption band positions and intensities were dependent on T{sub A} and proved the existence of Fe{sup 2+}, Fe{sup 4+} and Cr{sup 4+} ions in the crystal sublattices. The spontaneous and saturation magnetization and hyperfine magnetic field of the tetrahedral and octahedral sites were deduced and discussed as functions of T{sub A}.

  1. Application of nano-magnesso ferrite (n-MgFe{sub 2}O{sub 4}) for the removal of Co{sup 2+} ions from synthetic wastewater: Kinetic, equilibrium and thermodynamic studies

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Varsha, E-mail: varsha06bhu@gmail.com [Laboratory of Green Chemistry, Faculty of Technology, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland); Sharma, Y.C. [Department of Chemistry, Indian Institute of Technology, Banaras Hindu University, Varanasi 221005 (India); Sillanpää, Mika [Laboratory of Green Chemistry, Faculty of Technology, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland)

    2015-05-30

    Graphical abstract: - Highlights: • The removal efficiency of n-MgFe{sub 2}O{sub 4} for Co(II) ions was investigated. • Rapid removal efficiency was observed within 60 min of contact time. • The kinetic data of Co(II) followed the pseudo-second-order model. • Thermodynamic studies revealed that the adsorption reaction was spontaneous. • Desorption study demonstrated its reusability upto three adsorption–desorption cycles. - Abstract: The aim of this research is to investigate the adsorption characteristics of nano-magnesso ferrite (n-MgFe{sub 2}O{sub 4}) for the removal of Co(II) ions from aqueous solution. n-MgFe{sub 2}O{sub 4} was synthesized by precipitation method. XRD of synthesized particles reveals the formation of single-phase n-MgFe{sub 2}O{sub 4} nanoparticles. TEM confirms the formation of particle size in the range of 25–35 nm. AFM and SEM analysis also support the TEM result. BET surface area of nanoparticles was determined to be 53.83 m{sup 2}/g. The adsorption of Co(II) onto n-MgFe{sub 2}O{sub 4} was found to be dependent on pH and the removal increased in alkaline medium. Co(II) adsorption followed pseudo-second-order model. Thermodynamic study showed that the adsorption process was endothermic and spontaneous. The equilibrium adsorption data was analyzed by two parameters and three parameters isotherm. Langmuir adsorption capacity was determined to be 67.41 mg/g. Chi-square test, standard deviations and the sum of squares of the errors (SSE) were evaluated to find out the better isotherm model. Desorption and reusability test suggested that n-MgFe{sub 2}O{sub 4} can be efficiently used up to three adsorption–desorption cycles. The findings of the present study suggest that n-MgFe{sub 2}O{sub 4} is very efficient for the adsorption of Co(II) ions. Adsorption efficiency of n-MgFe{sub 2}O{sub 4} for Co(II) has not yet been studied, so this study can be helpful for the treatment of Co(II) rich wastewater in near future.

  2. Influence of preparation method on structural and magnetic properties of nickel ferrite nanoparticles

    Indian Academy of Sciences (India)

    Binu P Jacob; Ashok Kumar; R P Pant; Sukhvir Singh; E M Mohammed

    2011-12-01

    Nickel ferrite nanoparticles of very small size were prepared by sol–gel combustion and co-precipitation techniques. At the same annealing temperature sol–gel derived particles had bigger crystallite size. In both methods, crystallite size of the particles increased with annealing temperature. Sol–gel derived nickel ferrite particles were found to be of almost spherical shape and moderate particle size with a narrow size distribution; while co-precipitation derived particles had irregular shape and very small particle size with a wide size distribution. Nickel ferrite particles produced by sol–gel method exhibited more purity. Sol–gel synthesized nanoparticles were found to be of high saturation magnetization and hysteresis. Co-precipitation derived nickel ferrite particles, annealed at 400°C exhibited superparamagnetic nature with small saturation magnetization. Saturation magnetization increased with annealing temperature in both the methods. At the annealing temperature of 600°C, co-precipitation derived particles also became ferrimagnetic.

  3. One-pot production of copper ferrite nanoparticles using a chemical method

    Energy Technology Data Exchange (ETDEWEB)

    Nishida, Naoki, E-mail: nnishida@rs.tus.ac.jp; Amagasa, Shota [Tokyo University of Science, Department of Chemistry (Japan); Kobayashi, Yoshio [The University of Electro-Communications, Department of Engineering Science (Japan); Yamada, Yasuhiro [Tokyo University of Science, Department of Chemistry (Japan)

    2016-12-15

    Copper ferrite nanoparticles were synthesized via the oxidation of precipitates obtained from the reaction of FeCl{sub 2}, CuSO{sub 4} and N{sub 2}H{sub 4} in the presence of gelatin. These copper ferrite particles were subsequently examined using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and Mössbauer spectroscopy. The average size of the copper ferrite nanoparticles was less than 5 nm, and they exhibited superparamagnetic behavior as a result of their small size. The low temperature Mössbauer spectrum exhibited three sets of sextets, two corresponding to the tetrahedral and octahedral sites of the copper spinel structure and one with small hyperfine magnetic field corresponding to the surface or defects of the nanoparticles. When the ratio of copper salt was increased, the tetrahedral site became preferable for copper, and metallic copper and copper ferrite were both present in a single nanoparticle.

  4. Zinc substituted ferrite nanoparticles with Zn{sub 0.9}Fe{sub 2.1}O{sub 4} formula used as heating agents for in vitro hyperthermia assay on glioma cells

    Energy Technology Data Exchange (ETDEWEB)

    Hanini, Amel [Interface Traitement Organisation et Dynamique des Systèmes (TODYS), Université Paris Diderot, Sorbonne Paris Cité, CNRS UMR-7086, 75013, Paris (France); Institut Cochin, Université Paris Descartes, Sorbonne Paris Cité, CNRS UMR-8104, INSERM U1016, 75005 Paris (France); Laboratoire de Physiologie Intégrée (LPI), Université de Carthage, 7021, Jarzouna (Tunisia); Lartigue, Lenaic [Matière et Systèmes Complexes (MSC), Université Paris Diderot, Sorbonne Paris Cité, CNRS UMR-7057, 75013, Paris (France); Gavard, Julie [Institut Cochin, Université Paris Descartes, Sorbonne Paris Cité, CNRS UMR-8104, INSERM U1016, 75005 Paris (France); Kacem, Kamel [Laboratoire de Physiologie Intégrée (LPI), Université de Carthage, 7021, Jarzouna (Tunisia); Wilhelm, Claire; Gazeau, Florence [Matière et Systèmes Complexes (MSC), Université Paris Diderot, Sorbonne Paris Cité, CNRS UMR-7057, 75013, Paris (France); Chau, François [Interface Traitement Organisation et Dynamique des Systèmes (TODYS), Université Paris Diderot, Sorbonne Paris Cité, CNRS UMR-7086, 75013, Paris (France); and others

    2016-10-15

    In this paper we investigate the ability of zinc rich ferrite nanoparticles to induce hyperthermia on cancer cells using an alternating magnetic field (AMF). First, we synthesized ferrites and then we analyzed their physico-chemical properties by transmission electron microscopy, X-ray diffraction and magnetic and magnetocalorimetric measurements. We found that the polyol-made magnetically diluted particles are of 11 nm in size. They are superparamagnetic at body temperature (310 K) with a low but non-negligible magnetization. Interestingly, as nano-ferrimagnets they exhibit a Curie temperature of 366 K, close to the therapeutic temperature range. Their effect on human healthy endothelial (HUVEC) and malignant glioma (U87-MG) cells was also evaluated using MTT viability assays. Incubated with the two cell lines, at doses ≤100 µg mL{sup −1} and contact times ≤4 h, they exhibit a mild in vitro toxicity. In these same operating biological conditions and coupled to AMF (700 kHz and 34.4 Oe) for 1 h, they rapidly induce a net temperature increase. In the case of tumor cells it reaches 4 K, making the produced particles particularly promising for self-regulated magnetically-induced heating in local glioma therapy. - Highlights: • Highly crystallized monodisperse 11 nm sized Zn{sub 0.9}Fe{sub 2.1}O{sub 4} particles were produced in polyol. • They exhibit a superparamagnetic behavior at 37 °C with a magnetization of 12 emu g{sup −1} at 50 kOe. • Their Curie temperature reaches 88 °C, close to the therapeutic hyperthermia temperatures. • Incubated with glioma cells and exposed to ac-magnetic field they induce a 4 °C temperature increase. • They can be considered as potential self-regulated heating probes for glioma therapy.

  5. Synthesis and characterization of nanocrystalline zinc ferrite

    DEFF Research Database (Denmark)

    Jiang, J.S.; Yang, X.L.; Gao, L.

    1999-01-01

    Nanocrystalline zinc ferrite powders with a partially inverted spinel structure were synthesized by high-energy ball milling in a closed container at ambient temperature from a mixture of alpha-Fe2O3 and ZnO crystalline powders in equimolar ratio. From low-temperature and in-field Mossbauer...... measurements it is revealed that ZnFe2O4 particles prepared are in superparamagnetic state at ambient temperature. A doublet with an average quadrupole splitting of 0.8 nm/s is observed for the as-milled sample at 295 K, which is much larger than that for bulk ZnFe2O4 prepared by traditional ceramic method...... and that for ultrafine ZnFe2O4 particles prepared by the co-precipitation method. This indicates larger structural defects in the nanometer-sized ZnFe2O4 particles prepared by high-energy ball milling....

  6. Chromium removal from aqueous media by superparamagnetic starch functionalized maghemite nanoparticles

    Indian Academy of Sciences (India)

    P N Singh; D Tiwary; I Sinha

    2015-11-01

    Superparamagnetic starch functionalized maghemite nanoparticles (SMhNPs) were synthesised by a co-precipitation method via in situ functionalization and used as nano-adsorbents for the removal of Cr(VI) from aqueous waste. The characterization of the prepared nanoparticles was done by XRD, FTIR, TEM and VSM techniques. Adsorption of Cr(VI) on the surface of superparamagnetic starch functionalized maghemite nano-adsorbents was investigated and the removal was higher in acidic pH as compared to that exhibited in basic medium. The adsorption of Cr(VI) by the SMhNPs followed pseudo-second order kinetics and the adsorption isotherm data fits well the Freundlich adsorption isotherm. The F value for Cr(VI) removal by SMhNPs is found to be 24.76 mg.g−1, which is significantly better than the adsorption capacities reported in literature for maghemite nanoparticles. Thermodynamic studies revealed that the adsorption of Cr(VI) onto the superparamagnetic starch functionalized maghemite nano-adsorbents is spontaneous and endothermic in nature.

  7. Influence of superparamagnetic iron oxide nano-particles in different concentration on macrophage line RAW264.7 in mice%不同浓度超顺磁性氧化铁纳米粒子对小鼠RAW264.7巨噬细胞的影响

    Institute of Scientific and Technical Information of China (English)

    韩莎莎; 李俊峡

    2013-01-01

    Objective To review the influence of superparamagnetic iron oxide nano-particles ( SPIO ) in different concentration on the cell viability and phagocytic capacity of macrophage line RAW264.7 in mice. Methods RAW264.7 were cultured by using routine method, and then labeled with SPIO in different concentration ( 0 μg/mL, 14 μg/mL, 28μg/mL, 56 μg/mL, 84 μg/mL, 140 μg/mL, 280 μg/mL, 560 μg/mL and 840 μg/mL ) . The labeling yield was detected by using Prussian blue staining, cell viability was detected by using trypan blue, cell reproductive capacity was detected by using MTT assay, and cell phagocytic capacity was detected by using neutral red phagocytosis test. Results The labeling rate reached to 100% after labeling for 24 hours in SPIO with iron concentration of 84 μg/mL, and then as iron concentration in SPIO increased, the iron particles phagocytosed by RAW264.7 increased. When the iron concentration in SPIO was 280 μg/mL, the iron particles phagocytosed by RAW264.7 reached to saturation. When the iron concentration in SPIO was over 280 μg/mL, cell viability and phagocytic capacity decreased, and the iron concentration in SPIO was over 140 μg/mL, cell reproductive capacity decreased. Conclusion When the iron concentration in SPIO is ( 84-140 ) μg/mL and after labeling RAW 264.7 lor 24 hours, the labeling rale is 100% and cell viability, cell reproductive capacity and phagocytic capacity are not influenced.%目的 评价不同浓度超顺磁性氧化铁纳米粒子(superparamagnetic iron oxides,SPIO)对小鼠RAW264.7巨噬细胞的细胞活性及吞噬功能的影响.方法 常规方法培养小鼠RAW264.7巨噬细胞,应用不同浓度SPIO(0 μg/ml、14μg/ml、28μg/ml、56μg/ml、84μg/ml、140μg/ml、280μg/ml、560μg/ml、840μg/ml)标记小鼠RAW264.7巨噬细胞,采用普鲁士蓝染色检测细胞标记率,台盼蓝染色检测细胞活性,四唑盐(MTT)比色实验检测细胞增殖能力,中性红吞噬实验

  8. High heat generation ability in AC magnetic field for nano-sized magnetic Y{sub 3}Fe{sub 5}O{sub 12} powder prepared by bead milling

    Energy Technology Data Exchange (ETDEWEB)

    Aono, Hiromichi, E-mail: aono.hiromichi.mf@ehime-u.ac.jp [Graduate School of Science and Engineering, Ehime University, Matsuyama 790-8577 (Japan); Ebara, Hiroki; Senba, Ryota; Naohara, Takashi; Maehara, Tsunehiro [Graduate School of Science and Engineering, Ehime University, Matsuyama 790-8577 (Japan); Hirazawa, Hideyuki [Department of Environmental Materials Engineering, Niihama National College of Technology, Niihama 792-8580 (Japan); Watanabe, Yuji [Department of Surgery, Graduate School of Medicine, Ehime University, Toon 791-0295 (Japan)

    2012-06-15

    Nano-sized magnetic Y{sub 3}Fe{sub 5}O{sub 12} ferrite having a high heat generation ability in an AC magnetic field was prepared by bead milling. A commercial powder sample (non-milled sample) of ca. 2.9 {mu}m in particle size did not show any temperature enhancement in the AC magnetic field. The heat generation ability in the AC magnetic field improved with a decrease in the average crystallite size for the bead-milled Y{sub 3}Fe{sub 5}O{sub 12} ferrites. The highest heat ability in the AC magnetic field was for the fine Y{sub 3}Fe{sub 5}O{sub 12} powder with a 15-nm crystallite size (the samples were milled for 4 h using 0.1 mm{phi} beads). The heat generation ability of the excessively milled Y{sub 3}Fe{sub 5}O{sub 12} samples decreased. The main reason for the high heat generation property of the milled samples was ascribed to an increase in the Neel relaxation of the superparamagnetic material. The heat generation ability was not influenced by the concentration of the ferrite powder. For the samples milled for 4 h using 0.1 mm{phi} beads, the heat generation ability (W g{sup -1}) was estimated using a 3.58 Multiplication-Sign 10{sup -4} fH{sup 2} frequency (f/kHz) and the magnetic field (H/kA m{sup -1}), which is the highest reported value of superparamagnetic materials. - Highlights: Black-Right-Pointing-Pointer The nano-sized Y{sub 3}Fe{sub 5}O{sub 12} powder prepared by bead-milling has the highest heat generation ability in an AC magnetic field. Black-Right-Pointing-Pointer The heat generation properties are ascribed to an increase in the Neel relaxation of the superparamagnetic material. Black-Right-Pointing-Pointer The heat ability (W g{sup -1}) can be estimated using 3.58 Multiplication-Sign 10{sup -4} fH{sup 2} (f=kHz, H=kA m{sup -1}). Black-Right-Pointing-Pointer This is an expectable material for use in a drug delivery system for the thermal coagulation therapy of cancer tumors.

  9. Superparamagnetic iron oxide nanoparticles (SPIONs) for targeted drug delivery

    Science.gov (United States)

    Garg, Vijayendra K.; Kuzmann, Erno; Sharma, Virender K.; Kumar, Arun; Oliveira, Aderbal C.

    2016-10-01

    Studies of superparamagnetic iron oxide nanoparticles (SPIONs) have been extensively carried out. Since the earlier work on Mössbauer studies on SPIONs in 1970s, many biomedical applications and their uses in innovative methods to produce new materials with improved performance have appeared. Applications of SPIONs in environmental remediation are also forthcoming. Several different methods of synthesis and coating of the magnetic particles have been described in the literature, and Mössbauer spectroscopy has been an important tool in the characterization of these materials. It is quite possible that the interpretation of the Mössbauer spectra might not be entirely correct because the possible presence of maghemite in the end product of SPIONs might not have been taken into consideration. Nanotechnology is an emerging field that covers a wide range of new technologies under development in nanoscale (1 to 100 nano meters) to produce new products and methodology.

  10. Co-occurrence of Superparamagnetism and Anomalous Hall Effect in Highly Reduced Cobalt Doped Rutile TiO2 Films

    OpenAIRE

    2004-01-01

    We report a detailed magnetic and structural analysis of highly reduced Co doped rutile TiO2 films displaying an anomalous Hall effect (AHE). The temperature and field dependence of magnetization, and transmission electron microscopy clearly establish the presence of nano-sized superparamagnetic cobalt clusters of 8-10 nm size in the films at the interface. The co-occurrence of superparamagnetism and AHE raises questions regarding the use of the AHE as a test of the intrinsic nature of ferrom...

  11. Study of DNA interaction with cobalt ferrite nanoparticles.

    Science.gov (United States)

    Pershina, A G; Sazonov, A E; Novikov, D V; Knyazev, A S; Izaak, T I; Itin, V I; Naiden, E P; Magaeva, A A; Terechova, O G

    2011-03-01

    Interaction of cobalt ferrite nanopowder and nucleic acid was investigated. Superparamagnetic cobalt ferrite nanoparticles (6-12 nm) were prepared by mechanochemical synthesis. Structure of the nanopowder was characterized using X-ray diffraction. It was shown that cobalt ferrite nanoparticles were associated with ssDNA and dsDNA in Tris-buffer resulting in bionanocomposite formation with mass weight relation nanoparticles: DNA 1:(0.083 +/- 0.003) and 1:(0.075 +/- 0.003) respectively. The mechanism of interaction between a DNA and cobalt ferrite nanoparticles was considered basing on the whole set of obtained data: FTIR-spectroscopy, analyzing desorption of DNA from the surface of the particles while changing the chemical content of the medium, and on the modeling interaction of specific biomolecule fragments with surface of a inorganic material. It was supposed that the linkage was based on coordination interaction of the phosphate groups and oxygen atoms heterocyclic bases of DNA with metal ions on the particle surface. These data can be used to design specific magnetic DNA-nanoparticles hybrid structures.

  12. Parametric characterizations in superparamagnetic latex

    Indian Academy of Sciences (India)

    Seda Beyaz; Hakan Kockar; Taner Tanrisever

    2014-05-01

    The effect of synthesis parameters on the production of superparamagnetic latex, which are magnetite nanoparticles covered with a poly(methyl methacrylate) layer, were studied. The synthesis method was based on the developed route of emulsifier-free emulsion polymerization. Under this study, effects of the monomer and initiator concentrations, the amount of magnetic sol, the stirring rate and the adding rate of the magnetic sol on the properties of synthesized latexes were investigated. The characterizations were performed by a high resolution transmission electron microscopy, a dynamic light scattering, a vibrating sample magnetometer and a gel permeation chromatography. The results showed that the monomer concentration was found to be the most effective parameter on latex stability. As the initiator amount and the stirring rate increased, saturation magnetization and average molecular weight decreased due to the reactions occurring between surfaces of magnetite nanoparticles and initiator fragments. On increasing amount of magnetic sol, the saturation magnetization and polymer molecular weight increased but the size of nanospheres was unchanged because of the ions in magnetic sol. It was seen that the desired size and magnetic properties of the latex could be obtained since the parameters were found to have substantial impact on their properties.

  13. Ferritic Alloys with Extreme Creep Resistance via Coherent Hierarchical Precipitates

    Science.gov (United States)

    Song, Gian; Sun, Zhiqian; Li, Lin; Xu, Xiandong; Rawlings, Michael; Liebscher, Christian H.; Clausen, Bjørn; Poplawsky, Jonathan; Leonard, Donovan N.; Huang, Shenyan; Teng, Zhenke; Liu, Chain T.; Asta, Mark D.; Gao, Yanfei; Dunand, David C.; Ghosh, Gautam; Chen, Mingwei; Fine, Morris E.; Liaw, Peter K.

    2015-01-01

    There have been numerous efforts to develop creep-resistant materials strengthened by incoherent particles at high temperatures and stresses in response to future energy needs for steam turbines in thermal-power plants. However, the microstructural instability of the incoherent-particle-strengthened ferritic steels limits their application to temperatures below 900 K. Here, we report a novel ferritic alloy with the excellent creep resistance enhanced by coherent hierarchical precipitates, using the integrated experimental (transmission-electron microscopy/scanning-transmission-electron microscopy, in-situ neutron diffraction, and atom-probe tomography) and theoretical (crystal-plasticity finite-element modeling) approaches. This alloy is strengthened by nano-scaled L21-Ni2TiAl (Heusler phase)-based precipitates, which themselves contain coherent nano-scaled B2 zones. These coherent hierarchical precipitates are uniformly distributed within the Fe matrix. Our hierarchical structure material exhibits the superior creep resistance at 973 K in terms of the minimal creep rate, which is four orders of magnitude lower than that of conventional ferritic steels. These results provide a new alloy-design strategy using the novel concept of hierarchical precipitates and the fundamental science for developing creep-resistant ferritic alloys. The present research will broaden the applications of ferritic alloys to higher temperatures. PMID:26548303

  14. Modern Ferrite Technology

    CERN Document Server

    Goldman, Alex

    2006-01-01

    Modern Ferrite Technology, 2nd Ed. offers the readers an expert overview of the latest ferrite advances as well as their applications in electronic components. This volume develops the interplay among material properties, component specification and device requirements using ferrites. Throughout, emphasis is placed on practical technological concerns as opposed to mathematical and physical aspects of the subject. The book traces the origin of the magnetic effect in ferrites from the level of the simplest particle and then increases the scope to include larger hierarchies. From the desired magnetic properties, the author deduces the physical and chemical material parameters, taking into consideration major chemistry, impurity levels, ceramic microstructures and grain boundary effects. He then discusses the processing conditions and associated conditions required for implementation. In addition to conventional ceramic techniques, he describes non-conventional methods such as co-precipitation, co-spray roasting ...

  15. Magnetic composites based on hybrid spheres of aluminum oxide and superparamagnetic nanoparticles of iron oxides

    Energy Technology Data Exchange (ETDEWEB)

    Braga, Tiago P. [Langmuir - Laboratorio de Adsorcao e Catalise, Departamento de Quimica Analitica e Fisico-Quimica, Universidade Federal do Ceara, CP 6021, CEP 60455-970 Campus do Pici, Fortaleza (Brazil); Vasconcelos, Igor F. [Departamento de Engenharia Metalurgica e de Materiais, Universidade Federal do Ceara, Fortaleza (Brazil); Sasaki, Jose M. [Laboratorio de Raios X, Departamento de Fisica, Universidade Federal do Ceara, Campus do Pici, Fortaleza, CE (Brazil); Fabris, J.D.; Oliveira, Diana Q.L. de [Departamento de Quimica, Universidade Federal de Minas Gerais, Belo Horizonte (Brazil); Valentini, Antoninho, E-mail: valent@ufc.b [Langmuir - Laboratorio de Adsorcao e Catalise, Departamento de Quimica Analitica e Fisico-Quimica, Universidade Federal do Ceara, CP 6021, CEP 60455-970 Campus do Pici, Fortaleza (Brazil)

    2010-03-15

    Materials containing hybrid spheres of aluminum oxide and superparamagnetic nanoparticles of iron oxides were obtained from a chemical precursor prepared by admixing chitosan and iron and aluminum hydroxides. The oxides were first characterized with scanning electron microscopy, X-ray diffraction, and Moessbauer spectroscopy. Scanning electron microscopy micrographs showed the size distribution of the resulting spheres to be highly homogeneous. The occurrence of nano-composites containing aluminum oxides and iron oxides was confirmed from powder X-ray diffraction patterns; except for the sample with no aluminum, the superparamagnetic relaxation due to iron oxide particles were observed from Moessbauer spectra obtained at 298 and 110 K; the onset six line-spectrum collected at 20 K indicates a magnetic ordering related to the blocking relaxation effect for significant portion of small spheres in the sample with a molar ratio Al:Fe of 2:1.

  16. 纳米铁酸锌/丙氨酸改性聚乳酸复合磁性微球的制备和表征%Preparation and characterization of composite microspheres of nano zinc ferrite/poly (D, L-lactide-co-alanine)

    Institute of Scientific and Technical Information of China (English)

    曹雷健; 周勤华; 谷俐; 沈红霞; 李清华; 兰平; 方燕

    2012-01-01

    以改进液相化学法合成铁酸锌纳米磁流体来代替传统的铁氧化物磁粉,同时以D,L型丙交酯与丙氨酸为单体进行本体聚合,得到氨基酸改性聚乳酸,再以改性聚乳酸包封纳米磁流体构建磁性高分子微球.采用X射线衍射、傅立叶红外光谱仪、核磁共振仪、扫描电镜、透射电镜、振动样品磁强计、热重分析仪等对所合成的材料进行表征.结果表明:所制备的材料为尖晶石型的ZnFe2O4纳米晶,粒径为20~45 nm,磁饱和强度为32× 10-3 A·m2;丙氨酸成功接枝到了聚乳酸链上;铁酸锌纳米磁流体/聚乳酸复合微球的分散性较好,粒径为80~300 nm,聚乳酸的包覆率为45.5%,磁饱和强度为10.6× 10-3 A·m2,ZnFe2O4经改性聚乳酸封装后仍然保持较好的磁饱和强度.%Magnetic nano zinc ferrite fliuds were synthesized using an improved liquid phase chemical method,which would be used to replace tradditional iron oxides magnetic material.A novel copolymer (PLAA) with D,L-lactide (D,L-LA) and alanine was synthesized using stannous octoate as initiator.Magnetic polymer microspheres were fabricated with nano zinc ferrite fluid coated with alanine modified poly lactide.These as-prepared zinc ferrite fluids,modified poly lactide and magnetic composites,were characterized with X-ray diffraction diffractometer,FT-IR spectrometer,nuclear magnetic resonance spectrometer,scanning electron microscope,transmission electron microscope,vibrating sample magnetometer,and thermogravimetric analyzer.The results demonstrate that the as-prepared zinc ferrite is spinel type of ZnFe2O4 nano crystals with particle size of 20--45 nm and magnetization of 32×10-3 A·m2.Alanine is copolymerized with lactide,and the prepared composite magnetic microsphere is coated with the modified polylactide,with mass fraction of 45.5% of PLA,particle size ranging from 80-300 nm,and magnetization of 10.6× 10-3 A·m2,which suggests ZnFe2O4 enjoys a stable

  17. Thin Polymer Layers with Superparamagnetic Properties

    Directory of Open Access Journals (Sweden)

    Kristin Trommer

    2015-01-01

    Full Text Available Superparamagnetic particles were widely used in medical applications as well as for magnetic sensors and actuators. Generally, the size of the particles is in the range of 10–20 nm. To use such particles in large-scale applications, a simple processing as well as the use of commercially available particles is required. Therefore superparamagnetic nanoparticles available on the market were incorporated in flexible polymer films and the magnetic properties of the films were investigated. At ambient temperature no significant hysteresis was observed, indicating the superparamagnetic properties. Films containing up to 25% nanoparticles were prepared. The films show a saturation magnetization of 13.8 Am2/kg and a coercivity of 7 Oe at ambient temperature.

  18. Structural and Mössbauer investigation on barium titanate-cobalt ferrite composites

    Science.gov (United States)

    Leonel, Liliam V.; Silva, Juliana B.; Albuquerque, Adriana S.; Ardisson, José D.; Macedo, Waldemar A. A.; Mohallem, Nelcy D. S.

    2012-11-01

    Perovskite and spinels oxides have received renewed attention due to the possibility of combining both structures in di-phase composites to obtain multifunctional materials. In this work, barium titanate (perovskite)-cobalt ferrite (spinel) composite powders with different microstructures were obtained from thermal treatment of amorphous precursors at 500-1100 °C. The precursors were prepared by combining coprecipitation and sol-gel routes. Lyophilization of ferrite prior to mixing was used as a strategy to control interphase reaction. Mössbauer spectroscopy showed that the dispersion of coprecipitated ferrite in a viscous BaTiO3 precursor gel resulted in superparamagnetic behavior and reduction of the local magnetic field of site [B].

  19. Superparamagnetic segmentation by excitable neural systems.

    Science.gov (United States)

    Neirotti, Juan P; Kurcbart, Samuel M; Caticha, Nestor

    2003-09-01

    Magnetic modeling for clustering or segmentation purposes can either associate the image data to external quenched fields or to the interactions among a set of auxiliary variables. The latter gives rise to superparamagnetic segmentation and is usually done with Potts systems. We have used the superparamagnetic clustering technique to segment images, with the aid of different associated systems. Results using Potts model are comparable to those obtained using excitable FitzHugh-Nagumo and Morris-Lecar model neurons. Interactions between the associated system components are a function of the difference of luminosity on a gray scale of neighbor pixels and the difference of membrane potential.

  20. Structure and magnetic properties of granular NiZn-ferrite - SiO2

    Directory of Open Access Journals (Sweden)

    Albuquerque Adriana Silva de

    1999-01-01

    Full Text Available Granular systems composed by nanostructured magnetic materials embedded in a non-magnetic matrix present unique physical properties that depend crucially on their nanostructure. In this work, we have studied the structural and magnetic properties of NiZn-ferrite nanoparticles embedded in SiO2, a granular system synthesized by sol-gel processing. Samples with ferrite volumetric fraction x ranging from 6% to 78% were prepared, and characterized by X-ray diffraction, Mössbauer spectroscopy and vibrating sample magnetometry. Our results show the formation of pure stoichiometric NiZn-ferrite in the SiO2 matrix for x < 34%. Above these fraction, our samples presented also small amounts of Fe2O3. Mössbauer spectroscopy revealed the superparamagnetic behaviour of the ferrimagnetic NiZn-ferrite nanoparticles. The combination of different ferrite concentration and heat treatments allowed the obtaintion of samples with saturation magnetization between 1.3 and 68 emu/g and coercivity ranging from 0 to 123 Oe, value which is two orders of magnitude higher than the coercivity of bulk NiZn-ferrite.

  1. MZnFe{sub 2}O{sub 4} (M = Ni, Mn) cubic superparamagnetic nanoparticles obtained by hydrothermal synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Freire, R. M. [Universidade Federal do Ceara-UFC, Grupo de Quimica de Materiais Avancados (GQMAT)- Departamento de Quimica Analitica e Fisico-Quimica (Brazil); Ribeiro, T. S.; Vasconcelos, I. F. [Universidade Federal do Ceara, Departamento de Engenharia Metalurgica e de Materiais (Brazil); Denardin, J. C. [Universidad de Santiago de Chile, USACH, Departamento de Fisica (Chile); Barros, E. B. [Universidade Federal do Ceara-UFC, Departamento de Fisica (Brazil); Mele, Giuseppe [Universita del Salento, Dipartimento di Ingegneria dell' Innovazione (Italy); Carbone, L. [IPCF-CNR, UOS Pisa (Italy); Mazzetto, S. E.; Fechine, P. B. A., E-mail: fechine@ufc.br [Universidade Federal do Ceara-UFC, Grupo de Quimica de Materiais Avancados (GQMAT)- Departamento de Quimica Analitica e Fisico-Quimica (Brazil)

    2013-05-15

    MZnFe{sub 2}O{sub 4} (M = Ni or Mn) cubic nanoparticles have been prepared by hydrothermal synthesis in mild conditions and short time without any procedure of calcinations. The structural and magnetic properties of the mixed ferrites were investigated by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Moessbauer spectroscopy, vibrating sample magnetometer, and Transmission electron microscopy (TEM). X-ray analysis showed peaks characteristics of the spinel phase. The average diameter of the nanoparticles observed by TEM measurements was approximately between 4 and 10 nm. Spectroscopy study of the spinel structure was performed based on Group Theory. The predicted bands were observed in FTIR and Raman spectrum. The magnetic parameters and Moessbauer spectroscopy were measured at room temperature and superparamagnetic behavior was observed for mixed ferrites. This kind of nanoparticles can be used as precursor in drug delivery systems, magnetic hyperthermia, ferrofluids, or magnetic imaging contrast agents.

  2. Effect of temperature on sintered austeno-ferritic stainless steel microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Munez, C.J. [Departamento de Ciencia e Ingenieria de Materiales, Escuela Superior de Ciencias Experimentales y Tecnologia, Universidad Rey Juan Carlos, 28933 Mostoles, Madrid (Spain)], E-mail: claudio.munez@urjc.es; Utrilla, M.V.; Urena, A. [Departamento de Ciencia e Ingenieria de Materiales, Escuela Superior de Ciencias Experimentales y Tecnologia, Universidad Rey Juan Carlos, 28933 Mostoles, Madrid (Spain)

    2008-09-08

    The influence of temperature on microstructural changes of sintered austeno-ferritic steels has been investigated. PM stainless steels have been obtained by sintering mixtures of austenitic and ferritic stainless steel powders. Only temperature-induced phase transformation was observed in austenite, as a result of elements interdiffusion between both phases. Microstructural characterization was completed with atomic force microscopy (AFM) and micro- and nano-indentation test, it is revealed an increase in the hardness with respect to the solutionized materials.

  3. Impedance calculation for ferrite inserts

    Energy Technology Data Exchange (ETDEWEB)

    Breitzmann, S.C.; Lee, S.Y.; /Indiana U.; Ng, K.Y.; /Fermilab

    2005-01-01

    Passive ferrite inserts were used to compensate the space charge impedance in high intensity space charge dominated accelerators. They study the narrowband longitudinal impedance of these ferrite inserts. they find that the shunt impedance and the quality factor for ferrite inserts are inversely proportional to the imaginary part of the permeability of ferrite materials. They also provide a recipe for attaining a truly passive space charge impedance compensation and avoiding narrowband microwave instabilities.

  4. Morphology of Proeutectoid Ferrite

    Science.gov (United States)

    Yin, Jiaqing; Hillert, Mats; Borgenstam, Annika

    2017-03-01

    The morphology of grain boundary nucleated ferrite particles in iron alloys with 0.3 mass pct carbon has been classified according to the presence of facets. Several kinds of particles extend into both grains of austenite and have facets to both. It is proposed that they all belong to a continuous series of shapes. Ferrite plates can nucleate directly on the grain boundary but can also develop from edges on many kinds of particles. Feathery structures of parallel plates on both sides of a grain boundary can thus form. In sections, parallel to their main growth direction, plates have been seen to extend the whole way from the nucleation site at the grain boundary and to the growth front. This happens in the whole temperature range studied from 973 K to 673 K (700 °C to 400 °C). The plates thus grow continuously and not by subunits stopping at limited length and continuing the growth by new ones nucleating. Sometimes, the plates have ridges and in oblique sections they could be mistaken for the start of new plates. No morphological signs were observed indicating a transition between Widmanstätten ferrite and bainitic ferrite. It is proposed that there is only one kind of acicular ferrite.

  5. Superparamagnetic relaxation of weakly interacting particles

    DEFF Research Database (Denmark)

    Mørup, Steen; Tronc, Elisabeth

    1994-01-01

    The influence of particle interactions on the superparamagnetic relaxation time has been studied by Mossbauer spectroscopy in samples of maghemite (gamma-Fe2O3) particles with different particle sizes and particle separations. It is found that the relaxation time decreases with decreasing particl...

  6. Superparamagnetic relaxation in alpha-Fe particles

    DEFF Research Database (Denmark)

    Bødker, Franz; Mørup, Steen; Pedersen, Michael Stanley;

    1998-01-01

    The superparamagnetic relaxation time of carbon-supported alpha-Fe particles with an average size of 3.0 Mm has been studied over a large temperature range by the use of Mossbauer spectroscopy combined with AC and DC magnetization measurements. It is found that the relaxation time varies with tem...

  7. Ferrite logic reliability study

    Science.gov (United States)

    Baer, J. A.; Clark, C. B.

    1973-01-01

    Development and use of digital circuits called all-magnetic logic are reported. In these circuits the magnetic elements and their windings comprise the active circuit devices in the logic portion of a system. The ferrite logic device belongs to the all-magnetic class of logic circuits. The FLO device is novel in that it makes use of a dual or bimaterial ferrite composition in one physical ceramic body. This bimaterial feature, coupled with its potential for relatively high speed operation, makes it attractive for high reliability applications. (Maximum speed of operation approximately 50 kHz.)

  8. Structural and optical properties of Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} nano ferrites: Effect of sintering temperature

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Prashant, E-mail: prashant007thakur@gmail.com; Sharma, Rohit; Sharma, Vineet, E-mail: vineet.sharma@juiit.ac.in; Sharma, Pankaj, E-mail: pankaj.sharma@juit.ac.in

    2017-06-01

    Mn-Zn ferrites have shown various remarkable applications e.g. in magnetic amplifiers, power transformers and electromagnetic interference etc. due to their high initial permeability. Mn–Zn ferrite powder (Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}) has been prepared by the co-precipitation method and subsequently sintered at three different temperatures i.e. 973 K, 1173 K, 1373 K. Optical properties have been correlated with the structural properties. For structural properties X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR) have been employed. It has been observed that there is an increase in crystallite size with sintering from 973 K to 1373 K and FTIR confirms the formation of bond between metal ion and oxygen ion at the octahedral site and tetrahedral site. A red shift has been confirmed from UV–visible absorption spectra and photoluminescence spectra have been reported with an increase in sintering temperature. - Graphical abstract: Mn–Zn ferrite powder (Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}) has been prepared by the co-precipitation method and subsequently sintered at three different temperatures i.e. 973 K, 1173 K, 1373 K. A red shift has been confirmed from UV–visible absorption spectra and photoluminescence spectra have been reported with an increase in sintering temperature. - Highlights: • Nanoparticles of Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} have been prepared by the co-precipitation method. • There is an increase in crystallite size with sintering from 973 K to 1373 K. • A red shift is found in UV–visible and PL spectra with an increase in sintering temperature.

  9. Investigation on Tc tuned nano particles of magnetic oxides for hyperthermia applications.

    Science.gov (United States)

    Giri, Jyotsnendu; Ray, Amlan; Dasgupta, S; Datta, D; Bahadur, D

    2003-01-01

    Superparamagnetic as well as fine ferrimagnetic particles such as Fe3O4, have been extensively used in magnetic field induced localized hyperthermia for the treatment of cancer. The magnetic materials with Curie temperature (Tc) between 42 and 50 degrees C, with sufficient biocompatibility are the best candidates for effective treatment such that during therapy it acts as in vivo temperature control switch and thus over heating could be avoided. Ultrafine particles of substituted ferrite Co(1-a)Zn(a)Fe2O4 and substituted yttrium-iron garnet Y3Fe(5-x)Al(x)O12 have been prepared through microwave refluxing and citrate-gel route respectively. Single-phase compounds were obtained with particle size below 100 nm. In order to make these magnetic nano particles biocompatible, we have attempted to coat these above said composition by alumina. The coating of alumina was done by hydrolysis method. The coating of hydrous aluminium oxide has been done over the magnetic particles by aging the preformed solid particles in the solution of aluminium sulfate and formamide at elevated temperatures. In vitro study is carried out to verify the innocuousness of coated materials towards cells. In vitro biocompatibility study has been carried out by cell culture method for a period of three days using human WBC cell lines. Study of cell counts and SEM images indicates the cells viability/growth. The in vitro experiments show that the coated materials are biocompatible.

  10. Manganese iron oxide superparamagnetic powder by mechanochemical processing. Nanoparticles functionalization and dispersion in a nanofluid

    Energy Technology Data Exchange (ETDEWEB)

    Bellusci, M., E-mail: mariangela.bellusci@enea.it; Aliotta, C. [ENEA, CR Casaccia, Dipartimento di Chimica e Technologia dei Materiali (Italy); Fiorani, D. [ISM-CNR, Area della Ricerca (Italy); La Barbera, A.; Padella, F. [ENEA, CR Casaccia, Dipartimento di Chimica e Technologia dei Materiali (Italy); Peddis, D. [ISM-CNR, Area della Ricerca (Italy); Pilloni, M. [ENEA, CR Casaccia, Dipartimento di Chimica e Technologia dei Materiali (Italy); Secci, D. [Universita di Roma La Sapienza, Dipartimento di Chimica e Tecnologie del Farmaco (Italy)

    2012-06-15

    Manganese ferrite nanoparticles were synthesized using a High-Energy Ball-Milling mechanochemical method. After 1 h of milling, the process produces a material consisting of single crystalline domain nanoparticles having a diameter of about 8 nm. Chemical properties of the synthesized powders allow an easy functionalization with citric acid. Both as-obtained and functionalized samples show superparamagnetic behaviour at room temperature, and the functionalized powder is stably dispersible in aqueous media at physiological pH. The average hydrodynamic diameter is equal to {approx}60 nm. Nanoparticles obtained by the reported High-Energy Ball-Milling method can be synthesized with high yield and low costs and can be successfully utilized in ferrofluids development for biomedical applications.

  11. Ferrite-based magnetic nanofluids used in hyperthermia applications

    Energy Technology Data Exchange (ETDEWEB)

    Sharifi, Ibrahim [Electroceramics Group, Department of Materials Science and Engineering, Shiraz University of Technology, Shiraz (Iran, Islamic Republic of); Shokrollahi, H., E-mail: Shokrollahi@sutech.ac.ir [Electroceramics Group, Department of Materials Science and Engineering, Shiraz University of Technology, Shiraz (Iran, Islamic Republic of); Amiri, S. [Electroceramics Group, Department of Materials Science and Engineering, Shiraz University of Technology, Shiraz (Iran, Islamic Republic of)

    2012-03-15

    Magnetic ferrofluids (magnetic nanofluids) have received special attention due to their various biomedical applications such as drug delivery and hyperthermia treatment for cancer. The biological applications impose some special requirements. For example, the well-known iron oxide ferrofluids become undesirable because their iron atoms are poorly distinguishable from those of hemoglobin. A conceivable solution is to use mixed-ferrites (MFe{sub 2}O{sub 4} where M=Co, Mn, Ni, Zn) to have a range of magnetic properties. These ferrites have attracted special attention because they save time, and because of their low inherent toxicity, ease of synthesis, physical and chemical stabilities and suitable magnetic properties. Based on the importance of ferrite particles in ferrofluids for hyperthermia treatment, this paper gives a summary on the physical concepts of ferrofluids, hyperthermia principal, magnetic properties and synthesis methods of nanosized ferrites. - Highlights: Black-Right-Pointing-Pointer This paper gives a suitable summary and literature survey on the ferrofluids. Black-Right-Pointing-Pointer Ferrofluids have an important role in biomedicine and our life. Black-Right-Pointing-Pointer Ferrofluids include a magnetic core, surfactant and a liquid medium. Black-Right-Pointing-Pointer Nano-ferrites' cores are good candidates for hyperthermia purposes. Black-Right-Pointing-Pointer They present a suitable heat generation for hyperthermia.

  12. Structural and magnetic characterization of co-precipitated Ni{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4} ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Srinivas, Ch., E-mail: srinivas.chintoju75@gmail.com [Department of Physics, Sasi Institute of Technology and Engineering, Tadepalligudem 534101 (India); Tirupanyam, B.V. [Department of Physics, Government College (Autonomous), Rajamahendravaram 533103 (India); Meena, S.S.; Yusuf, S.M. [Solid State Physics Division, Bhabha Atomic Research Center, Mumbai 400085 (India); Babu, Ch. Seshu [Department of Physics, Sasi Institute of Technology and Engineering, Tadepalligudem 534101 (India); Ramakrishna, K.S. [Department of Physics, Srinivasa Institute of Engineering and Technology, Amalapuram 533222 (India); Potukuchi, D.M. [Department of Physics, University College of Engineering, Jawaharlal Nehru Technological University, Kakinada 533003 (India); Sastry, D.L., E-mail: dl_sastry@rediffmail.com [Department of Physics, Andhra University, Visakhapatnam 530003 (India)

    2016-06-01

    A series of Ni{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4} (x=0.5, 0.6 and 0.7) ferrite nanoparticles have been synthesized using a co-precipitation technique, in order to understand the doping effect of nickel on their structural and magnetic properties. XRD and FTIR studies reveal the formation of spinel phase of ferrite samples. Substitution of nickel has promoted the growth of crystallite size (D), resulting the decrease of lattice strain (η). It was also observed that the lattice parameter (a) increases with the increase of Ni{sup 2+} ion concentration. All particles exhibit superparamagnetism at room temperature. The hyperfine interaction increases with the increase of nickel substitution, which can be assumed to the decrease of core–shell interactions present in the nanoparticles. The Mössbauer studies witness the existence of Fe{sup 3+} ions and absence of Fe{sup 2+} ions in the present systems. These superparamagnetic nanoparticles are supposed to be potential candidates for biomedical applications. The results are interpreted in terms of microstructure, cation redistribution and possible core–shell interactions. - Highlights: • Thermodynamic solubility of Ni{sup 2+} in zinc ferrite influences the crystallite sizes. • At room temperature the ferrite systems exhibit superparamagnetism. • Core–shell model was exactly suited to explain magnetic behavior. • Core–shell interactions decrease with increase in Ni{sup 2+} ion concentration.

  13. Development and characterization of superparamagnetic coatings

    Directory of Open Access Journals (Sweden)

    Kuschnerus I.

    2015-09-01

    Full Text Available Since 2005, Magnetic Particle Imaging (MPI is handled as a key technology with great potential in medical applications as an imaging method [1]. The superparamagnetic iron oxide nanoparticles (SPIONs which are already used as a tracer in MPI, combined with various polymers, are being investigated in order to enhance this potential. A combination of polymers such as polyethylene (PE and polyurethane (PU and SPIONs could be used as a coating for medical devices, or added to semi-rigid polyurethane for the production of surgical instruments [2]. This would be of great interest, since the method provides high sensitivity with simultaneous high spatial resolution and three-dimensional imaging in real time. Therefore various superparamagnetic coatings were developed, tested and characterized. Finally SPIONs and various polymers were combined directly and used for MPI-compatible models.

  14. Precursor combustion synthesis of nanocrystalline cobalt substituted nickel zinc ferrites from hydrazinated mixed metal fumarates

    Energy Technology Data Exchange (ETDEWEB)

    Gawas, S.G.; Verenkar, V.M.S., E-mail: vmsv@rediffmail.com

    2015-04-10

    Highlights: • Convenient synthesis of hydrazinated mixed metal fumarates under nitrogen atmosphere. • Six hydrazine molecules in precursor provide high exothermicity for the decomposition. • Autocatalytic decomposition of precursors helps in ferritization at 410 °C. • Single domain-superparamagnetic particles of uniform size in the range of 15–30 nm. - Abstract: In present investigation, a systematic approach towards synthesis of nanocrystalline ferrites, Co{sub x}Ni{sub 0.6−x}Zn{sub 0.4}Fe{sub 2}O{sub 4} (x = 0.1 and 0.4) has been reported by room temperature decomposition of precursors, Co{sub x}Ni{sub 0.6−x}Zn{sub 0.4}Fe{sub 2} (C{sub 4}H{sub 2}O{sub 4}){sub 3}·6N{sub 2}H{sub 4} (x = 0.1 and 0.4). The precursor complexes were characterized by Fourier transform infrared spectroscopy (FTIR), chemical analysis and thermal studies like isothermal mass loss, total mass loss, thermogravimetry (TG), derivative of thermogravimetry (DTG) and differential thermal analysis (DTA). The TG–DTG–DTA patterns of both precursors reveal multistep decomposition with complete ferritization at 410 °C. The thermally decomposed products were characterized by X-ray diffractometry (XRD) for phase purity. The FT-IR spectroscopy studies of the same shows complete removal of all organic moieties from decomposed precursors. The nanophasic nature of synthesized ferrites was confirmed by transmission electron microscopy (TEM) analysis as well as from broadening of XRD peaks. The AC magnetization studies show the existence of single domain and superparamagnetic particles, which supports nanosize particles distribution in the ferrite system under study.

  15. Magnetite and cobalt ferrite nanoparticles used as seeds for acid mine drainage treatment

    Energy Technology Data Exchange (ETDEWEB)

    Kefeni, Kebede K., E-mail: kkefeni@gmail.com; Mamba, Bhekie B.; Msagati, Titus A.M.

    2017-07-05

    Highlights: • Presence of α-Fe{sub 2}O{sub 3} and Fe{sub 3}O{sub 4} in AMD resulted in formation of crystalline ferrite. • Increasing settling time improved removal of Mg, Ca, Mn and Na from AMD. • Mixtures of ferrite nanoparticles were produced from AMD. • Formations of crystalline ferrite were more favored in the presence of heat. - Abstract: In this study, magnetite and cobalt ferrite nanoparticles were used as seeds for acid mine drainage (AMD) treatment at pH of 7.05 ± 0.35. Duplicate samples of AMD, one without heating and another with heating at 60 °C was treated under continuous stirring for 1 h. The filtrate analysis results from ICP-OES have shown complete removal of Al, Mg, and Mn, while for Fe, Ni and Zn over 90% removals were recorded. Particularly, settling time has significant effect on the removal of Mg, Ca and Na. The results from SQUID have shown superparamagnetic properties of the synthesised magnetic nanoparticles and ferrite sludge. The recovered nanoparticles from AMD are economically important and reduce the cost of waste disposal.

  16. Magnetocaloric phenomena in Mg-ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Burianova, S; Holec, P; Plocek, J [Charles University, Faculty of Science, Department of Inorganic chemistry, Prague (Czech Republic); Poltierova-Vejpravova, J, E-mail: burianovasimona@email.c, E-mail: jana@mag.mff.cuni.c

    2010-01-01

    A comparative study of magnetocaloric effect (MCE) in superparamagnetic (SPM) regime is reported in two different types of magnesium ferrite nanostructures. The samples were prepared either by microemulsion method as MgFe{sub 2}O{sub 4} nanoparticles encapsulated in amorphous SiO{sub 2}, or as matrix-less nanoparticles using hydrothermal synthesis in supercritical water conditions. The particle diameter in all prepared samples was obtained from XRD measurements and TEM analysis. All samples show a SPM behavior above the blocking temperature, T{sub B}. The entropy change, {Delta}S was finally derived from the measurements of magnetization, M(H,T) curves at defined temperature intervals. We observed, that all samples show a broad peak of {Delta}S in the temperature range that is fairly above the T{sub B}. The values of the {Delta}S also depend on the particle size, and they are of about two orders lower than those reported in the famous giant magnetocaloric materials.

  17. Synthesis, characterization and hemolysis studies of Zn(1-x)CaxFe2O4 ferrites synthesized by sol-gel for hyperthermia treatment applications

    Science.gov (United States)

    Jasso-Terán, Rosario Argentina; Cortés-Hernández, Dora Alicia; Sánchez-Fuentes, Héctor Javier; Reyes-Rodríguez, Pamela Yajaira; de-León-Prado, Laura Elena; Escobedo-Bocardo, José Concepción; Almanza-Robles, José Manuel

    2017-04-01

    The synthesis of Zn(1-x)CaxFe2O4 nanoparticles, x=0, 0.25, 0.50, 0.75 and 1.0, was performed by sol-gel method followed by a heat treatment at 400 °C for 30 min. These ferrites showed nanometric sizes and nearly superparamagnetic behavior. The Zn0.50Ca0.50Fe2O4 and CaFe2O4 ferrites presented a size within the range of 12-14 nm and appropriate heating ability for hyperthermia applications. Hemolysis testing demonstrated that Zn0.50Ca0.50Fe2O4 ferrite was not cytotoxic when using 10 mg of ferrite/mL of solution. According to the results obtained, Zn0.50Ca0.50Fe2O4 is a potential material for cancer treatment by magnetic hyperthermia therapy.

  18. Structure and magnetic properties of ZnO coated MnZn ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Mallesh, Shanigaram [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Sunny, Annrose; Vasundhara, Mutta [Materials Science and Technology Division, CSIR-NIIST, Thiruvananthapuram, Kerala 695019 (India); Srinivas, Veeturi, E-mail: veeturi@iitm.ac.in [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)

    2016-11-15

    A comparative study of structural and magnetic properties of MnZn spinel ferrite (SF) and ZnO coated MnZn ferrite (ZF) nanoparticles (NPs) has been carried out. The as-prepared NPs show a single phase cubic spinel structure, with lattice parameter ~8.432 Å. However, α-Fe{sub 2}O{sub 3} impurity phase emerge from SF particles when subjected to annealing at 600 °C in air. The weight fraction of α-Fe{sub 2}O{sub 3} phase increases with increasing Mn concentration (9% for x=0.2 and 53% for x=0.6). On the other hand in ZF (x=0.2 and 0.4) NPs no trace of impurity phase is observed when annealed at 600 °C. The magnetic measurements as a function of field and temperature revealed superparamagnetic like behavior with cluster moment ~10{sup 4} μ{sub B} in as-prepared particles. The cluster size obtained from the magnetic data corroborates well with that estimated from structural analysis. Present results on ZnO coated MnZn ferrite particles suggest that an interfacial (ZnO@SF) reaction takes place during annealing, which results in formation of Zn-rich ferrite phase in the interface region. This leads to deterioration of magnetic properties even in the absence of α-Fe{sub 2}O{sub 3} impurity phase. - Highlights: • The properties of ZnO coated MnZn ferrite NPs are compared with uncoated NPs. • The structural data reveals that the ZnO shell protects ferrite core from degradation. • The field and temperature dependence of magnetization suggests SPM like behavior. • From the magnetic isotherms average cluster moment is estimated to be ~10{sup 4} μ{sub B.} • Magnetic data suggests formation of Zn-rich ferrite phase in interfacial region.

  19. Magnetic entropy and magnetocalonc effects in nanometer superparamagnetic system

    Institute of Scientific and Technical Information of China (English)

    邵元智; 熊正烨; 张介立; 张进修

    1996-01-01

    Calculation on magnetic entropy in a nanostructured superparamagnetic system has been carried out by means of both classical statistical thermodynamics and quantum theory. It turns out that there exists an optimal particle size for nanometer superparamagnets at which a maximum change of magnetic entropy is achieved, and that nanometer superparamagnets have an advantage of enhanced magnetocaloric effects over the conventional paramagnets within the wide distribution of particle size of nanometer materials. The enhanced magnetocaloric effects of nanometer superparamagnets revealed by the theoretical calculation mentioned above have been proved experimentally in the investigation of nanocomposite solid of Gd-Y alloy.

  20. Structure and magnetic properties of nanostructured Ni-ferrite

    Science.gov (United States)

    Albuquerque, A. S.; Ardisson, J. D.; Macedo, W. A. A.; López, J. L.; Paniago, R.; Persiano, A. I. C.

    2001-05-01

    The structural and magnetic properties of NiFe 2O 4 ultrafine powders synthesized by coprecipitation, a nonconventional method of preparation, were investigated. The samples were obtained by annealing at relatively low temperatures (300-600°C) and characterized by X-ray diffraction, Mössbauer spectroscopy, and vibrating sample magnetometry. The average particle diameter ranges from 4 to 15 nm, as determined by X-ray diffraction. All nanometric powder samples presented strong superparamagnetic relaxation at room temperature and reduced magnetic hyperfine fields at -193°C. Magnetometry measurements indicated different magnetic behavior related with crystallinity of samples, coercivity as high as 168 Oe at 27°C, value that is nearly two times higher than coercivity of bulk Ni-ferrite.

  1. Structure and magnetic properties of nanostructured Ni-ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Albuquerque, A.S. E-mail: asa@urano.cdtn.br; Ardisson, J.D.; Macedo, W.A.A.; Lopez, J.L.; Paniago, R.; Persiano, A.I.C

    2001-05-01

    The structural and magnetic properties of NiFe{sub 2}O{sub 4} ultrafine powders synthesized by coprecipitation, a nonconventional method of preparation, were investigated. The samples were obtained by annealing at relatively low temperatures (300-600 deg. C) and characterized by X-ray diffraction, Moessbauer spectroscopy, and vibrating sample magnetometry. The average particle diameter ranges from 4 to 15 nm, as determined by X-ray diffraction. All nanometric powder samples presented strong superparamagnetic relaxation at room temperature and reduced magnetic hyperfine fields at -193 deg. C. Magnetometry measurements indicated different magnetic behavior related with crystallinity of samples, coercivity as high as 168 Oe at 27 deg. C, value that is nearly two times higher than coercivity of bulk Ni-ferrite.

  2. Electrospun magnetically separable calcium ferrite nanofibers for photocatalytic water purification

    Science.gov (United States)

    EL-Rafei, A. M.; El-Kalliny, Amer S.; Gad-Allah, Tarek A.

    2017-04-01

    Three-dimensional random calcium ferrite, CaFe2O4, nanofibers (NFs) were successfully prepared via the electrospinning method. The effect of calcination temperature on the characteristics of the as-spun NFs was investigated. X-ray diffraction analysis showed that CaFe2O4 phase crystallized as a main phase at 700 °C and as a sole phase at 1000 °C. Field emission scanning electron microscopy emphasized that CaFe2O4 NFs were fabricated with diameters in the range of 50-150 nm and each fiber was composed of 20-50 nm grains. Magnetic hysteresis loops revealed superparamagnetic behavior for the prepared NFs. These NFs produced active hydroxyl radicals under simulated solar light irradiation making them recommendable for photocatalysis applications in water purification. In the meantime, these NFs can be easily separated from the treated water by applying an external magnetic field.

  3. Synthesis and characterization of Ni-Zn ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Shahane, G.S., E-mail: shahanegs@yahoo.co [Department of Electronics, DBF Dayanand College of Arts and Science, Solapur 413002, Maharashtra (India); Kumar, Ashok; Arora, Manju; Pant, R.P.; Lal, Krishan [National Physical Laboratory, New Delhi (India)

    2010-04-15

    Nickel zinc ferrite nanoparticles Ni{sub x}Zn{sub 1-x}Fe{sub 2}O{sub 4} (x=0.1, 0.3, 0.5) have been synthesized by a chemical co-precipitation method. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, electron paramagnetic resonance, dc magnetization and ac susceptibility measurements. The X-ray diffraction patterns confirm the synthesis of single crystalline Ni{sub x}Zn{sub 1-x}Fe{sub 2}O{sub 4} nanoparticles. The lattice parameter decreases with increase in Ni content resulting in a reduction in lattice strain. Similarly crystallite size increases with the concentration of Ni. The magnetic measurements show the superparamagnetic nature of the samples for x=0.1 and 0.3 whereas for x=0.5 the material is ferromagnetic. The saturation magnetization is 23.95 emu/g and increases with increase in Ni content. The superparamagnetic nature of the samples is supported by the EPR and ac susceptibility measurement studies. The blocking temperature increases with Ni concentration. The increase in blocking temperature is explained by the redistribution of the cations on tetrahedral (A) and octahedral (B) sites.

  4. Effect of heat treatment on structural and Mössbauer spectroscopic properties of coprecipitated Mn0.5Ni0.5Fe2O4 ferrite nanoparticles

    Science.gov (United States)

    Srinivas, Ch.; Tirupanyam, B. V.; Meena, S. S.; Babu, Ch. Seshu; Sastry, D. L.

    2015-06-01

    Results obtained in a systamatic study by X-ray diffraction and Mösssbauer spectroscopy on the structural and magnetic properties on Mn0.5Ni0.5Fe2O4 ferrite nanoparticles heat treated at 200 °C, 500 °C and 800 °C are reported. Average crystallite sizes are estimated to be in the range (2.6nm - 12.8nm). It is observed that crystallite sizes increase with increase in sintering temperature and random variation in lattice parameter was observed. At relatively low sintering temperatures the samples exhibit superparamagnetism and complete ferrite phase was observed at higher heat treatment.

  5. Application of nano indentation and EBSD techniques in complex microstructures steels; Aplicacion de tecnicas de nanoindentacion y EBSD en aceros con microestructuras complejas

    Energy Technology Data Exchange (ETDEWEB)

    Altuna, M. A.; Gutierrez, I.

    2008-07-01

    In the present work, the mechanical behaviour of ferritic-perlitic and ferritic-martensitic steels has been studied. these microstructures have been obtained with different thermic treatments. For this study, the volumetric fraction of each phase and the ferrite grain size have been quantified by metallography. For mechanical characterization, tensile tests have been carried out and the nano indentation technique has been used to analyze the mechanical behaviour of each phase. The nano hardness of ferrite increases when the ferrite is surrounding by the martensite instead of the pearlite. In order to study the effect of the martensite in the ferrite, the misorientation inside the ferrite grain have been analyzed the techniques EBSD/OIM. (Author) 33 refs.

  6. STRUCTURE AND M SSBAUER STUDY OF NANOCRYSTALLINE Ni-Zn FERRITE

    Institute of Scientific and Technical Information of China (English)

    WANG LI; LI FA-SHEN; ZHOU QING - GUO

    2000-01-01

    Ni1-xZnxFe204 (0.0≤ x≤1.0) nanoparticles have been prepared by the polyvinyl alcohol (PVA) sol-gel method.The lattice parameter of Ni-Zn ferrite nanoparticles is larger than that of the bulk material. The variation of saturation magnetization (Ms) as a function of x has been studied. The M ssbauer spectra of the samples at room temperature showed the presence of ultrafine particles, exhibiting superparamagnetic relaxation. At higher annealing temperature,the portion of the ferromagnetic ultrafine particles increased.

  7. Magnetite and cobalt ferrite nanoparticles used as seeds for acid mine drainage treatment.

    Science.gov (United States)

    Kefeni, Kebede K; Mamba, Bhekie B; Msagati, Titus A M

    2017-07-05

    In this study, magnetite and cobalt ferrite nanoparticles were used as seeds for acid mine drainage (AMD) treatment at pH of 7.05±0.35. Duplicate samples of AMD, one without heating and another with heating at 60°C was treated under continuous stirring for 1h. The filtrate analysis results from ICP-OES have shown complete removal of Al, Mg, and Mn, while for Fe, Ni and Zn over 90% removals were recorded. Particularly, settling time has significant effect on the removal of Mg, Ca and Na. The results from SQUID have shown superparamagnetic properties of the synthesised magnetic nanoparticles and ferrite sludge. The recovered nanoparticles from AMD are economically important and reduce the cost of waste disposal. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Superparamagnetic MFe2O 4 (M = Ni, Co, Zn, Mn) nanoparticles: synthesis, characterization, induction heating and cell viability studies for cancer hyperthermia applications.

    Science.gov (United States)

    Sabale, Sandip; Jadhav, Vidhya; Khot, Vishwajeet; Zhu, Xiaoli; Xin, Meiling; Chen, Hongxia

    2015-03-01

    Superparamagnetic nanoferrites are prepared by simple and one step refluxing in polyol synthesis. The ferrite nanoparticles prepared by this method exhibit particle sizes below 10 nm and high degree of crystallinity. These ferrite nanoparticles are compared by means of their magnetic properties, induction heating and cell viability studies for its application in magnetic fluid hyperthermia. Out of all studied nanoparticles in present work, only ZnFe2O4 and CoFe2O4 MNPs are able to produce threshold hyperthermia temperature. This rise in temperature is discussed in detail in view of their magneto-structural properties. Therefore ZnFe2O4 and CoFe2O4 MNPs with improved stability, magnetic induction heating and cell viability are suitable candidates for magnetic hyperthermia.

  9. The role of cobalt ferrite magnetic nanoparticles in medical science.

    Science.gov (United States)

    Amiri, S; Shokrollahi, H

    2013-01-01

    The nanotechnology industry is rapidly growing and promises that the substantial changes that will have significant economic and scientific impacts be applicable to a wide range of areas, such as aerospace engineering, nano-electronics, environmental remediation and medical healthcare. In this area, cobalt ferrite nanoparticles have been regarded as one of the competitive candidates because of their suitable physical, chemical and magnetic properties like the high anisotropy constant, high coercivity and high Curie temperature, moderate saturation magnetization and ease of synthesis. This paper introduces the magnetic properties, synthesis methods and some medical applications, including the hyperthermia, magnetic resonance imaging (MRI), magnetic separation and drug delivery of cobalt ferrite nanoparticles. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Facile synthesis of cobalt ferrite nanotubes using bacterial nanocellulose as template.

    Science.gov (United States)

    Menchaca-Nal, S; Londoño-Calderón, C L; Cerrutti, P; Foresti, M L; Pampillo, L; Bilovol, V; Candal, R; Martínez-García, R

    2016-02-10

    A facile method for the preparation of cobalt ferrite nanotubes by use of bacterial cellulose nanoribbons as a template is described. The proposed method relays on a simple coprecipitation operation, which is a technique extensively used for the synthesis of nanoparticles (either isolated or as aggregates) but not for the synthesis of nanotubes. The precursors employed in the synthesis are chlorides, and the procedure is carried out at low temperature (90 °C). By the method proposed a homogeneous distribution of cobalt ferrite nanotubes with an average diameter of 217 nm in the bacterial nanocellulose (BC) aerogel (3%) was obtained. The obtained nanotubes are formed by 26-102 nm cobalt ferrite clusters of cobalt ferrite nanoparticles with diameters in the 9-13 nm interval. The nanoparticles that form the nanotubes showed to have a certain crystalline disorder, which could be attributed in a greater extent to the small crystallite size, and, in a lesser extent, to microstrains existing in the crystalline lattice. The BC-templated-CoFe2O4 nanotubes exhibited magnetic behavior at room temperature. The magnetic properties showed to be influenced by a fraction of nanoparticles in superparamagnetic state.

  11. A study of nanocrystalline NiZn-ferrite-SiO 2 synthesized by sol-gel

    Science.gov (United States)

    Albuquerque, Adriana S.; Ardisson, José D.; Macedo, Waldemar A. A.

    1999-02-01

    We have investigated the structural and magnetic properties of Ni 0.5Zn 0.5Fe 2O 4 nanoparticles embedded in SiO 2 fabricated by a sol-gel processing. The obtained (Ni 0.5Zn 0.5Fe 2O 4) x(SiO 2) 100- x (6⩽ x⩽78%) samples were characterized by X-ray diffraction, Mössbauer spectroscopy (MS) and vibrating sample magnetometry. The results showed the formation of stoichiometric NiZn-ferrite in the SiO 2 matrix, for x<41%. Samples with higher ferrite fraction have small amounts of Fe 2O 3. MS revealed the superparamagnetism of the ferrite nanoparticles at room temperature. The combination of different ferrite content and annealing temperatures allowed the obtention of samples with saturation magnetization ranging from 1.3 to 68 emu/g and coercivity from 0 to 123 Oe, value two orders of magnitude higher than those presented by bulk Ni 0.5Zn 0.5Fe 2O 4.

  12. Magnetic properties of cobalt ferrite-silica nanocomposites prepared by a sol-gel autocombustion technique.

    Science.gov (United States)

    Cannas, C; Musinu, A; Piccaluga, G; Fiorani, D; Peddis, D; Rasmussen, H K; Mørup, S

    2006-10-28

    The magnetic properties of cobalt ferrite-silica nanocomposites with different concentrations (15, 30, and 50 wt %) and sizes (7, 16, and 28 nm) of ferrite particles have been studied by static magnetization measurements and Mossbauer spectroscopy. The results indicate a superparamagnetic behavior of the nanoparticles, with weak interactions slightly increasing with the cobalt ferrite content and with the particle size. From high-field Mossbauer spectra at low temperatures, the cationic distribution and the degree of spin canting have been estimated and both parameters are only slightly dependent on the particle size. The magnetic anisotropy constant increases with decreasing particle size, but in contrast to many other systems, the cobalt ferrite nanoparticles are found to have an anisotropy constant that is smaller than the bulk value. This can be explained by the distribution of the cations. The weak dependence of spin canting degree on particle size indicates that the spin canting is not simply a surface phenomenon but also occurs in the interiors of the particles.

  13. Structure and magnetic properties of ZnO coated MnZn ferrite nanoparticles

    Science.gov (United States)

    Mallesh, Shanigaram; Sunny, Annrose; Vasundhara, Mutta; Srinivas, Veeturi

    2016-11-01

    A comparative study of structural and magnetic properties of MnZn spinel ferrite (SF) and ZnO coated MnZn ferrite (ZF) nanoparticles (NPs) has been carried out. The as-prepared NPs show a single phase cubic spinel structure, with lattice parameter ~8.432 Å. However, α-Fe2O3 impurity phase emerge from SF particles when subjected to annealing at 600 °C in air. The weight fraction of α-Fe2O3 phase increases with increasing Mn concentration (9% for x=0.2 and 53% for x=0.6). On the other hand in ZF (x=0.2 and 0.4) NPs no trace of impurity phase is observed when annealed at 600 °C. The magnetic measurements as a function of field and temperature revealed superparamagnetic like behavior with cluster moment ~104 μB in as-prepared particles. The cluster size obtained from the magnetic data corroborates well with that estimated from structural analysis. Present results on ZnO coated MnZn ferrite particles suggest that an interfacial (ZnO@SF) reaction takes place during annealing, which results in formation of Zn-rich ferrite phase in the interface region. This leads to deterioration of magnetic properties even in the absence of α-Fe2O3 impurity phase.

  14. Structural and magnetic characteristics of PVA/CoFe{sub 2}O{sub 4} nano-composites prepared via mechanical alloying method

    Energy Technology Data Exchange (ETDEWEB)

    Rashidi, S.; Ataie, A., E-mail: aataie@ut.ac.ir

    2016-08-15

    Highlights: • Single phase CoFe{sub 2}O{sub 4} nano-particles synthesized in one step by mechanical alloying. • PVA/CoFe{sub 2}O{sub 4} magnetic nano-composites were fabricated via mechanical milling. • FTIR confirmed the interaction between PVA and magnetic CoFe{sub 2}O{sub 4} particles. • Increasing in milling time and PVA amount led to well dispersion of CoFe{sub 2}O{sub 4}. - Abstract: In this research, polyvinyl alcohol/cobalt ferrite nano-composites were successfully synthesized employing a two-step procedure: the spherical single-phase cobalt ferrite of 20 ± 4 nm mean particle size was synthesized via mechanical alloying method and then embedded into polymer matrix by intensive milling. The results revealed that increase in polyvinyl alcohol content and milling time causes cobalt ferrite particles disperse more homogeneously in polymer matrix, while the mean particle size and shape of cobalt ferrite have not been significantly affected. Transmission electron microscope images indicated that polyvinyl alcohol chains have surrounded the cobalt ferrite nano-particles; also, the interaction between polymer and cobalt ferrite particles in nano-composite samples was confirmed. Magnetic properties evaluation showed that saturation magnetization, coercivity and anisotropy constant values decreased in nano-composite samples compared to pure cobalt ferrite. However, the coercivity values of related nano-composite samples enhanced by increasing PVA amount due to domain wall mechanism.

  15. Synthesis and characterizations of manganese ferrites for hyperthermia applications

    Energy Technology Data Exchange (ETDEWEB)

    Doaga, A.; Cojocariu, A.M. [Faculty of Physics, Alexandru Ioan Cuza University, Bd. Carol I, Nr. 11, 700506 Iasi (Romania); Amin, W.; Heib, F. [Physical Chemistry, Universität des Saarlandes, 66123 Saarbrücken (Germany); Bender, P. [Experimental Physics, Universität des Saarlandes, 66123 Saarbrücken (Germany); Hempelmann, R. [Physical Chemistry, Universität des Saarlandes, 66123 Saarbrücken (Germany); Caltun, O.F., E-mail: caltun@uaic.ro [Faculty of Physics, Alexandru Ioan Cuza University, Bd. Carol I, Nr. 11, 700506 Iasi (Romania)

    2013-12-16

    In the last few years, magnetic nanoparticles have turned out to offer great potential in biomedical applications. This study was focused on Mn{sub x}Fe{sub 1−x}Fe{sub 2}O{sub 4} ferrite particles series with x ranging between 0 and 1. Manganese ferrites nanoparticles were prepared by co-precipitation method that allows a good control of their shape and size. The X-ray analysis indicated a crystallite size of the particles in the nanometers domain increasing with the Mn cation substitution level. Average grain size of the nanoparticles calculated from transmission electron microscopy images of the samples was ranging between 10.5 and 19.0 nm suggesting that the majority of the nanoparticles are monodomain. The hydrodynamic diameter of the water dispersed nanoparticles measured by dynamic light scattering was ranging between 60 and 105 nm proving the tendency of agglomeration. Vibrating sample magnetometer measurement confirmed the superparamagnetic behavior of the powders. The magnetic properties were analyzed considering the proposed cation distribution and Yafet–Kittel angles, while the specific absorption rate (SAR) measurement at 1.95 MHz frequency confirmed the influence of substitution level on magnetic properties and thermal transfer rate. From our results the highest value for specific absorption rate was 148.4 W g{sup −1} for Mn{sub 2}Fe{sub 2}O{sub 4} at an AC field of 4500 A m{sup −1}. - Highlights: • Mn{sub x}Fe{sub 1−x}Fe{sub 2}O{sub 4} nanoparticles (0 ≤ x ≤ 1) were synthesized by coprecipitation method. • The microstructure and average grain size of nanoparticles were determined from XRD and TEM. • The magnetic behavior was characterized using VSM and SAR. • The main results are discussed in terms of cation distribution and microstructure. • The Mn ferrite based ferrofluids can be used in medical application as hyperthermia.

  16. Morphological, Raman, electrical and dielectric properties of rare earth doped X-type hexagonal ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Majeed, Abdul, E-mail: abdulmajeed2276@gmail.com [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Center for Computational Materials Science, Department of Physics, University of Malakand, Chakdara, Dir (Lower) 18800 (Pakistan); Khan, Muhammad Azhar, E-mail: azhar.khan@iub.edu.pk [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Raheem, Faseeh ur [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Ahmad, Iftikhar [Center for Computational Materials Science, Department of Physics, University of Malakand, Chakdara, Dir (Lower) 18800 (Pakistan); Department of Physics, Abbottabad University of Science & Technology, Abbottabad (Pakistan); Akhtar, Majid Niaz [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Warsi, Muhammad Farooq [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan)

    2016-12-15

    The influence of rare-earth metals (La, Nd, Gd, Tb, Dy) on morphology, Raman, electrical and dielectric properties of Ba{sub 2}NiCoRE{sub x}Fe{sub 28−}xO{sub 46} ferrites were studied. The scanning electron microscopy (SEM) exhibited the platelet like structure of these hexagonal ferrites. The surface morphology indicated the formation of ferrite grains in the nano-regime scale. The bands obtained at lower wave number may be attributed to the metal-oxygen vibration at octahedral site which confirm the development of hexagonal phase of these ferrites. The resonance peaks were observed in dielectric constant, dielectric loss factor and quality factor versus frequency graphs. These dielectric parameters indicate that these ferrites nano-materials are potential candidates in the high frequency applications. The enhancement in DC electric resistivity from 2.48×10{sup 8} to 1.20×10{sup 9} Ω cm indicates that the prepared materials are beneficial for decreasing the eddy current losses at high frequencies and for the fabrication of multilayer chip inductor (MLCI) devices.

  17. Morphological, Raman, electrical and dielectric properties of rare earth doped X-type hexagonal ferrites

    Science.gov (United States)

    Majeed, Abdul; Khan, Muhammad Azhar; ur Raheem, Faseeh; Ahmad, Iftikhar; Akhtar, Majid Niaz; Warsi, Muhammad Farooq

    2016-12-01

    The influence of rare-earth metals (La, Nd, Gd, Tb, Dy) on morphology, Raman, electrical and dielectric properties of Ba2NiCoRExFe28-xO46 ferrites were studied. The scanning electron microscopy (SEM) exhibited the platelet like structure of these hexagonal ferrites. The surface morphology indicated the formation of ferrite grains in the nano-regime scale. The bands obtained at lower wave number may be attributed to the metal-oxygen vibration at octahedral site which confirm the development of hexagonal phase of these ferrites. The resonance peaks were observed in dielectric constant, dielectric loss factor and quality factor versus frequency graphs. These dielectric parameters indicate that these ferrites nano-materials are potential candidates in the high frequency applications. The enhancement in DC electric resistivity from 2.48×108 to 1.20×109 Ω cm indicates that the prepared materials are beneficial for decreasing the eddy current losses at high frequencies and for the fabrication of multilayer chip inductor (MLCI) devices.

  18. Washing effect on superparamagnetic iron oxide nanoparticles

    Directory of Open Access Journals (Sweden)

    Laura-Karina Mireles

    2016-06-01

    Full Text Available Much recent research on nanoparticles has occurred in the biomedical area, particularly in the area of superparamagnetic iron oxide nanoparticles (SPIONs; one such area of research is in their use as magnetically directed prodrugs. It has been reported that nanoscale materials exhibit properties different from those of materials in bulk or on a macro scale [1]. Further, an understanding of the batch-to-batch reproducibility and uniformity of the SPION surface is essential to ensure safe biological applications, as noted in the accompanying article [2], because the surface is the first layer that affects the biological response of the human body. Here, we consider a comparison of the surface chemistries of a batch of SPIONs, before and after the supposedly gentle process of dialysis in water.

  19. Switchable cell trapping using superparamagnetic beads

    Energy Technology Data Exchange (ETDEWEB)

    Bryan, M. T.; Smith, K. H.; Real, M. E.; Bashir, M. A.; Fry, P. W.; Fischer, P.; Im, M.-Y.; Schrefl, T.; Allwood, D. A.; Haycock, J. W.

    2010-04-30

    Ni{sub 81}Fe{sub 19} microwires are investigated as the basis of a switchable template for positioning magnetically-labeled neural Schwann cells. Magnetic transmission X-ray microscopy and micromagnetic modeling show that magnetic domain walls can be created or removed in zigzagged structures by an applied magnetic field. Schwann cells containing superparamagnetic beads are trapped by the field emanating from the domain walls. The design allows Schwann cells to be organized on a surface to form a connected network and then released from the surface if required. As aligned Schwann cells can guide nerve regeneration, this technique is of value for developing glial-neuronal co-culture models in the future treatment of peripheral nerve injuries.

  20. Synthesis, Investigation on Structural and Magnetic Behaviors of Spinel M-Ferrite [M = Fe; Zn; Mn] Nanoparticles from Iron Sand

    Science.gov (United States)

    Bahtiar, S.; Taufiq, A.; Sunaryono; Hidayat, A.; Hidayat, N.; Diantoro, M.; Mufti, N.; Mujamilah

    2017-05-01

    Spinel M-ferrite [M = Fe; Zn; Mn] nanoparticles were prepared from iron sand using a coprecipitation-sonochemical approach. The purified Fe3O4 from iron sand, ZnCl2 and MnCl2.4H2O, HCl, and NH4OH were used as raw materials. X-Ray Diffractometer (XRD), Fourier Transform Infra-Red (FTIR) spectroscopy, Transmission Electron Microscopy (TEM), and Vibration Sample Magnetometer (VSM) were employed to characterize the crystal structure, functional groups, particle size, morphology, and magnetic behavior of the prepared samples, respectively. From the XRD data analysis, M-ferrite particles exhibited a single phase in spinel structure. Furthermore, the M-ferrite particle increased their lattice parameter and crystal volume tracking the metallic-ionic radii of M. The particle size of the M-ferrites particles varied with M, whereas the biggest and lowest were for Zn and Mn, respectively. Based on the magnetization curve, the M-ferrite nanoparticles tended to perform a superparamagnetic behavior and their saturation magnetization as a function of their M ion and particle size.

  1. Superparamagnetic properties of carbon nanotubes filled with NiFe{sub 2}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Stojak Repa, K.; Israel, D.; Phan, M. H., E-mail: phanm@usf.edu, E-mail: sharihar@usf.edu; Srikanth, H., E-mail: phanm@usf.edu, E-mail: sharihar@usf.edu [Department of Physics, University of South Florida, Tampa, Florida 33620 (United States); Alonso, J. [Department of Physics, University of South Florida, Tampa, Florida 33620 (United States); BCMaterials Edificio No. 500, Parque Tecnológico de Vizcaya, 48160 Derio (Spain); Palmero, E. M.; Vazquez, M. [Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid (Spain)

    2015-05-07

    Multi walled carbon nanotubes (MWCNTs) were successfully synthesized using custom-made 80 nm pore-size alumina templates, and were uniformly filled with nickel ferrite (NFO) nanoparticles of 7.4 ± 1.7 nm diameter using a novel magnetically assisted capillary action method. X-ray diffraction confirmed the inverse spinel phase for the synthesized NFO. Transmission electron microscopy confirms spherical NFO nanoparticles with an average diameter of 7.4 nm inside MWCNTs. Magnetometry indicates that both NFO and NFO-filled MWCNTs present a blocking temperature around 52 K, with similar superparamagnetic-like behavior, and weak dipolar interactions, giving rise to a super-spin-glass-like behavior at low temperatures. These properties along with the uniformity of sub-100 nm structures and the possibility of tunable magnetic response in variable diameter carbon nanotubes make them ideal for advanced biomedical and microwave applications.

  2. A study on the relationship between microstructure and mechanical properties of acicular ferrite and upper bainite

    Energy Technology Data Exchange (ETDEWEB)

    Costin, Walter L.; Lavigne, Olivier, E-mail: Olivier.lavigne@adelaide.edu.au; Kotousov, Andrei

    2016-04-29

    Acicular ferrite and bainite are microstructural constituents commonly found in ferritic weld metal and many other ferrous alloys. These often highly localised microstructural volumes are known to have a significant impact on the mechanical properties of the bulk material they constitute. It is well established that acicular ferrite and bainite have substantially different morphologies and features that can be directly linked to their intrinsic mechanical properties. However, in the bulk material they usually co-exist and interact with other microstructural constituents and features. Therefore, the individual contributions of acicular ferrite and bainite still remain unclear. This work utilises micro-testing techniques to evaluate and compare the mechanical properties of these two micro-constituents with an ultimate objective to understand their impact on bulk properties of ferrous alloys. Microscopic regions consisting of either acicular ferrite or upper bainite were first selected and then characterised using a high resolution Scanning Electron Microscope (SEM) and Electron Backscattered Diffraction (EBSD). Conventional nano-indentation and an advanced characterisation procedure were implemented to evaluate elastic modulus, yield strength, hardness and strain hardening exponent of both micro-constituents. The fracture resistance was estimated from micro-fracture tests that were conducted within the selected regions. The experimental studies have indicated that, at the micro-scale, despite their different microstructures, acicular ferrite and upper bainite have very similar mechanical properties. Nevertheless, the fracture resistance of upper bainite was more dominated by the contribution of plastic deformations.

  3. Effect of sintering on structural and electrical properties of co-precipitated Mn-Zn ferrites

    Science.gov (United States)

    Mehmood, S.; Zahra, F.; Rehman, M. A.

    2016-08-01

    Mn-Zn ferrite is one of the important class of soft ferrites. These are famous for possessing high initial permeability. In the present work, we have studied the effect of sintering on Mn-Zn nano particles. The particles were synthesized using co-precipitation method. The structural characterization of the prepared sample after each sintering step were done by using XRD. The XRD analysis showed the spinel structure. The electrical properties were studied as a function of temperature. It was observed that dielectric constant, loss tangent and AC conductivity varies with respect to temperature. The prepared composition is useful in microwave devices.

  4. Nanotoxicological study of polyol-made cobalt-zinc ferrite nanoparticles in rabbit.

    Science.gov (United States)

    Hanini, Amel; Massoudi, Mohamed El; Gavard, Julie; Kacem, Kamel; Ammar, Souad; Souilem, Ouajdi

    2016-07-01

    The increasing use of engineered nanomaterials in commercial manufacturing and consumer products presents an important toxicological concern. Superparamagnetic zinc-cobalt ferrite nanoparticles (SFN) emerge as a promising tool for early cancer diagnostics and targeted therapy. However, toxicity and biological activities of SFN should be evaluated in vitro and in vivo in animal before any clinical application. In this study we aim to synthesize and characterize such objects using polyol process in order to assess its nanotoxicological profile in vitro as well as in vivo. The produced particles consist of a cobalt-zinc ferrite phase corresponding to the Zn0.8Co0.2Fe2O4 composition. They are isotropic in shape single crystals of 8nm in size. The thermal variation of their dc-magnetization confirms their superparamagnetic behavior. In vitro, acute exposure (4h) to them (100μgmL(-1)) induced an important decrease of healthy Human Umbilical Vein Endothelial Cells (HUVECs) viability. In vivo investigation in New-Zealand rabbits revealed that they lead to tissue toxicities; in lungs, liver and kidneys. Our investigations report, for the first time as far as we know, that SFN exhibit harmful properties in human cells and mammals.

  5. Ultrafast and continuous synthesis of crystalline ferrite nanoparticles in supercritical ethanol.

    Science.gov (United States)

    Pascu, Oana; Marre, Samuel; Aymonier, Cyril; Roig, Anna

    2013-03-07

    Magnetic nanoparticles (NPs) are of increasing interest in various industrially relevant products. For these, the development of greener and faster approaches facilitating scaling-up production is of paramount importance. Here, we report a novel, green and potentially scalable approach for the continuous and ultrafast (90 s) synthesis of superparamagnetic ferrite NPs (MnFe(2)O(4), Fe(3)O(4)) in supercritical ethanol (scEtOH) at a fairly moderate temperature (260 °C). ScEtOH exhibits numerous advantages such as its production from bio-resources, its lack of toxicity and its relatively low supercritical coordinates (p(c) = 6.39 MPa and T(c) = 243 °C), being therefore appropriate for the development of sustainable technologies. The present study is completed by the investigation of both in situ and ex situ NP surface functionalization. The as-obtained nanoparticles present good crystallinity, sizes below 8 nm, superparamagnetic behavior at room temperature and high saturation magnetization. Moreover, depending on the capping strategy, the ferrite NPs present extended (for in situ coated NPs) or short-term (for ex situ coated NPs) colloidal stability.

  6. Microwave applications of soft ferrites

    CERN Document Server

    Pardavi-Horvath, M P

    2000-01-01

    Signal processing requires broadband, low-loss, low-cost microwave devices (circulators, isolators, phase shifters, absorbers). Soft ferrites (garnets, spinels, hexaferrites), applied in planar microwave devices, are reviewed from the point of view of device requirements. Magnetic properties, specific to operation in high-frequency electromagnetic fields, are discussed. Recent developments in thick film ferrite technology and device design are reviewed. Magnetic losses related to planar shape and inhomogeneous internal fields are analyzed.

  7. Preparation and mechanism of Fe3O4/Au core/shell super-paramagnetic microspheres

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In the presence of Fe3O4 nano-particles, a new type of super-paramagnetic Fe3O4/Au microspheres with core/shell structures was prepared by reduction of Au3+ with hydroxylamine. The formation mechanism of the core/shell microspheres was studied in some detail. It was shown that the formation of the complex microspheres can be divided into two periods, that is, surface reaction-controlled process and diffusion-controlled process. The relative time lasted by either process depends upon the amount of Fe3O4 added and the initial concentration of Au3+. XPS analysis revealed that along with increasing in coating amount, the strength of the characteristic peaks of Au increased, and the Auger peaks of Fe weakened and even disappeared. Size distribution analysis showed that the core/shell microspheres are of an average diameter of 180 nm, a little bit larger than those before coating.

  8. Design of superparamagnetic nanoparticles for magnetic particle imaging (MPI).

    Science.gov (United States)

    Du, Yimeng; Lai, Pui To; Leung, Cheung Hoi; Pong, Philip W T

    2013-09-11

    Magnetic particle imaging (MPI) is a promising medical imaging technique producing quantitative images of the distribution of tracer materials (superparamagnetic nanoparticles) without interference from the anatomical background of the imaging objects (either phantoms or lab animals). Theoretically, the MPI platform can image with relatively high temporal and spatial resolution and sensitivity. In practice, the quality of the MPI images hinges on both the applied magnetic field and the properties of the tracer nanoparticles. Langevin theory can model the performance of superparamagnetic nanoparticles and predict the crucial influence of nanoparticle core size on the MPI signal. In addition, the core size distribution, anisotropy of the magnetic core and surface modification of the superparamagnetic nanoparticles also determine the spatial resolution and sensitivity of the MPI images. As a result, through rational design of superparamagnetic nanoparticles, the performance of MPI could be effectively optimized. In this review, the performance of superparamagnetic nanoparticles in MPI is investigated. Rational synthesis and modification of superparamagnetic nanoparticles are discussed and summarized. The potential medical application areas for MPI, including cardiovascular system, oncology, stem cell tracking and immune related imaging are also analyzed and forecasted.

  9. Microstructure and magnetic characteristics of nanocrystalline Ni0.5Zn0.5 ferrite synthesized by a spraying-coprecipitation method

    Institute of Scientific and Technical Information of China (English)

    Liu Yin; Qiu Tai

    2007-01-01

    Nanocrystalline Ni0.5Zn0.5 ferrite with average grain sizes ranging from 10 to 100 nm is prepared by using a spraying-coprecipitation method. The results indicate that the nanocrystalline Ni0.5Zn0.5 ferrite is ferromagnetic without the superparamagnetic phenomenon observed at room temperature. Specific saturation magnetization of nanocrystalline Ni0.5Zn0.5 ferrite increases from 40.2 to 75.6 emu/g as grain size increases from 11 to 94nm. Coercivity of nanocrystalline Ni0.5Zn0.5 ferrite increases monotonically when d < 62 nm. The relationship between the coercivity and the mean grain size is well fitted into a relation Hc ~ d3. A theoretically evaluated value of the critical grain size is 141nm larger than the experimental value 62nm for nanocrystalline Ni0.5Zn0.5 ferrite. The magnetic behaviour of nanocrystalline Ni0.5Zn0.5 ferrite may be explained by using the random anisotropy theory.

  10. Defect induced modification of structural, topographical and magnetic properties of zinc ferrite thin films by swift heavy ion irradiation

    Science.gov (United States)

    Raghavan, Lisha; Joy, P. A.; Vijaykumar, B. Varma; Ramanujan, R. V.; Anantharaman, M. R.

    2017-04-01

    Swift heavy ion irradiation provides unique ways to modify physical and chemical properties of materials. In ferrites, the magnetic properties can change significantly as a result of swift heavy ion irradiation. Zinc ferrite is an antiferromagnet with a Neel temperature of 10 K and exhibits anomalous magnetic properties in the nano regime. Ion irradiation can cause amorphisation of zinc ferrite thin films; thus the role of crystallinity on magnetic properties can be examined. The influence of surface topography in these thin films can also be studied. Zinc ferrite thin films, of thickness 320 nm, prepared by RF sputtering were irradiated with 100 MeV Ag ions. Structural characterization showed amorphisation and subsequent reduction in particle size. The change in magnetic properties due to irradiation was correlated with structural and topographical effects of ion irradiation. A rough estimation of ion track radius is done from the magnetic studies.

  11. Ferrite attenuator modulation improves antenna performance

    Science.gov (United States)

    Hooks, J. C.; Larson, S. G.; Shorkley, F. H.; Williams, B. T.

    1970-01-01

    Ferrite attenuator inserted into appropriate waveguide reduces the gain of the antenna element which is causing interference. Modulating the ferrite attenuator to change the antenna gain at the receive frequency permits ground tracking until the antenna is no longer needed.

  12. Influence of polyols on the formation of nanocrystalline nickel ferrite inside silica matrices

    Science.gov (United States)

    Stoia, Marcela; Barvinschi, Paul; Barbu-Tudoran, Lucian; Bunoiu, Mădălin

    2017-01-01

    We have synthesized nickel ferrite/silica nanocomposites, using a modified sol-gel method that combines the sol-gel processing with the thermal decomposition of metal-organic precursors, leading to a homogenous dispersion of ferrite nanoparticles within the silica matrix and a narrow size distribution. We used as starting materials tetraethyl orthosilicate (TEOS) as source of silica, Fe(III) and Ni(II) nitrates as sources of metal cations, and polyols as reducing agent (polyvinyl alcohol, 1,4-butanediol and their mixture). TG/DTA coupled technique evidenced the redox interaction between the polyol and the mixture of metal nitrates during the heating of the gel, with formation of nickel ferrite precursors in the pores of the silica-gels. FT-IR spectroscopy confirmed the formation of metal carboxylates inside the silica-gels and the interaction of the polyols with the Si-OH groups of the polysiloxane network. X-ray diffractometry evidenced that in case of nanocomposites obtained by using a single polyol, nickel ferrite forms as single crystalline phase inside the amorphous silica matrix, while in case of using a mixture of polyols the nickel oxide appears as a secondary phase. TEM microscopy and elemental mapping evidenced the fine nature of the obtained nickel ferrite nanoparticles that are homogenously dispersed within the silica matrix. The obtained nanocomposites exhibit magnetic behavior very close to superparamagnetism slightly depending on the presence and nature of the organic compounds used in synthesis; the magnetization reached at 5 kOe magnetic field was 7 emu/g for all composites.

  13. Lattice strain induced magnetism in substituted nanocrystalline cobalt ferrite

    Science.gov (United States)

    Kumar, Rajnish; Kar, Manoranjan

    2016-10-01

    Strontium (Sr) substituted cobalt ferrite i.e. Co1-xSrxFe2O4 (x=0.00, 0.01, 0.015, 0.02, 0.05, 0.1) have been synthesized by the citric acid modified sol-gel method. Crystal structure and phase purity have been studied by the X-ray powder diffraction technique. The Rietveld refinement of XRD pattern using the space group Fd 3 bar m shows monotonically increasing of lattice parameter with the increase in Sr concentration. Magnetic hysteresis loops measurement has been carried out at room temperature using a vibrating sample magnetometer (VSM) over a field range of ±1.5 T. Magnetocrystalline anisotropy constant were calculated by employing the Law of Approach (LA) to the saturation. It is observed that magnetocrystalline anisotropy has anomaly for x=0.01 (Co0.99Sr0.01Fe2O4) sample. Strain mediated modification of magnetic properties in Sr substituted cobalt ferrite has been observed. The saturation magnetization for doping concentration i.e. x=0.01 abruptly increase while for x>0.01 decreases with the increase in Sr concentration. A correlation between lattice strain and magnetic behavior in non-magnetic Sr- substituted nano-crystalline cobalt ferrite has been reported.

  14. Synthesis of Nanocrystalline Barium Ferrite in Ethanol/Water Media

    Institute of Scientific and Technical Information of China (English)

    M.Montazeri-Pour; A.Ataie

    2009-01-01

    Nanocrystalline particles of barium ferrite magnetic material have been prepared by co-precipitation route using aqueous and non-aqueous solutions of iron and barium chlorides with a Fe/Ba molar ratio of 11 and subsequent drying-annealing treatment. Water and ethanol/water mixture with volume ratio of 3:1 were used as solvents in the process. Coprecipitated powders were annealed at various temperatures for 1 h. FTIR (Fourier transform infrared spectroscopy), XRD (X-ray diffraction), DTA/TGA (differential thermal analy-sis/thermogravimetric analysis) and SEM (scanning electron microscopy) techniques were used to evaluate powder particle characteristics. DTA/TGA results confirmed by those obtained from XRD indicated that the formation of barium ferrite occurs in sample synthesized in ethanol/water solution at a relatively low temperature of 631℃. Nano-size particles of barium ferrite with mean particle size of almost 75 and 100 nm were observed in the SEM micrographs of the samples synthesized in ethanol/water solution after annealing at 700 and 800℃ for 1 h, respectively.

  15. Synthesis and characterization of cobalt and nickel ferrites containing nanoparticles dispersed in silicon; Sintese e carcacterizacao de ferritas de cobalto e niquel contendo nanoparticulas dispersas em oxido de silicio

    Energy Technology Data Exchange (ETDEWEB)

    Braga, T.P.; Sales, B.M.C.; Pinheiro, A.N.; Sousa, A.F. de; Valentini, A., E-mail: tiagoufc2003@yahoo.com.b [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil). Dept. de Quimica Analitica e Fisico-Quimica. Lab. de Adsorcao e Catalise; Herrera, W.T.; Baggio-Saitovitch, E. [Centro Brasileiro de Pesquisas em Fisica (CBPF), Rio de Janeiro, RJ (Brazil). Dept. de Fisica Experimental

    2010-07-01

    Cobalt and nickel ferrites containing nanoparticles dispersed in silicon oxides were prepared via polymeric precursor method. The samples were characterized by X-ray diffraction (XDR), Fourier-transform infrared spectroscopy (FTIR), Moessbauer spectroscopy (MS) and N{sub 2} adsorption/desorption isotherms (BET). The analysis results of FTIR, XRD and MS revealed the presence of nickel and cobalt ferrite besides the existence of {gamma}-Fe{sub 2}O{sub 3}. Additionally, Moessbauer spectroscopy measurements at 300 K show that nanoparticles are in the superparamagnetic regime being blocked at 4.2 K. Furthermore, all the solids showed by nitrogen adsorption/desorption isotherms profiles characteristic of mesoporous materials. (author)

  16. Acceleration of superparamagnetic particles with magnetic fields

    Science.gov (United States)

    Stange, R.; Lenk, F.; Bley, T.; Boschke, E.

    2017-04-01

    High magnetic capture efficiency in the context of Biomagnetic Separation (BMS) using superparamagnetic particles (SMPs) requires efficient mixing and high relative velocities between cellular and other targets and SMPs. For this purpose, batch processes or microfluidic systems are commonly used. Here, we analyze the characteristics of an in-house developed batch process experimental setup, the Electromagnetic Sample Mixer (ESM) described earlier. This device uses three electromagnets to increase the relative velocity between SMPs and targets. We carry out simulations of the magnetic field in the ESM and in a simpler paradigmatic setup, and thus were able to calculate the force field acting on the SMPs and to simulate their relative velocities and fluid dynamics due to SMP movement. In this way we were able to show that alternate charging of the magnets induces a double circular stream of SMPs in the ESM, resulting in high relative velocities of SMPs to the targets. Consequently, due to the conservation of momentum, the fluid experiences an acceleration induced by the SMPs. We validated our simulations by microscopic observation of the SMPs in the magnetic field, using a homemade apparatus designed to accommodate a long working-distance lens. By comparing the results of modeling this paradigmatic setup with the experimental observations, we determined that the velocities of the SMPs corresponded to the results of our simulations.

  17. Magnetic properties of LiZnCu ferrite synthesized by the microwave sintering method

    Energy Technology Data Exchange (ETDEWEB)

    Khot, Sujata S., E-mail: sujataskhot@rediffmail.com [D.B.J. College, Chiplun, Maharashtra (India); Smt. Chandibai Himathmal Mansukhani College, Ulhasnagar, Maharashtra (India); Shinde, Neelam S., E-mail: neelamshinde1976@gmail.com [D.B.J. College, Chiplun, Maharashtra (India); Smt. Chandibai Himathmal Mansukhani College, Ulhasnagar, Maharashtra (India); Basavaiah, Nathani, E-mail: bas@iigs.iigm.res.in [Indian Institute of Geomagnetism, New Panvel 410218, Maharashtra (India); Watawe, Shrikant C., E-mail: shrikantwatawe@yahoo.com [P.D.Karkhanis College, Ambernath (East), Maharashtra (India); Vaidya, Milind M., E-mail: milind_chm@yahoo.co.in [Vedanta College of Management and Information Technology, Vitthalvadi (West), Maharashtra (India)

    2015-01-15

    Lithium ferrites have attracted considerable attention because they have been used as replacements for garnets due to their low cost. A series of polycrystalline ferrite samples were prepared with the composition of Li{sub X}Zn{sub (0.6−2X)}Cu{sub 0.4}Fe{sub 2}O{sub 4}(X=0.05, 0.1, 0.15, 0.2, 0.25, 0.3) at chemical reaction temperature 150 °C by sintering with microwave assisted combustion method. The characterization shows the formation of single phase cubic structure when carried out by using the X-rays technique and I–R technique. Magnetization parameters such as saturation magnetization, coercivity, magnetic moment were calculated by using the Hysteresis graph. The Curie temperature obtained using the susceptibility data are found to be in the range 350–700 °C. Anhysteric remanent magnetization is used for estimating the grain size and domain structure of the composition. An attempt has been made to synthesis the nano-particles at lower reaction temperature by using non-conventional microwave sintering method. The advantage of this method is its lower sintering temperature and time compared to the conventional ceramic technique and direct formation of nano-ferrites without ball-milling. - Highlights: • Single spinel phases of LiZnCu ferrite are studied. • Different sized particles, ranging 43–63 nm were formed by using microwave sintering method. • The substitution of Zn{sup 2+} ions alters the domain structure from SD to MD and then to SP. • SD particle have higher ARM intensities per unit mass compared to MD particles. • A combination of lower chemical reaction temperature with microwave sintering could be useful for obtaining nano-ferrites.

  18. Articles comprising ferritic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Rakowski, James M.

    2016-06-28

    An article of manufacture comprises a ferritic stainless steel that includes a near-surface region depleted of silicon relative to a remainder of the ferritic stainless steel. The article has a reduced tendency to form an electrically resistive silica layer including silicon derived from the steel when the article is subjected to high temperature oxidizing conditions. The ferritic stainless steel is selected from the group comprising AISI Type 430 stainless steel, AISI Type 439 stainless steel, AISI Type 441 stainless steel, AISI Type 444 stainless steel, and E-BRITE.RTM. alloy, also known as UNS 44627 stainless steel. In certain embodiments, the article of manufacture is a fuel cell interconnect for a solid oxide fuel cell.

  19. High power ferrite microwave switch

    Science.gov (United States)

    Bardash, I.; Roschak, N. K.

    1975-01-01

    A high power ferrite microwave switch was developed along with associated electronic driver circuits for operation in a spaceborne high power microwave transmitter in geostationary orbit. Three units were built and tested in a space environment to demonstrate conformance to the required performance characteristics. Each unit consisted of an input magic-tee hybrid, two non-reciprocal latching ferrite phase shifters, an out short-slot 3 db quadrature coupler, a dual driver electronic circuit, and input logic interface circuitry. The basic mode of operation of the high power ferrite microwave switch is identical to that of a four-port, differential phase shift, switchable circulator. By appropriately designing the phase shifters and electronic driver circuits to operate in the flux-transfer magnetization mode, power and temperature insensitive operation was achieved. A list of the realized characteristics of the developed units is given.

  20. Dielectric Behavior and Magnetic Properties of Mn-Substituted Ni-Zn Ferrites

    Science.gov (United States)

    Irfan, Muhammad; Niaz, N. A.; Ali, Irshad; Nasir, S.; Shakoor, Abdul; Aziz, Abdul; Karamat, Nazia; Khalid, N. R.

    2015-07-01

    Nanocrystalline spinel ferrites of nominal stoichiometry Ni0.5Zn0.5Mn x Fe2- x O4 ( x = 0.0, 0.1, 0.2, 0.3, 0.4) were synthesized by chemical co-precipitation. X-ray diffraction analysis revealed formation of a single cubic phase with no metal oxide secondary phase; increased intensity of peaks of the doped samples suggests that, in the range studied, substituents are completely dissolved in the cubic lattice. Grain size was measured by scanning electron microscopy, by use of the line intercept method. Dielectric measurements were obtained as a function of frequency in the range 20 Hz to 3 MHz. It was found that hopping conduction was the predominant mechanism of conduction in frequency-dependent alternating current conductivity. Conductivity relaxation of the charge carriers was examined by use of the electrical modulus formalism; the results were indicative of the presence of the non-Debye-type relaxation in the ferrites. The grain boundary contribution was clearly apparent from Cole-Cole plots. Hysteresis loops for all the samples were narrow with low values of coercivity and retentivity, indicative of the superparamagnetic nature of these samples. On the basis of these sample characteristics it is suggested that Ni-Zn-Mn ferrites may be potential candidates for hyperthermia applications.

  1. Tailoring the super-paramagnetic nature of MgFe{sub 2}O{sub 4} nanoparticles by In{sup 3+} incorporation

    Energy Technology Data Exchange (ETDEWEB)

    Naik, M.Z.; Salker, A.V., E-mail: sal_arun@rediffmail.com

    2016-09-15

    Highlights: • In{sup 3+} doped MgFe{sub 2}O{sub 4} nanoparticles are prepared by sol-gel method. • XRD and IR showed the formation of pure spinel ferrites. • XPS confirmed the valance states as Fe{sup 3+}, Mg{sup 2+}, In{sup 3+} and O{sup 2−}. • Super-paramagnetic nature of nanoparticles is observed. • Blocking temperature is obtained at RT under applied field of 250 Oe. - Abstract: MgFe{sub 1−x}In{sub x}O{sub 4} nanoparticles (where x = 0.00, 0.04, 0.08, 0.12 and 0.16) have been prepared by sol-gel method using citric acid. The appearance of two distinct bands corresponding to tetrahedral and octahedral occupied M−O bonds has been demonstrated in Fourier Transform Infra Red spectra (FT-IR). X-ray powder pattern confirmed the presence of a cubic spinel phase. X-ray Photoelectron Spectroscopy (XPS) has been employed to confirm the valence states of the metal ions present. Mössbauer spectroscopy shows the sextet for pristine sample and on In{sup 3+} doping the super-paramagnetic doublet becomes prominent. AC susceptibility profiles shows transition from single domain structure to super-paramagnetic particles on doping. The magnetic properties have been studied using Vibrating Sample Magnetometer (VSM), here the M-H and M-T curves showed the formation of super-paramagnetic nanoparticles at room temperature, where the saturation magnetisation (M{sub s}), remnant magnetisation (M{sub r}) and coercivity (H{sub c}) values decreased with In{sup 3+} incorporation.

  2. The use of ferrites at microwave frequencies

    CERN Document Server

    Thourel, Léo

    1964-01-01

    The Use of Ferrites at Microwave Frequencies describes the applications of ferrites at microwave frequencies and the apparatus involved. Topics covered range from the properties of ferrites to gyromagnetic and non-reciprocal effects, ferrite isolators, circulators, and modulators. The use of ferrites in variable frequency filter cavities is also discussed. Mathematical explanations are reduced to the strict minimum and only the results of calculations are indicated. This book consists of seven chapters and opens with a review of the theory of magnetism, touching on subjects such as the BOHR m

  3. Low temperature synthesis of nanosized Mn1–ZnFe2O4 ferrites and their characterizations

    Indian Academy of Sciences (India)

    Rajesh Iyer; Rucha Desai; R V Upadhyay

    2009-04-01

    Nanosized Mn1–ZnFe2O4 ( = 0, 0.1, 0.3, 0.5, 0.6, 0.7, 0.9) mixed ferrite samples of particle size < 12 nm were prepared using the co-precipitation technique by doping the Zn2+ ion impurities. Autoclave was employed to maintain constant temperature of 80°C and a constant pressure. The X-ray analysis and the IR spectrum analysis were carried out to confirm the spinel phase formation as well as to ascertain the cation distribution in the ferrite samples. This clearly points to the fact that the Zn2+ ion’s presence is not restricted to A-site alone for some of the Mn–Zn ferrite series. The real part of a.c. susceptibility measurements clearly indicated the superparamagnetic behaviour of the ferrite samples. There is a systematic decrease in the particle size, Curie temperature and magnetization with the increase in the Zn2+ ion doping, measured using magneto thermal gravimetric analysis (MTGA) and vibrating sample magnetometer (VSM), respectively. The lattice constant is found to be constantly decreasing till = 0.6 and beyond this an unusual slight increase in the lattice constant is found.

  4. Preparation of Dysprosium Ferrite/Polyacrylamide Magnetic Composite Microsphere and Its Characterization

    Institute of Scientific and Technical Information of China (English)

    Hidehiro Kumazawa; Wang Zhifeng; Zhou Lanxiang; Zhang Hong; Li Yourong; Zhang Ming

    2005-01-01

    Using the technique of microemulsion polymerization with nano-reactor, dysprosium ferrite/polyacrylamide magnetic composite microsphere was prepared by one-step method in a single inverse microemulsion. The structure, average particle size, morphology of composite microsphere were characterized by FTIR, XRD, TEM and TGA. The magnetic responsibility of composite microsphere was also investigated. The results indicate that the magnetic composite microsphere possess high magnetic responsibility and suspension stability.

  5. Magnetically controllable Casimir force based on a superparamagnetic metametamaterial

    Science.gov (United States)

    Ma, Junming; Zhao, Qian; Meng, Yonggang

    2014-02-01

    We theoretically investigate the magnetically controllable Casimir force between a parallel metal plate and a superparamagnetic metametamaterial (MMM) plate based on Mie scattering and effective medium theory. A type of MMM composed of superparamagnetic nanoparticles is proposed to fulfill the high frequency magnetic effect to gain Casimir repulsion when interacting with the metal plate. The permeability of such MMM depends on an external magnetic field, which makes it possible to adjust the magnitude of Casimir force. The effects of size, filling ratio, and magnetic property of the superparamagnetic particles on the tuning range are also investigated. Construction of such MMM using the micro/nanofabrication technology is promising to achieve magnetically controllable repulsive Casimir force.

  6. A STUDY OF FERRITE CAVITY.

    Energy Technology Data Exchange (ETDEWEB)

    ZHAO, Y.

    2002-04-19

    This note addresses the general concerns for the design of a ferrite cavity. The parameters are specified for the RCMS, for which the frequency ramp is in the range of 1.27 MHz to 6.44 MHz, or a ratio of 1:5.

  7. Multifunctional superparamagnetic iron oxide nanoparticles: promising tools in cancer theranostics.

    Science.gov (United States)

    Santhosh, Poornima Budime; Ulrih, Nataša Poklar

    2013-08-09

    Iron-oxide nanoparticles of small dimensions that have superparamagnetic properties show immense potential to revolutionize the future of cancer theranostics, the combinatorial diagnosis and therapeutic approach towards cancer. Superparamagnetic iron-oxide nanoparticles (SPIONs) have unique magnetic properties, due to which they show excellent tumor-targeting efficiency, and this paves the way for effective personalized cancer treatment. The aim of this review is to focus on the ability of SPIONs to perform multiple roles in the field of cancer biology, such as in diagnosis, monitoring, targeting and therapy. Also, other topics are discussed, including the synthesis of SPIONs, the challenges and recent advances.

  8. Superparamagnetic nanoparticles for cancer diagnostics and therapeutics

    Science.gov (United States)

    Kohler, Nathan

    2005-11-01

    This dissertation describes the development of a magnetic nanoparticle conjugate that can potentially serve as both a contrast enhancement agent in magnetic resonance imaging (MRI) and as a drug carrier in controlled drug release, targeted for cancer diagnostics and therapeutics. In this work, we developed a unique method to synthesize well-dispersed 10-nm superparamagnetic iron oxide nanoparticles (SPION) without using chemical surfactants. This approach is especially advantageous for subsequent surface modification of nanoparticles with functional coatings. To target the SPION for cancer cells in vivo to facilitate MRI contrast enhancement of tumors, we immobilized folic acid on the particle surface. Folic acid is a low molecular weight growth factor over-expressed on many forms of cancer. The covalent immobilization of folic acid to the nanoparticle surface was characterized with FTIR and the intracellular uptake of the folic acid nanoparticles was visualized with scanning confocal microscopy. To use SPION for controlled drug release, we immobilized methotrexate (MTX), a chemotherapeutic drug, to the nanoparticle surface. MTX-modified nanoparticles have several combined advantages including real-time monitoring of drug delivery using MRI, higher intracellular concentrations of methotrexate that increase cellular cytotoxicity, and reduced non-specific uptake by healthy cells within the body. We successfully conducted drug release experiments demonstrating that MTX was released under low pH conditions that mimic the intracellular conditions in the lysozome. To assess cellular cytotoxicity, we tested MTX-nanoparticle conjugates in human breast cancer cells (MCF-7), human cervical cancer cells (HeLa), and glioma cells (9L), and showed that the drug efficacy of MTX-nanoparticle conjugates was similar to that of free MTX. To improve nanoparticle circulation time and intracellular uptake, we developed a novel bifunctional poly(ethylene glycol) (PEG) SAM capable of

  9. Magnetic heating of silica-coated manganese ferrite nanoparticles

    Science.gov (United States)

    Iqbal, Yousaf; Bae, Hongsub; Rhee, Ilsu; Hong, Sungwook

    2016-07-01

    Manganese ferrite nanoparticles were synthesized using the reverse micelle method; these particles were then coated with silica. The silica-coated nanoparticles were spherical in shape, with an average diameter of 14 nm. The inverse spinel crystalline structure was observed through X-ray diffraction patterns. The coating status of silica on the surface of the nanoparticles was confirmed with a Fourier transform infrared spectrometer. The superparamagnetic properties were revealed by the zero coercive force in the hysteresis curve. Controllable heating at a fixed temperature of 42 °C was achieved by changing either the concentration of nanoparticles in the aqueous solution or the intensity of the alternating magnetic field. We found that at a fixed field strength of 5.5 kA/m, the 2.6 mg/ml sample showed a saturation temperature of 42 °C for magnetic hyperthermia. On the other hand, at a fixed concentration of 3.6 mg/ml, a field intensity of 4.57 kA/m satisfied the required temperature of 42 °C.

  10. Magnetic manipulation of superparamagnetic nanoparticles in a microfluidic system for drug delivery applications

    Science.gov (United States)

    Agiotis, L.; Theodorakos, I.; Samothrakitis, S.; Papazoglou, S.; Zergioti, I.; Raptis, Y. S.

    2016-03-01

    Magnetic nanoparticles (MNPs), such as superparamagnetic iron oxide nanoparticles (SPIONS), have attracted major interest, due to their small size and unique magnetic properties, for drug delivery applications. In this context, iron oxide nanoparticles of magnetite (Fe3O4) (150 nm magnetic core diameter), were used as drug carriers, aiming to form a magnetically controlled nano-platform. The navigation capabilities of the iron oxide nanoparticles in a microfluidic channel were investigated by simulating the magnetic field and the magnetic force applied on the magnetic nanoparticles inside a microfluidic chip. The simulations have been performed using finite element method (ANSY'S software). The optimum setup which intends to simulate the magnetic navigation of the nanoparticles, by the use of MRI-type fields, in the human circulatory system, consists of two parallel permanent magnets to produce a homogeneous magnetic field, in order to ensure the maximum magnetization of the magnetic nanoparticles, an electromagnet for the induction of the magnetic gradients and the creation of the magnetic force and a microfluidic setup so as to simulate the blood flow inside the human blood vessels. The magnetization of the superparamagnetic nanoparticles and the consequent magnetic torque developed by the two permanent magnets, together with the mutual interactions between the magnetized nanoparticles lead to the creation of rhabdoid aggregates in the direction of the homogeneous field. Additionally, the magnetic gradients introduced by the operation of the electromagnet are capable of directing the aggregates, as a whole, to the desired direction. By removing the magnetic fields, the aggregates are disrupted, due to the super paramagnetic nature of the nanoparticles, avoiding thus the formation of undesired thrombosis.

  11. Magnetic manipulation of superparamagnetic nanoparticles in a microfluidic system for drug delivery applications

    Energy Technology Data Exchange (ETDEWEB)

    Agiotis, L.; Theodorakos, I.; Samothrakitis, S.; Papazoglou, S.; Zergioti, I.; Raptis, Y.S.

    2016-03-01

    Magnetic nanoparticles (MNPs), such as superparamagnetic iron oxide nanoparticles (SPIONS), have attracted major interest, due to their small size and unique magnetic properties, for drug delivery applications. In this context, iron oxide nanoparticles of magnetite (Fe{sub 3}O{sub 4}) (150 nm magnetic core diameter), were used as drug carriers, aiming to form a magnetically controlled nano-platform. The navigation capabilities of the iron oxide nanoparticles in a microfluidic channel were investigated by simulating the magnetic field and the magnetic force applied on the magnetic nanoparticles inside a microfluidic chip. The simulations have been performed using finite element method (ANSY’S software). The optimum setup which intends to simulate the magnetic navigation of the nanoparticles, by the use of MRI-type fields, in the human circulatory system, consists of two parallel permanent magnets to produce a homogeneous magnetic field, in order to ensure the maximum magnetization of the magnetic nanoparticles, an electromagnet for the induction of the magnetic gradients and the creation of the magnetic force and a microfluidic setup so as to simulate the blood flow inside the human blood vessels. The magnetization of the superparamagnetic nanoparticles and the consequent magnetic torque developed by the two permanent magnets, together with the mutual interactions between the magnetized nanoparticles lead to the creation of rhabdoid aggregates in the direction of the homogeneous field. Additionally, the magnetic gradients introduced by the operation of the electromagnet are capable of directing the aggregates, as a whole, to the desired direction. By removing the magnetic fields, the aggregates are disrupted, due to the super paramagnetic nature of the nanoparticles, avoiding thus the formation of undesired thrombosis. - Highlights: • Homogeneous field yields an aggregation of particles along the lines of the field. • Additional electromagnet field rotates the

  12. Increasing the high-frequency magnetic permeability of MnZn ferrite in polyaniline composites by incorporating silver

    Science.gov (United States)

    Babayan, V.; Kazantseva, N. E.; Sapurina, I.; Moučka, R.; Stejskal, J.; Sáha, P.

    2013-05-01

    A hybrid composite containing 73 vol% of MnZn ferrite, 21 vol% of polyaniline, and 6 vol% of silver is obtained by oxidative polymerization of aniline with silver nitrate in the presence of ferrite powder. The hybrid composite contains ferrite particles with a size of 40-80 μm coated by an inhomogeneous layer of polyaniline in the conducting emeraldine form. Silver in the form of nano- and submicrometre -size particles is localized both on the surface of ferrite particles and in the bulk of polyaniline coating. The electrical and magnetic properties of the hybrid composite are investigated and compared with the properties of a composite with 71 vol% of MnZn ferrite coated by a conducting polyaniline layer (29 vol%). The hybrid composite containing silver exhibits an increase in the real and imaginary parts of the complex permeability in the radio-frequency band by more than one and a half times compared with those of the MnZn ferrite-polyaniline composite. The high-frequency permittivity of both composites is determined by the properties of core-shell structure: electric properties of shell as well as its composition and uniformity.

  13. Structural and magnetic characterization of co-precipitated NixZn1-xFe2O4 ferrite nanoparticles

    Science.gov (United States)

    Srinivas, Ch.; Tirupanyam, B. V.; Meena, S. S.; Yusuf, S. M.; Babu, Ch. Seshu; Ramakrishna, K. S.; Potukuchi, D. M.; Sastry, D. L.

    2016-06-01

    A series of NixZn1-xFe2O4 (x=0.5, 0.6 and 0.7) ferrite nanoparticles have been synthesized using a co-precipitation technique, in order to understand the doping effect of nickel on their structural and magnetic properties. XRD and FTIR studies reveal the formation of spinel phase of ferrite samples. Substitution of nickel has promoted the growth of crystallite size (D), resulting the decrease of lattice strain (η). It was also observed that the lattice parameter (a) increases with the increase of Ni2+ ion concentration. All particles exhibit superparamagnetism at room temperature. The hyperfine interaction increases with the increase of nickel substitution, which can be assumed to the decrease of core-shell interactions present in the nanoparticles. The Mössbauer studies witness the existence of Fe3+ ions and absence of Fe2+ ions in the present systems. These superparamagnetic nanoparticles are supposed to be potential candidates for biomedical applications. The results are interpreted in terms of microstructure, cation redistribution and possible core-shell interactions.

  14. Evaluation of radiogallium-labeled, folate-embedded superparamagnetic nanoparticles in fibrosarcoma-bearing mice

    Directory of Open Access Journals (Sweden)

    Seyyedeh Leila Hosseini-Salekdeh

    2012-01-01

    Full Text Available Context: Elevated expression of the folate receptor (FR occurs in many human malignancies. Thus, folate targeting is widely utilized in drug delivery purposes specially using nano-radioactive agents. Aims: In this work, we report production and biological evaluation of gallium-67 labeled superparamagnetic iron oxide nanoparticles, embedded by folic acid ( 67 Ga-SPION-folate complex especially in tumor-bearing mice for tumor imaging studies. Settings and Design: The structure of SPION-folate was confirmed by X-ray diffraction (XRD, transmission electron microscopy (TEM and foureir transform infrared spectroscopy (FT-IR analyses. The radiolabeled SPION-folate formation was confirmed by instant thin layer chromatography (ITLC. Tumor induction was performed by the use of poly-aromatic hydrocarbon injection in rodents as reported previously. Materials and Methods: [ 67 Ga]-SPION-folate was shown to possess a particle size of ≈5-10 nm using instrumental methods followed by ITLC test. Biocompatibility of the compound was investigated using an 3-(4,5-Dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT assay followed by stability tests and tumor accumulation studies in fibrosarcoma-bearing mice after subcutaneous (s.c. application. Statistical Analysis Used: All values were expressed as mean ± standard deviation (mean ± SD and the data were compared using Student t-test. Statistical significance was defined as P95% radiochemical purity. Biodistribution studies demonstrated tumor:blood, tumor:bone and tumor:muscle ratios of 4.23, 4.98 and 11.54 respectively after 24 h. Conclusions: Due to the nano-scale size and high-penetrative property of the developed folate-containing nano-complex, this system can be an interesting drug delivery modality with therapeutic applications and folate receptor-targeting behavior, while possessing paramagnetic properties for thermotherapy.

  15. Development of a monolithic ferrite memory array

    Science.gov (United States)

    Heckler, C. H., Jr.; Bhiwandker, N. C.

    1972-01-01

    The results of the development and testing of ferrite monolithic memory arrays are presented. This development required the synthesis of ferrite materials having special magnetic and physical characteristics and the development of special processes; (1) for making flexible sheets (laminae) of the ferrite composition, (2) for embedding conductors in ferrite, and (3) bonding ferrite laminae together to form a monolithic structure. Major problems encountered in each of these areas and their solutions are discussed. Twenty-two full-size arrays were fabricated and fired during the development of these processes. The majority of these arrays were tested for their memory characteristics as well as for their physical characteristics and the results are presented. The arrays produced during this program meet the essential goals and demonstrate the feasibility of fabricating monolithic ferrite memory arrays by the processes developed.

  16. Cancer detection based on Raman spectra super-paramagnetic clustering

    Science.gov (United States)

    González-Solís, José Luis; Guizar-Ruiz, Juan Ignacio; Martínez-Espinosa, Juan Carlos; Martínez-Zerega, Brenda Esmeralda; Juárez-López, Héctor Alfonso; Vargas-Rodríguez, Héctor; Gallegos-Infante, Luis Armando; González-Silva, Ricardo Armando; Espinoza-Padilla, Pedro Basilio; Palomares-Anda, Pascual

    2016-08-01

    The clustering of Raman spectra of serum sample is analyzed using the super-paramagnetic clustering technique based in the Potts spin model. We investigated the clustering of biochemical networks by using Raman data that define edge lengths in the network, and where the interactions are functions of the Raman spectra's individual band intensities. For this study, we used two groups of 58 and 102 control Raman spectra and the intensities of 160, 150 and 42 Raman spectra of serum samples from breast and cervical cancer and leukemia patients, respectively. The spectra were collected from patients from different hospitals from Mexico. By using super-paramagnetic clustering technique, we identified the most natural and compact clusters allowing us to discriminate the control and cancer patients. A special interest was the leukemia case where its nearly hierarchical observed structure allowed the identification of the patients's leukemia type. The goal of this study is to apply a model of statistical physics, as the super-paramagnetic, to find these natural clusters that allow us to design a cancer detection method. To the best of our knowledge, this is the first report of preliminary results evaluating the usefulness of super-paramagnetic clustering in the discipline of spectroscopy where it is used for classification of spectra.

  17. Thermal Plasma Synthesis of Superparamagnetic Iron Oxide Nanoparticles

    NARCIS (Netherlands)

    Lei, P.Y.; Boies, A.M.; Calder, S.A.; Girshick, S.L.

    2012-01-01

    Superparamagnetic iron oxide nanoparticles were synthesized by injecting ferrocene vapor and oxygen into an argon/helium DC thermal plasma. Size distributions of particles in the reactor exhaust were measured online using an aerosol extraction probe interfaced to a scanning mobility particle sizer,

  18. NMR study of magnetism and superparamagnetism

    Science.gov (United States)

    Yuan, Shaojie

    behavior. The magnetic shape memory alloys Ni-Mn-Sn exhibit interesting properties including, field induced transformations, conventional and inverse magnetocaloric effects. They have potential for use as sensors, actuators and energy conversion devices. The Heusler alloy, Ni50Mn50-xSnx with x = 10 is one of these materials. It undergoes a transition from an austenite phase to a martensitic phase at 400 K, with the emergence of rich interesting magnetic properties below the transition. Coexistence of ferromagnetic (F) and AF spin configurations is reported in these compounds. 55Mn NMR has been used as a local probe to study the magnetic properties of this alloy. Rich peak features are observed with the various components assigned to nanoscale F or AF regions. Our results have provided detailed information on the AF regions, which has not been provided by other techniques. Measurements of the temperature dependence of the NMR spectra, in ZF and in a perturbing field were made. The spin-lattice relaxation dependence on T provides detailed information on the nanocluster size distribution and relative concentrations of the F and AF regions. Recently, the Heusler alloy Ni50-xCoxMn40Sn10, with 5 ≤ x ≤ 8, have attracted interest because the low thermal hysteresis and the large change in magnetization which they exhibit at the martensitic transition. Evidence for phase separation of ferromagnetic and antiferromagnetic regions at low temperatures is provided by magnetization and small angle neutron scattering measurements. Superparamagnetism and intrinsic exchange bias effects have been detected below 50 K. Zero field 55Mn NMR has provided detailed information on the nanoscale magnetic properties of samples with x = 7 and, for comparison, x = 14. For x = 7 F and AF regions, with a broad size distribution are identified and our results show that F clusters with the highest blocking temperatures are associated with regions rich in Co ions.

  19. Magnetic Field Emissions for Ferrite and Non-Ferrite Geometries for Wireless Power Transfer to Vehicles

    DEFF Research Database (Denmark)

    Batra, Tushar; Schaltz, Erik

    2014-01-01

    . For geometries without ferrite, these zones can be defined only on basis of distance from coils. The simulation results indicate that magnetic field profile in the surroundings is influenced for ferrite based geometries and the three zones tend to overlap. This overlapping is studied via Comsol simulations...... profile of magnetic field emissions (with and without ferrite) for wireless power transfer to vehicles....

  20. A comparative study of NiZn ferrites modified by the addition of cobalt

    Directory of Open Access Journals (Sweden)

    Pereira S.L.

    1999-01-01

    Full Text Available Off-stoichiometric NiZn ferrite was obtained by hydrothermal process and compacted in torus form under different pressures. Two samples A1 and A2 - cobalt doped (0.5 % were sintered at 1573 K in air atmosphere during 3 h. The magnetic properties were studied by vibrating sample magnetometry, Mössbauer spectroscopy and complex impedanciometry. X-ray diffraction and Hg porosimetry were used in order to determine the average grain size and the type of packing in the samples. Both samples exhibited superparamagnetic behavior in the hysteresis loop. This effect does not agree with Mössbauer results, which were fitted using Normos, a commercial computer program. All samples parameters were compared.

  1. Magneto-viscosity of hydrothermal synthesized Cu-Zn ferrite ferrofluids

    Directory of Open Access Journals (Sweden)

    Nisha Gautam

    2017-05-01

    Full Text Available The paraffin based ferrofluids were synthesized using the oleic acid coated Cu-Zn ferrite (CZF nanoparticles of compositions Cu0.6Zn0.4Fe2O4 (CZF1 and Cu0.4Zn0.6Fe2O4 (CZF2 synthesized by hydrothermal process. The transmission electron micrographs (TEM show the cubic shape particles of 4 to 10 nm and 4 to 18 nm size for CZF1 and CZF2 respectively. The nanoparticles show superparamagnetic behaviour. The viscosity increases with increase in magnetic field due to the formation of long chains of magnetic nanoparticles in ferrofluid. At higher flow rate, the magnetic chains break into smaller units and arrange along the flow direction. The flow curves show power law behavior. The size of magnetic nanoparticles influences the magneto-viscosity of the ferrofluids.

  2. Magneto-viscosity of hydrothermal synthesized Cu-Zn ferrite ferrofluids

    Science.gov (United States)

    Gautam, Nisha; Thirupathi, Gadipelly; Singh, Rajender

    2017-05-01

    The paraffin based ferrofluids were synthesized using the oleic acid coated Cu-Zn ferrite (CZF) nanoparticles of compositions Cu0.6Zn0.4Fe2O4 (CZF1) and Cu0.4Zn0.6Fe2O4 (CZF2) synthesized by hydrothermal process. The transmission electron micrographs (TEM) show the cubic shape particles of 4 to 10 nm and 4 to 18 nm size for CZF1 and CZF2 respectively. The nanoparticles show superparamagnetic behaviour. The viscosity increases with increase in magnetic field due to the formation of long chains of magnetic nanoparticles in ferrofluid. At higher flow rate, the magnetic chains break into smaller units and arrange along the flow direction. The flow curves show power law behavior. The size of magnetic nanoparticles influences the magneto-viscosity of the ferrofluids.

  3. Ferromagnetic resonance in Ni-Zn ferrite nanoparticles in different aggregation states

    Energy Technology Data Exchange (ETDEWEB)

    Valenzuela, Raul, E-mail: monjaras@servidor.unam.mx [Departamento de Materiales Metalicos y Ceramicos, Universidad Nacional Autonoma de Mexico, Mexico D.F. 04510 (Mexico); Herbst, Frederic; Ammar, Souad [ITODYS, UMR-CNRS 7086, Universite de Paris-Diderot, 75205 Paris Cedex (France)

    2012-10-15

    Ferrite nanoparticles of composition Zn{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4} were synthesized by forced hydrolysis in polyol from the corresponding zinc, nickel and iron acetates. By varying the preparation conditions, different aggregation states were obtained, ranging from isolated nanoparticles with average diameter of 5 nm, to clusters of some 20 nm, formed as well by nanoparticles with average diameter in the 5 nm range, as confirmed by X-ray diffraction and high resolution transmission electron microscopy. Ferromagnetic resonance measurements exhibited a ferrimagnetic behavior for both aggregation states at 77 K; at 300 K, however, isolated nanoparticles showed a superparamagnetic behavior while clustered ones remained ferrimagnetic with a broad linewidth. These results are interpreted on the basis of interactions between nanoparticles.

  4. Modeling of austenite to ferrite transformation

    Indian Academy of Sciences (India)

    Mohsen Kazeminezhad

    2012-06-01

    In this research, an algorithm based on the -state Potts model is presented for modeling the austenite to ferrite transformation. In the algorithm, it is possible to exactly track boundary migration of the phase formed during transformation. In the algorithm, effects of changes in chemical free energy, strain free energy and interfacial energies of austenite–austenite, ferrite–ferrite and austenite–ferrite during transformation are considered. From the algorithm, the kinetics of transformation and mean ferrite grain size for different cooling rates are calculated. It is found that there is a good agreement between the calculated and experimental results.

  5. Microwave dielectric properties of nanostructured nickel ferrite

    Indian Academy of Sciences (India)

    John Jacob; M Abdul Khadar; Anil Lonappan; K T Mathew

    2008-11-01

    Nickel ferrite is one of the important ferrites used in microwave devices. In the present work, we have synthesized nanoparticles of nickel ferrite using chemical precipitation technique. The crystal structure and grain size of the particles are studied using XRD. The microwave dielectric properties of nanostructured nickel ferrite samples of three different average grain sizes and those of two sintered samples were studied. The parameters like dielectric constant, dielectric loss and heating coefficient of the nanoparticles samples are studied in the frequency range from 2.4 to 4 GHz. The values of these parameters are compared with those of sintered pellets of the same samples. All these parameters show size dependent variations.

  6. Microwave Ferrites for Cryogenic Applications

    OpenAIRE

    G. Dionne

    1997-01-01

    Recent advances in microwave ferrite device technology have seen the introduction of superconductivity that virtually eliminates insertion losses due to electrical conduction in microstrip circuits. The conventional ferrimagnetic spinel and garnet compositions, however, are not generally optimized for temperatures in the vicinity of 77 K and may require chemical redesign in order to realize the full potential of these devices. For microwave transmission, absorption losses may be reduced by a ...

  7. Progress in ferrite phase shifters

    Science.gov (United States)

    Boyd, C. R., Jr.

    1983-10-01

    Advances in the technology of reciprocal ferrite phase shifters are outlined. Nonlatching rotary-field phase shifters have been produced with enhanced phase accuracy and modest control power. A significant quantity of dual-mode latching units has been built at 35 GHz, with good results. Both types of phase shifter can be adapted to perform other functions in addition to phase shifting. Examples of phase shifters that perform duplexing and polarization switching functions are given.

  8. Facile synthesis of manganese ferrite/graphene oxide nanocomposites for controlled targeted drug delivery

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guangshuo, E-mail: wgs8136@163.com; Ma, Yingying; Zhang, Lina; Mu, Jingbo; Zhang, Zhixiao; Zhang, Xiaoliang; Che, Hongwei; Bai, Yongmei; Hou, Junxian

    2016-03-01

    In this study, manganese ferrite/graphene oxide (MnFe{sub 2}O{sub 4}/GO) nanocomposites as controlled targeted drug delivery were prepared by a facile sonochemical method. It was found that GO nanosheets were fully exfoliated and decorated with MnFe{sub 2}O{sub 4} nanoparticles having diameters of 5–13 nm. The field-dependent magnetization curve indicated superparamagnetic behavior of the obtained MnFe{sub 2}O{sub 4}/GO with saturation magnetization of 34.9 emu/g at room temperature. The in vitro cytotoxicity testing exhibited negligible cytotoxicity of as-prepared MnFe{sub 2}O{sub 4}/GO even at the concentration as high as 150 μg/mL. Doxorubicin hydrochloride (DOX) as an anti-tumor model drug was utilized to explore the application potential of MnFe{sub 2}O{sub 4}/GO for controlled drug delivery. The drug loading capacity of this nanocarrier was as high as 0.97 mg/mg and the drug release behavior showed a sustained and pH-responsive way. - Highlights: • Manganese ferrite/graphene oxide (MnFe{sub 2}O{sub 4}/GO) were prepared by a facile sonochemical method. • GO nanosheets were fully exfoliated and decorated homogeneously with MnFe{sub 2}O{sub 4} nanoparticles. • MnFe{sub 2}O{sub 4}/GO exhibited superparamagnetic behavior with saturation magnetization of 34.9 emu/g. • The in vitro cytotoxicity testing showed negligible cytotoxicity of the obtained MnFe{sub 2}O{sub 4}/GO. • Drug loading capacity was as high as 0.97 mg/mg and drug release showed pH-sensitive feature.

  9. Monodisperse Co, Zn-Ferrite nanocrystals: Controlled synthesis, characterization and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Sanjeev, E-mail: sanjeevkumar.dubey2@gmail.com [University of Petroleum and Energy Studies, Dehradun 248007 (India); Singh, Vaishali; Aggarwal, Saroj [School of Basic and Applied Sciences (India); Mandal, Uttam Kumar [University School of Chemical Technology, GGS Indraprastha University, Kashmere Gate, Delhi 110403 (India); Kotnala, R.K. [National Physical laboratory, New Delhi 110012 (India)

    2012-11-15

    Co{sub x}Zn{sub y}Fe{sub 3-x-y}O{sub 4} ferrite (x=1 to 0; y=0 to1) nanocrystals have been synthesized by reverse microemulsion method. The nanocrystals are then comprehensively characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Field emission transmission electron microscopy (FETEM), and magnetic properties were measured by using Vibrating sample magnetometer. X-ray analysis showed that all the crystals were cubic spinel. The lattice constant increased with the increase in Zn substitution. FETEM reveals that particle size varies in the range from 3 to 6 nm. As the concentration of Zn increases the magnetic behavior varies from ferromagnetic at y=0 and 0.2 to superparamagnetic to paramagnetic at y=1. The Curie temperature decreases with increasing concentration of Zn. - Highlights: Black-Right-Pointing-Pointer Reverse microemulsion route is a very facile route for synthesis of Co{sub x}Zn{sub y}Fe{sub 3-x-y}O{sub 4} ferrite and all particles synthesized by reverse microemulsion is in the range of 3-6 nm. Black-Right-Pointing-Pointer Presence of Zn changes the structural and magnetic properties of the Zn substituted CoFe{sub 2}O{sub 4}. Black-Right-Pointing-Pointer The lattice constant increases with the increase in Zn substitution. Black-Right-Pointing-Pointer The curie temperature decreases with Zn concentration appreciably. Black-Right-Pointing-Pointer Magnetic behavior varies from ferromagnetic at y=0, 0.2 to superparamagnetic to paramagnetic at y=1.

  10. Dielectric properties of nanocrystalline Co-Mg ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Jyoti, E-mail: jyotijoshi.phy2008@gmail.com [Department of Physics, University of Rajasthan, Jaipur (India); Sharma, Neha [Department of Physics, VEC Lakhanpur, Sarguja University, Ambikapur (C.G.) (India); Parashar, Jyoti; Saxena, V.K.; Bhatnagar, D. [Department of Physics, University of Rajasthan, Jaipur (India); Sharma, K.B. [Department of Physics, S. S. Jain Subodh P. G. College, Jaipur (India)

    2015-11-15

    Nanocrystalline powder samples with chemical formula Co{sub x}Mg{sub 1−x}Fe{sub 2}O{sub 4} (x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) have been synthesized by sol–gel auto combustion method using citric acid as fuel agent. The rietveld refinement study of x-ray diffraction patterns confirmed the spinel single phase formation for all samples. Dielectric constant (ε′), dielectric loss tangent (tan δ) and AC conductivity of Co{sub x}Mg{sub 1−x}Fe{sub 2}O{sub 4} ferrite nanoparticles have been measured at room temperature in the frequency range from 1000 Hz to 120 MHz. The dielectric dispersion observed at lower frequency region is attributed to Maxwell–Wagner two layer model, which is in agreement with Koops phenomenological theory. The observed results have been explained by polarization which is attributed to the electron exchange between Fe{sup 2+} and Fe{sup 3+} ions. The temperature variation of ε′ and tanδ for some particular frequencies were studied. The rapid increase in ε′ and tan δ has been explained using thermally activated electron exchange between Fe{sup 2+} ↔ Fe{sup 3+} and Co{sup 2+} ↔ Co{sup 3+} ions at adjacent octahedral sites. The role of interfacial polarization has been focused to explain the high dispersion in ε′ and tanδ with temperature observed at low frequencies. - Graphical abstract: (a) TEM image of Co{sub 0.4}Mg{sub 0.6}Fe{sub 2}O{sub 4} shows the nano size of the synthesized ferrite particles and (b) Dielectric constant behavior with frequency of Co{sub x}Mg{sub 1−x}Fe{sub 2}O{sub 4} ferrite.

  11. Synthesis and characterization of carboxymethyl dextran-coated Mn/Zn ferrite for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Latorre-Esteves, Magda; Cortes, Angel; Torres-Lugo, Madeline [Department of Chemical Engineering, University of Puerto Rico at Mayagueez, PO Box 9046, Mayagueez, PR 00680 (Puerto Rico); Rinaldi, Carlos [Department of Chemical Engineering, University of Puerto Rico at Mayagueez, PO Box 9046, Mayagueez, PR 00680 (Puerto Rico)], E-mail: crinaldi@uprm.edu

    2009-10-15

    Previous studies have shown that magnetic nanoparticles possess great potential for various in vivo applications such as magnetic resonance imaging contrast enhancement, tissue repair, cancer treatment agents, and controlled drug delivery. Many of these applications require that magnetic nanoparticles be colloidally stable in biological media. The goal of this study was to obtain a magnetic fluid produced by the colloidal suspension of manganese/zinc ferrite (MZF) nanoparticles that could be stably dispersed in aqueous solution throughout the range of physiological pH and ionic strength. These superparamagnetic nanoparticles were stabilized through steric repulsion by coating with biologically compatible carboxymethyl dextran (CMDx). Samples of the resultant magnetic fluid were analyzed using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), X-ray diffraction (XRD), zeta potential measurements, dynamic light scattering, transmission electron microscopy (TEM), and SQUID magnetometry. Results show that we obtained superparamagnetic metal-oxide crystals with composition of Mn{sub 0.24}Zn{sub 0.76}Fe{sub 2}O{sub 4}. Cell viability measurements show the material is non-toxic to MCF-7 and CaCo-2 cell lines at concentrations of up to 7.5 mg/mL of particle fraction for contact time of up to 48 h.

  12. Structural, magnetic and gas sensing properties of nanosized copper ferrite powder synthesized by sol gel combustion technique

    Science.gov (United States)

    Sumangala, T. P.; Mahender, C.; Barnabe, A.; Venkataramani, N.; Prasad, Shiva

    2016-11-01

    Stoichiometric nano sized copper ferrite particles were synthesized by sol gel combustion technique. They were then calcined at various temperatures ranging from 300-800 °C and were either furnace cooled or quenched in liquid nitrogen. A high magnetisation value of 48.2 emu/g signifying the cubic phase of copper ferrite, was obtained for sample quenched to liquid nitrogen temperature from 800 °C. The ethanol sensing response of the samples was studied and a maximum of 86% response was obtained for 500 ppm ethanol in the case of a furnace cooled sample calcined at 800 °C. The chemical sensing is seen to be correlated with the c/a ratio and is best in the case of tetragonal copper ferrite.

  13. Temperature dependence of magnetic behaviour in very fine grained, spark plasma sintered NiCuZn ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Ahmadi, Behzad; Zehani, Karim; LoBue, Martino; Loyau, Vincent; Mazaleyrat, Frederic [SATIE, ENS Cachan, CNRS, UniverSud 61, avenue du President Wilson, F-94230 Cachan (France)

    2012-04-01

    Recently, using spark plasma sintering technique, a family of very fine grained, fully dense NiCuZn ferrites have been produced, which show constant permeability up to several 10 MHz. These ferrites can be used for filtering purposes in high frequency applications where a wide frequency band is required. In this paper, we study the magnetization processes taking place in these nano grained materials, in the frequency interval of 100 kHz to 5 MHz. Using a fluxmetric hysteresis graph, permeability, loss, and BH loops are measured at different temperatures, from -5 deg. C to 110 deg. C. Results are compared to the behavior of micrometric grain size ferrites, which are commonly used for power electronic and high frequency applications.

  14. Copper ferrites@reduced graphene oxide anode materials for advanced lithium storage applications.

    Science.gov (United States)

    Wang, Junyong; Deng, Qinglin; Li, Mengjiao; Jiang, Kai; Zhang, Jinzhong; Hu, Zhigao; Chu, Junhao

    2017-08-21

    Copper ferrites are emerging transition metal oxides that have potential applications in energy storage devices. However, it still lacks in-depth designing of copper ferrites based anode architectures with enhanced electroactivity for lithium-ion batteries. Here, we report a facile synthesis technology of copper ferrites anchored on reduced graphene oxide (CuFeO2@rGO and Cu/CuFe2O4@rGO) as the high-performance electrodes. In the resulting configuration, reduced graphene offers continuous conductive channels for electron/ion transfer and high specific surface area to accommodate the volume expansion of copper ferrites. Consequently, the sheet-on-sheet CuFeO2@rGO electrode exhibits a high reversible capacity (587 mAh g(-1) after 100 cycles at 200 mA g(-1)). In particular, Cu/CuFe2O4@rGO hybrid, which combines the advantages of nano-copper and reduced graphene, manifests a significant enhancement in lithium storage properties. It reveals superior rate capability (723 mAh g(-1) at 800 mA g(-1); 560 mAh g(-1) at 3200 mA g(-1)) and robust cycling capability (1102 mAh g(-1) after 250 cycles at 800 mA g(-1)). This unique structure design provides a strategy for the development of multivalent metal oxides in lithium storage device applications.

  15. Innovative Powder Processing of Oxide Dispersion Strengthened ODS Ferritic Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Rieken, Joel; Anderson, Iver; Kramer, Matthew

    2011-04-01

    An innovative gas atomization reaction synthesis technique was employed as a viable method to dramatically lower the processing cost for precursor oxide dispersion forming ferritic stainless steel powders (i.e., Fe-Cr-(Hf,Ti)-Y). During this rapid solidification process the atomized powders were enveloped by a nano-metric Cr-enriched metastable oxide film. Elevated temperature heat treatment was used to dissociate this metastable oxide phase through oxygen exchange reactions with Y-(Hf,Ti) enriched intermetallic compound precipitates. These solid state reactions resulted in the formation of highly stable nano-metric mixed oxide dispersoids (i.e., Y-Ti-O or Y-Hf-O) throughout the alloy microstructure. Subsequent high temperature (1200 C) heat treatments were used to elucidate the thermal stability of each nano-metric oxide dispersoid phase. Transmission electron microscopy coupled with X-ray diffraction was used to evaluate phase evolution within the alloy microstructure.

  16. Effect of Jahn-Teller distortion on the short range magnetic order in copper ferrite

    Science.gov (United States)

    Abdellatif, M. H.; Innocenti, Claudia; Liakos, Ioannis; Scarpellini, Alice; Marras, Sergio; Salerno, Marco

    2017-02-01

    Copper ferrite of spinel crystal structure was synthesized in the form of nano-particles using citrate-gel auto-combustion method. The sample morphology and composition were identified using scanning electron microscopy, X-ray diffraction, and X-ray spectroscopy. The latter technique reveals an inverse spinel structure with Jahn-Teller tetragonal distortion. The static magnetization was measured using vibrating sample magnetometer. Magnetic force microscopy was used in combination with the magnetization data to demonstrate the finite size effect of the magnetic spins and their casting behavior due to the introduction of copper ions in the tetrahedral magnetic sub-lattices, which results in tetragonal distorting the spinel structure of the copper ferrite. The magnetic properties of materials are a result of the collective behavior of the magnetic spins, and magnetic force microscopy can probe the collective behavior of the magnetic spins in copper ferrite, yet providing a sufficient resolution to map the effects below the micrometer size scale, such as the magnetic spin canting. A theoretical study was done to clarify the finite size effect of Jahn-Teller distortion on the magnetic properties of the material. When the particles are in the nano-scale, below the single domain size, their magnetic properties are very sensitive to their size change.

  17. Mössbauer and magnetic studies of nanocrystalline zinc ferrites synthesized by microwave combustion method

    Science.gov (United States)

    Mahmoud, Mohamed; Hassan, Azza Mohamed; Ahmed, Mamdouh Abdel aal; Zhu, Kaixin; Ganeshraja, Ayyakannu Sundaram; Wang, Junhu

    2016-12-01

    Zinc ferrite nano-crystals were synthesized by a microwave assisted combustion route with varying the urea to metal nitrates (U/N) molar ratio The process takes only a few minutes to obtain Zinc ferrite powders. The Effect of U/N ratio on the obtained phases, particle size, magnetization and structural properties has been investigated. The specimens were characterized by XRD, Mössbauer and VSM techniques. The sample prepared with urea/metal nitrate ratio of 1/1 was a poorly crystalline phase with very small crystallite size. A second phase is also detected in the sample. The crystallite size increases while the second phase decrease with increasing the urea ratio. The saturation magnetization and coercivity of the as prepared nano-particles changed with the change of the U/N ratio. The powder with the highest U/N ratio showed the presence of an unusually high saturation magnetization of 16 emu/g at room temperature. The crystallinity of the as prepared powder was developed by annealing the samples at 700 ∘C and 900 ∘C. Both the saturation magnetization ( Ms) and the remnant magnetization ( Mr) were found to be highly dependent upon the annealing temperature. Mössbauer studies show magnetic ordering in the powder even at room temperature. The Mössbauer and the magnetic parameters of this fraction are different from the standard values for bulk zinc ferrite.

  18. A study of some properties for Li–Mn nanoparticles ferrite using positron annihilation lifetime technique

    Energy Technology Data Exchange (ETDEWEB)

    Aly, E. Hassan, E-mail: emad_h_ali@yahoo.com; Samy, A.M., E-mail: amany_hegazy@sci.asu.edu.eg

    2015-10-25

    Nanoparticle samples of the composition Li{sub (0.5–0.5x)}Mn{sub x}Fe{sub (2.5-0.5x)}O{sub 4}, (x = 0, 0.25, 0.5 and 0.75) are prepared with a sol–gel auto combustion method. The nano grain size is decreased with increasing the manganese content. The analysis of PAL spectra indicated the existence of cluster defects. There are different correlations between the lifetime parameters with the manganese content. The relative intensity I{sub 2} and the trapping rate ķ are increased for samples with x = 0.25 & 0.75, and are decreased for the sample with x = 0.5 relative to the pure nano Li-ferrite. The electrical resistivity takes the same behavior as the G.S. by increasing Mn content. The size of the domain walls is decreased with Mn content for mono-grain Li ferrite samples. - Highlights: • Lifetime values τ{sub 2} confirm the existence of cluster defects at the domain walls. • The decrease of the domain walls thickness with increasing manganese content. • The decrease of the anisotropy energy and the exchange energy. • The decrease of the electrical resistivity is due to the decrease of the grain size. • It is a reverse behavior to the bulk ferrite.

  19. Ferrite Solutions for Electromagnetic Shock Lines

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, Phillip D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Dudley, Mark [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Primm, Paul [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-09-01

    The goal of this work is to develop tools and test procedures for identifying ferrites suitable for use in shock line applications. Electromagnetic shocklines have been used to provide fast rising voltage pulses for many applications. In these applications a slow rising pulse is injected into the line where currents drive the ferrites into saturation leading to a fast rising output pulse. A shockline’s unique capabilities could be applied to new detonator configurations. A properly conditioned voltage pulse is critical for fire set applications. A carefully designed shockline could provide a passive solution to generating a fast rising voltage pulse for the fire set. Traditional circuits use ferrites operating in a linear regime. Shock lines push the ferrites well into the nonlinear regime where very few tools and data currently exist. Ferrite material is key to the operation of these shock lines, and tools for identifying suitable ferrites are critical. This report describes an experimental setup to that allows testing of ferrite samples and comparison to models with the goal of identifying optimal ferrites for shockline use.

  20. Effect of size and shape dependent anisotropy on superparamagnetic property of CoFe2O4 nanoparticles and nanoplatelets

    Science.gov (United States)

    Chandekar, Kamlesh V.; Kant, K. Mohan

    2017-09-01

    Superparamagnetic cobalt ferrite (CoFe2O4) spherical nanoparticles and rhomboidal nanoplatelets were synthesized by co-precipitation at 80 °C (S1) and hydrothermal route at 150 °C (S2). X-ray diffraction (XRD) pattern confirms formation of cubic inverse spinel structure of as prepared cobalt ferrite samples (S1 and S2) with average crystallite size of 13 nm and 18.7 nm for S1 and S2 respectively. Transmission electron microscopy (TEM) reveals spherical and rhomboidal shaped with average particle size 16.7 nm (S1) and 19.8 nm (S2). The zero field cooled magnetization MZFCvs. T exhibit a broad maxima at 400 K and 510 K for S1 and S2 respectively. The blocking temperature TB is obtained as 310 K and 341 K for S1 and S2 respectively, by fitting coercive field at different temperatures to T 1 / 2 law. The morphology of S1 and S2 corresponds to shape dependence of continuum approach. The effective demagnetization factors estimated as ΔN1 = 0 and ΔN2 = 0 . 749 for S1 and S2 samples respectively. The uniaxial anisotropy and shape anisotropy observed to be dominant in spherical shaped and rhomboidal shaped CoFe2O4 nanoparticles respectively. The uniaxial anisotropy constant of S1 sample is estimated as 56 (kJ/m3) at TB = 310 K whereas the effective anisotropy constant for S2 sample is 627 (kJ/m3) at TB = 341 K , in which shape anisotropy constant 605 (kJ/m3) dominates over contribution from uniaxial anisotropy constant 22 (kJ/m3) in S2 sample.

  1. Synthesis and characterization of nanosized MgxMn1-xFe2O4 ferrites by both sol-gel and thermal decomposition methods

    Science.gov (United States)

    De-León-Prado, Laura Elena; Cortés-Hernández, Dora Alicia; Almanza-Robles, José Manuel; Escobedo-Bocardo, José Concepción; Sánchez, Javier; Reyes-Rdz, Pamela Yajaira; Jasso-Terán, Rosario Argentina; Hurtado-López, Gilberto Francisco

    2017-04-01

    This work reports the synthesis of MgxMn1-xFe2O4 (x=0-1) nanoparticles by both sol-gel and thermal decomposition methods. In order to determine the effect of synthesis conditions on the crystal structure and magnetic properties of the ferrites, the synthesis was carried out varying some parameters, including composition. By both methods it was possible to obtain ferrites having a single crystalline phase with cubic inverse spinel structure and a behavior near to that of superparamagnetic materials. Saturation magnetization values were higher for materials synthesized by sol-gel. Furthermore, in both cases particles have a spherical-like morphology and nanometric sizes (11-15 nm). Therefore, these materials can be used as thermoseeds for the treatment of cancer by magnetic hyperthermia.

  2. Microwave Measurements of Ferrite Polymer Composite Materials

    Directory of Open Access Journals (Sweden)

    Rastislav Dosoudil

    2004-01-01

    Full Text Available The article focuses on the microwave measurements performed on the nickel-zinc sintered ferrite with the chemical formula Ni0.3Zn0.7Fe2O4 produced by the ceramic technique and composite materials based on this ferrite and a non-magnetic polymer (polyvinyl chloride matrix. The prepared composite samples had the same particle size distribution 0-250um but different ferrite particle concentrations between 23 vol% and 80 vol%. The apparatus for measurement of the signal proportional to the absolute value of scattering parameter S11 (reflexion coefficient is described and the dependence of measured reflected signal on a bias magnetic field has been studied. By means of experiments, the resonances to be connected with the geometry of microwave experimental set-up were distinguished from ferromagnetic resonance arising in ferrite particles of composite structure. The role of local interaction fields of ferrite particles in composite material has been discussed.

  3. PREPARATION AND CHARACTERIZATION OF SUPERPARAMAGNETIC FUNCTIONAL POLYMERIC MICROPARTICLES

    Institute of Scientific and Technical Information of China (English)

    Xianqiao Liu; Huizhou Liu; Jianmin Xing; Yueping Guan; Zhiya Ma; Guobin Shan; Chengli Yang

    2003-01-01

    Superparamagnetic poly(styrene-divinylbenzene-glycidyl methacrylate) (Pst-DVB-GMA) microparticles were prepared via a modified suspension polymerization process. A magnetic fluid was first prepared by a chemical co-precipitation method. Then magnetic microparticles were produced by mixing the monomers and the magnetic fluid with water in the presence of a stabilizer poly(vinyl pyrrolidone) (PVP) to form a suspension, and finally benzoyl peroxide was added to initiate the co-polymerization. The morphology and magnetic properties of the microparticles were examined by TEM and VSM. The spherically shaped microparticles, with a size range of 4 to 7 μm, showed distinct superparamagnetic characteristics. XRD was used to investigate the structure of the magnetite particles dispersed in the polymer matrix. The microparticles with epoxy groups on their surface can be applied directly to the separation of biomolecules.

  4. Investigation of magnetically enhanced swelling behaviour of superparamagnetic starch nanoparticles

    Indian Academy of Sciences (India)

    A K Bajpai; Sweta Likhitkar

    2013-02-01

    The present study follows a novel strategy for the preparation of superparamagnetic nanoparticles of cross-linked starch impregnated homogeneously with nanosized iron oxide. The prepared magnetic nanoparticles were characterized by infra-red (FTIR) spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction and magnetization studies. The size of the magnetic polymeric particles was found to lie in the range of 20–80 nm, and they exhibited superparamagnetic properties. The particles were allowed to swell in phosphate buffer saline (PBS) and the influence of factors such as chemical composition of nanoparticles, pH and temperature of the swelling bath and applied magnetic field was investigated on the water intake capacity of the nanoparticles. The prepared nanoparticles showed potential to provide a possible option for controlled and targeted delivery of anticancer drugs, applying external magnetic field.

  5. Influence of the magnetic dead layer thickness of Mg-Zn ferrites nanoparticle on their magnetic properties

    Science.gov (United States)

    El-Sayed, H. M.; Ali, I. A.; Azzam, A.; Sattar, A. A.

    2017-02-01

    Nanoparticle ferrite with chemical formula Mg(1-x)ZnxFe2O4 (where x=0.0, 0.2, 0.4, 0.6, 0.8 and 1) were prepared by sol-gel technique. Single phase structure of these ferrites was confirmed using X-ray diffraction (XRD). Transmission Electron Microscope (TEM) showed that the particle size of the samples in the range of (5.7-10.6 nm). The hysteresis studies showed superparamagnetic behaviour at room temperature. The magnetization behaviour with Zn-content is expressed in the light of Yafet-Kittel angles. The dead layer thickness (t) was calculated and its effect on the magnetization and magnetic losses was debated. The Specific Absorption Rate (SAR) in an alternating magnetic field with frequency 198 kHz for these ferrites has been studied. It is found that, the thickness of magnetic dead layer of the surface of the materials has greatly affected the SAR value of the samples.

  6. Alternate current magnetic property characterization of nonstoichiometric zinc ferrite nanocrystals for inductor fabrication via a solution based process

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Hongseok [Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Kim, Jungkwun; Allen, Mark G. [Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Paik, Taejong [Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); School of Integrative Engineering, Chung-Ang University, Seoul 06974 (Korea, Republic of); Meng, Lingyao [Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Jo, Pil Sung [Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Complex Assemblies of Soft Matter, CNRS-SOLVAY-PENN UMI 3254, Bristol, Pennsylvania 19007-3624 (United States); Kikkawa, James M. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Kagan, Cherie R. [Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Murray, Christopher B., E-mail: cbmurray@sas.upenn.edu [Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)

    2016-03-21

    We investigate the ac magnetic behavior of solution processable, non-stoichiometric zinc ferrite nanocrystals with a series of sizes and zinc concentrations. Nearly monodisperse Zn{sub x}Fe{sub 3−x}O{sub 4} nanocrystals (x = 0–0.25) with an average size ranging from 7.4 nm to 13.8 nm are synthesized by using a solvothermal method. All the nanocrystals are in a superparamagnetic state at 300 K, which is confirmed by Superconductive Quantum Interference Device magnetometry. Due to the doping of non-magnetic Zn{sup 2+} into A site of ferrite, the saturation magnetization of nanocrystals increases as the size and Zn concentration increases. The ac magnetic permeability measurements at radio frequencies reveal that the real part of the magnetic permeability of similarly sized ferrite nanocrystals can be enhanced by almost twofold as the Zn{sup 2+} doping level increases from 0 to 0.25. The integration of 12.3 nm Zn{sub 0.25}Fe{sub 2.75}O{sub 4} nanocrystals into a toroidal inductor and a solenoid inductor prepared via a simple solution cast process yields a higher quality factors than air core inductors with the same geometries up to 5 MHz and 9 MHz, respectively, which is in the regime of the switching frequencies for the advanced integrated power converters.

  7. Selective manipulation of superparamagnetic beads by a magnetic microchip

    KAUST Repository

    Gooneratne, Chinthaka Pasan

    2013-07-01

    In this paper, a magnetic microchip (MMC) is presented, to first trap and then selectively manipulate individual, superparamagnetic beads (SPBs) to another trapping site. Trapping sites are realized through soft magnetic micro disks made of Ni80Fe20, and SPB motion is controlled by current-carrying, tapered, conducting lines made of Au. The MMC was realized using standard microfabrication techniques and provides a cheap and versatile platform for microfluidic systems for cell manipulation. © 2013 IEEE.

  8. Physical and technological principles of creating biocompatible superparamagnetic particles.

    Science.gov (United States)

    Levitin, Yevgen; Koval, Alla; Vedernikova, Irina; Ol'khovik, Larissa; Tkachenko, Mykola

    2011-01-01

    Nanodisperse powder of zinc-substituted magnetite has been developed. Functional characteristics (biocompatibility, dispersion, magnetic state) allow to recommend it for approbation in medical and biologic technologies. The character of the temperature dependences of magnetization investigated in the magnetic fields lower than the anisotropy field indicates that transfer from the magnetically stable state into the superparamagnetic state was realized for particles of 3-13 nm in the temperature range of 4.2-150 K. It reflects specificity of small particles magnetism.

  9. Structure and superparamagnetic behaviour of magnetite nanoparticles in cellulose beads

    Energy Technology Data Exchange (ETDEWEB)

    Correa, Jose R., E-mail: correa@fq.uh.cu [Department of General Chemistry, Faculty of Chemistry, University of Havana, Zapata and G, Havana City 10400 (Cuba); Bordallo, Eduardo [Sugar Cane-Cellulose Research Center, Cuba-9, Quivican (Cuba); Canetti, Dora [Department of Inorganic Chemistry, Faculty of Chemistry, University of Havana, Zapata and G, Havana City 10400 (Cuba); Leon, Vivian [Sugar Cane-Cellulose Research Center, Cuba-9, Quivican (Cuba); Otero-Diaz, Luis C. [Department of Inorganic Chemistry-1, Complutense University of Madrid, Madrid 28040 (Spain); Electron Microscopy Center, Complutense University of Madrid, Madrid 28040 (Spain); Negro, Carlos [Chemical Engineering Department, Complutense University of Madrid, Madrid 28040 (Spain); Gomez, Adrian [Electron Microscopy Center, Complutense University of Madrid, Madrid 28040 (Spain); Saez-Puche, Regino [Department of Inorganic Chemistry-1, Complutense University of Madrid, Madrid 28040 (Spain)

    2010-08-15

    Superparamagnetic magnetite nanoparticles were obtained starting from a mixture of iron(II) and iron(III) solutions in a preset total iron concentration from 0.04 to 0.8 mol l{sup -1} with ammonia at 25 and 70 {sup o}C. The regeneration of cellulose from viscose produces micrometrical spherical cellulose beads in which synthetic magnetite were embedded. The characterization of cellulose-magnetite beads by X-ray diffraction, Scanning and Transmission Electron Microscopy and magnetic measurement is reported. X-ray diffraction patterns indicate that the higher is the total iron concentration and temperature the higher is the crystal size of the magnetite obtained. Transmission Electron Microscopy studies of cellulose-magnetite beads revealed the distribution of magnetite nanoparticles inside pores of hundred nanometers. Magnetite as well as the cellulose-magnetite composites exhibit superparamagnetic characteristics. Field cooling and zero field cooling magnetic susceptibility measurements confirm the superparamagnetic behaviour and the blocking temperature for the magnetite with a mean size of 12.5 nm, which is 200 K.

  10. Magnetophoretic velocities of superparamagnetic particles, agglomerates and complexes

    Energy Technology Data Exchange (ETDEWEB)

    Wise, Naomi, E-mail: naomi.wise@eng.ox.ac.uk [Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, United Kindom (United Kingdom); Grob, Tim [Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, United Kindom (United Kingdom); Morten, Karl [Nuffield Department of Obstetrics and Gynaecology, University of Oxford, The Women Centre, John Radcliffe Hospital, Headley Way, Headington, Oxford OX3 9DU (United Kingdom); Thompson, Ian; Sheard, Steve [Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, United Kindom (United Kingdom)

    2015-06-15

    A study into the magnetically induced mobility of four types of superparamagnetic particles (SMPs) was conducted using a video camera, an inverted light microscope and ImageJ tracking software. The objective is to improve the understanding of how SMP-capture assays perform by measuring mobilities of SMPs, when aggregated together or attached to non-magnetic beads (NMB). The magnetically induced velocities of self-assembled SMP chains were measured and found to meet the proposed models. A study into the zeta potential of the SMPs was completed to determine a scenario for maximal electrostatic interactions and efficient capture of the SMPs to a target. SMPs were bound to biotinylated NMBs, representing attachment to a disease biomarker. The drift velocity of SMP chains and SMP–NMB complexes in a gradient magnetic field was compared. It is expected that the observable changes to the magnetophoretic mobility of SMPs attached to a disease biomarker will lead to new biosensor technology. - Highlights: • Analysis of the magnetically induced drift velocity of superparamagnetic particles. • Zeta potential of superparamagnetic particles and non-magnetic particles found. • Drift velocity of single particles, chains and complexes determined experimentally. • Magnetic drift velocities of chains and complexes predicted by simple models.

  11. Effects of Superparamagnetic Nanoparticle Clusters on the Polymerase Chain Reaction

    Directory of Open Access Journals (Sweden)

    Toshiaki Higashi

    2012-04-01

    Full Text Available The polymerase chain reaction (PCR method is widely used for the reproduction and amplification of specific DNA segments, and a novel PCR method using nanomaterials such as gold nanoparticles has recently been reported. This paper reports on the effects of superparamagnetic nanoparticles on PCR amplification without an external magnetic field, and clarifies the mechanism behind the effects of superparamagnetic particle clusters on PCR efficiency by estimating the structures of such clusters in PCR. It was found that superparamagnetic nanoparticles tend to inhibit PCR amplification depending on the structure of the magnetic nanoparticle clusters. The paper also clarifies that Taq polymerase is captured in the spaces formed among magnetic nanoparticle clusters, and that it is captured more efficiently as a result of their motion from heat treatment in PCR thermal cycles. Consequently, Taq polymerase that should be used in PCR is reduced in the PCR solution. These outcomes will be applied to novel PCR techniques using magnetic particles in an external magnetic field.

  12. Nanosized powders of NiZn ferrite: Synthesis, structure, and magnetism

    Science.gov (United States)

    Albuquerque, Adriana S.; Ardisson, José D.; Macedo, Waldemar A. A.; Alves, Maria C. M.

    2000-05-01

    The structure and magnetic behavior of nanostructured powders of stoichiometric NiZn ferrite, Ni0.5Zn0.5Fe2O4, synthesized by coprecipitation, are investigated by extended x-ray-absorption fine structure spectroscopy (EXAFS), x-ray diffraction, Mössbauer spectroscopy, and vibrating sample magnetometry. Samples of high purity and high homogeneity were obtained by annealing at relatively low temperatures (300-800 °C) resulting in nanoparticles with average diameter between 9 and 90 nm, as determined by x-ray diffraction. EXAFS was applied to follow Ni, Zn, and Fe cations distribution and the evolution of the short range order of the samples with increasing annealing temperature. Our results show ferrimagnetic NiZn ferrite nanosized powders with high purity, 1:1 Ni to Zn stoichiometric ratio and superparamagnetic behavior. Moreover, the samples exhibit good structural ordering already after heat treatment at 400 °C. Analysis by vibrating sample magnetometry indicated a critical particle diameter for the transition from monodomain to multidomain behavior close to 40 nm.

  13. Influence of the synthetic polypeptide c25-mms6 on cobalt ferrite nanoparticle formation

    Energy Technology Data Exchange (ETDEWEB)

    Wolff, Annalena, E-mail: awolff@physik.uni-bielefeld.de [Bielefeld University, Department of Physics (Germany); Frese, Katrin; Wissbrock, Marco [Bielefeld University, Department of Chemistry (Germany); Eckstaedt, Katrin [Bielefeld University, Department of Physics (Germany); Ennen, Inga; Hetaba, Walid; Loeffler, Stefan [Technische Universitaet Wien, Institut fuer Festkoerperphysik (Austria); Regtmeier, Anna; Thomas, Patrick [Bielefeld University, Department of Physics (Germany); Sewald, Norbert [Bielefeld University, Department of Chemistry (Germany); Schattschneider, Peter [Technische Universitaet Wien, Service Center fuer Elektronenmikroskopie (Austria); Huetten, Andreas [Bielefeld University, Department of Physics (Germany)

    2012-10-15

    Nanoparticle syntheses utilizing biomimetic approaches have advanced in recent years. Polypeptides, with their ability to influence inorganic crystal growth, are a topic of great interest. Their effect on the particle formation has not been completely understood yet. Here we report a bioinspired synthesis of cobalt ferrite nanoparticles carried out in vitro under mild conditions using a short, synthetic polypeptide c25-mms6. The influence of c25-mms6 on the nanoparticle formation was investigated by comparing the particles synthesized with the polypeptide to particles synthesized under equivalent conditions without c25-mms6. A separation into D{sub small,av} = 10 nm small, superparamagnetic spheres and D{sub big,av} = 48 nm disc-like single-domain particles was observed. Non-stoichiometric cobalt ferrite particles with a shape-dependent stoichiometry were produced in the polypeptide-free synthesis. Stoichiometric D{sub small,av} = 10 nm CoFe{sub 2}O{sub 4} spheres and D{sub big,av} = 60-70 nm Co{sub 2}FeO{sub 4} ferromagnetic discs were obtained in the polypeptide-enhanced synthesis. The results indicate that the polypeptide acts as a catalyst during the multistep biomineralization process and allows the formation of stoichiometric phases which cannot be synthesized at room temperature using conventional bottom-up syntheses.

  14. Delta ferrite in the weld metal of reduced activation ferritic martensitic steel

    Science.gov (United States)

    Sam, Shiju; Das, C. R.; Ramasubbu, V.; Albert, S. K.; Bhaduri, A. K.; Jayakumar, T.; Rajendra Kumar, E.

    2014-12-01

    Formation of delta(δ)-ferrite in the weld metal, during autogenous bead-on-plate welding of Reduced Activation Ferritic Martensitic (RAFM) steel using Gas Tungsten Arc Welding (GTAW) process, has been studied. Composition of the alloy is such that delta-ferrite is not expected in the alloy; but examination of the weld metal revealed presence of delta-ferrite in the weld metal. Volume fraction of delta-ferrite is found to be higher in the weld interface than in the rest of the fusion zone. Decrease in the volume fraction of delta-ferrite, with an increase in preheat temperature or with an increase in heat input, is observed. Results indicate that the cooling rate experienced during welding affects the volume fraction of delta-ferrite retained in the weld metal and variation in the delta-ferrite content with cooling rate is explained with variation in the time that the weld metal spends in various temperature regimes in which delta-ferrite is stable for the alloy during its cooling from the liquid metal to the ambient temperature. This manuscript will discuss the effect of welding parameters on formation of delta-ferrite and its retention in the weld metal of RAFM steel.

  15. Facile synthesis of inverse spinel NiFe2O4 nanocrystals and their superparamagnetic properties

    Directory of Open Access Journals (Sweden)

    Jie Tan

    2013-02-01

    Full Text Available Spinel NiFe2O4 nanocrystals have been obtained by means of a novel composite-hydroxide-salt-mediated approach, which is based on a reaction between metallic salt and metallic oxide in the solution of composite-hydroxide-salt eutectic at ~225 ºC and normal atmosphere without any organic dispersant or capping agent. The obtained products are characterized by an X-ray diffraction (XRD, a transmission electron microscopy (TEM and an alternating gradient magnetometer (AGM. The formation process of NiFe2O4 nanosheet is proposed to begin with a ‘‘dissolution-recrystallization’’ which is followed by an ‘‘Ostwald ripening’’ mechanism. The NiFe2O4 nano-octahedrons can be obtained through adjusting the reaction water content in the hydroxide melts at constant temperature. At 300 K, magnetic hysteresis loops at an applied field of 15 kOe show zero coercivity, indicating the superparamagnetic behavior of the as-prepared NiFe2O4 nanocrystals.

  16. Evolution of magnetism by rolling up hexagonal boron nitride nanosheets tailored with superparamagnetic nanoparticles.

    Science.gov (United States)

    Hwang, Da Young; Choi, Kyoung Hwan; Park, Jeong Eon; Suh, Dong Hack

    2017-02-01

    Controlling tunable properties by rolling up two dimensional nanomaterials is an exciting avenue for tailoring the electronic and magnetic properties of materials at the nanoscale. We demonstrate the tailoring of a magnetic nanocomposite through hybridization with magnetic nanomaterials using hexagonal boron nitride (h-BN) templates as an effective way to evolve magnetism for the first time. Boron nitride nanosheets exhibited their typical diamagnetism, but rolled-up boron nitride sheets (called nanoscrolls) clearly have para-magnetism in the case of magnetic susceptibility. Additionally, the Fe3O4 NP sample shows a maximum ZFC curve at about 103 K, which indicates well dispersed superparamagnetic nanoparticles. The ZFC curve for the h-BN-Fe3O4 NP scrolls exhibited an apparent rounded maximum blocking temperature at 192 K compared to the Fe3O4 NPs, leading to a dramatic increase in TB. These magnetic nanoscroll derivatives are remarkable materials and should be suitable for high-performance composites and nano-, medical- and electromechanical-devices.

  17. Facile synthesis of inverse spinel NiFe2O4 nanocrystals and their superparamagnetic properties

    Directory of Open Access Journals (Sweden)

    Jie Tan

    2012-01-01

    Full Text Available Spinel NiFe2O4 nanocrystals have been obtained by means of a novel composite-hydroxide-salt-mediated approach, which is based on a reaction between metallic salt and metallic oxide in the solution of composite-hydroxide-salt eutectic at ~225 ºC and normal atmosphere without any organic dispersant or capping agent. The obtained products are characterized by an X-ray diffraction (XRD, a transmission electron microscopy (TEM and an alternating gradient magnetometer (AGM. The formation process of NiFe2O4 nanosheet is proposed to begin with a ‘‘dissolution-recrystallization’’ which is followed by an ‘‘Ostwald ripening’’ mechanism. The NiFe2O4 nano-octahedrons can be obtained through adjusting the reaction water content in the hydroxide melts at constant temperature. At 300 K, magnetic hysteresis loops at an applied field of 15 kOe show zero coercivity, indicating the superparamagnetic behavior of the as-prepared NiFe2O4 nanocrystals.

  18. Tunable inkjet-printed slotted waveguide antenna on a ferrite substrate

    KAUST Repository

    Nafe, Ahmed

    2015-04-13

    In this work an inkjet-printed frequency-tunable slotted waveguide antenna on a ferrite substrate is reported. Unlike the typical substrate integrated waveguide approach with via holes, a true 3D rectangular waveguide is realized by inkjet-printing of nano-particle based conductive ink on the broad faces as well as on sides of the substrate. The operating frequency of the antenna can be tuned by applying a variable static bias magnetic field that controls the permeability of the host ferrite substrate. The antenna operates about a center frequency of approximately 14 GHz with an instantaneous impedance bandwidth of 75 MHz. A fabricated prototype has demonstrated a tuning range of 10% (1.5 GHz) using an applied bias magnetic field of 3 kOe yielding it especially attractive for tunable and reconfigurable yet low cost microwave systems.

  19. Phase controlled synthesis of (Mg, Ca, Ba)-ferrite magnetic nanoparticles with high uniformity

    Science.gov (United States)

    Wang, S. F.; Li, Q.; Zu, X. T.; Xiang, X.; Liu, W.; Li, S.

    2016-12-01

    (Mg, Ca, Ba)-ferrite magnetic nanoparticles were successfully synthesized through modifying the atomic ratio of polysaccharide and chelating agent at an optimal sintering temperature. In the process, the polysaccharide plays an important role in drastically shrinking the precursor during the gel drying process. In the metal-complex structure, M2+ ion active sites were coordinated by -OH of the water molecules except for EDTA anions. The MFe2O4 magnetic nanoparticles exhibited enhanced magnetic properties when compared with nano-MFe2O4 of similar particle size synthesized by other synthesis route reported in the literature. In particular, the sintering temperature improves the crystallinity and increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles significantly.

  20. Self-assembled mesoporous Co and Ni-ferrite spherical clusters consisting of spinel nanocrystals prepared using a template-free approach.

    Science.gov (United States)

    Yu, Byong Yong; Kwak, Seung-Yeop

    2011-10-21

    Based on a self-assembly strategy, spherical mesoporous cobalt and nickel ferrite nanocrystal clusters with a large surface area and narrow size distribution were successfully synthesized for the first time via a template-free solvothermal process in ethylene glycol and subsequent heat treatment. In this work, the mesopores in the ferrite clusters were derived mainly from interior voids between aggregated primary nanoparticles (with crystallite size of less than 7 nm) and disordered particle packing domains. The concentration of sodium acetate is shown herein to play a crucial role in the formation of mesoporous ferrite spherical clusters. These ferrite clusters were characterized in detail using wide-angle X-ray diffraction, thermogravimetric-differential thermal analysis, (57)Fe Mössbauer spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, standard and high-resolution transmission electron microscopy, and other techniques. The results confirmed the formation of both pure-phase ferrite clusters with highly crystalline spinel structure, uniform size (about 160 nm) and spherical morphology, and worm-like mesopore structures. The BET specific surface areas and mean pore sizes of the mesoporous Co and Ni-ferrite clusters were as high as 160 m(2) g(-1) and 182 m(2) g(-1), and 7.91 nm and 6.87 nm, respectively. A model for the formation of the spherical clusters in our system is proposed on the basis of the results. The magnetic properties of both samples were investigated at 300 K, and it was found that these materials are superparamagnetic.

  1. Characterization of magnetic nano particles of CoFe{sub 2}O{sub 4} and CoZnFe{sub 2}O{sub 4} prepared by the chemical co-precipitation method; Caracterizacion de nanoparticulas magneticas de CoFe{sub 2}O{sub 4} y CoZnFe{sub 2}O{sub 4} preparadas por el metodo de coprecipitacion quimica

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, J.; Zambrano, G.; Gomez, M. E. [Universidad del Valle, Departamento de Fisica, Laboratorio de Peliculas Delgadas, Ciudad Universitaria Melendez, 25360 Cali (Colombia); Prieto, P. [Universidad del Valle, Centro de Excelencia en Nuevos Materiales, Ciudad Universitaria Melendez, 25360 Cali (Colombia); Espinoza B, F. J., E-mail: javierlo21@gmail.com [IPN, Centro de Investigacion y de Estudios Avanzados, Unidad Queretaro, Libramiento Norponiente No. 2000, Fracc. Real de Juriquilla, 76230 Queretaro (Mexico)

    2012-07-01

    Magnetic cobalt ferrite nanoparticles of CoFe{sub 2}O{sub 4} and CoZnFe{sub 2}O{sub 4} were prepared by co-precipitation technique from aqueous salt solutions of Co (II), ZnSO{sub 4} and Fe (III), in an alkaline medium. CoFe{sub 2}O{sub 4} powder samples were structurally characterized by X-ray diffraction, showing the presence of the most intense peat at 2{theta} = 413928{sup o} (Co K{alpha}1) corresponding to the (311) crystallographic orientation of the CoFe{sub 2}O{sub 4} spinel phase. The mean size of the crystalline of CoFe{sub 2}O{sub 4} and CoZnFe{sub 2}O{sub 4} nanoparticles determined from the full width at half maximum of the strongest reflection of the (311) peak by using the Scherrer approximation was calculated to be 11.4 and 7.0 ({+-} o.2) nm, respectively. Transmission electron microscopy studies permitted determining nanoparticle size of CoZnFe{sub 2}O{sub 4}. Fourier transform infrared spectroscopy was used to confirm the formation of Fe-O bonds, allowing identifying the presence of ferrite spinel structure. Magnetic properties were investigated with the aid of a vibrating sample magnetometer at room temperature Herein, the sample showed superparamagnetic behavior, determined by the hysteresis loop finally, due to the hysteresis loop of the CoZnFe{sub 2}O{sub 4} is very small, our magnetic nanoparticles can be considered as a soft magnetic material. These magnetic nanoparticles have interesting technological applications in biomedicine given their biocompatibility, in nano technology, and in ferro fluid preparation. (Author)

  2. Study on the efficiency of nanosized magnetite and mixed ferrites in magnetic hyperthermia.

    Science.gov (United States)

    Saldívar-Ramírez, M M G; Sánchez-Torres, C G; Cortés-Hernández, D A; Escobedo-Bocardo, J C; Almanza-Robles, J M; Larson, A; Reséndiz-Hernández, P J; Acuña-Gutiérrez, I O

    2014-10-01

    Magnetic materials, which have the potential for application in heating therapy by hyperthermia, were prepared. This alternative treatment is used to eliminate cancer cells. Magnetite, magnesium-calcium ferrites and manganese-calcium ferrites were synthesized by sol-gel method followed by heat treatment at different temperatures for 30 min in air. Materials with superparamagnetic behavior and nanometric sizes were obtained in all the cases. Thus, these nanopowders may be suitable for their use in human tissue. The average sizes were 14 nm for magnetite, 10 nm for both Mg(0.4)Ca(0.6)Fe(2)O(4) and Mg(0.6)Ca(0.4)Fe(2)O(4) and 11 nm for Mn(0.2)Ca(0.8)Fe(2)O(4). Taking into account that the Mg(0.4)Ca(0.6)Fe(2)O(4) and Mg(0.6)Ca(0.4)Fe(2)O(4) treated at 350 °C showed the lower coercivity values, these nanoparticles were selected for heating tests and cell viability. Heating curves of Mg(0.4)Ca(0.6)Fe(2)O(4) subjected to a magnetic field of 195 kHz and 10 kA/m exhibited a temperature increase up to 45 °C in 15 min. A high human osteosarcoma cell viability of 90-99.5% was displayed. The human osteosarcoma cell with magnesium-calcium ferrites exposed to a magnetic field revealed a death cell higher than 80% in all the cases.

  3. Zn,Ni ferrite/NiO nanocomposite powder obtained from acetylacetonato complexes

    Science.gov (United States)

    Vucinic-Vasic, M.; Antic, B.; Kremenovic, A.; Nikolic, A. S.; Stoiljkovic, M.; Bibic, N.; Spasojevic, V.; Colomban, Ph

    2006-10-01

    The results on the synthesis, microstructure, structure and DC magnetization studies of nanocomposite Zn,Ni ferrite/NiO powder obtained by thermal decomposition of acetylacetonato complexes are reported in this paper. According to the results obtained by inductively coupled plasma optical emission spectroscopy (ICP-OES) element analysis and multiphase Rietveld refinement, the three samples made are composed of spinel-ferrite (86.7% 96.7%) and NiO (3.3% 13.3%) phases. The compositions of the spinel-ferrite (SP) phase in the investigated samples, S1 S3, are Zn0.72Ni0.24Fe1.98O4, Zn0.56Ni0.29Fe2.07O4 and Zn0.40Ni0.40Fe2.10O4, respectively. Due to the cation deficiency in spinels, created vacancies induce a partial change in the cation valence, \\mathrm {Ni^{2+}} \\to \\mathrm {Ni^{3+}} . The vacancy distribution is found to be random at 8a and 16d cation sites, except in sample S3, where all vacancies are over octahedral sites. The x-ray line broadening due to crystallite size effect is found to be isotropic for all spinels, while the x-ray line broadening due to the strain effect is anisotropic. A correlation between the Zn2+ occupancy of the tetrahedral site and the 650 cm-1 Raman peak intensities is shown. The observed coercivity decrease and shift in hysteresis loop in the samples are caused by the interaction between spinel and NiO phase. The results of M(H) measurements point to the properties of an ensemble of interacting nanoparticles. High saturation magnetization values and superparamagnetic behaviour at room temperature point to the technological significance of the title compounds.

  4. Influence of Sn4+ on Structural and DC Electrical Resistivity of Ni-Zn Ferrite Thick Films

    Science.gov (United States)

    Dalawai, S. P.; Shinde, T. J.; Gadkari, A. B.; Tarwal, N. L.; Jang, J. H.; Vasambekar, P. N.

    2016-12-01

    Among the soft ferrites, Ni-Zn ferrite is one of the most versatile ceramic materials because of their important electrical and magnetic properties. These properties were improved by substituting Sn4+ in Ni-Zn ferrites with chemical composition of Ni x Zn1+y-x Fe2-2y Sn y O4 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0; y = 0.1, 0.2). To achieve homogenous ferrite powder at lower sintering temperature and smaller duration in nano-size form, the oxalate co-precipitation method was preferred as compared to other physical and chemical methods. Using this powder, ferrite thick films (FTFs) were prepared by the screen printing technique because of its low cost and easy use. To study structural behavior, the FTFs were characterized by different techniques. The x-ray diffraction and thermo-gravimetric and differential thermal analysis studies show the formation of cubic spinel structure and ferrite phase formation, respectively. There is no remarkable trend observed in lattice constants for the Sn4+ (y = 0.1)- and Sn4+ (y = 0.2)-substituted Ni-Zn ferrites. The bond lengths as well as ionic radii on the A-site of Ni-Zn-Sn ferrites were found to decrease with increasing nickel content. The bond length and ionic radii on the B-sites remained almost constant for Sn4+ (y = 0.1, 0.2)-substituted Ni-Zn ferrites. The energy dispersive x-ray analysis confirms the elemental analysis of FTFs. The Fourier transform infrared spectra show two major absorption bands near 400 cm-1 and 600 cm-1 corresponding to octahedral and tetrahedral sites, respectively, which also confirms the formation of the ferrites. The field emission scanning electron microscopy images shows that the particles are highly porous in nature and located in loosely packed agglomerates. The average particle size of the FTFs lies in the range 20-60 nm. Direct current (DC) resistivity of Ni-Zn-Sn FTFs shows the semiconductor nature. The DC resistivity of Ni-Zn-Sn0.2FTFs is lower than Ni-Zn-Sn0.1 FTFs. The DC resistivity is found to

  5. Influence of Sn4+ on Structural and DC Electrical Resistivity of Ni-Zn Ferrite Thick Films

    Science.gov (United States)

    Dalawai, S. P.; Shinde, T. J.; Gadkari, A. B.; Tarwal, N. L.; Jang, J. H.; Vasambekar, P. N.

    2017-03-01

    Among the soft ferrites, Ni-Zn ferrite is one of the most versatile ceramic materials because of their important electrical and magnetic properties. These properties were improved by substituting Sn4+ in Ni-Zn ferrites with chemical composition of Ni x Zn1+ y- x Fe2-2 y Sn y O4 ( x = 0, 0.2, 0.4, 0.6, 0.8, 1.0; y = 0.1, 0.2). To achieve homogenous ferrite powder at lower sintering temperature and smaller duration in nano-size form, the oxalate co-precipitation method was preferred as compared to other physical and chemical methods. Using this powder, ferrite thick films (FTFs) were prepared by the screen printing technique because of its low cost and easy use. To study structural behavior, the FTFs were characterized by different techniques. The x-ray diffraction and thermo-gravimetric and differential thermal analysis studies show the formation of cubic spinel structure and ferrite phase formation, respectively. There is no remarkable trend observed in lattice constants for the Sn4+ ( y = 0.1)- and Sn4+ ( y = 0.2)-substituted Ni-Zn ferrites. The bond lengths as well as ionic radii on the A-site of Ni-Zn-Sn ferrites were found to decrease with increasing nickel content. The bond length and ionic radii on the B-sites remained almost constant for Sn4+ ( y = 0.1, 0.2)-substituted Ni-Zn ferrites. The energy dispersive x-ray analysis confirms the elemental analysis of FTFs. The Fourier transform infrared spectra show two major absorption bands near 400 cm-1 and 600 cm-1 corresponding to octahedral and tetrahedral sites, respectively, which also confirms the formation of the ferrites. The field emission scanning electron microscopy images shows that the particles are highly porous in nature and located in loosely packed agglomerates. The average particle size of the FTFs lies in the range 20-60 nm. Direct current (DC) resistivity of Ni-Zn-Sn FTFs shows the semiconductor nature. The DC resistivity of Ni-Zn-Sn0.2FTFs is lower than Ni-Zn-Sn0.1 FTFs. The DC resistivity is

  6. Tailoring magnetic and dielectric properties of rubber ferrite composites containing mixed ferrites

    Indian Academy of Sciences (India)

    M R Anantharaman; K A Malini; S Sindhu; E M Mohammed; S K Date; S D Kulkarni; P A Joy; Philip Kurian

    2001-12-01

    Rubber ferrite composites containing various mixed ferrites were prepared for different compositions and various loadings. The magnetic and dielectric properties of the fillers as well as the ferrite filled matrixes were evaluated separately. The results are correlated. Simple equations are proposed to predetermine the magnetic and dielectric properties. The validity of these equations is verified and they are found to be in good agreement. These equations are useful in tailoring the magnetic and dielectric properties of these composites with predetermined properties.

  7. Spinel ferrite thin-film synthesis by spin-spray ferrite plating

    Energy Technology Data Exchange (ETDEWEB)

    Hai, Tran Hoang; Van, Ha Thi Bich; Phong, Tran Canh; Abe, Masanori

    2003-04-01

    By spin-spray ferrite plating with optimizing conditions in the oxidizing and reaction solutions, we can synthesize polycrystalline ferrite film of spinel type (Fe, M){sub 3}O{sub 4}, where M=Fe, Co, Ni, Zn, etc., in low temperatures (<100 deg. C). By this method we can synthesize Co, Co-Ni ferrite for perpendicular magnetic recording media with high coercivity H{sub c} in the plane perpendicular to the film.

  8. Structural analysis of emerging ferrite: Doped nickel zinc ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Rajinder; Kumar, Hitanshu; Singh, Ragini Raj; Barman, P. B., E-mail: pb.barman@juit.ac.in [Nanotechnology Lab, Department of Physics & Materials Science, Jaypee University of Information Technology, Waknaghat, Solan (H.P)-173234 (India)

    2015-08-28

    Ni{sub 0.6-x}Zn{sub 0.4}Co{sub x}Fe{sub 2}O{sub 4} (x = 0, 0.033, 0.264) nanoparticles were synthesized by sol-gel method and annealed at 900°C. Structural properties of all prepared samples were examined with X-ray diffraction (XRD). The partial formation of hematite (α-Fe{sub 2}O{sub 3}) secondary phase with spinel phase cubic structure of undoped and cobalt doped nickel zinc ferrite was found by XRD peaks. The variation in crystallite size and other structural parameters with cobalt doping has been calculated for most prominent peak (113) of XRD and has been explained on the basis of cations ionic radii difference.

  9. Effect of preparation conditions on Nickel Zinc Ferrite nanoparticles: A comparison between sol–gel auto combustion and co-precipitation methods

    Directory of Open Access Journals (Sweden)

    Manju Kurian

    2016-09-01

    Full Text Available The experimental conditions used in the preparation of nano crystalline mixed ferrite materials play an important role in the particle size of the product. In the present work a comparison is made on sol–gel auto combustion methods and co-precipitation methods by preparing Nickel Zinc Ferrite (Ni0.5Zn0.5Fe2O4 nano particles. The prepared ferrite samples were calcined at different temperatures and characterized by using standard methods. X-ray diffraction analysis indicated the formation of single phase ferrite nanoparticles for samples calcined at 500 °C. The lattice parameter range of 8.32–8.49 Å confirmed the cubic spinel structure. Average crystallite size estimated from X-ray diffractogram was found to be between 17 and 40 nm. The IR spectra showed two main absorption bands, the high frequency band ν1 around 600 cm−1 and the low frequency band ν2 around 400 cm−1 arising from tetrahedral (A and octahedral (B interstitial sites in the spinel lattice. TEM pictures showed particles in the nanometric range confirming the XRD data. The studies revealed that the sol–gel auto combustion method was superior to the co-precipitation method for producing single phase nano particles with smaller crystallite size.

  10. Extending the boundaries of mechanical properties of Ti-Nb low-carbon steel via combination of ultrafast cooling and deformation during austenite-to-ferrite transformation

    Science.gov (United States)

    Deng, Xiangtao; Fu, Tianliang; Wang, Zhaodong; Liu, Guohuai; Wang, Guodong; Misra, R. D. K.

    2017-01-01

    We underscore here a novel approach to extend the boundaries of mechanical properties of Ti-Nb low-carbon steel via combination of ultrafast cooling and deformation during austenite-to-ferrite transformation. The proposed approach yields a refined microstructure and high density nano-sized precipitates, with consequent increase in strength. Steels subjected to ultra-fast cooling during austenite-to-ferrite transformation led to 145 MPa increase in yield strength, while the small deformation after ultra-fast cooling process led to increase in strength of 275 MPa. The ultra-fast cooling refined the ferrite and pearlite constituents and enabled uniform dispersion, while the deformation after ultra-fast cooling promoted precipitation and broke the lamellar pearlite to spherical cementite and long thin strips of FexC. The contribution of nano-sized precipitates to yield strength was estimated to be 247.9 MPa and 358.3 MPa for ultrafast cooling and deformation plus ultrafast cooling processes. The nano precipitates carbides were identified to be (Ti, Nb)C and had a NaCl-type crystal structure, and obeyed the Baker-Nutting orientation relationship with the ferrite matrix.

  11. Manganese ferrite thin films Part II: Properties

    NARCIS (Netherlands)

    Hulscher, W.S.

    1972-01-01

    Some properties of evaporated manganese ferrite thin films are investigated, e.g. resistivity, magnetization reversal, Curie temperature, Faraday rotation and optical absorption. The properties are partly related to the partial oxygen pressure present during a preceding annealing process.

  12. ALL-FERRITE RHIC INJECTION KICKER

    Energy Technology Data Exchange (ETDEWEB)

    HAHN,H.; FISCHER,W.; PTITSYN,V.I.; TUOZZOLO,J.E.

    2001-06-18

    Ion beams are transferred from the AGS into RHIC in boxcar fashion as single bunches. The nominal design assumes 60 bunches per ring but increasing the number of bunches to gain luminosity is possible, thereby requiring injection kickers with a shorter rise time. The original injection system consists of traveling-wave dielectric loaded kicker magnets and a Blumlein pulser with a rise time adequate for the present operation. Voltage breakdown in the dielectric kickers suggested the use of all-ferrite magnets. In order to minimize the conversion cost, the design of the all-ferrite kicker uses the same components as the dielectric loaded units. The all-ferrite kickers showed in bench measured good breakdown properties and a current rise time of < 50 ns. A prototype kicker has been installed in the blue ring and was tested with beam. Beam measurements indicate suitability of all-ferrite kicker magnets for upgraded operation.

  13. Ferrite HOM Absorber for the RHIC ERL

    Energy Technology Data Exchange (ETDEWEB)

    Hahn,H.; Choi, E.M.; Hammons, L.

    2008-10-01

    A superconducting Energy Recovery Linac is under construction at Brookhaven National Laboratory to serve as test bed for RHIC upgrades. The damping of higher-order modes in the superconducting five-cell cavity for the Energy-Recovery linac at RHIC is performed exclusively by two ferrite absorbers. The ferrite properties have been measured in ferrite-loaded pill box cavities resulting in the permeability values given by a first-order Debye model for the tiled absorber structure and an equivalent permeability value for computer simulations with solid ring dampers. Measured and simulated results for the higher-order modes in the prototype copper cavity are discussed. First room-temperature measurements of the finished niobium cavity are presented which confirm the effective damping of higher-order modes in the ERL. by the ferrite absorbers.

  14. Development and application of ferrite materials for low temperature co-fired ceramic technology

    Science.gov (United States)

    Zhang, Huai-Wu; Li, Jie; Su, Hua; Zhou, Ting-Chuan; Long, Yang; Zheng, Zong-Liang

    2013-11-01

    Development and application of ferrite materials for low temperature co-fired ceramic (LTCC) technology are discussed, specifically addressing several typical ferrite materials such as M-type barium ferrite, NiCuZn ferrite, YIG ferrite, and lithium ferrite. In order to permit co-firing with a silver internal electrode in LTCC process, the sintering temperature of ferrite materials should be less than 950 °C. These ferrite materials are research focuses and are applied in many ways in electronics.

  15. Mössbauer effect studies and X-ray diffraction analysis of cobalt ferrite prepared in powder form by thermal decomposition method

    Indian Academy of Sciences (India)

    M D Joseph Sebastian; B Rudraswamy; M C Radhakrishna; Ramani

    2003-08-01

    Cobalt ferrite (Co$_x$Fe$_{3–x}$O4) is prepared in powder form by thermal decomposition of iron and cobalt salts and is analysed by X-ray diffraction and Mössbauer spectroscopic techniques. The variation of Mössbauer parameters, lattice parameters and crystallite size of the products formed with variation in the composition of Fe and Co ratios are studied. The studies confirm the formation of nano-size cobalt ferrite particles with defect structure and it is found to be maximum for the Fe : Co = 60 : 40 ratio of the initial precursor oxides.

  16. In situ hybridization of superparamagnetic iron-biomolecule nanoparticles.

    Science.gov (United States)

    Moghimi, Nafiseh; Donkor, Apraku David; Mohapatra, Mamata; Thomas, Joseph Palathinkal; Su, Zhengding; Tang, Xiaowu Shirley; Leung, Kam Tong

    2014-07-23

    The increase in interest in the integration of organic-inorganic nanostructures in recent years has promoted the use of hybrid nanoparticles (HNPs) in medicine, energy conversion, and other applications. Conventional hybridization methods are, however, often long, complicated, and multistepped, and they involve biomolecules and discrete nanostructures as separate entities, all of which hinder the practical use of the resulting HNPs. Here, we present a novel, in situ approach to synthesizing size-specific HNPs using Fe-biomolecule complexes as the building blocks. We choose an anticancer peptide (p53p, MW 1.8 kDa) and an enzyme (GOx, MW 160 kDa) as model molecules to demonstrate the versatility of the method toward different types of molecules over a large size range. We show that electrostatic interaction for complex formation of metal hydroxide ion with the partially charged side of biomolecule in the solution is the key to hybridization of metal-biomolecule materials. Electrochemical deposition is then used to produce hybrid NPs from these complexes. These HNPs with controllable sizes ranging from 30 nm to 3.5 μm are found to exhibit superparamagnetic behavior, which is a big challenge for particles in this size regime. As an example of greatly improved properties and functionality of the new hybrid material, in vitro toxicity assessment of Fe-GOx HNPs shows no adverse effect, and the Fe-p53p HNPs are found to selectively bind to cancer cells. The superparamagnetic nature of these HNPs (superparamagnetic even above the size regime of 15-20 nm!), their biocompatibility, and the direct integration approach are fundamentally important to biomineralization and general synthesis strategy for bioinspired functional materials.

  17. Production of superparamagnetic nanobiocatalysts for green chemistry applications.

    Science.gov (United States)

    Gasser, Christoph A; Ammann, Erik M; Schäffer, Andreas; Shahgaldian, Patrick; Corvini, Philippe F-X

    2016-08-01

    Immobilization of enzymes on solid supports is a convenient method for increasing enzymatic stability and enabling enzyme reuse. In the present work, a sorption-assisted surface conjugation method was developed and optimized to immobilize enzymes on the surface of superparamagnetic nanoparticles. An oxidative enzyme, i.e., laccase from Trametes versicolor was used as model enzyme. The immobilization method consists of the production of superparamagnetic nanoparticles by co-precipitation of FeCl2 and FeCl3. Subsequently, the particle surface is modified with an organosilane containing an amino group. Next, the enzymes are adsorbed on the particle surface before a cross-linking agent, i.e., glutaraldehyde is added which links the amino groups on the particle surface with the amino groups of the enzymes and leads to internal cross-linking of the enzymes as well. The method was optimized using response surface methodology regarding optimal enzyme and glutaraldehyde amounts, pH, and reaction times. Results allowed formulation of biocatalysts having high specific enzymatic activity and improved stability. The biocatalysts showed considerably higher stability compared with the dissolved enzymes over a pH range from 3 to 9 and in the presence of several chemical denaturants. To demonstrate the reusability of the immobilized enzymes, they were applied as catalysts for the production of a phenoxazinone dye. Virtually, 100 % of the precursor was transformed to the dye in each of the ten conducted reaction cycles while on average 84.5 % of the enzymatic activity present at the beginning of a reaction cycle was retained after each cycle highlighting the considerable potential of superparamagnetic biocatalysts for application in industrial processes.

  18. Tensile properties and deformation mechanisms of a 14Cr ODS ferritic steel

    Science.gov (United States)

    Steckmeyer, A.; Praud, M.; Fournier, B.; Malaplate, J.; Garnier, J.; Béchade, J. L.; Tournié, I.; Tancray, A.; Bougault, A.; Bonnaillie, P.

    2010-10-01

    The search for a new cladding material is part of the research studies carried out at CEA to develop a sodium-cooled fast reactor meeting the expectations of the Generation IV International Forum. In this study, the tensile properties of a ferritic oxide dispersion strengthened steel produced by hot extrusion at CEA have been evaluated. They prove the studied alloy to be as resistant as and more ductile than the other nano-reinforced alloys of literature. The effects of the strain rate and temperature on the total plastic strain of the material remind of diffusion phenomena. Intergranular damage and intergranular decohesion are clearly highlighted.

  19. Manganese ion-assisted assembly of superparamagnetic graphene oxide microbowls

    Science.gov (United States)

    Tian, Zhengshan; Xu, Chunxiang; Li, Jitao; Zhu, Gangyi; Xu, Xiaoyong; Dai, Jun; Shi, Zengliang; Lin, Yi

    2014-03-01

    A facile manganese ion Mn(II)-assisted assembly has been designed to fabricate microbowls by using graphene oxide nanosheets as basic building blocks, which were exfoliated ultrasonically from the oxidized soot powders in deionized water. From the morphology evolution observations of transmission electron microscope and scanning electron microscope, a coordinating-tiling-collapsing manner is proposed to interpret the assembly mechanism based on attractive Van der Waals forces, π-π stacking, and capillary action. It is interesting to note that the as-prepared microbowls present a room temperature superparamagnetic behavior.

  20. Magnetic properties of superparamagnetic nanoparticles loaded into silicon nanotubes

    Science.gov (United States)

    Granitzer, Petra; Rumpf, Klemens; Gonzalez, Roberto; Coffer, Jeffery; Reissner, Michael

    2014-08-01

    In this work, the magnetic properties of silicon nanotubes (SiNTs) filled with Fe3O4 nanoparticles (NPs) are investigated. SiNTs with different wall thicknesses of 10 and 70 nm and an inner diameter of approximately 50 nm are prepared and filled with superparamagnetic iron oxide nanoparticles of 4 and 10 nm in diameter. The infiltration process of the NPs into the tubes and dependence on the wall-thickness is described. Furthermore, data from magnetization measurements of the nanocomposite systems are analyzed in terms of iron oxide nanoparticle size dependence. Such biocompatible nanocomposites have potential merit in the field of magnetically guided drug delivery vehicles.

  1. Effect of key parameters on synthesis of superparamagnetic nanoparticles (SPIONs

    Directory of Open Access Journals (Sweden)

    Malhotra Ankit

    2016-09-01

    Full Text Available There are various methods to synthesize superparamagnetic nanoparticles (SPIONs useful for MPI (magnetic particle imaging and in therapy (Hypothermia such as co-precipitation, hydrothermal reactions etc. In this research, the focus is to analyse the effects of crucial parameters such as effect of molecular mass of dextran and temperature of the co-precipitation. These parameters play a crucial role in the inherent magnetic properties of the resulting SPIONs. The amplitude spectrum and hysteresis curve of the SPIONs is analysed with MPS (magnetic particle spectrometer. PCCS (photon cross-correlation spectroscopy measurements are done to analyse the size distribution of hydrodynamic diameter the resulting SPIONs.

  2. Polymer bonded ferrite materials as EMC components

    Energy Technology Data Exchange (ETDEWEB)

    Toepfer, J. [Fachhochschule Jena, FB Werkstofftechnik, Carl-Zeiss-Promenade 2, 07745 Jena (Germany); Hermsdorfer Institut fuer Technische Keramik e.V., M.-Curie-Str. 17, 07629 Hermsdorf (Germany); Pawlowski, B. [Hermsdorfer Institut fuer Technische Keramik e.V., M.-Curie-Str. 17, 07629 Hermsdorf (Germany); Graebner, F. [IMG Nordhausen, An der Salza 8a, 99734 Nordhausen (Germany)

    2003-07-01

    Polymer bonded ferrites composed of a mixture of Mn-Zn ferrites or Ni-Zn ferrites in a polymer binder (PE, PA) were prepared and tested as electromagnetic-wave absorbing materials. Test samples and cases were prepared by hot or injection molding. Permeability spectra show loss contributions in the frequency range 100-1000 MHz. Absorption measurements of injection molded polymer-ferrite cases display a 3-5 dB better attenuation characteristics compared to graphite-loaded polyamide housings. (Abstract Copyright [2003], Wiley Periodicals, Inc.) [German] Polymer-gebundene Ferritwerkstoffe auf der Basis von Ferrit (Mn-Zn oder Ni-Zn Ferrite) - Thermoplast Mischungen wurden praepariert und hinsichtlich ihrer Eignung zur Absorption elektromagnetischer Strahlung untersucht. Es wurden sowohl Testproben wie auch komplette Gehaeusekomponenten durch Heisspressen oder Spritzgiessen hergestellt. Die Permeabilitaetsspektren weisen verlustbehaftete Komponenten im Frequenzbereich von 100-1000 MHz auf. Schirmdaempfungsmessungen an spritzgegossenen Gehaeuseteilen zeigen eine um 3-5 dB bessere Daempfung im Vergleich zu Graphit-gefuellten Polyamid-Gehaeusen. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  3. Synthesis of cobalt ferrite core/metallic shell nanoparticles for the development of a specific PNA/DNA biosensor.

    Science.gov (United States)

    Pita, Marcos; Abad, José María; Vaz-Dominguez, Cristina; Briones, Carlos; Mateo-Martí, Eva; Martín-Gago, José Angel; Morales, Maria del Puerto; Fernández, Víctor M

    2008-05-15

    Controlled synthesis of cobalt ferrite superparamagnetic nanoparticles covered with a gold shell has been achieved by an affinity and trap strategy. Magnetic nanoparticles are functionalized with a mixture of amino and thiol groups that facilitate the electrostatic attraction and further chemisorption of gold nanoparticles, respectively. Using these nanoparticles as seeds, a complete coating shell is achieved by gold salt-iterative reduction leading to monodisperse water-soluble gold-covered magnetic nanoparticles, with an average diameter ranging from 21 to 29 nm. These constitute a versatile platform for immobilization of biomolecules via thiol chemistry, which is exemplified by the immobilization of peptide nucleic acid (PNA) oligomers that specifically hybridize with complementary DNA molecules in solution. Hybridation with DNA probes has been measured using Rhodamine 6G fluorescence marker and the detection of a single nucleotide mutation has been achieved. These results suggest the PNA-nanoparticles application as a biosensor for DNA genotyping avoiding commonly time-consuming procedures employed.

  4. Solvothermal synthesis of cobalt ferrite hollow spheres with chitosan.

    Science.gov (United States)

    Briceño, Sarah; Suarez, Jorge; Gonzalez, Gema

    2017-09-01

    Cobalt ferrite hollow spheres with chitosan (CoFe2O4/CS) were synthesized by two different approaches using the solvothermal method. The first approach involves in-situ incorporation of FeCl3:6H2O and CoNO3:6H2O in the solvothermal reaction (M1) and in second approach already prepared CoFe2O4 nanoparticles (NPs) using the thermal decomposition method was placed in the solvothermal reaction to form the hollow spheres (M2). Structural identification of the samples were characterized by Fourier transform infrared spectra (FTIR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analyses (DSC-TGA) and energy dispersive X-ray spectroscopy (EDX). The magnetic properties were evaluated using a vibrating sample magnetometer (VSM). The presence of chitosan on the hollow sphere was confirmed by FTIR. The XRD analyses proved that the synthesized samples were cobalt ferrite with spinel structure. The structure of the surface and the average particle size of the spheres were observed by SEM and TEM showing the nano scale of the CoFe2O4 component. Structural characterization demonstrating that chitosan does not affect the crystallinity, chemical composition, and magnetic properties of the CoFe2O4/CS. This work demonstrates that the CoFe2O4/CS prepared using the as synthesized CoFe2O4 NPs have better structural and magnetic properties. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Highly fluorescent and superparamagnetic nanosystem for biomedical applications

    Science.gov (United States)

    Cabrera, Mariana P.; E Cabral Filho, Paulo; Silva, Camila M. C. M.; Oliveira, Rita M.; Geraldes, Carlos F. G. C.; Castro, M. Margarida C. A.; Costa, Benilde F. O.; Henriques, Marta S. C.; Paixão, José A.; Carvalho, Luiz B., Jr.; Santos, Beate S.; Hallwass, Fernando; Fontes, Adriana; Pereira, Giovannia A. L.

    2017-07-01

    This work reports on highly fluorescent and superparamagnetic bimodal nanoparticles (BNPs) obtained by a simple and efficient method as probes for fluorescence analysis and/or contrast agents for MRI. These promising BNPs with small dimensions (ca. 17 nm) consist of superparamagnetic iron oxide nanoparticles (SPIONs) covalently bound with CdTe quantum dots (ca. 3 nm). The chemical structure of the magnetic part of BNPs is predominantly magnetite, with minor goethite and maghemite contributions, as shown by Mössbauer spectroscopy, which is compatible with the x-ray diffraction data. Their size evaluation by different techniques showed that the SPION derivatization process, in order to produce the BNPs, does not lead to a large size increase. The BNPs saturation magnetization, when corrected for the organic content of the sample, is ca. 68 emu g-1, which is only slightly reduced relative to the bare nanoparticles. This indicates that the SPION surface functionalization does not change considerably the magnetic properties. The BNP aqueous suspensions presented stability, high fluorescence, high relaxivity ratio (r 2/r 1 equal to 25) and labeled efficiently HeLa cells as can be seen by fluorescence analysis. These BNP properties point to their applications as fluorescent probes as well as negative T 2-weighted MRI contrast agents. Moreover, their potential magnetic response could also be used for fast bioseparation applications.

  6. Nano Materials

    Science.gov (United States)

    2007-03-01

    hard coatings: – Molecular sieves – Lubricant additive to engine oil – Reinforcing fillers for plastics and rubbers – Chromatographic carriers 32...nanomaterials, November 2006 NanoCeramics applications (PlasmaChem) • Lapping and polishing • Low temperature sintering • New Ceramic alloys • Ceramic-metal...Nanotechnology lectures: Henne van Heeren, enablingMNT, nanomaterials, November 2006 MoS2 nanospheres (1) (Apnano) • Common solid lubricants are layered

  7. Oxide dispersion strengthened ferritic steels: a basic research joint program in France

    Science.gov (United States)

    Boutard, J.-L.; Badjeck, V.; Barguet, L.; Barouh, C.; Bhattacharya, A.; Colignon, Y.; Hatzoglou, C.; Loyer-Prost, M.; Rouffié, A. L.; Sallez, N.; Salmon-Legagneur, H.; Schuler, T.

    2014-12-01

    AREVA, CEA, CNRS, EDF and Mécachrome are funding a joint program of basic research on Oxide Dispersion Strengthened Steels (ODISSEE), in support to the development of oxide dispersion strengthened 9-14% Cr ferritic-martensitic steels for the fuel element cladding of future Sodium-cooled fast neutron reactors. The selected objectives and the results obtained so far will be presented concerning (i) physical-chemical characterisation of the nano-clusters as a function of ball-milling process, metallurgical conditions and irradiation, (ii) meso-scale understanding of failure mechanisms under dynamic loading and creep, and, (iii) kinetic modelling of nano-clusters nucleation and α/α‧ unmixing.

  8. The Z-Phase in 9Cr Ferritic/martensitic Heat Resistant Steel

    Science.gov (United States)

    Yin, Fengshi; Chen, Fuxia; Jiang, Xuebo; Xue, Bing; Zhou, Li; Jung, Woosang

    The precipitation behavior of Z-phase was investigated during long-term aging at 650°C in an ultra low carbon 9Cr ferritic/martensitic heat resistant steel. The steel was prepared by vacuum induction melting followed by hot forging and rolling into a plate. The plate was normalized at 1100°C for 1h, cooled in air and tempered at 700°C for 1h. Bimodal nano-sized MX precipitates distribute densely and homogeneously in the matrix within martensitic lath after normalizing-and-tempering heat treatment. After aging at 650°C for 1200h, the Z-phase was found to nucleate on the larger nano-sized MX. The Z-phase and MX have the following orientation relationship: Z-phase//MX and (1bar 10){Z-phase}//(200){MX} .

  9. Nanodisperse Nickel Ferrite: Methods of Production, Structure and Magnetic Properties

    National Research Council Canada - National Science Library

    N Zaporina; J Grabis; M Maiorov; A Krumina; G Heidemane; D Bocharov

    2012-01-01

      Nanodisperse Nickel Ferrite: Methods of Production, Structure and Magnetic Properties The nickel ferrite nanoparticles were prepared using combustion synthesis and plasma chemical synthesis based on evaporation of coarse-grained...

  10. Effect of samarium substitution on structural and magnetic properties of magnesium ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Thankachan, Smitha; Jacob, Binu P.; Xavier, Sheena; Mohammed, E.M., E-mail: emmohammed_2005@yahoo.com

    2013-12-15

    Samarium doped magnesium ferrite was prepared (MgSm{sub x}Fe{sub 2−x}O{sub 4}) by sol–gel method. X-ray diffraction analysis reveals that the samples are single phasic with crystallite sizes in the 13–25 nm regime. Increase in lattice parameter with doping concentration suggests the expansion in unit cell with Sm{sup 3+} doping. Fourier Transform Infrared Spectrum shows substitution of Sm{sup 3+} ions in octahedral B site. Transmission Electron Micrograph shows the spherical shape of nano-particles. Magnetic measurement shows a decrease in magnetization with doping which is explained using dependence on particle size. - Highlights: • Single phasic cubic samarium substituted magnesium ferrite nanocrystals without any secondary phase was successfully synthesized by sol–gel technique. • TEM images show the samples are spherical in shape and agglomerated. • The absorption bands in FTIR are found in the expected range of spinel ferrites. • Saturation magnetization, remanence and coercivity is decreased with doping due to the decrease in particle size and increase in surface area. • Decrease in hysteresis loss suggests that we can tune the properties with the selection of appropriate Sm{sup 3+} concentration.

  11. Nanocrystalline magnesium ferrite prepared for photocatalytic applications by using the polymerized complex method

    Science.gov (United States)

    Dom, Rekha; Borse, Pramod H.; Hong, Kyong-Soo; Choi, Seyong; Lee, Byeong Seob; Ha, Myoung Gyu; Kim, Jong Pil; Jeong, Euh Duck; Kim, Hyun Gyu

    2015-11-01

    Magnesium ferrite (MgFe2O4) exhibiting a spinel phase was synthesized by using the polymerized complex and the solid-state reaction methods, and its physico-chemical properties were studied to explore the water-splitting under visible light photons. The study revealed the potential for using MgFe2O4 particles for photo-catalytic application. The structural study provided information on ferrite nano-crystallites fabricated by using the polymer complex method. The morphological studies demonstrated that, in contrast to the solid-state reaction method, a homogenous, monodispersed ferrite photocatalyst could be formed by using the polymerized complex method. The optical study revealed a larger visible-light absorption capability for the nanosized MgFe2O4 photocatalysts prepared by using the polymer complex methods, and indicated a red-shift of the bandgap by 0.06 eV as compared to the bandgap of the bulk. These nanocrystallites were highly photoactive with respect to the photodegradation and photocatalytic hydrogen evolution applications. The electrochemical analysis showed that they exhibited favorable bandedge positions suitable for photocatalytic H2 evolution. Thus, nanocrystalline MgFe2O4 is an active visible-light photocatalyst, that might be useful for the decomposition of water.

  12. Synthesis of p-type and n-type nickel ferrites and associated electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Šutka, Andris, E-mail: andris.sutka@rtu.lv [Faculty of Material Science and Applied Chemistry, Riga Technical University, Paula Valdena 3, Riga, LV-1048 (Latvia); Institute of Physics, University of Tartu, Ravila 14c, 50411, 51014 Tartu (Estonia); Pärna, Rainer [Institute of Physics, University of Tartu, Ravila 14c, 50411, 51014 Tartu (Estonia); Estonian Nanotechnology Competence Centre, Ravila 14c, 50411, 51014 Tartu (Estonia); Käämbre, Tanel [Institute of Physics, University of Tartu, Ravila 14c, 50411, 51014 Tartu (Estonia); Kisand, Vambola [Institute of Physics, University of Tartu, Ravila 14c, 50411, 51014 Tartu (Estonia); Estonian Nanotechnology Competence Centre, Ravila 14c, 50411, 51014 Tartu (Estonia)

    2015-01-01

    We used sol–gel auto combustion to synthesize nickel ferrites of p-type and n-type conductivity by controlling the relative amounts of nickel and iron during synthesis. The obtained samples have been characterized by XRD, FE-SEM, electrical measurements and XPS. We observe huge differences in the effect of grain size on the electrical resistivity between the p-type and the n-type material when the grain size increases from nano to micro scale during annealing at temperatures from 900 {sup o}C to 1300 {sup o}C. The observed resistivity decrease (due to grain size) is four orders of magnitude in the n-type nickel ferrite, whereas the p-type material remains virtually unaffected. We rationalize this drastic difference to stem from a reverse contrast of the surface (grain shell) versus bulk (grain core) conductivity between p- and n-type ferrite. With the grain shells in p-type the easier charge carrier path the effect of scatter at grain boundaries is accordingly diminished, whereas in the n-type charge transport properties are controlled by (the number of) grain boundaries in a conduction path.

  13. The influence of Cr content on the mechanical properties of ODS ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shaofu [School of Materials Science and Engineering, University of Science and Technology Beijing, No. 30 Xueyuan Road, Beijing (China); Korea Atomic Energy Research Institute, Daedeokdaero 989-111, Yuseong gu, Daejeon 305-353 (Korea, Republic of); Zhou, Zhangjian, E-mail: zhouzhj@mater.ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology Beijing, No. 30 Xueyuan Road, Beijing (China); Jang, Jinsung [Korea Atomic Energy Research Institute, Daedeokdaero 989-111, Yuseong gu, Daejeon 305-353 (Korea, Republic of); Wang, Man [School of Materials Science and Engineering, University of Science and Technology Beijing, No. 30 Xueyuan Road, Beijing (China); Korea Atomic Energy Research Institute, Daedeokdaero 989-111, Yuseong gu, Daejeon 305-353 (Korea, Republic of); Hu, Helong; Sun, Hongying; Zou, Lei; Zhang, Guangming; Zhang, Liwei [School of Materials Science and Engineering, University of Science and Technology Beijing, No. 30 Xueyuan Road, Beijing (China)

    2014-12-15

    The present investigation aimed at researching the mechanical properties of the oxide dispersion strengthened (ODS) ferritic steels with different Cr content, which were fabricated through a consolidation of mechanical alloyed (MA) powders of 0.35 wt.% nano Y{sub 2}O{sub 3} dispersed Fe–12.0Cr–0.5Ti–1.0W (alloy A), Fe–16.0Cr–0.5Ti–1.0W (alloy B), and Fe–18.0Cr–0.5Ti–1.0W (alloy C) alloys (all in wt.%) by hot isostatic pressing (HIP) with 100 MPa pressure at 1150 °C for 3 h. The mechanical properties, including the tensile strength, hardness, and impact fracture toughness were tested by universal testers, while Young’s modulus was determined by ultrasonic wave non-destructive tester. It was found that the relationship between Cr content and the strength of ODS ferritic steels was not a proportional relationship. However, too high a Cr content will cause the precipitation of Cr-enriched segregation phase, which is detrimental to the ductility of ODS ferritic steels.

  14. Nano-bio-sensing

    CERN Document Server

    Carrara, Sandro

    2011-01-01

    This book examines state-of-the-art applications of nano-bio-sensing. It brings together researchers from nano-electronics and bio-technology, providing multidisciplinary content from nano-structures fabrication to bio-sensing applications.

  15. In-situ formation of complex oxide precipitates during processing of oxide dispersion strengthened ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Jayasankar, K., E-mail: jayasankar.met@gmail.com [CSIR-Institute of Minerals & Materials Technology, Bhubaneswar 751013 (India); Pandey, Abhishek [CSIR-Advanced Materials & Processes Research Institute, Bhopal 462026 (India); Mishra, B.K. [CSIR-Institute of Minerals & Materials Technology, Bhubaneswar 751013 (India); Das, Siddhartha [Indian Institute of Technology, Kharagpur 721302 (India)

    2016-01-15

    Highlights: • Use of dual drive planetary ball mill for Bench scale (>1 kg) production. • X-ray diffraction and TEM were used to study transformations during sintering. • HIPped and rolled samples with nearly 99% density successfully produced. - Abstract: In fusion and fission reactor material development, ODS alloys are the most suitable candidate materials due to its high temperature creep properties and irradiation resistance properties. This paper describes the preparation of oxide dispersion strengthened alloy powder in large quantity (>1 kg batch) in dual drive planetary ball mill using pre-alloyed ferrtic steel powder with nano sized Y{sub 2}O{sub 3}. The consolidation of the powders was carried out in hot isostatic press (HIP) followed by hot rolling. 99% of the theoretical density was achieved by this method. The vickers hardness values of pressed and rolled samples were in the range of 380 ± 2HV and 719 ± 2HV, respectively. Samples were further investigated using X-ray diffraction particle size analyzer and electron microscope. Initial increase in particle size with milling was observed showing flattening of the particle. It was found that 5 h of milling time is sufficient to reduce the particle size to achieve the desired size. Transmission electron microscopy analysis of milled ODS steel powder revealed a uniform distribution of combustion synthesized nano-Y{sub 2}O{sub 3} in ferritic steel matrix after a milling time of 5 h. Preliminary results demonstrated suitability of dual drive planetary ball mill for mass production of alloy within a short time due to various kinds of forces acting at a time during milling process. Fine monoclinic Y{sub 2}Si{sub 2}O{sub 7} precipitates were also observed in the steel. This study explains the particle characteristics of nano Y{sub 2}O{sub 3} dispersed ODS powder and formation of nano clusters in ODS ferritic alloy.

  16. Measuring Permeability and Q-factor of Ferrite Toroids

    Institute of Scientific and Technical Information of China (English)

    XuZhe; WangChunxiao; ZhangWenzhi

    2003-01-01

    In the process of design RF cavity of CSRe, we use ferrite as the loading material of cavity. The characteristic of ferrite directly affects whether the cavity can obtain the target designed, so the measurement of ferrite material appears most important obviously.

  17. Characteristics of Strain-Induced Ferrite in Low Carbon Steel

    Institute of Scientific and Technical Information of China (English)

    LI Wei-juan; LIU Cui-qin; WANG Guo-dong; LIU Xiang-hua

    2003-01-01

    The strain-induced ferrite formed under different conditions was observed with SEM and optical microscope. The nucleation sites of strain-induced ferrite include grain boundary, grain inside, deformed band and annealing twin boundary. The shapes of the ferrite accordingly are equiaxed irregular polygonal, strip-shaped and acicular.

  18. Synthesis of ferrite and nickel ferrite nanoparticles using radio-frequency thermal plasma torch

    Science.gov (United States)

    Son, S.; Taheri, M.; Carpenter, E.; Harris, V. G.; McHenry, M. E.

    2002-05-01

    Nanocrystalline (NC) ferrite powders have been synthesized using a 50 kW-3 MHz rf thermal plasma torch for high-frequency soft magnet applications. A mixed powder of Ni and Fe (Ni:Fe=1:2), a NiFe permalloy powder with additional Fe powder (Ni:Fe=1:2), and a NiFe permalloy powder (Ni:Fe=1:1) were used as precursors for synthesis. Airflow into the reactor chamber was the source of oxygen for oxide formation. XRD patterns clearly show that the precursor powders were transformed into NC ferrite particles with an average particle size of 20-30 nm. SEM and TEM studies indicated that NC ferrite particles had well-defined polygonal growth forms with some exhibiting (111) faceting and many with truncated octahedral and truncated cubic shapes. The Ni content in the ferrite particles was observed to increase in going from mixed Ni and Fe to mixed permalloy and iron and finally to only permalloy starting precursor. The plasma-torch synthesized ferrite materials using exclusively the NiFe permalloy precursor had 40%-48% Ni content in the Ni-ferrite particle, differing from the NiFe2O4 ideal stoichiometry. EXAFS was used to probe the cation coordination in low Ni magnetite species. The coercivity and Neel temperature of the high Ni content ferrite sample were 58 Oe and ˜590 °C, respectively.

  19. Development of europium doped core-shell silica cobalt ferrite functionalized nanoparticles for magnetic resonance imaging.

    Science.gov (United States)

    Kevadiya, Bhavesh D; Bade, Aditya N; Woldstad, Christopher; Edagwa, Benson J; McMillan, JoEllyn M; Sajja, Balasrinivasa R; Boska, Michael D; Gendelman, Howard E

    2017-02-01

    The size, shape and chemical composition of europium (Eu(3+)) cobalt ferrite (CFEu) nanoparticles were optimized for use as a "multimodal imaging nanoprobe" for combined fluorescence and magnetic resonance bioimaging. Doping Eu(3+) ions into a CF structure imparts unique bioimaging and magnetic properties to the nanostructure that can be used for real-time screening of targeted nanoformulations for tissue biodistribution assessment. The CFEu nanoparticles (size ∼7.2nm) were prepared by solvothermal techniques and encapsulated into poloxamer 407-coated mesoporous silica (Si-P407) to form superparamagnetic monodisperse Si-CFEu nanoparticles with a size of ∼140nm. Folic acid (FA) nanoparticle decoration (FA-Si-CFEu, size ∼140nm) facilitated monocyte-derived macrophage (MDM) targeting. FA-Si-CFEu MDM uptake and retention was higher than seen with Si-CFEu nanoparticles. The transverse relaxivity of both Si-CFEu and FA-Si-CFEu particles were r2=433.42mM(-1)s(-1) and r2=419.52mM(-1)s(-1) (in saline) and r2=736.57mM(-1)s(-1) and r2=814.41mM(-1)s(-1) (in MDM), respectively. The results were greater than a log order-of-magnitude than what was observed at replicate iron concentrations for ultrasmall superparamagnetic iron oxide (USPIO) particles (r2=31.15mM(-1)s(-1) in saline) and paralleled data sets obtained for T2 magnetic resonance imaging. We now provide a developmental opportunity to employ these novel particles for theranostic drug distribution and efficacy evaluations.

  20. The role of pH on the particle size and magnetic consequence of cobalt ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Safi, Rohollah, E-mail: r.safi@gmx.com; Ghasemi, Ali; Shoja-Razavi, Reza; Tavousi, Majid

    2015-12-15

    Cobalt ferrite (CoFe{sub 2}O{sub 4}) nanoparticles with various size distributions were prepared by a chemical co-precipitation method at different pH condition from 8 to 13. The structural characterizations of the prepared samples were carried out using powder X-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electron microscope. The XRD results revealed that a single cubic CoFe{sub 2}O{sub 4} phase with the average crystallite sizes of about 5–24 nm were formed. Cation distribution occupancy in tetrahedral and octahedral sites were estimated by employing Rietveld refinement technique. The results showed that the whole series of samples contain a partial inverse spinel structure. FTIR measurements between 370 and 4000 cm{sup −1} confirmed the intrinsic cation vibrations of spinel structure of the samples. The room temperature magnetic properties of the samples have been examined using vibrating sample magnetometer. It is found that with increasing the pH of reaction, the magnetization and coercive field could be increased. The sample synthesized at pH~8 and 9 showed superparamagnetic behavior and highest coercive field up to 650 Oe is attributed to the sample synthesized with pH~13. - Highlights: • CoFe{sub 2}O{sub 4} nanoparticles were prepared by co-precipitation method at different pH. • Τhe single cubic phase with the average crystallite sizes of 5–24 nm were formed. • Cation distribution in tetrahedral and octahedral sites was estimated using XRD data. • The sample synthesized at pH~8 and 9 showed superparamagnetic behavior. • The crystallinity and crystallite size were increased by increasing the pH.

  1. Structural, magnetic and gas sensing properties of nanosized copper ferrite powder synthesized by sol gel combustion technique

    Energy Technology Data Exchange (ETDEWEB)

    Sumangala, T.P.; Mahender, C. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Barnabe, A. [Université de Toulouse, Institut Carnot CIRIMAT – UMR CNRS-UPS-INP 5085, Université Paul Sabatier, Toulouse 31062 (France); Venkataramani, N. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Prasad, Shiva, E-mail: shiva.pd@gmail.com [Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India)

    2016-11-15

    Stoichiometric nano sized copper ferrite particles were synthesized by sol gel combustion technique. They were then calcined at various temperatures ranging from 300–800 °C and were either furnace cooled or quenched in liquid nitrogen. A high magnetisation value of 48.2 emu/g signifying the cubic phase of copper ferrite, was obtained for sample quenched to liquid nitrogen temperature from 800 °C. The ethanol sensing response of the samples was studied and a maximum of 86% response was obtained for 500 ppm ethanol in the case of a furnace cooled sample calcined at 800 °C. The chemical sensing is seen to be correlated with the c/a ratio and is best in the case of tetragonal copper ferrite. - Highlights: • One of the first study on ethanol sensing of cubic copper ferrite. • In-situ High temperature XRD done shows phase transition from cubic to tetragonal. • A non-monotonic increase in magnetization was seen with calcination temperature. • A response of 86% was obtained towards 500 ppm ethanol. • Tried to correlate sensing response and ion content in spinel structure.

  2. Effect of heat treatment on structural and Mössbauer spectroscopic properties of coprecipitated Mn{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4} ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Srinivas, Ch.; Babu, Ch. Seshu [Department of physics, Sasi Institute of Technology and Engineering, Tadepalligudem-534101 (India); Tirupanyam, B. V. [Department of physics, Government Arts College (Autonomous), Rajahmundry-533401 (India); Meena, S. S. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai-4000085 (India); Sastry, D. L., E-mail: dl-sastry@gmail.com [Department of physics, Andhra University, Visakhapatnam-530003 (India)

    2015-06-24

    Results obtained in a systamatic study by X-ray diffraction and Mösssbauer spectroscopy on the structural and magnetic properties on Mn{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4} ferrite nanoparticles heat treated at 200 °C, 500 °C and 800 °C are reported. Average crystallite sizes are estimated to be in the range (2.6nm – 12.8nm). It is observed that crystallite sizes increase with increase in sintering temperature and random variation in lattice parameter was observed. At relatively low sintering temperatures the samples exhibit superparamagnetism and complete ferrite phase was observed at higher heat treatment.

  3. A study of nanosized magnesium ferrite particles with high magnetic moment

    Energy Technology Data Exchange (ETDEWEB)

    Sumangala, T.P.; Mahender, C.; Venkataramani, N. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, 400076 Mumbai (India); Prasad, Shiva, E-mail: shiva.pd@gmail.com [Department of Physics, Indian Institute of Technology Bombay, Powai, 400076 Mumbai (India)

    2015-05-15

    Nano-sized magnesium ferrite particles were prepared by sol gel combustion synthesis and were either furnace cooled or quenched after calcining at various temperatures ranging from 300 to 800 °C. A magnetisation value of 61 emu/g was obtained at 5 K for sample calcined at 800 °C and quenched in liquid nitrogen temperature. This is one of the highest reported values of magnetisation obtained from quenching at such a lower temperature. An estimate of the number of Fe{sup 3+} ions on A and B sites was made after applying Néel Model on the magnetisation values measured at 5 K. It was estimated that Fe{sup 3+} ions segregates out from both sites disproportionately so as to cause a net decrease in the overall moment. The resultant cation distribution is found to be consistent with the coercivity data. - Highlights: • Highest magnetisation (M) among nano sized magnesium ferrite particles was obtained. • The obtained magnetisation was nearly double of furnace cooled bulk sample. • Coercivity (H{sub c}) is anti correlated to M for samples with different heat treatment. • Coefficient of non saturation of magnetisation in M–H loop (a), is correlated with H{sub c}. • H{sub c}, M and a are explained in terms of cation distribution obtained using NNéel model.

  4. Influence of Ce-Substitution on Structural, Magnetic and Electrical Properties of Cobalt Ferrite Nanoparticles

    Science.gov (United States)

    Hashhash, A.; Kaiser, M.

    2016-01-01

    Nano-crystalline samples of cerium substituted cobalt ferrites with chemical formula CoCe x Fe2- x O4 (0.0 ≤ x ≤ 0.1) were prepared using the citrate auto-combustion method. The prepared ferrites were characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy spectra (FTIR), transmission electron microscopy (TEM), and a vibrating sample magnetometer (VSM). The XRD patterns and FTIR spectra confirm that the prepared samples reveal the formation of a single-phase spinel structure. TEM micrographs showed that the particles are made up of spherical and elongated nano-metric shapes. A limitation of the size of nanoparticles is observed as the Ce3+ concentration increases. VSM measurements showed that the coercivity H c and magnetization values M s are strongly dependent on Ce3+ content and particle size. The values of H c lie in the range of (411-1600 G), which suggest that these samples are convenient for different applications. The alternating current electrical conductivity ( σ), dielectric permittivities ( ɛ', ɛ″), and dielectric loss tangent (tan δ) were studied at different ranges of frequency and temperature. The relation of conductivity with temperature revealed a semiconductor to semi-metallic behavior as cerium concentration increases. The variation in (tan δ) with frequency at different temperature shows abnormal behavior with more than one relaxation peak. The conduction mechanism used in the present study has been discussed in the light of cation-anion-cation interactions over the octahedral B-site.

  5. Magnetic Nanoparticles: Synthesis, Characterization and Magnetic Properties of Cobalt Aluminum Ferrite.

    Science.gov (United States)

    Zaki, H M; Al-Heniti, Saleh H; Al-Hadeethi, Y; Alsanoosi, A M

    2016-05-01

    Nanoparticles of the ferrite system CoFe(2-x)Al(x)O4 (x = 0.0, 0.3, 0.7 and 1.0) were synthesized through the co-precipitation technique. Thermal decomposition process and formation of a single crystalline phase were followed using thermal differential analysis technique (DTA). X-ray powder diffraction patterns of the samples confirmed the formation of a nano-size single spinel phase. The average crystallite size was found to be in the range 20-63 nm for all samples. This was further confirmed by TEM of one of the samples, with concentration x = 1.0 which was found statistically to be 27 nm. This agrees well with the value of 24 nm deduced by means of X-ray diffraction method for the same sample. A considerable decrease in the intensity of the octahedral bands is observed as the aluminum concentration increases, and even vanishes completely at x = 1.0 indicating the migration of cations between the octahedral and tetrahedral sites. The magnetic hysteresis loops at room temperature showed decrease in both, coercivity and saturation magnetization as the non-magnetic Al3+ ions content increases. The relative values of M(r0/M(s) were found to be between 0.44 and 0.31 for the samples with a remarkable change in the squareness of the loops. This is highly beneficial for the microwave and memory devices applications of these nano sized ferrite system.

  6. Structural and magnetic properties correlated with cation distribution of Mo-substituted cobalt ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Heiba, Z.K. [Faculty of Science, Taif University, P.O. Box: 888, Al-Haweiah, Taif (Saudi Arabia); Physics Department, Faculty of Science, Ain Shams University, Cairo (Egypt); Mostafa, Nasser Y., E-mail: nmost69@yahoo.com [Faculty of Science, Taif University, P.O. Box: 888, Al-Haweiah, Taif (Saudi Arabia); Chemistry Department, Faculty of Science, Suez Canal University, Ismailia 41522 (Egypt); Abd-Elkader, Omar H. [Department of Zoology, Science College, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Electron Microscope and Thin Films Department, National Research Center (NRC), El-Behooth Street, Dokki, Cairo 12622 (Egypt)

    2014-11-15

    Mo-substituted cobalt ferrite nanoparticles; CoFe{sub 2−2x}Mo{sub x}O{sub 4} (0.0≤x≤0.3) were prepared by a one-step solution combustion synthesis technique. The reactants were metal nitrates and glycine as a fuel. The samples were characterized using an X-ray diffraction (XRD), a transmission electron microscope (TEM) and a vibrating sample magnetometer (VSM). XRD analysis revealed a pure single phase of cubic spinel ferrites for all samples with x up to 0.3. The lattice parameter decreases with Mo{sup 6+} substitution linearly up to x=0.15, then nonlinearly for x≥0.2. Rietveld analysis and saturation magnetization (M{sub s}) revealed that Mo{sup 6+} replaced Fe{sup 3+} in the tetrahedral A-sites up to x=0.15, then it replaced Fe{sup 3+} in both A-sites and B-sites for x≥0.2. The saturation magnetization (M{sub s}) increases with increasing Mo{sup 6+} substitution up to x=0.15 then decreases. The crystallite size decreased while the microstrain increased with increasing Mo{sup 6+} substitution. Inserting Mo{sup 6+} produces large residents of defects and cation vacancies. - Highlights: • Nano-sized Mo-substituted cobalt ferrite CoFe{sub 2−2x}Mo{sub x}O{sub 4} (0.0≤x≤0.3) were prepared by solution combustion. • The change in M{sub s} with increasing Mo-substitution was investigated. • The cations distributions of ferrites were obtained from Rietveld analysis. • Inserting Mo{sup 6+} produces large residents of defects and cation vacancies.

  7. Hardening of ODS ferritic steels under irradiation with high-energy heavy ions

    Science.gov (United States)

    Ding, Z. N.; Zhang, C. H.; Yang, Y. T.; Song, Y.; Kimura, A.; Jang, J.

    2017-09-01

    Influence of the nanoscale oxide particles on mechanical properties and irradiation resistance of oxide-dispersion-strengthened (ODS) ferritic steels is of critical importance for the use of the material in fuel cladding or blanket components in advanced nuclear reactors. In the present work, impact of structures of oxide dispersoids on the irradiation hardening of ODS ferritic steels was studied. Specimens of three high-Cr ODS ferritic steels containing oxide dispersoids with different number density and average size were irradiated with high-energy Ni ions at about -50 °C. The energy of the incident Ni ions was varied from 12.73 MeV to 357.86 MeV by using an energy degrader at the terminal so that a plateau of atomic displacement damage (∼0.8 dpa) was produced from the near surface to a depth of 24 μm in the specimens. A nanoindentor (in constant stiffness mode with a diamond Berkovich indenter) and a Vickers micro-hardness tester were used to measure the hardeness of the specimens. The Nix-Gao model taking account of the indentation size effect (ISE) was used to fit the hardness data. It is observed that the soft substrate effect (SSE) can be diminished substantially in the irradiated specimens due to the thick damaged regions produced by the Ni ions. A linear correlation between the nano-hardeness and the micro-hardness was found. It is observed that a higher number density of oxide dispersoids with a smaller average diameter corresponds to an increased resistance to irradiation hardening, which can be ascribed to the increased sink strength of oxides/matrix interfaces to point defects. The rate equation approach and the conventional hardening model were used to analyze the influence of defect clusters on irradiation hardening in ODS ferritic steels. The numerical estimates show that the hardening caused by the interstitial type dislocation loops follows a similar trend with the experiment data.

  8. Investigation of hydrogen assisted cracking in acicular ferrite using site-specific micro-fracture tests

    Energy Technology Data Exchange (ETDEWEB)

    Costin, Walter L. [School of Mechanical Engineering, The University of Adelaide, SA 5005 (Australia); Lavigne, Olivier, E-mail: Olivier.lavigne@adelaide.edu.au [School of Mechanical Engineering, The University of Adelaide, SA 5005 (Australia); Kotousov, Andrei; Ghomashchi, Reza [School of Mechanical Engineering, The University of Adelaide, SA 5005 (Australia); Linton, Valerie [Energy Pipelines Cooperative Research Centre, Faculty of Engineering, University of Wollongong, NSW 2522 (Australia)

    2016-01-10

    Hydrogen assisted cracking (HAC) is a common type of failure mechanism that can affect a wide range of metals and alloys. Experimental studies of HAC are cumbersome due to various intrinsic and extrinsic parameters and factors (associated with stress, hydrogen and the materials microstructure) contributing to the hydrogen crack kinetics. The microstructure of many materials consists of diverse constituents with characteristic features and mechanical properties which only occur in very small material volumes. The only way to differentiate the effect of these individual constituents on the hydrogen crack kinetics is to miniaturise the testing procedures. In this paper we present a new experimental approach to investigate hydrogen assisted crack growth in a microstructural constituent, i.e. acicular ferrite. For this purpose, sharply notched micro-cantilevers were fabricated with a Focus Ion Beam within this selected microscopic region. Acicular ferrite can be found in many ferrous alloys including ferritic weld metal and has specific features that control its intrinsic susceptibility to HAC. These features were characterised via Electron Backscatter Diffraction and the specimens were subsequently loaded under uncharged and hydrogen charged conditions with a nano-indenter. The outcomes of the testing, demonstrated that the threshold stress intensity factor, K{sub th}, to initiate crack propagation in acicular ferrite ranges between 1.56 MPa m{sup 1/2} and 4.36 MPa m{sup 1/2}. This range is significantly below the values of K{sub th} reported for various ferrous alloys in standard macro-tests. This finding indicates that the mechanisms and resistance to HAC at micro-scale could be very different than at the macro-scale as not all fracture toughening mechanisms may be activated at this scale level.

  9. Nano CMOS

    Directory of Open Access Journals (Sweden)

    Malay Ranjan Tripathy

    2009-05-01

    Full Text Available Complementary metal-oxide-semiconductor (CMOS has become major challenge to scaling and integration. However, innovation in transistor structures and integration of novel materials are needed to sustain this performance trend. CMOS variability in the scaling technology becoming very important concern because of limitation of process control over statistical variability related to the fundamental discreteness of charge and matter. Different aspects responsible for device variability are discussed in this article. The challenges and opportunities of nano CMOS technology are outlined here.

  10. Genotoxicity of Superparamagnetic Iron Oxide Nanoparticles in Granulosa Cells

    Directory of Open Access Journals (Sweden)

    Marina Pöttler

    2015-11-01

    Full Text Available Nanoparticles that are aimed at targeting cancer cells, but sparing healthy tissue provide an attractive platform of implementation for hyperthermia or as carriers of chemotherapeutics. According to the literature, diverse effects of nanoparticles relating to mammalian reproductive tissue are described. To address the impact of nanoparticles on cyto- and genotoxicity concerning the reproductive system, we examined the effect of superparamagnetic iron oxide nanoparticles (SPIONs on granulosa cells, which are very important for ovarian function and female fertility. Human granulosa cells (HLG-5 were treated with SPIONs, either coated with lauric acid (SEONLA only, or additionally with a protein corona of bovine serum albumin (BSA; SEONLA-BSA, or with dextran (SEONDEX. Both micronuclei testing and the detection of γH2A.X revealed no genotoxic effects of SEONLA-BSA, SEONDEX or SEONLA. Thus, it was demonstrated that different coatings of SPIONs improve biocompatibility, especially in terms of genotoxicity towards cells of the reproductive system.

  11. Deviation from the superparamagnetic behaviour of fine-particle systems

    CERN Document Server

    Malaescu, I

    2000-01-01

    Studies concerning superparamagnetic behaviour of fine magnetic particle systems were performed using static and radiofrequency measurements, in the range 1-60 MHz. The samples were: a ferrofluid with magnetite particles dispersed in kerosene (sample A), magnetite powder (sample B) and the same magnetite powder dispersed in a polymer (sample C). Radiofrequency measurements indicated a maximum in the imaginary part of the complex magnetic susceptibility, for each of the samples, at frequencies with the magnitude order of tens of MHz, the origin of which was assigned to Neel-type relaxation processes. The static measurements showed a Langevin-type dependence of magnetisation M and of susceptibility chi, on the magnetic field for sample A. For samples B and C deviations from this type of dependence were found. These deviations were analysed qualitatively and explained in terms of the interparticle interactions, dispersion medium influence and surface effects.

  12. Relaxometry imaging of superparamagnetic magnetite nanoparticles at ambient conditions

    Science.gov (United States)

    Finkler, Amit; Schmid-Lorch, Dominik; Häberle, Thomas; Reinhard, Friedemann; Zappe, Andrea; Slota, Michael; Bogani, Lapo; Wrachtrup, Jörg

    We present a novel technique to image superparamagnetic iron oxide nanoparticles via their fluctuating magnetic fields. The detection is based on the nitrogen-vacancy (NV) color center in diamond, which allows optically detected magnetic resonance (ODMR) measurements on its electron spin structure. In combination with an atomic-force-microscope, this atomic-sized color center maps ambient magnetic fields in a wide frequency range from DC up to several GHz, while retaining a high spatial resolution in the sub-nanometer range. We demonstrate imaging of single 10 nm sized magnetite nanoparticles using this spin noise detection technique. By fitting simulations (Ornstein-Uhlenbeck process) to the data, we are able to infer additional information on such a particle and its dynamics, like the attempt frequency and the anisotropy constant. This is of high interest to the proposed application of magnetite nanoparticles as an alternative MRI contrast agent or to the field of particle-aided tumor hyperthermia.

  13. Potential toxicity of superparamagnetic iron oxide nanoparticles (SPION

    Directory of Open Access Journals (Sweden)

    Neenu Singh

    2010-09-01

    Full Text Available Superparamagnetic iron oxide nanoparticles (SPION are being widely used for various biomedical applications, for example, magnetic resonance imaging, targeted delivery of drugs or genes, and in hyperthermia. Although, the potential benefits of SPION are considerable, there is a distinct need to identify any potential cellular damage associated with these nanoparticles. Besides focussing on cytotoxicity, the most commonly used determinant of toxicity as a result of exposure to SPION, this review also mentions the importance of studying the subtle cellular alterations in the form of DNA damage and oxidative stress. We review current studies and discuss how SPION, with or without different surface coating, may cause cellular perturbations including modulation of actin cytoskeleton, alteration in gene expression profiles, disturbance in iron homeostasis and altered cellular responses such as activation of signalling pathways and impairment of cell cycle regulation. The importance of protein–SPION interaction and various safety considerations relating to SPION exposure are also addressed.

  14. Multifunctional superparamagnetic nanoparticles for enhanced drug transport in cystic fibrosis

    Science.gov (United States)

    Armijo, Leisha M.; Brandt, Yekaterina I.; Rivera, Antonio C.; Cook, Nathaniel C.; Plumley, John B.; Withers, Nathan J.; Kopciuch, Michael; Smolyakov, Gennady A.; Huber, Dale L.; Smyth, Hugh D.; Osinski, Marek

    2012-10-01

    Iron oxide colloidal nanoparticles (ferrofluids) are investigated for application in the treatment of cystic fibrosis lung infections, the leading cause of mortality in cystic fibrosis patients. We investigate the use of iron oxide nanoparticles to increase the effectiveness of administering antibiotics through aerosol inhalation using two mechanisms: directed particle movement in the presence of an inhomogeneous static external magnetic field and magnetic hyperthermia. Magnetic hyperthermia is an effective method for decreasing the viscosity of the mucus and biofilm, thereby enhancing drug, immune cell, and antibody penetration to the affected area. Iron oxide nanoparticles of various sizes and morphologies were synthesized and tested for specific losses (heating power). Nanoparticles in the superparamagnetic to ferromagnetic size range exhibited excellent heating power. Additionally, iron oxide / zinc selenide core/shell nanoparticles were prepared, in order to enable imaging of the iron oxide nanoparticles. We also report on synthesis and characterization of MnSe/ZnSeS alloyed quantum dots.

  15. Superparamagnetic bimetallic iron-palladium nanoalloy: synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Nazir, Rabia; Mazhar, Muhammad [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Akhtar, M Javed; Nadeem, M; Siddique, Muhammad [Physics Division, PINSTECH, PO Nilore, Islamabad 44000 (Pakistan); Shah, M Raza [HEJ Research Institute of Chemistry, University of Karachi, Karachi 75270 (Pakistan); Khan, Nawazish A [Material Science Laboratory, Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Mehmood, Mazhar [National Centre for Nanotechnology, PIEAS, Islamabad 45650 (Pakistan); Butt, N M [Pakistan Science Foundation, Islamabad 44000 (Pakistan)], E-mail: mazhar42pk@yahoo.com

    2008-05-07

    Iron-palladium nanoalloy in the particle size range of 15-30 nm is synthesized by the relatively low temperature thermal decomposition of coprecipitated [Fe(Bipy){sub 3}]Cl{sub 2} and [Pd(Bipy){sub 3}]Cl{sub 2} in an inert ambient of dry argon gas. The silvery black Fe-Pd alloy nanoparticles are air-stable and have been characterized by EDX-RF, XRD, AFM, TEM, magnetometry, {sup 57}Fe Moessbauer and impedance spectroscopy. This Fe-Pd nanoalloy is in single phase and contains iron sites having up to 11 nearest-neighboring atoms. It is superparamagnetic in nature with high magnetic susceptibility, low coercivity and hyperfine field.

  16. Facile Method for Preparation of Silica Coated Monodisperse Superparamagnetic Microspheres

    Directory of Open Access Journals (Sweden)

    Xuan-Hung Pham

    2016-01-01

    Full Text Available This paper presents a facile method for preparation of silica coated monodisperse superparamagnetic microsphere. Herein, monodisperse porous polystyrene-divinylbenzene microbeads were prepared by seeded emulsion polymerization and subsequently sulfonated with acetic acid/H2SO4. The as-prepared sulfonated macroporous beads were magnetized in presence of Fe2+/Fe3+ under alkaline condition and were subjected to silica coating by sol-gel process, providing water compatibility, easily modifiable surface form, and chemical stability. FE-SEM, TEM, FT-IR, and TGA were employed to characterize the silica coated monodisperse magnetic beads (~7.5 μm. The proposed monodisperse magnetic beads can be used as mobile solid phase particles candidate for protein and DNA separation.

  17. Relating Brownian motion to diffusion with superparamagnetic colloids

    Science.gov (United States)

    Darras, A.; Fiscina, J.; Vandewalle, N.; Lumay, G.

    2017-04-01

    An original experiment is introduced that allows students to relate the Brownian motion of a set of superparamagnetic colloidal particles to their macroscopic diffusion. An external and constant magnetic field is first applied to the colloidal suspension so that the particles self-organize into chains. When the magnetic field is removed, the particles then freely diffuse from their positions in the chain, starting from the same coordinate on the axis perpendicular to the initial chain. This configuration thus enables an observer to study the one dimensional diffusion process, while also observing the underlying Brownian motion of the microscopic particles. Moreover, by studying the evolution of the particle distribution, a measurement of the diffusion coefficient can be obtained. In addition, by repeating this measurement with fluids of various viscosities, the Stokes-Einstein relation may be illustrated.

  18. High frequency lateral flow affinity assay using superparamagnetic nanoparticles

    Science.gov (United States)

    Lago-Cachón, D.; Rivas, M.; Martínez-García, J. C.; Oliveira-Rodríguez, M.; Blanco-López, M. C.; García, J. A.

    2017-02-01

    Lateral flow assay is one of the simplest and most extended techniques in medical diagnosis for point-of-care testing. Although it has been traditionally a positive/negative test, some work has been lately done to add quantitative abilities to lateral flow assay. One of the most successful strategies involves magnetic beads and magnetic sensors. Recently, a new technique of superparamagnetic nanoparticle detection has been reported, based on the increase of the impedance induced by the nanoparticles on a RF-current carrying copper conductor. This method requires no external magnetic field, which reduces the system complexity. In this work, nitrocellulose membranes have been installed on the sensor, and impedance measurements have been carried out during the sample diffusion by capillarity along the membrane. The impedance of the sensor changes because of the presence of magnetic nanoparticles. The results prove the potentiality of the method for point-of-care testing of biochemical substances and nanoparticle capillarity flow studies.

  19. Super-paramagnetic clustering of yeast gene expression profiles

    CERN Document Server

    Getz, G; Domany, E; Zhang, M Q

    2000-01-01

    High-density DNA arrays, used to monitor gene expression at a genomic scale, have produced vast amounts of information which require the development of efficient computational methods to analyze them. The important first step is to extract the fundamental patterns of gene expression inherent in the data. This paper describes the application of a novel clustering algorithm, Super-Paramagnetic Clustering (SPC) to analysis of gene expression profiles that were generated recently during a study of the yeast cell cycle. SPC was used to organize genes into biologically relevant clusters that are suggestive for their co-regulation. Some of the advantages of SPC are its robustness against noise and initialization, a clear signature of cluster formation and splitting, and an unsupervised self-organized determination of the number of clusters at each resolution. Our analysis revealed interesting correlated behavior of several groups of genes which has not been previously identified.

  20. Super-paramagnetic clustering of yeast gene expression profiles

    Science.gov (United States)

    Getz, G.; Levine, E.; Domany, E.; Zhang, M. Q.

    2000-04-01

    High-density DNA arrays, used to monitor gene expression at a genomic scale, have produced vast amounts of information which require the development of efficient computational methods to analyze them. The important first step is to extract the fundamental patterns of gene expression inherent in the data. This paper describes the application of a novel clustering algorithm, super-paramagnetic clustering (SPC) to analysis of gene expression profiles that were generated recently during a study of the yeast cell cycle. SPC was used to organize genes into biologically relevant clusters that are suggestive for their co-regulation. Some of the advantages of SPC are its robustness against noise and initialization, a clear signature of cluster formation and splitting, and an unsupervised self-organized determination of the number of clusters at each resolution. Our analysis revealed interesting correlated behavior of several groups of genes which has not been previously identified.

  1. Ferrite LTCC based phased array antennas

    KAUST Repository

    Ghaffar, Farhan A.

    2016-11-02

    Two phased array antennas realized in multilayer ferrite LTCC technology are presented in this paper. The use of embedded bias windings in these designs allows the negation of external magnets which are conventionally employed with bulk ferrite medium. This reduces the required magnetostatic field strength by 90% as compared to the traditional designs. The phase shifters are implemented using the SIW technology. One of the designs is operated in the half mode waveguide topology while the other design is based on standard full mode waveguide operation. The two phase shifter designs are integrated with two element patch antenna array and slotted SIW array respectively. The array designs demonstrate a beam steering of 30° and ±19° respectively for a current excitation of 200 mA. The designs, due to their small factor can be easily integrated in modern communication systems which is not possible in the case of bulk ferrite based designs.

  2. Dual-mode latching ferrite devices

    Science.gov (United States)

    Xu, Y.; Jiang, Z.

    1986-05-01

    A primary consideration with microwave ferrite control devices is related to the switching speed. In order to achieve fast switching with the considered devices, an operation in the latching mode is required. A description is given of a new class of ferrite latching devices, taking into account latching quadrupole devices and their modifications. It is pointed out that the advantages of the new devices include fast switching, high electrical performance, and simple construction. According to the utilization of external or internal magnetic return paths, there are two modes of operation in latching ferrite devices. Attention is given to constructions and calculations, the design of a model for each of the two modes of operation, polarization insensitive phase shifters (PIPS) with external magnetic return paths, and PIPS with internal magnetic return paths.

  3. NANO PARÇACIKLAR VE NANO TELLER

    OpenAIRE

    Hakan ATEŞ

    2015-01-01

    Bu makale nano parçacık ve nano tellerin sentezi, yapısı ve geniş bir alanda özelliklerinin yanı sıra nano teknoloji hakkında da bir irdelemeyi sunmaktadır. Çalışma nano teknoloji ve malzemeleri tanımlamakta ve kısa bir tarih, üretim teknikleri ve uygulama alanları hakkında bilgi vermektedir.

  4. Shape-controlled anisotropy of superparamagnetic micro-/nanohelices

    Science.gov (United States)

    Leshansky, Alexander M.; Morozov, Konstantin I.; Rubinstein, Boris Y.

    2016-07-01

    Micro-/nanopropellers can be actuated remotely by a rotating magnetic field and steered at high precision through various fluidic environments. Recent progress comprises microfabrication of superparamagnetic microhelices not possessing remanent magnetization, but rather magnetized by an applied magnetic field. In this article we present a numerical approach for computing, from first principles, the effective susceptibility of polarizable helical micro-/nanopropellers. We show that nanopropeller geometry, in particular, filament cross-section elongation and orientation, play a central role in determining its magnetic anisotropy and polarizability. The numerical predictions are in qualitative agreement with the previously reported experiments, showing that tight polarizable helices are propulsive. The numerical results are also supported by the approximate slender-body theory. Finally, we propose a semi-quantitative energy criterion to rank polarizable helices with different geometries of the filament by their propulsive capacity and also estimate their maximal propulsion speed.Micro-/nanopropellers can be actuated remotely by a rotating magnetic field and steered at high precision through various fluidic environments. Recent progress comprises microfabrication of superparamagnetic microhelices not possessing remanent magnetization, but rather magnetized by an applied magnetic field. In this article we present a numerical approach for computing, from first principles, the effective susceptibility of polarizable helical micro-/nanopropellers. We show that nanopropeller geometry, in particular, filament cross-section elongation and orientation, play a central role in determining its magnetic anisotropy and polarizability. The numerical predictions are in qualitative agreement with the previously reported experiments, showing that tight polarizable helices are propulsive. The numerical results are also supported by the approximate slender-body theory. Finally, we

  5. Superparamagnetic iron oxide nanoparticles: magnetic nanoplatforms as drug carriers

    Directory of Open Access Journals (Sweden)

    Wahajuddin

    2012-07-01

    Full Text Available Wahajuddin,1,2 Sumit Arora21Pharmacokinetics and Metabolism Division, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, 2Department of Pharmaceutics, National Institute of Pharmaceutical Education and Research, Rae Bareli, IndiaAbstract: A targeted drug delivery system is the need of the hour. Guiding magnetic iron oxide nanoparticles with the help of an external magnetic field to its target is the principle behind the development of superparamagnetic iron oxide nanoparticles (SPIONs as novel drug delivery vehicles. SPIONs are small synthetic γ-Fe2O3 (maghemite or Fe3O4 (magnetite particles with a core ranging between 10 nm and 100 nm in diameter. These magnetic particles are coated with certain biocompatible polymers, such as dextran or polyethylene glycol, which provide chemical handles for the conjugation of therapeutic agents and also improve their blood distribution profile. The current research on SPIONs is opening up wide horizons for their use as diagnostic agents in magnetic resonance imaging as well as for drug delivery vehicles. Delivery of anticancer drugs by coupling with functionalized SPIONs to their targeted site is one of the most pursued areas of research in the development of cancer treatment strategies. SPIONs have also demonstrated their efficiency as nonviral gene vectors that facilitate the introduction of plasmids into the nucleus at rates multifold those of routinely available standard technologies. SPION-induced hyperthermia has also been utilized for localized killing of cancerous cells. Despite their potential biomedical application, alteration in gene expression profiles, disturbance in iron homeostasis, oxidative stress, and altered cellular responses are some SPION-related toxicological aspects which require due consideration. This review provides a comprehensive understanding of SPIONs with regard to their method of preparation, their utility as drug delivery vehicles, and some concerns which need to

  6. Activity of an enzyme immobilized on superparamagnetic particles in a rotational magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Mizuki, Toru; Watanabe, Noriyuki; Nagaoka, Yutaka [Bio-Nano Electronics Research Centre, Toyo University, Saitama 350-8585 (Japan); Fukushima, Tadamasa [Shimadzu GLC Ltd., Phenomenex Support Centre, Tokyo 110-0016 (Japan); Morimoto, Hisao; Usami, Ron [Bio-Nano Electronics Research Centre, Toyo University, Saitama 350-8585 (Japan); Maekawa, Toru, E-mail: maekawa@toyonet.toyo.ac.jp [Bio-Nano Electronics Research Centre, Toyo University, Saitama 350-8585 (Japan)

    2010-03-19

    We immobilize {alpha}-amylase extracted from Bacillus Iicheniformis on the surfaces of superparamagnetic particles and investigate the effect of a rotational magnetic field on the enzyme's activity. We find that the activity of the enzyme molecules immobilized on superparamagnetic particles increases in the rotational magnetic field and reaches maximum at a certain frequency. We clarify the effect of the cluster structures formed by the superparamagnetic particles on the activity. Enzyme reactions are enhanced even in a tiny volume of solution using the present method, which is very important for the development of efficient micro reactors and micro total analysis systems ({mu}-TAS).

  7. Micromagnetic simulations of spinel ferrite particles

    Energy Technology Data Exchange (ETDEWEB)

    Dantas, Christine C., E-mail: ccdantas@iae.cta.b [Divisao de Materiais (AMR), Instituto de Aeronautica e Espaco (IAE), Departamento de Ciencia e Tecnologia Aeroespacial - DCTA (Brazil); Gama, Adriana M., E-mail: adriana-gama@uol.com.b [Divisao de Materiais (AMR), Instituto de Aeronautica e Espaco (IAE), Departamento de Ciencia e Tecnologia Aeroespacial - DCTA (Brazil)

    2010-10-15

    This paper presents the results of simulations of the magnetization field ac response (at 2-12 GHz) of various submicron ferrite particles (cylindrical dots). The ferrites in the present simulations have the spinel structure, expressed here by M{sub 1}-{sub n}Zn{sub n}Fe{sub 2}O{sub 4} (where M stands for a divalent metal), and the parameters chosen were the following: (a) for n=0: M={l_brace}Fe, Mn, Co, Ni, Mg, Cu {r_brace}; (b) for n=0.1: M = {l_brace}Fe, Mg{r_brace} (mixed ferrites). These runs represent full 3D micromagnetic (one-particle) ferrite simulations. We find evidences of confined spin waves in all simulations, as well as a complex behavior nearby the main resonance peak in the case of the M = {l_brace}Mg, Cu{r_brace} ferrites. A comparison of the n=0 and n=0.1 cases for fixed M reveals a significant change in the spectra in M = Mg ferrites, but only a minor change in the M=Fe case. An additional larger scale simulation of a 3 by 3 particle array was performed using similar conditions of the Fe{sub 3}O{sub 4} (magnetite; n=0, M = Fe) one-particle simulation. We find that the main resonance peak of the Fe{sub 3}O{sub 4} one-particle simulation is disfigured in the corresponding 3 by 3 particle simulation, indicating the extent to which dipolar interactions are able to affect the main resonance peak in that magnetic compound.

  8. Study of magnetic and structural properties of ferrofluids based on cobalt-zinc ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, J., E-mail: javierlo21@gmail.com [Thin Film Group, Universidad del Valle, A.A. 25360, Cali (Colombia); Gonzalez-Bahamon, L.F. [Analytical Chemistry Laboratory, Universidad del Valle, A.A. 25360, Cali (Colombia); Prado, J.; Caicedo, J.C.; Zambrano, G.; Gomez, M.E. [Thin Film Group, Universidad del Valle, A.A. 25360, Cali (Colombia); Esteve, J. [Department de Fisica Aplicada i Optica, Universitat de Barcelona, Catalunya (Spain); Prieto, P. [Center of Excellence for Novel Materials, Universidad del Valle, Cali (Colombia)

    2012-02-15

    Ferrofluids are colloidal systems composed of a single domain of magnetic nanoparticles with a mean diameter around 30 nm, dispersed in a liquid carrier. Magnetic Co{sub (1-x)}Zn{sub x}Fe{sub 2}O{sub 4} (x=0.25, 0.50, 0.75) ferrite nanoparticles were prepared via co-precipitation method from aqueous salt solutions in an alkaline medium. The composition and structure of the samples were characterized through Energy Dispersive X-ray Spectroscopy and X-ray diffraction, respectively. Transmission Electron Microscopy (TEM) studies permitted determining nanoparticle size; grain size of nanoparticle conglomerates was established via Atomic Force Microscopy. The magnetic behavior of ferrofluids was characterized by Vibrating Sample Magnetometer (VSM); and finally, a magnetic force microscope was used to visualize the magnetic domains of Co{sub (1-x)}Zn{sub x}Fe{sub 2}O{sub 4} nanoparticles. X-ray diffraction patterns of Co{sub (1-x)}Zn{sub x}Fe{sub 2}O{sub 4} show the presence of the most intense peak corresponding to the (311) crystallographic orientation of the spinel phase of CoFe{sub 2}O{sub 4}. Fourier Transform Infrared Spectroscopy confirmed the presence of the bonds associated to the spinel structures; particularly for ferrites. The mean size of the crystallite of nanoparticles determined from the full-width at half maximum of the strongest reflection of the (311) peak by using the Scherrer approximation diminished from (9.5{+-}0.3) nm to (5.4{+-}0.2) nm when the Zn concentration increases from 0.21 to 0.75. The size of the Co-Zn ferrite nanoparticles obtained by TEM is in good agreement with the crystallite size calculated from X-ray diffraction patterns, using Scherer's formula. The magnetic properties investigated with the aid of a VSM at room temperature presented super-paramagnetic behavior, determined by the shape of the hysteresis loop. In this study, we established that the coercive field of Co{sub (1-x)}Zn{sub x}Fe{sub 2}O{sub 4} magnetic

  9. Anhydride functionalised calcium ferrite nanoparticles: a new selective magnetic material for enrichment of lead ions from water and food samples.

    Science.gov (United States)

    Pirouz, Mojgan Jafari; Beyki, Mostafa Hossein; Shemirani, Farzaneh

    2015-03-01

    In this research a sonochemistry route for manufacture of uniform nanocrystalline CaFe2O4 and its anhydride functionalisation were reported. The potential of raw and modified material as a magnetically separable sorbent in selective enrichment of lead ions from water and food samples is outlined. This material was characterised using FT-IR, XRD, SEM and VSM techniques. The SEM and VSM results indicated that the calcium ferrite nanoparticles are sphere-like particles possessing superparamagnetic properties with an average diameter of 40 nm. Various analytical parameters, including pH, contact time, type and concentration of eluent, adsorption capacity, sample volume and interference of ions, were optimised. Following a modification by anhydride, calcium ferrite selectivity toward lead ions was raised more than twofold compared to the unmodified nanoparticles. Finally a pre-concentration procedure was applied for determination of trace Pb(II) in canned tuna fish, canned tomato paste, parsley, milk and well-water samples with satisfactory results.

  10. A Novel Research on Behavior of Zinc Ferrite Nanoparticles in Different Concentration of Poly(vinyl pyrrolidone (PVP

    Directory of Open Access Journals (Sweden)

    Halimah Mohamed Kamari

    2014-04-01

    Full Text Available Zinc ferrite nanocrystals were prepared from an aqueous solution containing metal nitrates and various of concentrations of poly(vinyl pyrrolidone (PVP, i.e., 0, 15, 40, and 55 g/L, as a capping agent. To stabilize the particles, they were thermally treated at 873 K, as an optimum calcination temperature. The behaviors of the polymeric precursor were analyzed by use of simultaneous thermo-gravimetry (TG and derivative thermo-gravimetry analyses (DTG. The presence of the crystalline phase in each sample was confirmed by X-ray diffraction (XRD analysis. The average particle size and the morphology of the nanoparticles were determined by transmission electron microscopy (TEM, and these parameters were found to differ at various concentrations of PVP. Fourier transform infrared spectroscopy (FT-IR confirmed the presence of metal oxide bands for all the PVP concentrations and confirmed the absence of organic bands for PVP concentrations less than 55 g/L. Measurements of the magnetization value of the zinc ferrite nanoparticles were obtained at room temperature by using a vibrating sample magnetometer (VSM, which showed that, in the absence of PVP, the sample exhibited a paramagnetic behavior while, in the presence of PVP, samples have a super-paramagnetic behavior.

  11. TEM observation of sintered permanent magnetic strontium ferrite

    Institute of Scientific and Technical Information of China (English)

    YU Hongya; LIU Zhengyi; ZENG Dechang

    2006-01-01

    Sintered permanent magnetic strontium ferrites were studied using transmission electron microscopy to investigate the microstructure morphology and its correlation with the magnetic properties. The present study shows that the microstructure of sintered permanent magnetic strontium ferrites is an important parameter in determining their magnetic properties. The microstructure morphology in low-performance ferrite magnet is obviously different from high-performance one. Themagnetic properties of sintered permanent strontium ferrite depend strongly on the orientation degree of strong magnetic crystals. The presence of ferric oxidephase in ferrite magnet can deteriorate the magnetic properties. Moreover, proper quantities of crystal defects are beneficial to high coercive force due to the fixing of magnetic domain.

  12. Simulation of non-linear coaxial line using ferrite beads

    Energy Technology Data Exchange (ETDEWEB)

    Furuya, S.; Matsumoto, H.; Tachi, K.; Takano, S.; Irisawa, J. [Nagaoka Univ. of Technology, Niigata (Japan)

    2002-06-01

    A ferrite sharpener is a non-linear coaxial line using ferrite beads, which produces high-voltage, high-dV/dt pulses. We have been examining the characteristics of ferrite sharpeners experimentally, varying various parameters. Also we have made the simulation of the ferrite sharpener and compared the predictions with the experimental results in detail to analyze the characteristics of the sharpener. In this report, calculating the magnetization M of the ferrite bead, we divide the bead into n sections radially instead of adopting M at the average radius in the previous report. (author)

  13. Cation distributions on rapidly solidified cobalt ferrite

    Science.gov (United States)

    De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.

    1990-01-01

    The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

  14. Cation distributions on rapidly solidified cobalt ferrite

    Science.gov (United States)

    De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.

    1990-01-01

    The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

  15. Magnesium-zinc ferrite nanoparticles: effect of copper doping on the structural, electrical and magnetic properties.

    Science.gov (United States)

    Zaki, H M; Al-Heniti, S; Umar, Ahmad; Al-Marzouki, F; Abdel-Daiem, A; Elmosalami, T A; Dawoud, H A; Al-Hazmi, F S; Ata-Allah, S S

    2013-06-01

    In this paper, Mg0.5Zn0.5-Cu(x)Fe2O4 ferrites nanoparticles were synthesized by facile co-precipitation route and characterized in detail in terms of their structural, electrical and magnetic properties as a function of Cu concentration. The prepared samples have cubic spinel phase as confirmed by X-ray diffraction patterns. The decrease of the lattice constant and increase of X-ray density indicate the solubility of Cu ions in the spinel lattice. The AC conductivity measurements between 300 K and 773 K at different frequencies 1 KHz up to 1 MHz, showed two different behaviors as semiconductor-like at high temperature and frequency depending behavior associated with dispersion phenomena at low temperatures. The conduction mechanism in the system is influenced by Cu concentration and the dominant one is the hopping conduction mechanism. Dielectric measurements at the same conditions of temperatures and frequencies exhibited that the dielectric loss increases with increasing the temperature and decreasing the frequency indicating the semiconducting nature of the ferrite compounds. An anomalous behavior of the dielectric loss is observed in samples with high Cu content which explained in terms of resonance between frequency accompanied the electronic hopping and the frequency of the external electric field. The analysis of Mössbauer spectra revealed that copper free compound is super-paramagnetically relaxed in nature and zinc free compound demonstrates ferrimagnetic order. Moreover, hyperfine field spectrum shows the migration of Cu ions from octahedral to tetrahedral site in zinc free compound.

  16. Synthesis, characterization and magnetic properties of monodisperse Ni, Zn-ferrite nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Sanjeev, E-mail: sanjeevkumar.dubey2@gmail.com [University of Petroleum and Energy Studies, Dehradun, Uttarakhand (India); Kumar, Pankaj [University of Petroleum and Energy Studies, Dehradun, Uttarakhand (India); Singh, Vaishali [University School of Basic and Applied Science (India); Kumar Mandal, Uttam [University of Chemical Technology, GGS Indraprastha University, Sector 16, Dwarka, Delhi 110403 (India); Kumar Kotnala, Ravinder [National Physical laboratory, New Delhi 110012 (India)

    2015-04-01

    Synthesization of monodisperse Ni, Zn-ferrite (Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4}, x=1, 0.8, 0.6, 0.5, 0.4, 0.2, 0.0) nanocrystals has been achieved by the inverse microemulsion method using CTAB as surfactant and kerosene as an oil phase. The detailed characterization of the synthesized nanocrystals and measurement of the magnetic properties has been done by techniques like X-ray diffraction (XRD), field emission transmission electron microscopy (FETEM), Fourier transform infrared spectroscopy (FITR) and Vibrating Sample Magnetometer (VSM) respectively. The relationship between the structure and composition of the nanocrystals with magnetic properties has been investigated. The nanocrystals size is found to be in the range 1–5 nm. The effect of Zn substitution on size and magnetic properties has been studied. It has been observed that magnetism changed from ferromagnetic at X= 0 to super paramagnetic to paramagnetic at X=1 as Zn concentration increased. The Curie temperature is found to decrease with an increase in Zn concentration. - Highlights: • Reverse microemulsion route is very facile route for synthesis of Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} ferrite. • Presence of Zn changes the structural and magnetic properties of the Zn substituted NiFe{sub 2}O{sub 4.} • The lattice constant increases with the increase in Zn substitution. • The curie temperature decreases with Zn concentration appreciably. • Magnetic behavior varies from ferromagnetic at x=0 to superparamagnetic to paramagnetic at x=1.

  17. Scattering characteristics of conducting cylinder coated with nonuniform magnetized ferrite

    Institute of Scientific and Technical Information of China (English)

    Hu Bin-Jie; Edward Yung Kai-Ning; Zhang Jun; Toutain Serge

    2005-01-01

    An analytical technique, referred to as the scattering matrix method (SMM), is developed to analyse the scattering of a planar wave from a conducting cylinder coated with nonuniform magnetized ferrite. The SMM solution for the nonuniform ferrite coating can be reduced to the expressions for the scattering and penetrated coefficients in four particular cases: nonuniform magnetized ferrite cylinder, uniform magnetized ferrite-coated conducting cylinder, uniform ferrite cylinder as well as homogeneous dielectric-coated conducting cylinder. The resonant condition for the nonuniform ferrite coating is obtained. The distinctive differences in scattering between the nonuniform ferrite coating and the nonuniform dielectric coating are demonstrated. The effects of applied magnetic fields and wave frequencies on the scattering characteristics for two types of the linear profiles are revealed.

  18. Synthesis of cobalt ferrite with enhanced magnetostriction properties by the sol−gel−hydrothermal route using spent Li-ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Lu, E-mail: yaolu1020@126.com [Key Laboratory for Yellow River and Huai River Water Environment and Pollution Control, Ministry of Education, College of Environment, Henan Normal University, Xinxiang 453007 (China); College of Chemistry and Chemical Engineering, Xinxiang University, Xinxiang Henan 453003 (China); Xi, Yuebin [Key Laboratory for Yellow River and Huai River Water Environment and Pollution Control, Ministry of Education, College of Environment, Henan Normal University, Xinxiang 453007 (China); Xi, Guoxi, E-mail: yaolu001@163.com [Key Laboratory for Yellow River and Huai River Water Environment and Pollution Control, Ministry of Education, College of Environment, Henan Normal University, Xinxiang 453007 (China); Feng, Yong [Key Laboratory for Yellow River and Huai River Water Environment and Pollution Control, Ministry of Education, College of Environment, Henan Normal University, Xinxiang 453007 (China)

    2016-09-25

    The combination of a sol–gel method and a hydrothermal method was successfully used for synthesizing the nano-crystalline cobalt ferrite powders with a spinel structure using spent Li-ion batteries as the raw materials. The phase composition, microstructure, magnetic properties and magnetostriction coefficient of cobalt ferrite were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), magnetometer and magnetostrictive measurement instrument. The microstructure of the products exhibited hedgehog-like microspheres with particle size of approximately 5 μm. The different crystalline sizes and the microstructure of cobalt ferrites precursor were controlled by varying the hydrothermal time, which significantly affected the super-exchange and the deflection direction of the magnetic domain, and led to the change of the magnetic properties of sintered cylindrical samples. The saturation magnetization and maximum magnetostriction coefficient were 81.7 emu/g and −158.5 ppm, respectively, which was larger than that of products prepared by the sol-gel sintered method alone. - Graphical abstract: The magnetostriction of cobalt ferrites with a spinel structure was successfully prepared using the sol–gel–hydrothermal route using spent Li-ion batteries. On the basis of the aforementioned SEM observation, the formation of a hedgehog-like microsphere structure might involve two important steps: Ostwald ripening and self-assembly. - Highlights: • The cobalt ferrites were prepared by the sol–gel–hydrothermal route. • The cobalt ferrites show hedgehog-like microsphere particles in shape. • The microspheres size increased with increasing hydrothermal time. • The magnetostriction properties of the cobalt ferrite were enhanced.

  19. Effect of Cr{sup 3+} substitution on properties of nano-ZnFe{sub 2}O{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Kumari, Naveen; Kumar, Vinod, E-mail: vinod.phy@dcrustm.org; Singh, S.K.

    2015-02-15

    Highlights: • Zn-Cr nano-ferrites were synthesized successfully. • Single spinel ferrite phase formation is confirmed by XRD and TEM. • Lattice constant of prepared ferrites decreases with increasing Cr{sup 3+} ion content. • DC conductivity and activation energy increases with increasing Cr{sup 3+} and temperature. • Dielectric loss, permittivity and ac conductivity decrease with increase in Cr{sup 3+} substitution. - Abstract: Nano-crystalline ferrite materials with general formula ZnCr{sub x}Fe{sub 2-x}O{sub 4} (x = 0.1, 0.2, 0.3, 0.4 and 0.5) have been synthesized by chemical co precipitation method. The developed materials were characterized for structural, shape/size and electrical properties by using analytical techniques viz. X-ray diffraction (XRD), transmission electron microscopy (TEM), and impedance analyzer respectively. X-ray diffraction pattern confirms the formation of single phase spinel structure of prepared ferrites. The lattice constant of ZnCr{sub x}Fe{sub 2-x}O{sub 4} (x = 0.1, 0.2, 0.3, 0.4 and 0.5) nano-particles decreases with increasing Cr{sup 3+} ion content. Nano-size of synthesized ferrite particles were confirmed by electron microscopy. DC-electrical conductivity and activation energy increases with increasing Cr{sup 3+} ion content. Dielectric loss (tan δ), real part of dielectric constant (ε′), imaginary part of dielectric constant (ε″), ac conductivity (σ{sub ac}), real (resistive) part of impedance (Z′) and imaginary part of impedance (Z′′) were analyzed as a function of frequency, composition and temperature using impedance analyzer in the frequency range of (1 KHz-5 MHz) and temperature range of (300-523 K). Dielectric loss (tan δ), dielectric permittivity (ε′) and ac conductivity (σ{sub ac}) decreases with increase in Cr{sup 3+} substitution which has been explained on the basis of hopping mechanism. Electrical conductivity increases with increasing temperature revealing the semiconducting behavior

  20. Co-containing spinel ferrite thin-film perpendicular magnetic recording media with Mn-Zn ferrite backlayer

    OpenAIRE

    Yamamoto, Setsuo; Kuniki, Hirofumi; Kurisu, Hiroki; Matsuura, Mitsuru

    2003-01-01

    Co-containing ferrite thin-film/Mn-Zn ferrite thin-film double-layered perpendicular media were prepared using reactive ECR sputtering and magnetron sputtering methods, and their magnetic and structural properties and recording characteristics were studied. The Mn-Zn ferrite thin-film backlayer had saturation magnetization of 3.5 kG and coercivity of 60 Oe. Reproduced voltage for the Co-containing ferrite thin-film/Mn-Zn ferrite thin-film double-layered medium was about twice of that for the ...

  1. Electroless Ni-P-ferrite composite coatings for microwave applications

    Indian Academy of Sciences (India)

    Ramesh Chandra Agarwala

    2005-11-01

    Electroless, EL coating technique is one of the elegant ways of coating by controlling the temperature and pH of the coating bath in which there is no usage of electric current. It is estimated that the market for this chemistry will increase at a rate of about 15% per year. Use of microwave energy for synthesis of material with novel microstructures is an exciting new field in material science with enormous application. In this investigation, nanograined BaZn2-CoFe16O27 ( = 0.0, 0.4, 0.8, 1.2, 1.6 and 2.0) powders have been synthesized by citrate precursor method followed by heat treatment at various specified temperatures like 650, 750 and 850°C for 3 h in the furnace. In addition heat treatments are also carried out in the microwave oven of the power rating of 760 W. The powders thus produced have been characterized by SEM, EPMA, VSM, XRD and thermal analysis techniques. As a forward step towards EL nano-composite coatings, Ni-P- ( = BaZn2- CoFe16O27) coatings with thickness less than ∼ 0.1 mm thick has been produced. Such coating exhibits absorption of microwave in the range of 12-18 GHz up to about 20 db depending upon the volume fraction of the ferrite particles embedded in the Ni-P matrix.

  2. Discovery of superparamagnetism in sub-millimeter-sized magnetite porous single crystals

    Science.gov (United States)

    Ma, Ji; Chen, Kezheng

    2016-10-01

    In this work, sub-millimeter-sized magnetite porous single crystals were found to exhibit unique superparamagnetism rather than the known ferrimagnetism. This superparamagnetism was intimately related to the hydrothermal formation process, during which high lattice stress of ca. 6 GPa and large lattice strain of ca. - 1.21 ×10-2 would change the exchange constants of α, β, and ν to concurrently meet criterions of (i) ν1 =ν2 = β, (ii) α1 =α2 = α, and (iii) αβ = 1. These criterions, deduced from the molecular-field theory, were proposed to be the general transition conditions for any ferrimagnetic material exhibiting superparamagnetism when their size was beyond their superparamagnetic size limit.

  3. Effect of ferrite addition above the base ferrite on the coupling factor of wireless power transfer for vehicle applications

    DEFF Research Database (Denmark)

    Batra, Tushar; Schaltz, Erik; Ahn, Seungyoung

    2015-01-01

    Power transfer capability of wireless power transfer systems is highly dependent on the magnetic design of the primary and secondary inductors and is measured quantitatively by the coupling factor. The inductors are designed by placing the coil over a ferrite base to increase the coupling factor...... and reduce magnetic emissions to the surroundings. Effect of adding extra ferrite above the base ferrite at different physical locations on the self-inductance, mutual inductance and coupling factor is under investigation in this paper. The addition can increase or decrease the mutual inductance depending...... on the placement of ferrite. Also, the addition of ferrite increases the self-inductance of the coils and there is a probability for an overall decrease in the coupling factor. Correct placement of ferrite on the other hand can increase the coupling factor relatively higher than the base ferrite as it is closer...

  4. Crystal structure of superparamagnetic Mg{sub 0.2}Ca{sub 0.8}Fe{sub 2}O{sub 4} nanoparticles synthesized by sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Escamilla-Pérez, A.M., E-mail: angel.mep@gmail.com [Cinvestav-Unidad Saltillo, Industria Metalúrgica No. 1062, Parque Industrial Saltillo-Ramos Arizpe, C.P. 25900, Ramos Arizpe, Coahuila (Mexico); Cortés-Hernández, D.A., E-mail: dora.cortes@cinvestav.edu.mx [Cinvestav-Unidad Saltillo, Industria Metalúrgica No. 1062, Parque Industrial Saltillo-Ramos Arizpe, C.P. 25900, Ramos Arizpe, Coahuila (Mexico); Almanza-Robles, J.M. [Cinvestav-Unidad Saltillo, Industria Metalúrgica No. 1062, Parque Industrial Saltillo-Ramos Arizpe, C.P. 25900, Ramos Arizpe, Coahuila (Mexico); Mantovani, D.; Chevallier, P. [Laboratory for Biomaterials and Bioengineering, Department of Materials Engineering and University Hospital Research Center, Laval University, Quebec City, QC (Canada)

    2015-01-15

    Powders of magnetic iron oxide nanoparticles (Mg{sub 0.2}Ca{sub 0.8}Fe{sub 2}O{sub 4}) were prepared by a sol–gel method using ethylene glycol and nitrates of Fe, Ca and Mg as starting materials. Those powders were heat treated at different temperatures (573, 673, 773 and 873 K). In order to evaluate the effect of the heat treatment temperature on the nanoferrites properties, X-ray diffraction (XRD), vibrating sample magnetometry (VSM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) techniques were used. It was found that the reaction products exhibit nanometric sizes and superparamagnetic behavior. It is also demonstrated that, as the heat treatment temperature increases, the particle size and the saturation magnetization of the nanoferrites are increased. - Highlights: • Mg{sub 0.2}Ca{sub 0.8}Fe{sub 2}O{sub 4} superparamagnetic nanoparticles were successfully synthesized. • Particle average sizes of Ca–Mg ferrites were within the range of 8–25 nm. • The nanoferrite treated at 873 K showed a stoichiometry close to Mg{sub 0.2}Ca{sub 0.8}Fe{sub 2}O{sub 4}. • The heat treatment temperature has a strong effect on the crystal structure. • These nanoparticles are potential materials for magnetic hyperthermia.

  5. Temperature stabilization of microwave ferrite devices

    Science.gov (United States)

    Kaminsky, R.; Wendt, E. J.

    1978-01-01

    Thin-film heating element for strip-line circulator is sandwiched between insulation and copper laminations. Disks conform to shape of circulator ferrite disks and are installed between copper-clad epoxy ground planes. Heater design eliminates external cartridges and reduces weight by approximately one-third.

  6. Adding calcium improves lithium ferrite core

    Science.gov (United States)

    Lessoff, H.

    1969-01-01

    Adding calcium increases uniformity of grain growth over a wide range of sintering temperatures and reduces porosity within the grain. Ferrite cores containing calcium have square hysteresis loops and high curie temperatures, making them useful in coincident current memories of digital electronic computers.

  7. Transmission through Ferrite Samples at Submillimeter Frequencies

    Science.gov (United States)

    1986-05-01

    y Y In all the equations given above, c and 1’e are, in general, complex. Measurements are generally made on the power transmitted which is ITaI ? in...Frequency (cm-’) using measurements of2T 1 given eby Figure 8. Power transmission coeffi- equation( 2),Tp1 = ITaI ~cient for 100-m-thick ferrite slab

  8. Spinel cobalt ferrite by complexometric synthesis

    NARCIS (Netherlands)

    Pham Duc Thang, P.D.T.; Rijnders, Augustinus J.H.M.; Blank, David H.A.

    2005-01-01

    Magnetic fine particles of cobalt ferrite (CoFe2O4) have been synthesized using complexometric method in which ethylene diamine tetra acetic acid C10H16N2O8 (EDTA) acts as a complexing agent. The crystallographic structure, microstructure and magnetic properties of the synthesized powder were

  9. Synthesis of lithium ferrites from polymetallic carboxylates

    Directory of Open Access Journals (Sweden)

    STEFANIA STOLERIU

    2008-10-01

    Full Text Available Lithium ferrite was prepared by the thermal decomposition of three polynuclear complex compounds containing as ligands the anions of malic, tartaric and gluconic acid: (NH42[Fe2.5Li0.5(C4H4O53(OH4(H2O2]×4H2O (I, (NH46[Fe2.5Li0.5(C4H4O63(OH8]×2H2O (II and (NH42[Fe2.5Li0.5(C6H11O73(OH7] (III. The polynuclear complex precursors were characterized by chemical analysis, IR and UV–Vis spectra, magnetic measurements and thermal analysis. The obtained lithium ferrites were characterized by XRD, scanning electron microscopy, IR spectra and magnetic measurements. The single α-Li0.5Fe2.5O4 phase was obtained by thermal decomposition of the tartarate complex annealed at 700 °C for 1 h. The magnetization value ≈ 50 emu g-1 is lower than that obtained for the bulk lithium ferrite due to the nanostructural character of the ferrite. The particle size was smaller than 100 nm.

  10. Ferrite Quantification Methodologies for Duplex Stainless Steel

    Directory of Open Access Journals (Sweden)

    Arnaldo Forgas Júnior

    2016-07-01

    Full Text Available In order to quantify ferrite content, three techniques, XRD, ferritoscope and optical metallography, were applied to a duplex stainless steel UNS S31803 solution-treated for 30 min at 1,000, 1,100 and 1,200 °C, and then compared to equilibrium of phases predicted by ThermoCalc® simulation. As expected, the microstructure is composed only by austenite and ferrite phases, and ferrite content increases as the solution treatment temperature increases. The microstructure presents preferred grains orientation along the rolling directions even for a sample solution treated for 30 min at 1,200 °C. For all solution treatment temperatures, the ferrite volume fractions obtained by XRD measurements were higher than those achieved by the other two techniques and ThermoCalc® simulation, probably due to texturing effect of previous rolling process. Values obtained by quantitative metallography look more assertive as it is a direct measurement method but the ferritoscope technique should be considered mainly for in loco measurement.

  11. Barium Ferrite Films Grown by Laser Ablation

    NARCIS (Netherlands)

    Lisfi, A.; Lodder, J.C.; Haan, de P.; Smithers, M.A.; Roesthuis, F.J.G.

    1998-01-01

    Pulsed laser ablation (PLA) has been used to grow barium ferrite films on Al2O3 single crystal substrates. When deposition occurs in an oxidising atmosphere at high temperatures, the films are single BaFe12O19 phase, very well oriented with (001) texture, and exhibit a large perpendicular magnetic a

  12. Characterization of magnetic nano materials by Moessbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Sangeeta; Katyal, S C [Jaypee University of information technology, Waknaghat, Solan 173215 (India); Gupta, A; Reddy, V R [UGC-DAE Consortium for scientific research, Khandwa Road, Indore 452017 (India); Singh, M, E-mail: megha2k6@gmail.co [Department of physics, Himachal Pradesh University, Shimla 171005 (India)

    2010-03-01

    The use of a non-destructive nuclear-physical method, namely {sup 57}Fe Moessbauer spectroscopy, is discussed for the investigation of magnetic and structural arrangement of Fe-based nano-crystalline nickel-zinc-indium ferrites (NZIFO). Nano NZIFO particles (Ni{sub 0.58}Zn{sub 0.42}In{sub x}Fe{sub 2-x}O{sub 4}) with varied quantities of indium (x = 0, 0.1, 0.2) have been chemically synthesized through a reverse micelle reaction and investigated by X-ray diffraction, transmission electron microscopy and by magnetic and Moessbauer spectral studies. Here a comparison between low-temperature and room temperature Moessbauer spectra is presented. Well defined sextets at 5 K provide information about the structure and magnetic states of atoms located in different structural positions. The dependence of Moessbauer parameters, viz, isomer shift, quadrupole splitting, linewidth and hyperfine magnetic field on In{sup 3+} concentration have been discussed. Detailed Moessbauer results, as well as the interest of these materials both for applied science perspectives are presented. Moessbauer results are also supported by magnetization data. With these interesting ferromagnetic properties Indium substituted nano nickel-zinc ferrites have potential applications in magnetic storage data.

  13. Characterization of magnetic nano materials by Mössbauer spectroscopy

    Science.gov (United States)

    Thakur, Sangeeta; Katyal, S. C.; Gupta, A.; Reddy, V. R.; Singh, M.

    2010-03-01

    The use of a non-destructive nuclear-physical method, namely 57Fe Mössbauer spectroscopy, is discussed for the investigation of magnetic and structural arrangement of Fe-based nano-crystalline nickel-zinc-indium ferrites (NZIFO). Nano NZIFO particles (Ni0.58Zn0.42InxFe2-xO4) with varied quantities of indium (x = 0, 0.1, 0.2) have been chemically synthesized through a reverse micelle reaction and investigated by X-ray diffraction, transmission electron microscopy and by magnetic and Mössbauer spectral studies. Here a comparison between low-temperature and room temperature Mössbauer spectra is presented. Well defined sextets at 5 K provide information about the structure and magnetic states of atoms located in different structural positions. The dependence of Mössbauer parameters, viz, isomer shift, quadrupole splitting, linewidth and hyperfine magnetic field on In3+ concentration have been discussed. Detailed Mössbauer results, as well as the interest of these materials both for applied science perspectives are presented. Mössbauer results are also supported by magnetization data. With these interesting ferromagnetic properties Indium substituted nano nickel-zinc ferrites have potential applications in magnetic storage data.

  14. Strong plasmon coupling in self-assembled superparamagnetic nanoshell chains

    Science.gov (United States)

    Xiong, Min; Jin, Xiulong; Ye, Jian

    2016-02-01

    Construction of ordered patterns of plasmonic nanoparticles is greatly important for nanophotonics relevant applications. We have reported a facile and low-cost magnetic field induced self-assembly approach to construct plasmonic superparamagnetic nanoshell (SN) chains up to several hundred micrometers in a few seconds in a large area without templates or other assistance processes. Experimental and theoretical investigations of the near- and far-field optical properties indicate that the super- and sub-radiant modes of the SN chains continuously redshift with the increase of SN number and the Fano resonance emerges in the infinite double- and triple-line SN chains. Strong plasmon coupling effects in the SN chains result in great electric field enhancements at visible and infrared wavelengths, which indicates that these chain structures potentially can be used as a common substrate for both surface enhanced Raman scattering (SERS) and surface-enhanced infrared absorption (SEIRA) application. This fabrication method also offers a general strategy alternative to top-down processing that enables the construction of nanostructures for metamaterials, electromagnetic energy transport, and optical waveguide.Construction of ordered patterns of plasmonic nanoparticles is greatly important for nanophotonics relevant applications. We have reported a facile and low-cost magnetic field induced self-assembly approach to construct plasmonic superparamagnetic nanoshell (SN) chains up to several hundred micrometers in a few seconds in a large area without templates or other assistance processes. Experimental and theoretical investigations of the near- and far-field optical properties indicate that the super- and sub-radiant modes of the SN chains continuously redshift with the increase of SN number and the Fano resonance emerges in the infinite double- and triple-line SN chains. Strong plasmon coupling effects in the SN chains result in great electric field enhancements at visible

  15. Gaussian process classification of superparamagnetic relaxometry data: Phantom study.

    Science.gov (United States)

    Sovizi, Javad; Mathieu, Kelsey B; Thrower, Sara L; Stefan, Wolfgang; Hazle, John D; Fuentes, David

    2017-07-24

    Superparamagnetic relaxometry (SPMR) is an emerging technology that holds potential for use in early cancer detection. Measurement of the magnetic field after the excitation of cancer-bound superparamagnetic iron oxide nanoparticles (SPIONs) enables the reconstruction of SPIONs spatial distribution and hence tumor detection. However, image reconstruction often requires solving an ill-posed inverse problem that is computationally challenging and sensitive to measurement uncertainty. Moreover, an additional image processing module is required to automatically detect and localize the tumor in the reconstructed image. Our goal is to examine the use of data-driven machine learning technique to detect a weak signal induced by a small cluster of SPIONs (surrogate tumor) in presence of background signal and measurement uncertainty. We aim to investigate the performance of both data-driven and image reconstruction models to characterize situations that one can replace the computationally-challenging reconstruction technique by the data-driven model. We utilize Gaussian process (GP) classification model and a physics-based image reconstruction method, tailored to SPMR datasets that are obtained from (i) in silico simulations designed based on mouse cancer models and (ii) phantom experiments using MagSense system (Imagion Biosystems, Inc.). We investigate the performance of the GP classifier against the reconstruction technique, for different levels of measurement noise, different scenarios of SPIONs distribution, and different concentrations of SPIONs at the surrogate tumor. In our in silico source detection analysis, we were able to achieve high sensitivity results using GP model that outperformed the image reconstruction model for various choices of SPIONs concentration at the surrogate tumor and measurement noise levels. Moreover, in our phantom studies we were able to detect the surrogate tumor phantoms with 5% and 7.3% of the total used SPIONs, surrounded by 9 low

  16. Superparamagnetic nanoparticles for effective delivery of malaria DNA vaccine.

    Science.gov (United States)

    Al-Deen, Fatin Nawwab; Ho, Jenny; Selomulya, Cordelia; Ma, Charles; Coppel, Ross

    2011-04-05

    Low efficiency is often observed in the delivery of DNA vaccines. The use of superparamagnetic nanoparticles (SPIONs) to deliver genes via magnetofection could improve transfection efficiency and target the vector to its desired locality. Here, magnetofection was used to enhance the delivery of a malaria DNA vaccine encoding Plasmodium yoelii merozoite surface protein MSP1(19) (VR1020-PyMSP1(19)) that plays a critical role in Plasmodium immunity. The plasmid DNA (pDNA) containing membrane associated 19-kDa carboxyl-terminal fragment of merozoite surface protein 1 (PyMSP1(19)) was conjugated with superparamagnetic nanoparticles coated with polyethyleneimine (PEI) polymer, with different molar ratio of PEI nitrogen to DNA phosphate. We reported the effects of SPIONs-PEI complexation pH values on the properties of the resulting particles, including their ability to condense DNA and the gene expression in vitro. By initially lowering the pH value of SPIONs-PEI complexes to 2.0, the size of the complexes decreased since PEI contained a large number of amino groups that became increasingly protonated under acidic condition, with the electrostatic repulsion inducing less aggregation. Further reaggregation was prevented when the pHs of the complexes were increased to 4.0 and 7.0, respectively, before DNA addition. SPIONs/PEI complexes at pH 4.0 showed better binding capability with PyMSP1(19) gene-containing pDNA than those at neutral pH, despite the negligible differences in the size and surface charge of the complexes. This study indicated that the ability to protect DNA molecules due to the structure of the polymer at acidic pH could help improve the transfection efficiency. The transfection efficiency of magnetic nanoparticle as carrier for malaria DNA vaccine in vitro into eukaryotic cells, as indicated via PyMSP1(19) expression, was significantly enhanced under the application of external magnetic field, while the cytotoxicity was comparable to the benchmark nonviral

  17. Synthesis and characterization of superparamagnetic CoFe2O4/MWCNT hybrids for tumor-targeted therapy.

    Science.gov (United States)

    Sun, Chuanyu; Liu, Yong; Ding, Weihong; Gou, Yuancheng; Xu, Ke; Xia, Guowei; Ding, Qiang

    2013-01-01

    Owing to their great potentialities of carbon nanotubes (CNTs)-based magnetic nano-composites, numerous applications of them have been found in nanotechnology, integrated functional system, and in medicine. Herein, nearly monodisperse CoFe2O4 nanoparticles have been deposited on multi-walled carbon nanotubes (MWCNTs) by high-temperature hydrolysis and inorganic polymerization of ionic Co(II) and Fe(III) salts and MWCNTs in a polyol solution. X-ray diffraction, energy-dispersive X-ray spectrometry and transmission electron microscopy were used to characterize the final products. The average size of CoFe2O4 nanoparticles and their coverage density on MWCNTs can be adjusted to some extent by altering the reaction parameters. A proposed formation mechanism of the magnetic hybrids is presented. Magnetic measurements showed that the hybrids were superparamagnetic at room temperature and their saturation magnetization could be fine tuned by changing the loading of CoFe2O4 nanoparticles on the MWCNTs.

  18. Differential cytotoxicity of copper ferrite nanoparticles in different human cells.

    Science.gov (United States)

    Ahmad, Javed; Alhadlaq, Hisham A; Alshamsan, Aws; Siddiqui, Maqsood A; Saquib, Quaiser; Khan, Shams T; Wahab, Rizwan; Al-Khedhairy, Abdulaziz A; Musarrat, Javed; Akhtar, Mohd Javed; Ahamed, Maqusood

    2016-10-01

    Copper ferrite nanoparticles (NPs) have the potential to be applied in biomedical fields such as cell labeling and hyperthermia. However, there is a lack of information concerning the toxicity of copper ferrite NPs. We explored the cytotoxic potential of copper ferrite NPs in human lung (A549) and liver (HepG2) cells. Copper ferrite NPs were crystalline and almost spherically shaped with an average diameter of 35 nm. Copper ferrite NPs induced dose-dependent cytotoxicity in both types of cells, evident by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide and neutral red uptake assays. However, we observed a quite different susceptibility in the two kinds of cells regarding toxicity of copper ferrite NPs. Particularly, A549 cells showed higher susceptibility against copper ferrite NP exposure than those of HepG2 cells. Loss of mitochondrial membrane potential due to copper ferrite NP exposure was observed. The mRNA level as well as activity of caspase-3 enzyme was higher in cells exposed to copper ferrite NPs. Cellular redox status was disturbed as indicated by induction of reactive oxygen species (oxidant) generation and depletion of the glutathione (antioxidant) level. Moreover, cytotoxicity induced by copper ferrite NPs was efficiently prevented by N-acetylcysteine treatment, which suggests that reactive oxygen species generation might be one of the possible mechanisms of cytotoxicity caused by copper ferrite NPs. To the best of our knowledge, this is the first report showing the cytotoxic potential of copper ferrite NPs in human cells. This study warrants further investigation to explore the mechanisms of differential toxicity of copper ferrite NPs in different types of cells. Copyright © 2016 John Wiley & Sons, Ltd.

  19. Mn-Zn ferrite nanoparticles for ferrofluid preparation: Study on thermal-magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Arulmurugan, R. [Department of Physics, Pondicherry Engineering College, Pondicherry 605014 (India)]. E-mail: arulphysics@rediffmail.com; Vaidyanathan, G. [Department of Physics, Pondicherry Engineering College, Pondicherry 605014 (India)]. E-mail: gvn_pec@yahoo.com; Sendhilnathan, S. [Department of Physics, Sri Manakula Vinayagar Engineering College, Pondicherry 605107 (India); Jeyadevan, B. [Graduate School of Environmental Studies, Tohoku University, Sendai 980-8579 (Japan)

    2006-03-15

    Mn{sub 1-x}Zn{sub x}Fe{sub 2}O{sub 4} (with x varying from 0.1 to 0.5) ferrite nanoparticles used for ferrofluid preparation have been prepared by chemical co-precipitation method and characterized. Characterization techniques like elemental analysis by atomic absorption spectroscopy and spectrophotometry, thermal analysis using simultaneous TG-DTA, XRD, TEM, VSM and Moessbauer spectroscopy have been utilized. The final cation contents estimated agree with the initial degree of substitution. The Curie temperature (T{sub c}) and particle size decrease with the increase in zinc substitution. In the case of particles with higher zinc concentration, both ferrimagnetic nanoparticles and particles exhibiting superparamagnetic behavior at room temperature are present. In addition, some of the results obtained by slightly altering the preparation condition are also discussed. The precipitated particles were used for ferrofluid preparation. The fine particles were suitably dispersed in heptane using oleic acid as the surfactant. The volatile nature of the carrier chosen helps in altering the number concentration of the magnetic particles in a ferrofluid. Magnetic properties of the fine particles and ferrofluids are discussed. Ferrofluids having Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} particles can be used for the energy conversion application utilizing the magnetically induced convection for thermal dissipation.

  20. Magnetic phase transitions in ferrite nanoparticles characterized by electron spin resonance

    Energy Technology Data Exchange (ETDEWEB)

    Flores-Arias, Yesica, E-mail: yeika01@hotmail.com; Vázquez-Victorio, Gabriela; Ortega-Zempoalteca, Raul; Acevedo-Salas, Ulises; Valenzuela, Raul [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México D.F. 04510 (Mexico); Ammar, Souad [Laboratoires ITODYS, Université de Paris-Diderot, PRES Sorbonne Paris Cité, CNRS-UMR 7086, 75205 Paris Cedex (France)

    2015-05-07

    Ferrite magnetic nanoparticles in the composition Zn{sub 0.7}Ni{sub 0.3}Fe{sub 2}O{sub 4} were synthesized by the polyol method, with an average size of 8 nm. Electron spin resonance (ESR) measurements were carried out at a frequency of 9.45 GHz in the 100–500 K temperature range. Obtained results exhibited a characteristic ESR signal in terms of resonance field, H{sub res}, linewidth, ΔH, and peak ratio, R, for each magnetic phase. At low temperatures, the ferrimagnetic phase showed low H{sub res}, broad ΔH, and asymmetric R. At high temperatures, these parameters exhibited opposite values: high H{sub res}, small ΔH, and R ∼ 1. For intermediate temperatures, a different phase was observed, which was identified as a superparamagnetic phase by means of zero-field cooling-field cooling and hysteresis loops measurements. The observed differences were explained in terms of the internal fields and especially due to the cubic anisotropy in the ordered phase.

  1. Synergetic effect of size and morphology of cobalt ferrite nanoparticles on proton relaxivity.

    Science.gov (United States)

    N, Venkatesha; Srivastava, Chandan; Hegde, Veena

    2014-12-01

    Cobalt ferrite nanoparticles with average sizes of 14, 9 and 6 nm were synthesised by the chemical co-precipitation technique. Average particle sizes were varied by changing the chitosan surfactant to precursor molar ratio in the reaction mixture. Transmission electron microscopy images revealed a faceted and irregular morphology for the as-synthesised nanoparticles. Magnetic measurements revealed a ferromagnetic nature for the 14 and 9 nm particles and a superparamagnetic nature for the 6 nm particles. An increase in saturation magnetisation with increasing particle size was noted. Relaxivity measurements were carried out to determine T2 value as a function of particle size using nuclear magnetic resonance measurements. The relaxivity coefficient increased with decrease in particle size and decrease in the saturation magnetisation value. The observed trend in the change of relaxivity value with particle size was attributed to the faceted nature of as-synthesised nanoparticles. Faceted morphology results in the creation of high gradient of magnetic field in the regions adjacent to the facet edges increasing the relaxivity value. The effect of edges in increasing the relaxivity value increases with decrease in the particle size because of an increase in the total number of edges per particle dispersion.

  2. Facile synthesis of manganese ferrite/graphene oxide nanocomposites for controlled targeted drug delivery

    Science.gov (United States)

    Wang, Guangshuo; Ma, Yingying; Zhang, Lina; Mu, Jingbo; Zhang, Zhixiao; Zhang, Xiaoliang; Che, Hongwei; Bai, Yongmei; Hou, Junxian

    2016-03-01

    In this study, manganese ferrite/graphene oxide (MnFe2O4/GO) nanocomposites as controlled targeted drug delivery were prepared by a facile sonochemical method. It was found that GO nanosheets were fully exfoliated and decorated with MnFe2O4 nanoparticles having diameters of 5-13 nm. The field-dependent magnetization curve indicated superparamagnetic behavior of the obtained MnFe2O4/GO with saturation magnetization of 34.9 emu/g at room temperature. The in vitro cytotoxicity testing exhibited negligible cytotoxicity of as-prepared MnFe2O4/GO even at the concentration as high as 150 μg/mL. Doxorubicin hydrochloride (DOX) as an anti-tumor model drug was utilized to explore the application potential of MnFe2O4/GO for controlled drug delivery. The drug loading capacity of this nanocarrier was as high as 0.97 mg/mg and the drug release behavior showed a sustained and pH-responsive way.

  3. Ferroferric oxide/polystyrene (Fe3O4/PS superparamagnetic nanocomposite via facile in situ bulk radical polymerization

    Directory of Open Access Journals (Sweden)

    2010-03-01

    Full Text Available Organo-modified ferroferric oxide superparamagnetic nanoparticles, synthesized by the coprecipitation of superparamagnetic nanoparticles in presence of oleic acid (OA, were incorporated in polystyrene (PS by the facile in situ bulk radical polymerization by using 2,2-azobisisobutyronitrile (AIBN as initiator. The transmission electron microscopy (TEM analysis of the resultant uniform ferroferric oxide/polystyrene superparamagnetic nanocomposite (Fe3O4/PS showed that the superparamagnetic nanoparticles had been dispersed homogeneously in the polymer matrix due to the surface grafted polystyrene, confirmed by Fourier transform infrared (FT-IR spectroscopy and thermogravimetric analysis (TGA. The superparamagnetic property of the Fe3O4/PS nanocomposite was testified by the vibrating sample magnetometer (VSM analysis. The strategy developed is expected to be applied for the large-scale industrial manufacturing of the superparamagnetic polymer nanocomposite.

  4. Specific loss power in superparamagnetic hyperthermia: nanofluid versus composite

    Science.gov (United States)

    Osaci, M.; Cacciola, M.

    2017-01-01

    Currently, the magnetic hyperthermia induced by nanoparticles is of great interest in biomedical applications. In the literature, we can find a lot of models for magnetic hyperthermia, but many of them do not give importance to a significant detail, such as the geometry of nanoparticle positions in the system. Usually, a nanofluid is treated by considering random positions of the nanoparticles, geometry that is actually characteristic to the composite nanoparticles. To assess the error which is frequently made, in this paper we propose a comparative analysis between the specific loss power (SLP) in case of a nanofluid and the SLP in case of a composite with magnetic nanoparticles. We are going to use a superparamagnetic hyperthermia model based on the improved model for calculating the Néel relaxation time in a magnetic field oblique to the nanoparticle magnetic anisotropy axes, and on the improved theoretical model LRT (linear response theory) for SLP. To generate the nanoparticle geometry in the system, we are going to apply a Monte Carlo method to a nanofluid, by minimising the interaction potentials in liquid medium and, for a composite environment, a method for generating random positions of the nanoparticles in a given volume.

  5. Microstructure of pre-sintered permanent magnetic strontium ferrite powder

    Institute of Scientific and Technical Information of China (English)

    YU Hongya; LIU Zhengyi; ZENG Dechang

    2006-01-01

    The microstructure and characteristics of pre-sintered strontium ferrite powderwere investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The present study shows that the pre-sintered strontium ferrite powder is provided with a certain particle size distribution, which results in high-density magnets. The strontium ferrite particle has a laminar hexagonal structure with a size similar to ferrite single domain. Ferric oxidephase due to an incomplete solid phase reaction in the first sintering is discovered, which will deteriorate the magnetic properties of ferrite magnet. In addition, the waste ferrite magnets with needle shape arranging along C axis in good order into the powders are found, which have no negative effects on finished product quality.

  6. Ferrite-Piezoelectric Layered Composites: Synthesis and Magnetoelectric Characterization

    Science.gov (United States)

    Hayes, R. W.; Srinivasan, G.

    2004-10-01

    The observation of strong magnetoelectric effects is reported in thick film bilayers and multilayers of ferrite-lead titanate zirconate (PZT). The ferrites used in our studies included pure and zinc substituted cobalt-, nickel- and lithium ferrites. Samples were prepared by sintering 10-40 mm thick films obtained by tape-casting. Measurements of ME voltage coefficients at 10-1000 Hz indicated a giant ME effect in nickel ferrite-PZT, but a relatively weak coupling in other ferrite-PZT systems. Evidence was found for enhancement in ME coefficients when Zn was substituted in ferrites. The Zn-assisted increase was attributed to low anisotropy and high permeability that resulted in favorable magneto-mechanical coupling in the composites. G. Srinivasan, E. T. Rasmussen, and R. Hayes, Phys. Rev. B 67, 014418 (2003) Supported by NSF and ARO grants.

  7. Removing Cd2+ by Composite Adsorbent Nano-Fe3O4/Bacterial Cellulose

    Institute of Scientific and Technical Information of China (English)

    LU Min; GUAN Xiao-hui; WEI De-zhou

    2011-01-01

    A new composite adsorbent,nano-Fe3O4/bacterial cellulose(BC),was prepared through blending method.The process of adsorbing Cd2+ including its isotherm and kinetics measured was studied.The results show that the adsorption efficiency is improved because of huge surface area and surface coordination of nano-Fe3O4 particles.Its adsorption capacity is 27.97 mg/g and the maximum of Cd2+ removal is 74%.The adsorption kinetics can be described by pseudo-second rate model and the adsorption equilibrium by Langmuir type.The superparamagnetism of nano-Fe3O4 particles can help to solve the difficult separation of single BC adsorbent and lead to the quick separation of composite adsorbent from the liquid if a magnetic field was applied.Cd2+ can be desorbed effectively by EDTA and HCl from the composite adsorbent,which can make it be reused.

  8. An investigation of co-fired varistor-ferrite materials

    OpenAIRE

    Rafferty, Aran; Gun'ko, Yurii; Raghavendra, Ramesh

    2004-01-01

    The purpose of this work was to co-fire crack-free varistor-ferrite ceramic multilayers fabricated via a dry pressing route. Multilayers were sintered using a standard industrial grade varistor sintering regime. Sinter shrinkages of both varistor and ferrite materials were measured using dilatometry and showed that the varistor shrunk significantly more than the ferrite material. X-ray diffraction analysis indicated that no significant phase changes occurred in the materials under in...

  9. The Development of Low Activation Ferritic Steels for Fusion Application

    OpenAIRE

    Kohyama, A; Hishinuma, A.; Kohno, Y; Shiba, K; Sagara, A.

    1997-01-01

    The development of low-activation ferritic/martensitic steels is a key to the achievement of nuclear fusion as a safe, environmentally attractive and economically competitive energy source. The Japanese and the European Fusion Materials programs have put low-activation ferritic and martensitic steels R & D at the highest priority for a demonstration reactor (DEMO) and the beyond. An international collaborative test program on low-activation ferritic/martensitic steels for fusion is in progres...

  10. Annealing-induced Grain Refinement in a Nanostructured Ferritic Steel

    Institute of Scientific and Technical Information of China (English)

    Limin Wang; Zhenbo Wangt; Sheng Guo; Ke Lu

    2012-01-01

    A nanostructured surface layer with a mean ferrite grain size of -8 nm was produced on a Fe-gCr steel by means of surface mechanical attrition treatment. Upon annealing, ferrite grains coarsen with increasing temperature and their sizes increase to -40 nm at 973 K. Further increasing annealing temperature leads to an obvious reduction of ferrite grain sizes, to -14 nm at 1173 K. The annealing-induced grain refinement is analyzed in terms of phase transformations in the nanostructured steel.

  11. Structural and magnetic properties of Ni{sub 0.15}Mg{sub 0.1}Cu{sub 0.3}Zn{sub 0.45}Fe{sub 2}O{sub 4} ferrite prepared by NaOH-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Wei-xiao; Wang, Zhi, E-mail: zhiwang@tju.edu.cn

    2015-09-15

    Highlights: • NiMgCuZn ferrites were successfully prepared by low-temperature sintering. • NiMgCuZn ferrites have the advantages of both NiCuZn and MgCuZn ferrites. • NiMgCuZn ferrites exhibit high Curie temperature & high stability of permeability. - Abstract: The Ni{sub 0.15}Mg{sub 0.1}Cu{sub 0.3}Zn{sub 0.45}Fe{sub 2}O{sub 4} ferrite powders have been prepared by NaOH co-precipitation method and characterized by X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The XRD patterns confirm the single phase spinel structure of synthesized nanoparticles. The average crystallite size of the particles increases from 12 to 36 nm with calcining temperature (T{sub a}) from 500 to 800 °C. The saturation magnetization (M{sub s}) of the superparamagnetic particles was deduced by Langevin theory. Subsequently, the densification characteristics and magnetic properties of the low-temperature 950 °C-sintered ferrite bulk samples were also investigated. The magnetic measurement showed that the sintered bulk sample of T{sub a} = 600 °C has the highest initial permeability (μ{sub i}), lowest coercivity (H{sub c}), largest saturation magnetization (M{sub s}) and satisfactory thermal stability of μ{sub i}. The microstructures of sintered samples were examined using field emission scanning electric microscope (FESEM). The T{sub a} has significant influence on the bulk density, initial permeability, saturation magnetization and coercivity of Ni{sub 0.15}Mg{sub 0.1}Cu{sub 0.3}Zn{sub 0.45}Fe{sub 2}O{sub 4} ferrite.

  12. Tunable dielectric properties of ferrite-dielectric based metamaterial.

    Science.gov (United States)

    Bi, K; Huang, K; Zeng, L Y; Zhou, M H; Wang, Q M; Wang, Y G; Lei, M

    2015-01-01

    A ferrite-dielectric metamaterial composed of dielectric and ferrite cuboids has been investigated by experiments and simulations. By interacting with the electromagnetic wave, the Mie resonance can take place in the dielectric cuboids and the ferromagnetic precession will appear in the ferrite cuboids. The magnetic field distributions show the electric Mie resonance of the dielectric cuboids can be influenced by the ferromagnetic precession of ferrite cuboids when a certain magnetic field is applied. The effective permittivity of the metamaterial can be tuned by modifying the applied magnetic field. A good agreement between experimental and simulated results is demonstrated, which confirms that these metamaterials can be used for tunable microwave devices.

  13. Ferrite microwave electronics Citations from the NTIS data base

    Science.gov (United States)

    Reed, W. E.

    1980-07-01

    Research reports on single crystals, thin films, dielectrics, semiconductor devices, integrated circuits, phase shifters, and waveguide components are cited. Studies on the microwave properties of ferrites are included.

  14. Ferritic-austenitic cast steel - selected problems

    Directory of Open Access Journals (Sweden)

    Z. Stradomski

    2011-07-01

    Full Text Available The author has been involved in the problems occurring in the manufacture of ferritic-austenitic cast steel castings for many years. The author’s remarks and investigation results reported in this article will enable potential manufacturers to determine their own technical capabilities and structural determinants related to the chemical composition of material, which are crucial to the good quality of a casting. Particular emphasis should be laid on the role of enhanced carbon content, the presence of copper, the precipitates of the ζ phase, and the nature of solidification structure in the tendency of duplex-type cast steel to cracking. It seems that in view of the pro-ecological activities undertaken, including flue gas desulphurization in coal-fired power plants, efforts should be made in steel foundries to introduce selected grades of ferritic-austenitic cast steel to production.

  15. High Efficiency ELID Grinding of Garnet Ferrite

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Hard and brittle materials such as ferrite, optical glass and ceramics have been widely used in many fields because of their good characteristics and still gain more attentions. However, it is difficult to machine and get good surface quality. Some parts made of these materials have large machining allowances and need to be produced with large batch, but the machining efficiency is very low with usual grinding method. So it is of great importance to research the high efficiency grinding technology of hard ...

  16. Preparation and Characterization of Manganese Ferrite Aluminates

    Directory of Open Access Journals (Sweden)

    R. L. Dhiman

    2008-01-01

    Full Text Available Aluminum doped manganese ferrites MnAlxFe2−xO4 with 0.0≤x≤1.0 have been prepared by the double ceramic route. The formation of mixed spinel phase has been confirmed by X-ray diffraction analysis. The unit cell parameter `aO' is found to decrease linearly with aluminum concentration due to smaller ionic radius of aluminum. The cation distributions were estimated from X-ray diffraction intensities of various planes. The theoretical lattice parameter, X-ray density, oxygen positional parameter, ionic radii, jump length, and bonds and edges lengths of the tetrahedral (A and octahedral (B sites were determined. 57Fe Mössbauer spectra recorded at room temperature were fitted with two sextets corresponding to Fe3+ ions at A- and B-sites. In the present ferrite system, the area ratio of Fe3+ ions at the A- and B-sites determined from the spectral analysis of Mössbauer spectra gives evidence that Al3+ ions replace iron ions at B-sites. This change in the site preference reflects an abrupt change in magnetic hyperfine fields at A- and B-sites as aluminum concentration increases, which has been explained on the basis of supertransferred hyperfine field. On the basis of estimated cation distribution, it is concluded that aluminum doped manganese ferrites exhibit a 55% normal spinel structure.

  17. Magnetoviscoelastic characteristics of superparamagnetic oxides (Fe, Ni) based ferrofluids

    Science.gov (United States)

    Katiyar, Ajay; Dhar, Purbarun; Nandi, Tandra; Das, Sarit K.

    2017-08-01

    Ferrofluids have been popular among the academic and scientific communities owing to their intelligent physical characteristics under external stimuli and are in fact among the first nanotechnology products to be employed in real world applications. However, studies on the magnetoviscoelastic behavior of concentrated ferrofluids, especially of superparamagnetic oxides of iron and nickel are rare. The present article comprises the formulation of magneto-colloids utilizing the three various metal oxides nanoparticles viz. Iron (II, III) oxide (Fe3O4), Iron (III) oxide (Fe2O3) and Nickel oxide (NiO) in oil. Iron (II, III) oxide based colloids demonstrate high magnetoviscous characteristics over the other oxides based colloids under external magnetic fields. The maximum magnitude of yield stress and viscosity is found to be 3.0 kPa and 2.9 kPa.s, respectively for iron (II, III) oxide based colloids at 2.6 vol% particle concentration and 1.2 T magnetic field. Experimental investigations reveal that the formulated magneto-nanocolloids are stable, even in high magnetic fields and almost reversible when exposed to rising and drop of magnetic fields of the same magnitude. Observations also reveal that the elastic behavior dominates over the viscous behavior with enhanced relaxation and creep characteristics under the magnetic field. The effect of temperature on viscosity and yield stress of magneto-nanocolloids under magnetic fields has also been discussed. Thus, the present findings have potential applications in various fields such as electromagnetic clutch and brakes of automotive, damping, sealing, optics, nanofinishing etc.

  18. Nano devices and sensors

    CERN Document Server

    Liaw, Shien-Kuei; Chung, Yung-Hui

    2016-01-01

    This volume on semiconductor devices focuses on such topics as nano-imprinting, lithography, nanowire charge-trapping, thermo-stability in nanowires, nano-electrodes, and voltage and materials used for fabricating and improving electrical characteristics of nano-materials.

  19. 阳离子配比对共沉淀法制备的镍锌铁陵盐纳米颗粒的结构和磁性的影响%Effect of Cation Proportion on the Structural and Magnetic Properties of Ni-Zn Ferrites Nano-Size Particles Prepared By Co-Precipitation Technique

    Institute of Scientific and Technical Information of China (English)

    Santosh S.Jadhav; Sagar E.Shirsath; B.G.Toksha; S.J.Shukla; K.M.Jadhav

    2008-01-01

    用共沉淀法制备了结构式为Ni1-xZnxFe2O4(x=0.0,0.1,0.2,0.3,0.4,0.5,0.6,0.7)的铁酸盐纳米颗粒,并对这些纳米颗粒进行了X射线衍射,磁化和交流易感性的测量.X射线衍射的分析结果确认了样品中形成的单相结构.从X射线衍射嘴获得的晶格参数随锌的配比x的增大而增大.通过X射线衍射强度比的计算获得了阳离子分布.磁化研究的结果表明在x0.4时没有共线性关系.交流易感性测量获得的居里温度TC被发现随xz的升高而降低.%Ferrites having general formula Ni1-xZnxFe2O4 with x=0.0,0.1,0.2,0.3,0.4,0.5,0.6,and 0.7 were prepared by wet chemical co-precipitation method.The structural and magnetic properties were studied by means of X-ray diffraction,magnetization,and AC susceptibility measurements.The X-ray analysis confirmed the single-phase formation of the samples.The lattice parameter obtained from XRD data was found to increase with Zn content x.The cation distribution Was studied by X-ray intensity ratio calculations.Magnetization results exhibit collinear ferrimagnetic structure for x≤0.4,and which changes to non-collinear for x>0.4.Curie temperature Tc obtained from AC susceptibility data decreases with increasing x.

  20. The Formation Process of Silico-Ferrite of Calcium (SFC) from Binary Calcium Ferrite

    Science.gov (United States)

    Ding, Xiang; Guo, Xing-Min

    2014-08-01

    Silico-ferrite of calcium (SFC) is a significant equilibrium crystalline phase in the Fe2O3-CaO-SiO2 (FCS) ternary system and a key bonding phase in the sintering process of fine iron ore. In this work, the formation process of SFC from binary calcium ferrite has been determined by X-ray diffraction and field-emission scanning electron microscopy. Experiments were carried out under air at 1473 K (1200 °C) by adding SiO2 and Fe2O3 into CaO·Fe2O3 (CF). It was found that the formation of SFC is dominated by solid-state reactions in the FCS ternary system, in which Fe2O3 reacts with CaO·Fe2O3 to form the binary calcium ferrite phase. The chemical composition of binary calcium ferrite is Ca2.5Fe15.5O25 and approximately Ca2Fe12O20 (CaO·3Fe2O3). Then Si4+ and Ca2+ ions take the place of Fe3+ ion in preference located on the octahedral layers which belongs to (0 0 18) plane of binary calcium ferrite. The crystal structure of binary calcium ferrite gradually transforms from orthorhombic to triclinic, and the grain is refined with the addition of silica due to the smaller radius of Si4+ ion. A solid solution SFC forms completely when the content of SiO2 reaches approximately 3.37 wt pct at 1473 K (1200 °C).

  1. Structural, electrical and magnetic properties of Sc3+ doped Mn-Zn ferrite nanoparticles

    Science.gov (United States)

    Angadi, V. Jagdeesha; Choudhury, Leema; Sadhana, K.; Liu, Hsiang-Lin; Sandhya, R.; Matteppanavar, Shidaling; Rudraswamy, B.; Pattar, Vinayak; Anavekar, R. V.; Praveena, K.

    2017-02-01

    Sc3+ doped Mn0.5Zn0.5ScyFe2-yO4 (y=0.00, 0.01, 0.03 and 0.05) nanoparticles were synthesized by solution combustion method using mixture of fuels were reported for the first time. The mixture of fuels plays an important role in obtaining nano crystalline, single phase present without any heat treatment. X-ray diffraction (XRD) results confirm the formation of the single-phase ferrites which crystallize in cubic spinel structure. The Fourier transform infrared spectra (FTIR) exhibit two prominent bands around 360 cm-1 and 540 cm-1 which are characteristic feature of spinel ferrite. The transmission electron microscope (TEM) micrographs revealed the nanoparticles to be nearly spherical in shape and of fairly uniform size. The room temperature impedance spectra (IS) and vibrating sample magnetometry (VSM) measurements were carried out in order to study the effect of doping (Sc3+) on the characteristic properties of Mn-Zn ferrites. Further, the frequency dependent dielectric constant and dielectric loss were found to decrease with increasing multiple Sc3+ concentration. Nyquist plot in the complex impedance spectra suggest the existence of multiple electrical responses. Magnetic measurements reveals that saturation magnetization (Ms), remnant magnetization (Mr), magnetic moment (ηB) and magnetic particle size (Dm) increase with Sc3+ ion concentration up to x=0.03 and then decrease. The values of spin canting angle (αY-K) and the magnetic particle size (Dm) are found to be in the range of 68-75° and 10-19 nm respectively with Sc3+ concentration. The room temperature Mössbauer spectra were fitted with two sextets corresponding to ions at tetrahedral (A-) and octahedral (B-) sites confirms the spinel lattice. The ferromagnetic resonance (FMR) spectra's has shown that high concentration of scandium doping leads to an increase in dipolar interaction and decrease in super exchange interaction.

  2. Influence of mechanical milling and thermal annealing on electrical and magnetic properties of nanostructured Ni–Zn and cobalt ferrites

    Indian Academy of Sciences (India)

    A Narayanasamy; N Sivakumar

    2008-06-01

    The present article reports some of the interesting and important electrical and magnetic properties of nanostructured spinel ferrites such as Ni0.5Zn0.5Fe2O4 and CoFe2O4. In the case of Ni0.5Zn0.5Fe2O4, d.c. electrical conductivity increases upon milling, and it is attributed to oxygen vacancies created by high energy mechanical milling. The real part of dielectric constant (') for the milled sample is found to be about an order of magnitude smaller than that of the bulk nickel zinc ferrite. The increase in Néel temperature from 538 K in the bulk state to 611 K on the reduction of grain size upon milling has been explained based on the change in the cation distribution. The dielectric constant is smaller by an order of magnitude and the dielectric loss is three orders of magnitude smaller for the milled sample compared to that of the bulk. In the case of cobalt ferrite, the observed decrease in conductivity, when the grain size is increased from 8–92 nm upon thermal annealing is clearly due to the predominant effect of migration of some of the Fe3+ ions from octahedral to tetrahedral sites, as is evident from in-field Mössbauer and EXAFS measurements. The dielectric loss (tan ) is an order of magnitude smaller for the nano sized particles compared to that of the bulk counterpart.

  3. Study of electrical and dielectric behavior of Tb{sup +3} substituted Y-type hexagonal ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Irshad, E-mail: irshadalibzu@gmail.com [Department of Physics, Bahauddin Zakariya University, Multan (Pakistan); Shaheen, Nasira; Islam, M.U.; Irfan, Muhammad [Department of Physics, Bahauddin Zakariya University, Multan (Pakistan); Ashiq, Muhammad Naeem, E-mail: naeemashiqqau@yahoo.com [Institute of Chemical Sciences, Bahauddin Zakariya University, Multan (Pakistan); Asif Iqbal, M.; Iftikhar, Aisha [Department of Physics, Bahauddin Zakariya University, Multan (Pakistan)

    2014-12-25

    Highlights: • Y-type hexa-ferrites were synthesized by sol–gel auto-combustion technique. • XRD analysis revealed the nano-crystalline nature of the prepared samples. • Materials can be used for high frequency applications due to the high resistivity. - Abstract: A series of Y-type hexa-ferrites with composition, Ba{sub 2}Zn{sub 2}Tb{sub x}Fe{sub 12−x}O{sub 22} (0 ⩽ x ⩽ 0.1), were synthesized by the sol–gel auto-combustion technique. The X-ray powder diffraction technique was employed to confirm the formation of Y-type phase. The dispersion in dielectric constant, dielectric loss, and σ{sub ac} with frequency shows that the dispersion at low frequencies is due to Maxwell–Wagner type of interfacial polarization in general and the hopping of charge carrier between Fe{sup 2+} and Fe{sup 3+} ions. The substitution of Tb{sup +3} inhibit the valence exchange of Fe{sup +2} and Fe{sup 3+} and therefore the dielectric permittivity decreased. The DC resistivity increased from 7.29 × 10{sup 7} to 4.73 × 10{sup 8} Ω cm with increasing Tb-contents due to the unavailability of Fe{sup 3+} ions at octahedral sites. The enhanced resistivity of Y-type hexa ferrites makes them suitable candidates for multi-layer chip inductor applications.

  4. Dextrin-coated zinc substituted cobalt-ferrite nanoparticles as an MRI contrast agent: In vitro and in vivo imaging studies.

    Science.gov (United States)

    Sattarahmady, N; Zare, T; Mehdizadeh, A R; Azarpira, N; Heidari, M; Lotfi, M; Heli, H

    2015-05-01

    Application of superparamagnetic iron oxide nanoparticles (NPs) as a negative contrast agent in magnetic resonance imaging (MRI) has been of widespread interest. These particles can enhance contrast of images by altering the relaxation times of the water protons. In this study, dextrin-coated zinc substituted cobalt-ferrite (Zn0.5Co0.5Fe2O4) NPs were synthesized by a co-precipitation method, and the morphology, size, structure and magnetic properties of the NPs were investigated. These NPs had superparamagnetic behavior with an average size of 3.9 (±0.9, n=200)nm measured by transmission electron microscopy. Measurements on the relaxivities (r2 and r2(*)) of the NPs were performed in vitro by agarose phantom. In addition, after subcutaneous injection of the NPs into C540 cell line in C-57 inbred mice, the relaxivities were measured in vivo by a 1.5T MRI system. These NPs could effectively increase the image contrast in both T2-and T2(*)-weighted samples.

  5. Development of cobalt ferrite powder preparation employing the sol-gel technique and its structural characterisation

    Directory of Open Access Journals (Sweden)

    Olabi A.G.

    2010-06-01

    Full Text Available This work focuses on the development of a method to make nano cobalt ferrite powder using a solgel process. A particular emphasis is devoted to the understanding of the role of the chemical parameters involved in the solgel technique, and of the heat treatment on the structures and morphologies of the materials obtained. Several samples of cobalt ferrite powder were obtained by varying the initial parameters of the process in addition to the heat treatment temperature. Xray diffraction and scanning electron microscopy were used to identify the structure and morphology of samples demonstrating the influence of the initial parameters. DTA/TGA was carried out on one sample to identify important reaction temperatures during the heat treatment. The average particle size, as estimated for one sample by the full width at half maximum (FWHM of the strongest Xray diffraction (XRD peak, was found to be about 45 nm. It has been found that the chelating agent and the crosslinker have a critical influence on the resultant structure, the particle size and the particle size distribution.

  6. Cobalt Zinc Ferrite Nanoparticles as a Potential Magnetic Resonance Imaging Agent: An In vitro Study

    Science.gov (United States)

    Ghasemian, Zeinab; Shahbazi-Gahrouei, Daryoush; Manouchehri, Sohrab

    2015-01-01

    Background: Magnetic Nanoparticles (MNP) have been used for contrast enhancement in Magnetic Resonance Imaging (MRI). In recent years, research on the use of ferrite nanoparticles in T2 contrast agents has shown a great potential application in MR imaging. In this work, Co0.5Zn0.5Fe2O4 and Co0.5Zn0.5Fe2O4-DMSA magnetic nanoparticles, CZF-MNPs and CZF-MNPs-DMSA, were investigated as MR imaging contrast agents. Methods: Cobalt zinc ferrite nanoparticles and their suitable coating, DMSA, were investigated under in vitro condition. Human prostate cancer cell lines (DU145 and PC3) with bare (uncoated) and coated magnetic nanoparticles were investigated as nano-contrast MR imaging agents. Results: Using T2-weighted MR images identified that signal intensity of bare and coated MNPs was enhanced with increasing concentration of MNPs in water. The values of 1/T2 relaxivity (r2) for bare and coated MNPs were found to be 88.46 and 28.80 (mM−1 s−1), respectively. Conclusion: The results show that bare and coated MNPs are suitable as T2-weighted MR imaging contrast agents. Also, the obtained r2/r1 values (59.3 and 50) for bare and coated MNPs were in agreement with the results of other previous relevant works. PMID:26140183

  7. Magnetic and magneto elastic properties of cobalt ferrite ceramic compacted through cold isostatic pressing

    Energy Technology Data Exchange (ETDEWEB)

    Indla, Srinivas; Das, Dibakar, E-mail: ddse@uohyd.ernet.in [School of Engineering Sciences and Technology, University of Hyderabad, Hyderabad 500046 (India); Chelvane, Arout [Advanced Magnetic Group, Defense Metallurgical Research Laboratory, Kanchanbagh, Hyderabad 500058 (India)

    2016-05-06

    Nano crystalline CoFe{sub 2}O{sub 4} powder was prepared by combustion synthesis method. As synthesized powder was calcined at an appropriate condition to remove the impurities and to promote phase formation. Phase pure CoFe{sub 2}O{sub 4} powder was pressed into cylindrical rod at an applied pressure of 200 MPa using a cold isostatic pressing. Sintering of the green compact at 1350°c for 12 hrs resulted in sintered cylindrical rod with ~85% of the theoretical density. Single phase cubic spinel structure was observed in the powder x-ray diffraction pattern of the sintered pellet. Scanning electron micrographs (SEM) of the as sintered pellet revealed the microstructure to be composed of ferrite grains of average size ~4 µm. Saturation magnetization of 72 emu/g and coercivity of 355 Oe were observed for cobalt ferrite sample. The magnetostriction was measured on a circular disc (12 mm diameter and 12 mm length) with the strain gauge (350 Ω) mounted on the flat surface of the circular disc. Magnetostriciton of 180 ppm and strain derivative of 1 × 10{sup −9} m/A were observed for the sintered CoFe{sub 2}O{sub 4} sample.

  8. Synthesis of superparamagnetic iron oxide nanoparticles coated with a DDNP-carboxyl derivative for in vitro magnetic resonance imaging of Alzheimer's disease.

    Science.gov (United States)

    Zhou, Jingting; Fa, Huanbao; Yin, Wei; Zhang, Jin; Hou, Changjun; Huo, Danqun; Zhang, Dong; Zhang, Haifeng

    2014-04-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) have been proposed for use in magnetic resonance imaging as versatile ultra-sensitive nanoprobes for Alzheimer's disease imaging. In this work, we synthetized an efficient contrast agent of Alzheimer's disease using 1,1-dicyano-2-[6-(dimethylamino)naphthalene-2-yl]propene (DDNP) carboxyl derivative to functionalize the surface of SPIONs. The DDNP-SPIONs are prepared by conjugating DDNP carboxyl derivative to oleic acid-treated SPIONs through ligand exchange. The structure, size distribution and magnetic property were identified by IR, TGA-DTA, XRD, TEM, Zetasizer Nano and VSM. TEM and Zetasizer Nano observations indicated that the DDNP-SPIONs are relatively mono-dispersed spherical distribution with an average size of 11.7nm. The DDNP-SPIONs were then further analyzed for their MRI relaxation properties using MR imaging and demonstrated high T2 relaxivity of 140.57s(-1)FemM(-1), and the vitro experiment that DDNP-SPIONs binding to β-Amyloid aggregates were then investigated by fluorophotometry, the results showed that the combination had induced the fluorescence enhancement of the DDNP-SPIONs and displayed tremendous promise for use as a contrast agent of Alzheimer's disease in MRI. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Barium ferrite/epoxy resin nanocomposite system: Fabrication, dielectric, magnetic and hydration studies

    Directory of Open Access Journals (Sweden)

    A. Kanapitsas

    2016-03-01

    Full Text Available Composite systems of epoxy resin and barium ferrite nanoparticles have been prepared, and studied varying the content of the inclusions. Morphology of prepared samples has been examined via scanning electron microscopy and X-ray diffraction spectra, while electrical and magnetic properties were investigated by means of broadband dielectric spectroscopy, and magnetization tests respectively. Finally, water vapor sorption measurements were conducted in order to study the water sorption dynamics of the system. Electron microscopy images revealed the successful fabrication of nanocomposites. Dielectric permittivity increases with filler content, while three relaxation processes were detected in the relative spectra. These processes are attributed to interfacial polarization, glass to rubber transition of the matrix, and re-orientation of polar side groups of the polymer’s chain. Magnetization and magnetic saturation increase with magnetic nano-powder content. Nanocomposites absorb a small amount of water, not exceeding 1.7 wt%, regardless filler content, indicating their hydrophobic character.

  10. Temperature dependence of the spin relaxation time of Fe3O4 and hemozoin superparamagnetic nanocrystals

    Science.gov (United States)

    Khmelinskii, I.; Makarov, V.

    2017-08-01

    We report experimental temperature and concentration dependences of the natural spin relaxation time of superparamagnetic Fe3O4 and hemozoin nanocrystals. We recorded the 1H NMR spectrum of 0.5% benzene dissolved in CS2 in function of superparamagnetic particle concentration and temperature, interpreting the 7.261 ± 0.002 ppm benzene line broadening. Our model for the line broadening includes natural, hyperfine magnetic dipole-dipole, and contact hyperfine contributions. The latter arises due to exchange interaction between benzene molecules and suspended nanoparticles. Estimated frequency of fluctuation in the 1 cm3 sample volume is in the 107 Hz scale. Estimated natural electron spin-lattice relaxation frequencies of the superparamagnetic nanocrystals using frequency of fluctuations, and developed theoretical model applied to analysis of experimental data are in good agreement between each other. Thus the presently developed approach may be used to study fluctuations and natural spin-lattice relaxation frequencies in different media.

  11. Magnetomechanics of superparamagnetic beads on a magnetic merry-go-round: from micromagnetics to radial looping

    Science.gov (United States)

    Sajjad, Umer; Bahne Holländer, Rasmus; Klingbeil, Finn; McCord, Jeffrey

    2017-04-01

    The motion of functionalized superparamagnetic beads provides the foundation for the manipulation of labelled chemical and biological species in microfluidic environments, where patterned ferromagnetic thin films serve as a versatile and reconfigurable platform for biomedical applications. A recurring release and capture of superparamagnetic microbeads is achieved by moving stray magnetic field gradients generated by a circulating micromagnetic state of a soft magnetic disc. The full micromagnetic analysis of the transport dynamics fully describes the fundamental alternating behaviour of microsphere motion. An excellent level of agreement is obtained between experiment and modelling for all stages of motion, confirming the validity of describing particle motion dynamics in the applied quasi ab initio modelling approach. The demonstrated comprehension of the non-linear microbead displacement opens the way towards the modelling of various alternative dynamic excitation schemes, even for complicated integrated micromagnetic platforms, for controlled biological analyte–superparamagnetic bead manipulation.

  12. Computational study on superparamagnetic hyperthermia with biocompatible SPIONs to destroy the cancer cells

    Science.gov (United States)

    Caizer, C.

    2014-06-01

    Superparamagnetic hyperthermia (SPMHT) appears nowadays as the most promising method of the future, non-invasive and with low toxicity, for destroys the cancer cells through the magnetic relaxation in superparamagnetic nanoparticles. In our research we focused on finding the optimal conditions using a 3D computational study to obtain a maximum specific absorption rate (SAR) by the magnetic relaxation in Fe3O4 and γ-Fe2O3 superparamagnetic iron oxide nanoparticles (SPIONs), which give the most pronounced SAR and with low toxicity on cells. The effect of the diameter of the nanoparticles, frequency and amplitude of external alternating magnetic field and the thickness of biological coating of nanoparticles in the case of their encapsulation in biocompatible membranes, like liposomes (Ls) and cyclodextrins (CDs), on Néel-Brown magnetic relaxation and maximum SAR, are presented and discussed in this paper, within the biological admitted limit.

  13. Hypothetical superparamagnetic magnetometer in a pigeon's upper beak probably does not work.

    Science.gov (United States)

    Jandačka, Petr; Alexa, Petr; Pištora, Jaromír; Trojková, Jana

    2013-04-01

    We reanalysed the role of superparamagnetic magnetite clusters observed in a pigeon's upper beak to decide if this matter can be a component of some sort of pigeon magnetometer for Earth orientation. We investigated the mutual interaction of the magnetite clusters induced by the geomagnetic field. The force sensitivity of the hypothetical magnetometer in a pigeon's upper beak was estimated considering the previously presented threshold magnetic sensitivity of pigeons, measured in electrophysiological and behavioural investigations. The typical intercluster magnetic force seems to be 10(-19)N well above the threshold magnetic sensitivity. To strengthen our results, we measured the magnetic susceptibility of superparamagnetic magnetite using a vibrating sample magnetometer. Finally we performed theoretical kinematic analysis of the motion of magnetite clusters in cell plasma. The results indicate that magnetite clusters, constituted by superparamagnetic nanoparticles and observed in a pigeon's upper beak, may not be a component of a measuring system providing the magnetic map.

  14. Silica nanocapsules of fluorescent conjugated polymers and superparamagnetic nanocrystals for dual-mode cellular imaging.

    Science.gov (United States)

    Tan, Happy; Wang, Miao; Yang, Chang-Tong; Pant, Shilpa; Bhakoo, Kishore Kumar; Wong, Siew Yee; Chen, Zhi-Kuan; Li, Xu; Wang, John

    2011-06-01

    We describe here a facile and benign synthetic strategy to integrate the fluorescent behavior of conjugated polymers and superparamagnetic properties of iron oxide nanocrystals into silica nanocapsules, forming a new type of bifunctional magnetic fluorescent silica nanocapsule (BMFSN). The resultant BMFSNs are uniform, colloidally stable in aqueous medium, and exhibit the desired dual functionality of fluorescence and superparamagnetism in a single entity. Four conjugated polymers with different emissions were used to demonstrate the versatility of employing this class of fluorescent materials for the preparation of BMFSNs. The applicability of BMFSNs in cellular imaging was studied by incubating them with human liver cancer cells, the result of which demonstrated that the cells could be visualized by dual-mode fluorescence and magnetic resonance imaging. Furthermore, the superparamagnetic behavior of the BMFSNs was exploited for in vitro magnetic-guided delivery of the nanocapsules into the cancer cells, thereby highlighting their potential for targeting biomedical applications.

  15. Effect of zinc concentration on the structural and magnetic properties of mixed Co–Zn ferrites nanoparticles synthesized by sol/gel method

    Energy Technology Data Exchange (ETDEWEB)

    Ben Ali, M., E-mail: m.benali06@gmail.com [MAScIR Foundation, Institute of Nanomaterials and Nanotechnologies, Materials & Nanomaterials Center, B.P., 10100 Rabat (Morocco); Laboratory of Magnetism and the Physics of the high Energies, URAC 12, Department of Physics, B.P. 1014, Faculty of Science, Mohammed V University, Rabat (Morocco); El Maalam, K. [MAScIR Foundation, Institute of Nanomaterials and Nanotechnologies, Materials & Nanomaterials Center, B.P., 10100 Rabat (Morocco); Laboratory of Magnetism and the Physics of the high Energies, URAC 12, Department of Physics, B.P. 1014, Faculty of Science, Mohammed V University, Rabat (Morocco); El Moussaoui, H.; Mounkachi, O. [MAScIR Foundation, Institute of Nanomaterials and Nanotechnologies, Materials & Nanomaterials Center, B.P., 10100 Rabat (Morocco); Hamedoun, M., E-mail: m.hamedoun@mascir.com [MAScIR Foundation, Institute of Nanomaterials and Nanotechnologies, Materials & Nanomaterials Center, B.P., 10100 Rabat (Morocco); Masrour, R. [Laboratory of Materials, Processes, Environment and Quality, Cady Ayyed University, National School of Applied Sciences, PB 63 46000, Safi (Morocco); Hlil, E.K. [Institut Néel, CNRS-UJF, B.P. 166, 38042 Grenoble Cedex (France); Benyoussef, A. [MAScIR Foundation, Institute of Nanomaterials and Nanotechnologies, Materials & Nanomaterials Center, B.P., 10100 Rabat (Morocco); Laboratory of Magnetism and the Physics of the high Energies, URAC 12, Department of Physics, B.P. 1014, Faculty of Science, Mohammed V University, Rabat (Morocco)

    2016-01-15

    Synthesization of zinc-substituted cobalt ferrites nano-particles Co{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} (x=0.0–0.3) has been achieved by the sol/gel method. The characterization of the synthesized nano-particles has been done by X-ray diffractometry (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FITR). The relation between the composition and magnetic properties has been investigated by Magnetic Properties Measurement System (MPMS). The results revealed that the nanoparticles size is in the range of 11–28 nm. It was found that the zinc substitution in cobalt ferrite increases saturation magnetization from 60.92 emu/g (x=0) to 74.67 emu/g (x=0.3). Nevertheless, zinc concentrations cause a significant decrease in coercivity.▪ - Highlights: • The nanocrystals size of synthesized of Co{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} is of 11–28 nm. • The zinc substitution in cobalt ferrite increase saturation magnetization. • The increase of zinc concentration causes a significant decrease in coercivity.

  16. Photoelectrochemical properties of ferrites with the spinel structure

    NARCIS (Netherlands)

    Haart, L.G.J. De; Blasse, G.

    1985-01-01

    The photoelectrochemical properties of the ferrites ZnFe2O4, MgFe2O4 and Li0.5O4 with the spinel structure are reported. The ferrites seem reasonable candidates for photoanodes in a photoelectrochemical cell, because of their 2.2 eV bandgap. The results show, however, that the visible absorptivity,

  17. A model for ferrite-loaded transversely biased coaxial resonators

    DEFF Research Database (Denmark)

    Acar, Öncel; Zhurbenko, Vitaliy; Johansen, Tom Keinicke

    2013-01-01

    This work describes a simple model for shortened coaxial cavity resonators with transversely biased ferrite elements. The ferrite allows the resonance frequency to be tuned, and the presented model provides a method of approximately calculating these frequencies to generate the tuning curve...

  18. Fundamental study of a one-step ambient temperature ferrite ...

    African Journals Online (AJOL)

    Fundamental study of a one-step ambient temperature ferrite process for treatment ... The approach involves the controlled oxidation of ferrous-containing AMD water at ... The resulting oxidation product is the ferrite (M13+2M22+O4) magnetite ...

  19. Structural investigation of an extended milled ferrite powder

    Energy Technology Data Exchange (ETDEWEB)

    Moisin, A.M.; Macrin, M. (Institutul de Cercetari Electronice, Bucharest (Romania))

    1980-01-01

    An investigation of the structural modifications introduced by the extended milling and annealing processes in the barium ferrite powder during its preparation is presented. X-ray diffraction measuements on a barium ferrite powder in various milling and annealing conditions have been carried out and the results concerning the phase compositions, lattice constants and crystallite sizes are discussed.

  20. Defects, phase transformations and magnetic properties of lithium ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, R.K.

    1977-03-01

    Achieving suitable magnetic properties in ceramic ferrites through thermomechanical treatments rather than through varying the processing and fabrication parameters alone has been investigated. Ferrimagnetic lithium ferrite and some other spinel structure materials were chosen for this investigation. Extensive characterization of phase transformations and lattice defects was done.

  1. Recent advances in synthesis and surface modification of superparamagnetic iron oxide nanoparticles with silica

    Science.gov (United States)

    Sodipo, Bashiru Kayode; Aziz, Azlan Abdul

    2016-10-01

    Research on synthesis of superparamagnetic iron oxide nanoparticles (SPION) and its surface modification for biomedical applications is of intense interest. Due to superparamagnetic property of SPION, the nanoparticles have large magnetic susceptibility, single magnetic domain and controllable magnetic behaviour. However, owing to easy agglomeration of SPION, surface modification of the magnetic particles with biocompatible materials such as silica nanoparticle has gained much attention in the last decade. In this review, we present recent advances in synthesis of SPION and various routes of producing silica coated SPION.

  2. Binding assays with streptavidin-functionalized superparamagnetic nanoparticles and biotinylated analytes using fluxgate magnetorelaxometry

    Energy Technology Data Exchange (ETDEWEB)

    Heim, Erik [TU Braunschweig, Institut fuer Elektrische Messtechnik und Grundlagen der Elektrotechnik, Hans-Sommer-Str. 66, 38106 Braunschweig (Germany)], E-mail: e.heim@tu-bs.de; Ludwig, Frank; Schilling, Meinhard [TU Braunschweig, Institut fuer Elektrische Messtechnik und Grundlagen der Elektrotechnik, Hans-Sommer-Str. 66, 38106 Braunschweig (Germany)

    2009-05-15

    Binding assays based on the magnetorelaxation of superparamagnetic nanoparticles as markers are presented utilizing a differential fluxgate system. As ligand and receptor, streptavidin and biotin, respectively, are used. Superparamagnetic nanoparticles are functionalized with streptavidin and bound to two types of biotinylated analytes: agarose beads and bovine serum (BSA) proteins. The size difference of the two analytes causes a different progress of the reaction. As a consequence, the analysis of the relaxation signal is carried out dissimilarly for the two analytes. In addition, we studied the reaction kinetics of the two kinds of analytes with the fluxgate system.

  3. Decoherence effects on the tunneling rate of paramagnetic and superparamagnetic particles

    CERN Document Server

    Ferreira, E H M; Pfannes, H D

    2003-01-01

    We analyze the effects of the environment on the spin tunneling process of paramagnetic and superparamagnetic particles and conclude that the non assisted macroscopic tunneling rate is hardly affected in such case, but other more effective (phonon mediated) processes change the magnetization state of the particle. We conclude that for both, paramagnetic and superparamagnetic particles, the decoherence time scale is extremely short (~ 10^(-8..-16)seg), indicating thar coherent tunneling should be strongly suppressed in favor of incoherent tunneling, i.e., the population of higher levels with subsequent decay.

  4. A sonochemical approach to the direct surface functionalization of superparamagnetic iron oxide nanoparticles with (3-aminopropyltriethoxysilane

    Directory of Open Access Journals (Sweden)

    Bashiru Kayode Sodipo

    2014-09-01

    Full Text Available We report a sonochemical method of functionalizing superparamagnetic iron oxide nanoparticles (SPION with (3-aminopropyltriethoxysilane (APTES. Mechanical stirring, localized hot spots and other unique conditions generated by an acoustic cavitation (sonochemical process were found to induce a rapid silanization reaction between SPION and APTES. FTIR, XPS and XRD measurements were used to demonstrate the grafting of APTES on SPION. Compared to what was reported in literature, the results showed that the silanization reaction time was greatly minimized. More importantly, the product displayed superparamagnetic behaviour at room temperature with a more than 20% higher saturation magnetization.

  5. Measuring and modeling the magnetic settling of superparamagnetic nanoparticle dispersions.

    Science.gov (United States)

    Prigiobbe, Valentina; Ko, Saebom; Huh, Chun; Bryant, Steven L

    2015-06-01

    In this paper, we present settling experiments and mathematical modeling to study the magnetic separation of superparamagnetic iron-oxide nanoparticles (SPIONs) from a brine. The experiments were performed using SPIONs suspensions of concentration between 3 and 202g/L dispersed in water and separated from the liquid under the effect of a permanent magnet. A 1D model was developed in the framework of the sedimentation theory with a conservation law for SPIONs and a mass flux function based on the Newton's law for motion in a magnetic field. The model describes both the hindering effect of suspension concentration (n) during settling due to particle collisions and the increase in settling rate due to the attraction of the SPIONs towards the magnet. The flux function was derived from the settling experiments and the numerical model validated against the analytical solution and the experimental data. Suspensions of SPIONs were of 2.8cm initial height, placed on a magnet, and monitored continuously with a digital camera. Applying a magnetic field of 0.5T of polarization, the SPION's velocity was of approximately 3·10(-5)m/s close to the magnet and decreases of two orders of magnitude across the domain. The process was characterized initially by a classical sedimentation behavior, i.e., an upper interface between the clear water and the suspension slowly moving towards the magnet and a lower interface between the sediment layer and the suspension moving away from the magnet. Subsequently, a rapid separation of nanoparticle occured suggesting a non-classical settling phenomenon induced by magnetic forces which favor particle aggregation and therefore faster settling. The rate of settling decreased with n and an optimal condition for fast separation was found for an initial n of 120g/L. The model agrees well with the measurements in the early stage of the settling, but it fails to describe the upper interface movement during the later stage, probably because of particle

  6. Modeling non-saturated ferrite-based devices: Application to twin toroid ferrite phase shifters

    Science.gov (United States)

    Le Gouellec, A.; Vérissimo, G.; Laur, V.; Queffelec, P.; Albert, I.; Girard, T.

    2016-08-01

    This article describes a new set of tools developed to improve the conception and modeling of non-saturated ferrite-based devices such as twin toroid phase shifters. These new simulation tools benefit from a generalized permeability tensor model able to describe the permeability tensor of a ferrite sample whatever its magnetization state. This model is coupled to a homemade 3D multi-scale magnetostatic analysis program, which describes the evolution of the magnetization through the definition of a hysteresis loop in every mesh cell. These computed spectra are then integrated into 3D electromagnetic simulation software that retains the spatial variations of the ferrite properties by using freshly developed macro programming functions. This new approach allows the designers to accurately model complex ferrite devices such as twin toroid phase shifters. In particular, we demonstrated a good agreement between simulated and measured phase shifts as a function of applied current values with a predicted maximum phase shift of 0.96 times the measured value.

  7. Substrate integrated ferrite phase shifters and active frequency selective surfaces

    CERN Document Server

    Cahill, B M

    2002-01-01

    There are two distinct parts to this thesis; the first investigates the use of ferrite tiles in the construction of printed phase shifting transmission lines, culminating in the design of two compact electromagnetic controlled beam steered patch and slot antenna arrays. The second part investigates the use of active frequency selective surfaces (AFSS), which are later used to cover a uPVC constructed enclosure. Field intensity measurements are taken from within the enclosure to determine the dynamic screening effectiveness. Trans Tech G-350 Ferrite is investigated to determine its application in printed microstrip and stripline phase shifting transmission lines. 50-Ohm transmission lines are constructed using the ferrite tile and interfaced to Rogers RT Duroid 5870 substrate. Scattering parameter measurements are made under the application of variable magnetic fields to the ferrite. Later, two types of planar microwave beam steering antennas are constructed. The first uses the ferrites integrated into the Dur...

  8. Electrical transport behavior of nonstoichiometric magnesium-zinc ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Ghatak, S. [Department of Physics, National Institute of Technology, Deemed University, Mahatma Gandhi Avenue, Durgapur 713209, West Bengal (India); Sinha, M. [Department of Physics, University of Burdwan, Golapbag, Burdwan 713104, West Bengal (India); Meikap, A.K., E-mail: meikapnitd@yahoo.com [Department of Physics, National Institute of Technology, Deemed University, Mahatma Gandhi Avenue, Durgapur 713209, West Bengal (India); Pradhan, S.K. [Department of Physics, University of Burdwan, Golapbag, Burdwan 713104, West Bengal (India)

    2010-08-15

    This paper presents the direct current conductivity, alternate current conductivity and dielectric properties of nonstoichiometric magnesium-zinc ferrite below room temperature. The frequency exponent (s) of conductivity shows an anomalous temperature dependency. The magnitude of the temperature exponent (n) of dielectric permittivity strongly depends on frequency and its value decreases with increasing frequency. The grain boundary contribution is dominating over the grain contribution in conduction process and the temperature dependence of resistance due to grain and grain boundary contribution exhibits two activation regions. The ferrite shows positive alternating current magnetoconductivity. The solid state processing technique was used for the preparation of nanocrystalline ferrite powder from oxides of magnesium, zinc and iron. The X-ray diffraction methods were used in determining the structure and composition of obtained ferrite, while multimeter, impedance analyzer, liquid nitrogen cryostat and electromagnet were used in the study of conducting and dielectric properties of ferrite.

  9. Accumulation and biological effects of cobalt ferrite nanoparticles in human pancreatic and ovarian cancer cells.

    Science.gov (United States)

    Pašukonienė, Vita; Mlynska, Agata; Steponkienė, Simona; Poderys, Vilius; Matulionytė, Marija; Karabanovas, Vitalijus; Statkutė, Urtė; Purvinienė, Rasa; Kraśko, Jan Aleksander; Jagminas, Arūnas; Kurtinaitienė, Marija; Strioga, Marius; Rotomskis, Ričardas

    2014-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) emerge as a promising tool for early cancer diagnostics and targeted therapy. However, both toxicity and biological activity of SPIONs should be evaluated in detail. The aim of this study was to synthesize superparamagnetic cobalt ferrite nanoparticles (Co-SPIONs), and to investigate their uptake, toxicity and effects on cancer stem-like properties in human pancreatic cancer cell line MiaPaCa2 and human ovarian cancer cell line A2780. Co-SPIONs were produced by Massart's co-precipitation method. The cells were treated with Co-SPIONs at three different concentrations (0.095, 0.48, and 0.95μg/mL) for 24 and 48h. Cell viability and proliferation were analyzed after treatment. The stem-like properties of cells were assessed by investigating the cell clonogenicity and expression of cancer stem cell-associated markers, including CD24/ESA in A2780 cell line and CD44/ALDH1 in MiaPaCa2 cell line. Magnetically activated cell sorting was used for the separation of magnetically labeled and unlabeled cells. Both cancer cell lines accumulated Co-SPIONs, however differences in response to nanoparticles were observed between MiaPaCa2 and A2780 cell. In particular, A2780 cells were more sensitive to exposition to Co-SPIONs than MiaPaCa2 cells, indicating that a safe concentration of nanoparticles must be estimated individually for a particular cell type. Higher doses of Co-SPIONs decreased both the clonogenicity and ESA marker expression in A2780 cells. Co-SPIONs are not cytotoxic to cancer cells, at least when used at a concentration of up to 0.95μg/mL. Co-SPIONs have a dose-dependent effect on the clonogenic potential and ESA marker expression in A2780 cells. Magnetic detection of low concentrations of Co-SPIONS in cancer cells is a promising tool for further applications of these nanoparticles in cancer diagnosis and treatment; however, extensive research in this field is needed. Copyright © 2014 Lithuanian University of

  10. Corrosion behavior of magnetic ferrite coating prepared by plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yi; Wei, Shicheng, E-mail: wsc33333@163.com; Tong, Hui; Tian, Haoliang; Liu, Ming; Xu, Binshi

    2014-12-15

    Graphical abstract: The saturation magnetization (M{sub s}) of the ferrite coating is 34.417 emu/g while the M{sub s} value of the ferrite powder is 71.916 emu/g. It can be seen that plasma spray process causes deterioration of the room temperature soft magnetic properties. - Highlights: • Spinel ferrite coatings have been prepared by plasma spraying. • The coating consists of nanocrystalline grains. • The saturation magnetization of the ferrite coating is 34.417 emu/g. • Corrosion behavior of the ferrite coating was examined in NaCl solution. - Abstract: In this study, spray dried spinel ferrite powders were deposited on the surface of mild steel substrate through plasma spraying. The structure and morphological studies on the ferrite coatings were carried out using X-ray diffraction, scanning electron microscope and Raman spectroscopy. It was showed that spray dried process was an effective method to prepare thermal spraying powders. The coating showed spinel structure with a second phase of LaFeO{sub 3}. The magnetic property of the ferrite samples were measured by vibrating sample magnetometer. The saturation magnetization (M{sub s}) of the ferrite coating was 34.417 emu/g. The corrosion behavior of coating samples was examined by electrochemical impedance spectroscopy. EIS diagrams showed three corrosion processes as the coating immersed in 3.5 wt.% NaCl solution. The results suggested that plasma spraying was a promising technology for the production of magnetic ferrite coatings.

  11. Assessment of the integrity of ferritic-austenitic dissimilar weld joints of different grades of Cr-Mo ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Laha, K.; Chandravathi, K.S.; Parameswaran, P.; Goyal, Sunil; Mathew, M.D. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Metallurgy and Materials Group

    2010-07-01

    Integrity of the 2.25 Cr-1Mo / Alloy 800, 9Cr-1Mo / Alloy 800 and 9Cr-1Mo-VNb / Alloy 800 ferritic-austenitic dissimilar joints, fusion welded employing Inconel 182 electrode, has been assessed under creep conditions at 823 K. The dissimilar weld joints displayed lower creep rupture strength than their respective ferritic steel base metals. The strength reduction was more for 2.25Cr-1Mo steel joint and least for 9Cr-1Mo steel joint. The failure location in the joints was found to shift from the ferritic steel base metal to the intercritical region of heat-affected zone (HAZ) in ferritic steel (type IV cracking) with decrease in stress. At still lower stresses the failure occurred at the ferritic / austenitic weld interface. Localized creep deformation and cavitation in the soft intercritical HAZ induced type IV failure whereas creep cavitation at the weld interface particles induced ferritic / austenitic interface cracking due to high creep strength mismatch across it. Micromechanisms of type IV failure and interface cracking in the ferritic / austenitic joints and different susceptibility to failure for different grades of ferritic steels are discussed based on microstructural investigation, mechanical testing and finite element analysis. (Note from indexer: paper contains many typographical errors.)

  12. Control of the saturation temperature in magnetic heating by using polyethylene-glycol-coated rod-shaped nickel-ferrite (NiFe2O4) nanoparticles

    Science.gov (United States)

    Iqbal, Yousaf; Bae, Hongsub; Rhee, Ilsu; Hong, Sungwook

    2016-02-01

    Polyethylene-glycol (PEG)-coated nickel-ferrite nanoparticles were prepared for magnetic hyperthermia applications by using the co-precipitation method. The PEG coating occurred during the synthesis of the nanoparticles. The coated nanoparticles were rod-shaped with an average length of 16 nm and an average diameter of 4.5 nm, as observed using transmission electron microscopy. The PEG coating on the surfaces of the nanoparticles was confirmed from the Fourier-transform infrared spectra. The nanoparticles exhibited superparamagnetic characteristics with negligible coercive force. Further, magnetic heating effects were observed in aqueous solutions of the coated nanoparticles. The saturation temperature could be controlled at 42 ℃ by changing the concentration of the nanoparticles in the aqueous solution. Alternately, the saturation temperature could be controlled for a given concentration of nanoparticles by changing the intensity of the magnetic field. The Curie temperature of the nanoparticles was estimated to be 495 ℃. These results for the PEG-coated nickel-ferrite nanoparticles showed the possibility of utilizing them for controlled magnetic hyperthermia at 42 ℃.

  13. Cobalt ferrite nanoparticles under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Saccone, F. D.; Ferrari, S.; Grinblat, F.; Bilovol, V. [Instituto de Tecnologías y Ciencias de la Ingeniería, “Ing. H. Fernández Long,” Av. Paseo Colón 850 (1063), Buenos Aires (Argentina); Errandonea, D., E-mail: daniel.errandonea@uv.es [Departamento de Fisica Aplicada, Institut Universitari de Ciència dels Materials, Universitat de Valencia, c/ Doctor Moliner 50, E-46100 Burjassot, Valencia (Spain); Agouram, S. [Departamento de Física Aplicada y Electromagnetismo, Universitat de València, 46100 Burjassot, Valencia (Spain)

    2015-08-21

    We report by the first time a high pressure X-ray diffraction and Raman spectroscopy study of cobalt ferrite (CoFe{sub 2}O{sub 4}) nanoparticles carried out at room temperature up to 17 GPa. In contrast with previous studies of nanoparticles, which proposed the transition pressure to be reduced from 20–27 GPa to 7.5–12.5 GPa (depending on particle size), we found that cobalt ferrite nanoparticles remain in the spinel structure up to the highest pressure covered by our experiments. In addition, we report the pressure dependence of the unit-cell parameter and Raman modes of the studied sample. We found that under quasi-hydrostatic conditions, the bulk modulus of the nanoparticles (B{sub 0} = 204 GPa) is considerably larger than the value previously reported for bulk CoFe{sub 2}O{sub 4} (B{sub 0} = 172 GPa). In addition, when the pressure medium becomes non-hydrostatic and deviatoric stresses affect the experiments, there is a noticeable decrease of the compressibility of the studied sample (B{sub 0} = 284 GPa). After decompression, the cobalt ferrite lattice parameter does not revert to its initial value, evidencing a unit cell contraction after pressure was removed. Finally, Raman spectroscopy provides information on the pressure dependence of all Raman-active modes and evidences that cation inversion is enhanced by pressure under non-hydrostatic conditions, being this effect not fully reversible.

  14. Book Review: Nano physics & Nano technology

    Directory of Open Access Journals (Sweden)

    Abdolkhaled Zaree

    2012-12-01

    Full Text Available During last decades, there are a lot of emphases on studying material behavior in atomic scale. In most scientific and engineering fields, one can see the effect of nanotechnology. The aim of nanoscience is to design and fabrication of new and applicable materials. Nowadays, Nano is a popular science which chemists, physicist, doctors, engineers, financial managers and environment's fans for creating a good life via nanoscience have a great cooperation with each others. Materials in nano scale such as nanotubes and nanowires have extraordinary properties which by optimization of these properties in nano scale and then develop these properties to macro scale, they've been challenging issues. For instance, materials in nano scale improve mechanical properties of polymers and metallic materials via nano particles and on the other hand by producing a thin film on surfaces improve surface hardening. Besides, nanotechnology is in hi-tech industries such as magnetic devices, surface coating, and biomaterial, material having sensors, polymers, gels, ceramics and intelligent membrane. Nano-carbon tubes are considered intelligent due to the fact that they couple electrochemical and elastic properties simultaneously, hence have greater activation energy density in comparison with other intelligent materials. Studying nanoscience is important because it causes the life to be better. Future Materials and structures will have a lot of outstanding properties. Intelligent machines can repair, recycle and reconstruct themselves. All these features are only possible in nano zone. Nano in engineering science can provide the possibility of making light missiles for exploring space. The reduced weight can be achieved by replacing traditional materials with hybrid nanocomposites.

  15. CASS Ferrite and Grain Structure Relationship

    Energy Technology Data Exchange (ETDEWEB)

    Ruud, Clayton O. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ramuhalli, Pradeep [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Meyer, Ryan M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Diaz, Aaron A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Anderson, Michael T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-07-13

    This document summarizes the results of research conducted at Pacific Northwest National Laboratory (PNNL) to determine whether, based on experimental measurements, a correlation existed between grain structure in cast austenitic stainless steel (CASS) piping and ferrite content of the casting alloy. The motivation for this research lies in the fact that ultrasonic testing (UT) is strongly influenced by CASS grain structure; knowledge of this grain structure may help improve the ability to interpret UT responses, thereby improving the overall reliability of UT inspections of CASS components.

  16. Atomically flat ultrathin cobalt ferrite islands.

    Science.gov (United States)

    Martín-García, Laura; Quesada, Adrián; Munuera, Carmen; Fernández, Jose F; García-Hernández, Mar; Foerster, Michael; Aballe, Lucía; de la Figuera, Juan

    2015-10-21

    A route for fabricating structurally perfect cobalt ferrite magnetic nanostructures is demonstrated. Ultrathin islands of up to 100 μm(2) with atomically flat surfaces and free from antiphase boundaries are developed. The extremely low defect concentration leads to a robust magnetic order, even for thicknesses below 1 nm, and exceptionally large magnetic domains. This approach allows the evaluation of the influence of specific extrinsic effects on domain wall pinning. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Superparamagnetic tunnel junctions for bio-inspired computing (Conference Presentation)

    Science.gov (United States)

    Grollier, Julie; Torrejon, Jacob; Riou, Mathieu; Cros, Vincent; Querlioz, Damien; Tsunegi, Sumito; Fukushima, Akio; Kubota, Hitoshi; Yuasa, Shinji; Stiles, Mark D.; Khalsa, Guru

    2016-10-01

    The brain displays many features typical of non-linear dynamical networks, such as synchronization or chaotic behaviour. These observations have inspired a whole class of models that harness the power of complex non-linear dynamical networks for computing. In this framework, neurons are modeled as non-linear oscillators, and synapses as the coupling between oscillators. These abstract models are very good at processing waveforms for pattern recognition or at generating precise time sequences useful for robotic motion. However there are very few hardware implementations of these systems, because large numbers of interacting non-linear oscillators are indeed. In this talk, I will show that coupled spin-torque nano-oscillators are very promising for realizing cognitive computing at the nanometer and nanosecond scale, and will present our first results in this direction.

  18. Formation and microstructure of carbon encapsulated superparamagnetic Co nanoparticles

    Science.gov (United States)

    Sun, Xiang-Cheng; Reyes-Gasga, J.; Dong, X. L.

    Carbon encapsulated magnetic cobalt nanoparticles have been synthesized by the modified arc-discharge method. Both high resolution transmission electron microscopy (HREM) and powder X-ray diffraction (XRD) profiles reveal the presence of 8-15nm diameter crystallites coated with 1-3 carbon layers. In particular, HREM images indicate that the intimate and contiguous carbon fringe around those Co nanoparticles is good evidence for complete encapsulation by carbon shell layers. The encapsulated phases are identified as hcp α-Co, fcc β-Co and cobalt carbide (Co 3 C) nanocrystals using X-ray diffraction (XRD), nano-area electron diffraction (SAED) and energy dispersive X-ray analysis (EDX). However, some fcc β-Co particles with a significant fraction of stacking faults are observed by HREM and confirmed by means of numerical fast Fourier transform (FFT) of HREM lattice images. The carbon encapsulation formation and growth mechanism are also reviewed.

  19. 共沉淀法锰锌铁氧体的制备及其磁性能%Preparation and magnetic performance of Mn-Zn ferrites by coprecipitation method

    Institute of Scientific and Technical Information of China (English)

    赵慧君; 张娟; 范积伟

    2011-01-01

    Mn - Zn ferrite precursor powder was prepared by co-precipitation method. The Mn - Zn ferrite was obtained by sintering after being pressed,and its particle size of ferrite precursor was analyzed. XRD and magnetic properties of Mn -Zn ferrite were tested and analyzed. Results showed that uniformly distributed nano-particles can be obtained by chemical co-precipitation method under suitable conditions. After sintering,the sample is in a single phase of Mn - Zn ferrite spinel. The prepared Mn - Zn ferrite possessed high magnetic susceptibility and standard hysteresis loop. The magnetic susceptibility of ferrite increased gradually with the zinc volume reducing and the iron content increasing.%采用共沉淀法制备了锰锌铁氧体前驱体粉末,对其进行压块处理后,通过烧结得到锰锌铁氧体.测试分析了锰锌铁氧体前驱体粉末的粒度,并对锰锌铁氧体的X射线衍射及磁性能进行了测试与分析.结果表明:在适当的条件下,采用化学共沉淀法,可以制得分布均匀的纳米级锰锌铁氧体前驱体微粒.经过烧结的样品为单一的尖晶石相锰锌铁氧体.所制得的锰锌铁氧体具有较高的磁化率,标准的磁滞回线,锰锌铁氧体的磁化率随着含锌量的降低、含铁量的增加而逐渐升高.

  20. Dipole nano-laser

    Energy Technology Data Exchange (ETDEWEB)

    Protsenko, I E; Uskov, A V; Krotova, K E [Lebedev Physical Institute, Leninsky prospect 53, Moscow (Russian Federation); O' Reilly, E P [Tyndall National Institute, ' Lee Maltings' , Prospect Row, Cork (Ireland)], E-mail: protsen@sci.lebedev.ru, E-mail: protsenk@gmail.com

    2008-03-15

    Theoretically predicted 'dipole lasing', i.e., spontaneous excitation of coherent metal nano-particle dipole oscillations through interaction with a quantum-dot two-level system subject to population inversion is demonstrated. Equations for dipole lasing are the same as equations for ordinary laser, where the dipole momentum of nano-particle stands for the electromagnetic field cavity mode. Dipole lasing frequency corresponds to the localized plasmon resonance of the nano-particle. Dipole momentum of nano-particle leads to coherent dipole radiation. Optical cavity is not necessary, the size of the dipole laser can be smaller than the optical wavelength, i.e. it is dipole nano-laser. Threshold conditions and optical bistability in dipole nano-lasers are considered.

  1. Quantitative analysis of superparamagnetic contrast agent in sentinel lymph nodes using ex vivo vibrating sample magnetometry

    NARCIS (Netherlands)

    Visscher, M.; Pouw, Joost Jacob; van Baarlen, J.; Klaase, J.M.; ten Haken, Bernard

    2013-01-01

    As the first step in developing a new clinical technique for the magnetic detection of colorectal sentinel lymph nodes (SLNs), a method is developed to measure the magnetic content in intact, formalin fixated lymph nodes using a vibrating sample magnetometer (VSM). A suspension of superparamagnetic

  2. Effect of Inter-Particle Interactions on the Superparamagnetic Relaxation Time in Ferrofluids

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Mørup, Steen; Svedlindh, P.

    1996-01-01

    The influence of dipolar interactions in a frozen ferrofluid consisting of maghemite particles has been studied by Mossbauer spectroscopy in the temperature range from 60 to 200 K. Four samples with volume concentrations ranging from 0.3 to 17.7 % have been investigated. The superparamagnetic...

  3. Synthesis of pseudopolyrotaxanes-coated Superparamagnetic Iron Oxide Nanoparticles as new MRI contrast agent

    NARCIS (Netherlands)

    Hosseini, F.; Panahifar, A.; Adeli, M.; Amiri, H.; Lascialfari, A.; Orsini, F.; Doschak, M.R.; Mahmoudi, M.

    2013-01-01

    Superparamagnetic Iron Oxide Nanoparticles (SPIONs) were synthesized and coated with pseudopolyrotaxanes (PPRs) and proposed as a novel hybrid nanostructure for medical imaging and drug delivery. PPRs were prepared by addition of alpha-cyclodextrin rings to functionalized polyethylene glycol (PEG) c

  4. Surface spin disorder and spin-glass-like behaviour in manganese-substituted cobalt ferrite nanoparticles

    Science.gov (United States)

    Topkaya, R.; Akman, Ö.; Kazan, S.; Aktaş, B.; Durmus, Z.; Baykal, A.

    2012-10-01

    Manganese-substituted cobalt ferrite nanoparticles coated with triethylene glycol (TREG) have been prepared by the glycothermal reaction. The effect of Mn substitution and coating on temperature-dependent magnetic properties of the TREG-coated Mn x Co1- x Fe2O4 nanoparticles (0.0 ≤ x ≤ 0.8) with size of 5-7 nm has been investigated in the temperature range of 10-300 K in a magnetic field up to 9 T. After the irreversible processes of the magnetic hysteresis curves were completed, the high-field regions of these curves were fitted by using a `law of approach to saturation' to extract the magnetic properties, such as the effective anisotropy constant ( K eff) and the anisotropy field ( H A) etc. High coercive field of 12.6 kOe is observed in pure cobalt ferrite coated with TREG at 10 K. The low temperature unsaturated magnetization behaviour indicates the core-shell structure of the Mn x Co1- x Fe2O4 NPs. Zero-field-cooled (ZFC) and field-cooled (FC) measurements revealed superparamagnetic phase of TREG-coated Mn x Co1- x Fe2O4 nanoparticles at room temperature. The blocking and irreversibility temperatures obtained from ZFC-FC curves decrease at highest Mn concentration ( x = 0.8). The existence of spin-glass-like surface layer with freezing temperature of 215 K was established with the applied field dependence of the blocking temperatures following the de Almeida-Thouless line for the Mn0.6Co0.4Fe2O4 NPs. The shifted hysteresis loops with exchange bias field of 60 Oe and high-field irreversibility up to 60 kOe in FC M- H curve at 10 K show that spin-glass-like surface spins surrounds around ordered core material of the Mn0.6Co0.4Fe2O4 NPs. FMR measurement show that all the TREG-coated Mn x Co1- x Fe2O4 nanoparticles absorb microwave in broad field range of about ten thousands Oe. The spectra for all the samples have broad linewidth because of angular distributions of easy axis and internal fields of nanoparticles.

  5. Surface spin disorder and spin-glass-like behaviour in manganese-substituted cobalt ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Topkaya, R., E-mail: rtopkaya@gyte.edu.tr [Gebze Institute of Technology, Department of Physics (Turkey); Akman, Oe. [Sakarya University, Department of Physics (Turkey); Kazan, S.; Aktas, B. [Gebze Institute of Technology, Department of Physics (Turkey); Durmus, Z.; Baykal, A. [Fatih University, Department of Chemistry (Turkey)

    2012-10-15

    Manganese-substituted cobalt ferrite nanoparticles coated with triethylene glycol (TREG) have been prepared by the glycothermal reaction. The effect of Mn substitution and coating on temperature-dependent magnetic properties of the TREG-coated Mn{sub x}Co{sub 1-x}Fe{sub 2}O{sub 4} nanoparticles (0.0 {<=} x {<=} 0.8) with size of {approx}5-7 nm has been investigated in the temperature range of 10-300 K in a magnetic field up to 9 T. After the irreversible processes of the magnetic hysteresis curves were completed, the high-field regions of these curves were fitted by using a 'law of approach to saturation' to extract the magnetic properties, such as the effective anisotropy constant (K{sub eff}) and the anisotropy field (H{sub A}) etc. High coercive field of 12.6 kOe is observed in pure cobalt ferrite coated with TREG at 10 K. The low temperature unsaturated magnetization behaviour indicates the core-shell structure of the Mn{sub x}Co{sub 1-x}Fe{sub 2}O{sub 4} NPs. Zero-field-cooled (ZFC) and field-cooled (FC) measurements revealed superparamagnetic phase of TREG-coated Mn{sub x}Co{sub 1-x}Fe{sub 2}O{sub 4} nanoparticles at room temperature. The blocking and irreversibility temperatures obtained from ZFC-FC curves decrease at highest Mn concentration (x = 0.8). The existence of spin-glass-like surface layer with freezing temperature of 215 K was established with the applied field dependence of the blocking temperatures following the de Almeida-Thouless line for the Mn{sub 0.6}Co{sub 0.4}Fe{sub 2}O{sub 4} NPs. The shifted hysteresis loops with exchange bias field of 60 Oe and high-field irreversibility up to 60 kOe in FC M-H curve at 10 K show that spin-glass-like surface spins surrounds around ordered core material of the Mn{sub 0.6}Co{sub 0.4}Fe{sub 2}O{sub 4} NPs. FMR measurement show that all the TREG-coated Mn{sub x}Co{sub 1-x}Fe{sub 2}O{sub 4} nanoparticles absorb microwave in broad field range of about ten thousands Oe. The spectra for all the

  6. Electrical and switching properties of NiAl{sub x}Fe{sub 2-x}O{sub 4} ferrites synthesized by chemical method

    Energy Technology Data Exchange (ETDEWEB)

    Patange, S.M., E-mail: smpatange@rediffmail.co [Department of Material Science, Shrikrishna College, Gunjoti 413613 (India); Shirsath, Sagar E. [Department of Physics, Dr. B.A.M. University, Aurangabad (India); Lohar, K.S. [Department of Material Science, Shrikrishna College, Gunjoti 413613 (India); Jadhav, S.S. [Department of Physics, D.S.M. College, Jintur (India); Kulkarni, Nilesh [Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Mumbai (India); Jadhav, K.M. [Department of Physics, Dr. B.A.M. University, Aurangabad (India)

    2011-02-01

    Nickel-aluminum ferrite system NiAl{sub x}Fe{sub 2-x}O{sub 4} has been synthesized by wet chemical co-precipitation method. The samples were studied by means of X-ray diffraction, d.c. electrical resistivity, a.c. electrical resistivity, a.c. conductivity and switching properties. The XRD patterns confirm the cubic spinel structure for all the synthesized samples. The crystallite size calculated from XRD data which confirm the nano-size dimension of the prepared samples. Electrical properties such as a.c. and d.c. resistivities as function of temperature were studied for various Al substitution in nickel ferrite. The dielectric constant and dielectric loss tangent were also studied as a function of frequency. The dielectric constant follows the Maxwell-Wagner interfacial polarization. A.C. conductivity increases with increase in applied frequency. The d.c. resistivity decreases as temperature increases, which indicate that the sample have semi-conducting nature. Verwey hoping mechanism explains the observed variation in resistivity. The activation energy is derived from the temperature variation of resistivity. Electrical switching properties were studied as I-V measurements. The current controlled negative resistance type switching is observed in all the samples. The Al substitution in nickel ferrite decreases the required switching field. -- Research highlights: {yields} Nano-crystalline Al{sup 3+} substituted nickel ferrite. {yields} D.C. resistivity. {yields} Dielectric properties such as dielectric constant and dielectric loss tangent (with temperature and frequency). {yields} A.C. conductivity. {yields} Switching property.

  7. Cast Stainless Steel Ferrite and Grain Structure

    Energy Technology Data Exchange (ETDEWEB)

    Ruud, Clayton O.; Ramuhalli, Pradeep; Meyer, Ryan M.; Mathews, Royce; Diaz, Aaron A.; Anderson, Michael T.

    2012-09-01

    In-service inspection requirements dictate that piping welds in the primary pressure boundary of light-water reactors be subject to a volumetric examination based on the rules contained within the American Society of Mechanical Engineers Boiler and Pressure Vessel Code, Section XI. The purpose of the inspection is the reliable detection and accurate sizing of service-induced degradation and/or material flaws introduced during fabrication. The volumetric inspection is usually carried out using ultrasonic testing (UT) methods. However, the varied metallurgical macrostructures and microstructures of cast austenitic stainless steel piping and fittings, including statically cast stainless steel and centrifugally cast stainless steel (CCSS), introduce significant variations in the propagation and attenuation of ultrasonic energy. These variations complicate interpretation of the UT responses and may compromise the reliability of UT inspection. A review of the literature indicated that a correlation may exist between the microstructure and the delta ferrite content of the casting alloy. This paper discusses the results of a recent study where the goal was to determine if a correlation existed between measured and/or calculated ferrite content and grain structure in CCSS pipe.

  8. Preparation and characterization of PEG-PEI/Fe3O4 nano-magnetic fluid by co-precipitation method

    Institute of Scientific and Technical Information of China (English)

    PENG Jian; ZOU Fen; LIU Lu; TANG Liang; YU Li; CHEN Wei; LIU Hui; TANG Jing-bo; WU Li-xiang

    2008-01-01

    PEG-PEI/Fe3O4 nano-magnetic fluids with different mass fractions of reactant were prepared by co-precipitation method. Besides particle size analyzer, the methods of XRD, IR, VSM and AFM were adopted to characterize the synthesized samples. Covalent bonding of PEG, PEI and Fe3O4 exhibits superparamagnetism. The TEM photograph shows that the particles are of stable dispersion and little aggregation, with smooth surface, spherical shape and a diameter of about 80 nm, which meets the requirements of nano-materials. When the mass fraction of PEI in reactant is 25%, the particle size, Zeta-potential and pEGFP-C1 DNA loading efficiency are all satisfactory. In this case, PEG-PEI/ Fe3O4 nano-magnetic fluids can be used as gene vectors or targeted drug carriers.

  9. Dysprosium Modification of Cobalt Ferrite Ionic Magnetic Fluids

    Institute of Scientific and Technical Information of China (English)

    JIANG Rong-li; LIU Yong-chao; GENG Quan-rong; ZHAO Wen-tao

    2005-01-01

    Dysprosium composite cobalt ferrite ionic magnetic fluids were prepared by precipitation in the presence of Tri-sodium citrate. Influence of dysprosium modification on magnetic property is studied. The result shows that magnetic response toward exterior magnetic field can be improved by adding Dy3+. Studies also show that the increase of reaction temperature may improve the modification effect of dysprosium. By adding dysprosium ions, the average diameter of the magnetic nanoparticles will be decreased evidently. It is clear that the particles appear as balls, Cobalt ferrite with sizes of 12-15 nm, rare earth composite cobalt ferrite with sizes of 6-8 nm.

  10. Preparation and characterization of rice husk/ferrite composites

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A novel ferrite composite using rice husk as substrate has been prepared via high temperature treatment under nitrogen atmosphere.The rice husk substrate consists of porous activated carbon and silica,where spinel ferrite particles with average diameter of 59 nm are distributed.The surface area of the composite is greater than 170 m~2 g~(-1) and the bulk density is less than 0.6 g cm~(-3).Inert atmosphere is indispensable for the synthesis of pure ferrite composites,while different preparation temperatur...

  11. Nickel hydroxide/cobalt-ferrite magnetic nanocatalyst for alcohol oxidation.

    Science.gov (United States)

    Bhat, Pooja B; Inam, Fawad; Bhat, Badekai Ramachandra

    2014-08-11

    A magnetically separable, active nickel hydroxide (Brønsted base) coated nanocobalt ferrite catalyst has been developed for oxidation of alcohols. High surface area was achieved by tuning the particle size with surfactant. The surface area of 120.94 m2 g(-1) has been achieved for the coated nanocobalt ferrite. Improved catalytic activity and selectivity were obtained by synergistic effect of transition metal hydroxide (basic hydroxide) on nanocobalt ferrite. The nanocatalyst oxidizes primary and secondary alcohols efficiently (87%) to corresponding carbonyls in good yields.

  12. Modeling of Incubation Time for Austenite to Ferrite Phase Transformation

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xiao-guang; LIU Zhen-yu; WU Di; WANG Wei; JIAO Si-hai

    2006-01-01

    On the basis of the classical nucleation theory, a new model of incubation time for austenite to ferrite transformation has been developed, in which the effect of deformation on austenite has been taken into consideration. To prove the precision of modeling, ferrite transformation starting temperature (Ar3) has been calculated using the Scheil′s additivity rule, and the Ar3 values were measured using a Gleeble 1500 thermomechanical simulator. The Ar3 values provided by the modeling method coincide with the measured ones, indicating that the model is precise in predicting the incubation time for austenite to ferrite transformation in hot deformed steels.

  13. Ultra-fine ferrite grains obtained in the TSDR process

    Institute of Scientific and Technical Information of China (English)

    Ling Zhang; Wangyue Yang; Chunxia Xue; Zuqing Sun

    2008-01-01

    By careful design of rolling schedule, ultra-fine (~2 μm) ferrite grains in a low carbon high niobium (0.09wt%Nb) micro-alloying steel with average austenite grain sizes above 800 μm can be achieved in the simulated thin slab direct rolling process. The 5-pass deformation was divided into two stages: the refinement of austenite through complete recrystallization and the refinement of ferrite through dynamic strain-induced transformation. The effects of Nb in solution and strain-induced NbCN precipitates on the fer-rite transformation were also extensively discussed.

  14. Ferric Oxide from Hematite Used in Microwave Ferrite Material

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Ferric Oxide is an essential and raw material in the production of ferrite materials. At present, ferric oxide used by many domestic factories is mainly produced by chemical method. In this paper, we use ferric oxide refined from hematite and applied in the microwave ferrite material production test. Compared with the normal ferric oxide, we get the same or similar results. It shows that ferric oxide from hematite and applied in the microwave ferrite material production test. Compared with the normal ferric oxide, we get the same or similar results. It shows that ferric oxide from hematite has a bright application prospect.

  15. Effect of hydrothermal heat treatment on magnetic properties of copper zinc ferrite rf sputtered films

    Directory of Open Access Journals (Sweden)

    Jasmeet Kaur

    2016-05-01

    Full Text Available The hydrothermal treatment to the nano-structured films can overcome the destruction of the films. The Cu-Zn Ferrite films were fabricated by RF-sputtering on quartz substrates. Subsequently, the as deposited films were heat treated using hydrothermal process. The X-ray diffraction pattern of the as-deposited and hydrothermal treated films indicate nano-crystalline cubic spinel structure. The amorphous nature of the films is removed after hydrothermal treatment with decreased crystallite size. The field emission scanning electron micrographs showed merged columnar growth for as deposited films, which changes to well define columns after hydrothermal heating. The homogeneous cluster distribution is observed in surface view of the hydrothermal treated films. Hydrothermal treated films show merging of in-plane and out of plane magnetization plots (M(H whereas the M(H plots of as deposited films show angular dependence. The strong angular dependence is observed in the FMR spectra due to the presence of a uniaxial anisotropy in the films. The ferromagnetic interactions decrease in hydrothermal heated films due to the reduced shape anisotropy and crystallite size.

  16. Magnetic hyperthermia studies on water-soluble polyacrylic acid-coated cobalt ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Krishna Surendra, M. [Indian Institute of Technology Madras, Department of Physics, Nano Functional Materials Technology Centre, Materials Research Centre (India); Annapoorani, S. [Anna University of Technology, Department of Nanotechnology (India); Ansar, Ereath Beeran; Harikrishna Varma, P. R. [Sree Chitra Tirunal Institute for Medical Sciences and Technology, Bioceramics Laboratory (India); Ramachandra Rao, M. S., E-mail: msrrao@iitm.ac.in [Indian Institute of Technology Madras, Department of Physics, Nano Functional Materials Technology Centre, Materials Research Centre (India)

    2014-12-15

    We report on synthesis and hyperthermia studies in the water-soluble ferrofluid made of polyacrylic acid-coated cobalt ferrite (CoFe{sub 2}O{sub 4}) nanoparticles with different particle sizes. Magnetic nanoparticles were synthesized using co-precipitation method and particle size was varied as 6, 10, and 14 nm by varying the precursor to surfactant concentration. PAA surfactant bonding and surfactant thickness were studied by FTIR and thermogravimetric analysis. At room temperature, nanoparticles show superparamagnetism and saturation magnetization was found to vary from 33 to 44 emu/g with increase in the particle size from 6 to 14 nm, and this increase was attributed to the presence of a magnetic inert layer of 4 Å thick. Effect of particle size, concentration, and alternating magnetic field strength at 275 kHz on specific absorption rate were studied by preparing ferrofluids in deionized water at different concentrations. Ferrofluids at a concentration of 1.25 g/L, with 10 min of AMF exposure of strength ∼15.7 kA/m show stable temperatures ∼48, 58, and 68 °C with increase in the particle sizes 6, 10, and 14 nm. A maximum specific absorption rate of 251 W/g for ferrofluid with a particle size of 10 nm at 1.25 g/L, 15.7 kA/m, and 275 kHz was observed. Viability of L929 fibroblasts is measured by MTT assay cytotoxicity studies using the polyacrylic acid-coated CoFe{sub 2}O{sub 4} nanoparticles.

  17. Photodynamic Anticancer Activities of Multifunctional Cobalt Ferrite Nanoparticles in Various Cancer Cells.

    Science.gov (United States)

    Park, Bong Joo; Choi, Kyong-Hoon; Nam, Ki Chang; Ali, Anser; Min, Joe Eun; Son, Hyungbin; Uhm, Han S; Kim, Ho-Joong; Jung, Jin-Seung; Choi, Eun Ha

    2015-02-01

    To develop novel multifunctional magnetic nanoparticles (MNPs) with good magnetic properties, biocompatibility, and anticancer activities by photodynamic therapy (PDT), we synthesized multifunctional cobalt ferrite (CoFe2O4) nanoparticles (CoFe2O4-HPs-FAs) functionalized by coating them with hematoporphyrin (HP) for introducing photo-functionality and by conjugating with folic acid (FA) for targeting cancer cells. We evaluated the activities of the CoFe2O4-HPs-FAs by checking magnetic resonance imaging (MRI) in vitro, its biocompatibility, and photodynamic anticancer activities on FA receptor (FR)-positive and FR-negative cancer cell lines, Hela, KB, MCF-7, and PC-3 cells, to use for clinical applications. In this study, we have demonstrated that the CoFe2O4-HPs-FAs have good MRI and biocompatibility with non-cytotoxicity, and remarkable photodynamic anticancer activities at very low concentrations regardless of cell types. Particularly, the photo-killing abilities in 3.13 μg/mL of CoFe2O4-HPs-FAs were measured to be 91.8% (p < 0.002) for Hela, 94.5% (p < 0.007) for KB, 79.1% (p < 0.003) for MCF-7, and 71.3% (p < 0.006) for PC-3. The photodynamic anticancer activities in 6.25 and 12.5 μg/mL of CoFe2O4-HPs-FAs were measured to be over 95% (p < 0.004) to almost 100% regardless of cell types. The newly developed multifunctional CoFe2O4-HPs-FAs are effective for PDT and have potential as therapeutic agents for MRI-based PDT, because they have a high saturation value of magnetization and superparamagnetism.

  18. Synthesis and cytotoxicity study of magnesium ferrite-gold core-shell nanoparticles.

    Science.gov (United States)

    Nonkumwong, Jeeranan; Pakawanit, Phakkhananan; Wipatanawin, Angkana; Jantaratana, Pongsakorn; Ananta, Supon; Srisombat, Laongnuan

    2016-04-01

    In this work, the core-magnesium ferrite (MgFe2O4) nanoparticles were prepared by hydrothermal technique. Completed gold (Au) shell coating on the surfaces of MgFe2O4 nanoparticles was obtained by varying core/shell ratios via a reduction method. Phase identification, morphological evolution, optical properties, magnetic properties and cytotoxicity to mammalian cells of these MgFe2O4 core coated with Au nanoparticles were examined by using a combination of X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy, UV-visible spectroscopy (UV-vis), vibrating sample magnetometry and resazurin microplate assay techniques. In general, TEM images revealed different sizes of the core-shell nanoparticles generated from various core/shell ratios and confirmed the completed Au shell coating on MgFe2O4 core nanoparticles via suitable core/shell ratio with particle size less than 100 nm. The core-shell nanoparticle size and the quality of coating influence the optical properties of the products. The UV-vis spectra of complete coated MgFe2O4-Au core-shell nanoparticles exhibit the absorption bands in the near-Infrared (NIR) region indicating high potential for therapeutic applications. Based on the magnetic property measurement, it was found that the obtained MgFe2O4-Au core-shell nanoparticles still exhibit superparamagnetism with lower saturation magnetization value, compared with MgFe2O4 core. Both of MgFe2O4 and MgFe2O4-Au core-shell also showed in vitro non-cytotoxicity to mouse areola fibroblast (L-929) cell line.

  19. Structural and magnetic properties of Gd{sup 3+} ion substituted magnesium ferrite nanopowders

    Energy Technology Data Exchange (ETDEWEB)

    Elkady, Ashraf S. [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); Department of Reactor Physics, NRC, Atomic Energy Authority, Cairo (Egypt); Hussein, Shaban I. [Department of Reactor Physics, NRC, Atomic Energy Authority, Cairo (Egypt); Rashad, Mohamed M., E-mail: rashad133@yahoo.com [Central Metallurgical Research and Development Institute, Helwan, Cairo 11421 (Egypt)

    2015-07-01

    Nanocrystalline MgGd{sub x}Fe{sub 2−x}O{sub 4} powders (where x=0, 0.05, 0.1, 0.2, 0.25, 0.3) have been synthesized by the ethylene diamine tetraacetic acid (EDTA)-based sol–gel combustion method. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, high resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer (VSM) were applied in order to study the effect of variation of Gd{sup 3+} ion substitution and its impact on crystal structure, crystallite size, lattice parameters, nanostructure and magnetic properties of the formed powders. XRD indicated that, after doping and calcination at 400 °C for 2 h, all samples have two spinel ferrite structures namely cubic and tetragonal phases, which are dependent on Gd{sup 3+} ion concentration. The cubic phase is found to increase with increasing the Gd{sup 3+} ion molar ratio up to 0.1, compared to pure MgFe{sub 2}O{sub 4} and higher Gd{sup 3+} content samples. Indeed, with increasing Gd{sup 3+} ion, the crystallite size was almost unchanged whereas the lattice parameter was found to increase. FT-IR spectrum showed broadening of the ν{sub 2} band and the presence of another band in the range (465–470 cm{sup −1}) upon adding Gd{sup 3+} ion, which confirm the presence of Gd{sup 3+} ion in addition to Fe{sup 3+} ion at octahedral site. Besides, these bands were assigned to the formation of (Gd{sup 3+}–O{sup 2−}) complexes at B-sites. HRTEM images showed that the studied samples consist of nanocrystallites having average particle sizes around 9 nm for pure MgFe{sub 2}O{sub 4} up to 27 and 42 nm for the Gd{sup 3+} ion substituted MgFe{sub 2}O{sub 4} of molar ratio 0.05 and 0.30, respectively. An examination of the magnetic properties revealed an increase in saturation magnetization with increasing Gd concentration incorporation up to x=0.1, as a result of the change of cubic and tetragonal spinel ratio and lattice parameters. Meanwhile, the formed powders exhibited

  20. Sustainable nano-catalysis

    Science.gov (United States)

    A novel nano-catalyst system which bridges the homogenous and heterogeneous system is described that is cheaper, easily accessible (sustainable) and requires no need of catalyst filtration during the work-up. Because of its nano-size, i.e. high surface area, the contact between r...

  1. The Nano Solar Case

    DEFF Research Database (Denmark)

    Hollensen, Svend

    2011-01-01

    ISO PAINT Nordic A/S produces roof coatings, facade painting as well as specialised products for surface treatments. The company decided that they would develop a nano solar ICT based project having the capacity to change the whole cost structure of a building, for example by a nano roof coating...

  2. A microfluidic nano-biosensor for the detection of pathogenic Salmonella.

    Science.gov (United States)

    Kim, Giyoung; Moon, Ji-Hea; Moh, Chang-Yeon; Lim, Jong-guk

    2015-05-15

    Rapid detection of pathogenic Salmonella in food products is extremely important for protecting the public from salmonellosis. The objective of the present study was to explore the feasibility of using a microfluidic nano-biosensor to rapidly detect pathogenic Salmonella. Quantum dot nanoparticles were used to detect Salmonella cells. For selective detection of Salmonella, anti-Salmonella polyclonal antibodies were covalently immobilized onto the quantum dot surface. To separate and concentrate the cells from the sample, superparamagnetic particles and a microfluidic chip were used. A portable fluorometer was developed to measure the fluorescence signal from the quantum dot nanoparticles attached to Salmonella in the samples. The sensitivity for detection of pathogenic Salmonella was evaluated using serially diluted Salmonella Typhimurium in borate buffer and chicken extract. The fluorescence response of the nano-biosensor increased with increasing cell concentration. The detection limit of the sensor was 10(3) CFU/mL Salmonella in both borate buffer and food extract.

  3. Preparation and Characterization of Fe2O3/Al2O3 Nano-composites

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Al2O3/Fe2O3 nano-composites were prepared by sol-gel route. The effect of Fe2O3 content on the structure, grain size and characterization of the composite were investigated through X-ray diffraction and M(o)ssbauer spectrum. The X-ray diffraction results show that Al2O3/Fe2O3 nano-composites with the Fe2O3, content of 40 wt% can be obtained after heat-treated at 900℃. The M(o)ssbauer effect results show that all samples exhibit clear super-paramagnetic phenomenon. Particles grow and defects reduce with the increasing of Fe2O3 conteni and some α-Fe2O3 stay magnetic order.

  4. Coupling functionalized cobalt ferrite nanoparticle enrichment with online LC/MS/MS for top-down phosphoproteomics.

    Science.gov (United States)

    Chen, Bifan; Hwang, Leekyoung; Ochowicz, William; Lin, Ziqing; Guardado-Alvarez, Tania M; Cai, Wenxuan; Xiu, Lichen; Dani, Kunal; Colah, Cyrus; Jin, Song; Ge, Ying

    2017-06-01

    Phosphorylation plays pivotal roles in cellular processes and dysregulated phosphorylation is considered as an underlying mechanism in many human diseases. Top-down mass spectrometry (MS) analyzes intact proteins and provides a comprehensive analysis of protein phosphorylation. However, top-down MS-based phosphoproteomics is challenging due to the difficulty in enriching low abundance intact phosphoproteins as well as separating and detecting the enriched phosphoproteins from complex mixtures. Herein, we have designed and synthesized the next generation functionalized superparamagnetic cobalt ferrite (CoFe2O4) nanoparticles (NPs), and have further developed a top-down phosphoproteomics strategy coupling phosphoprotein enrichment enabled by the functionalized CoFe2O4 NPs with online liquid chromatography (LC)/MS/MS for comprehensive characterization of phosphoproteins. We have demonstrated the highly specific enrichment of a minimal amount of spike-in β-casein from a complex tissue lysate as well as effective separation and quantification of its phosphorylated genetic variants. More importantly, this integrated top-down phosphoproteomics strategy allows for enrichment, identification, quantification, and comprehensive characterization of low abundance endogenous phosphoproteins from complex tissue extracts on a chromatographic time scale.

  5. Hyperfine interaction and tuning of magnetic anisotropy of Cu doped CoFe2O4 ferrite nanoparticles

    Science.gov (United States)

    Batoo, Khalid Mujasam; Salah, Dina; Kumar, Gagan; Kumar, Arun; Singh, Mahavir; Abd El-sadek, M.; Mir, Feroz Ahmad; Imran, Ahamad; Jameel, Daler Adil

    2016-08-01

    Ferrimagnetic oxides may contain single or multi domain particles which get converted into superparamagnetic state near a critical size. To explore the existence of these particles, we have made Mössbauer and magnetic studies of Cu2+ substitution effect in CoFe2-xO4 Ferrites (0.0, 0.1, 0.2, 0.3, 0.4, and 0.5). All the samples have a cubic spinel structure with lattice parameters increasing linearly with increase in Cu content. The hysteresis loops yield a saturation magnetization, coercive field, and remanent magnetization that vary significantly with Cu content. The magnetic hysteresis curves shows a reduction in saturation magnetization and an increase in coercitivity with Cu2+ ion substitution. The anisotropy constant, K1, is found strongly dependent on the composition of Cu2+ ions. The variation of saturation magnetization with increasing Cu2+ ion content has been explained in the light of Neel's molecular field theory. Mössbauer spectra at room temperature shows two ferrimagnetically relaxed Zeeman sextets. The dependence of Mössbauer parameters such as isomer shift, quadrupole splitting, line width and hyperfine magnetic field on Cu2+ ion concentration have been discussed.

  6. Microstructural Features During Strain Induced Ferrite Transformation in 08 and 20Mn Steels

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The microstructure evolution during strain induced ferrite transformation was followed in thermal-simulation tests of clean 08 and 20Mn steels. The influences of carbon equivalence and initial austenite grain size on ferrite grain refinement and the volume fraction of ferrite during straining were inspected. The results revealed that the accelerating effect of ferrite transformation by strain was increased as the carbon equivalence decreased. However, finer ferrite grains were obtained at higher carbon content. At strain of ~1.5 ferrite grains less than 3m and 2m can be obtained in 08 and 20Mn steels respectively. Whereas the ferrite grain refinement in 08 steel was due to both effects of strain induced transformation and ferrite dynamic recrystallization, that in 20Mn was mainly due to strain induced transformation. Heavy strain can produce fine ferrite grains in coarse austenite grained 08 steel, but it would lead to band microstructure in coarse austenite grained 20Mn.

  7. Performance Variation of Ferrite Magnet PMBLDC Motor with Temperature

    DEFF Research Database (Denmark)

    Fasil, Muhammed; Mijatovic, Nenad; Jensen, Bogi Bech

    2015-01-01

    a different approach when deciding their operating point. In this work, laboratory measured BH curves of a ferrite magnet are used for estimating the possibility of demagnetization in a segmented axial torus (SAT) permanent magnet brushless DC (PMBLDC) motor. The BH characteristics for different temperatures...... have been used to study the performance variation of the ferrite magnet SAT PMBLDC motor with temperature. A detailed analysis is carried out to ensure that, the designed ferrite magnet motor is capable of delivering the specified torque throughout the operating speed, without any irreversible...... demagnetization of magnets. It has been shown that the ferrite magnet PMBLDC motor operation is influenced by the magnet temperature and the maximum motor speed for a given load torque decreases as the magnet temperature drops....

  8. New sintering process adjusts magnetic value of ferrite cores

    Science.gov (United States)

    Vinal, A. W.

    1964-01-01

    A two-phase sintering technique based on time and temperature permits reversible control of the coercive threshold of sintered ferrite cores. Threshold coercivity may be controlled over a substantial range of values by selective control of the cooling rate.

  9. Ferrite core coupled slapper detonator apparatus and method

    Science.gov (United States)

    Boberg, Ralph E.; Lee, Ronald S.; Weingart, Richard C.

    1989-01-01

    Method and apparatus are provided for coupling a temporally short electric power pulse from a thick flat-conductor power cable into a thin flat-conductor slapper detonator circuit. A first planar and generally circular loop is formed from an end portion of the power cable. A second planar and generally circular loop, of