Synthesis, structural investigation and magnetic properties of Zn2+ substituted cobalt ferrite nanoparticles prepared by the sol–gel auto-combustion technique

International Nuclear Information System (INIS)

Raut, A.V.; Barkule, R.S.; Shengule, D.R.; Jadhav, K.M.

2014-01-01

Structural morphology and magnetic properties of the Co 1−x Zn x Fe 2 O 4 (0.0≤x≥1.0) spinel ferrite system synthesized by the sol–gel auto-combustion technique using nitrates of respective metal ions have been studied. The ratio of metal nitrates to citric acid was taken at 1:3. The as prepared powder of cobalt zinc ferrite was sintered at 600 °C for 12 h after TG/DTA thermal studies. Compositional stoichiometry was confirmed by energy dispersive analysis of the X-ray (EDAX) technique. Single phase cubic spinel structure of Co–Zn nanoparticles was confirmed by XRD data. The average crystallite size (t), lattice constant (a) and other structural parameters of zinc substituted cobalt ferrite nanoparticles were calculated from XRD followed by SEM and FTIR. It is observed that the sol–gel auto-combustion technique has many advantages for the synthesis of technologically applicable Co–Zn ferrite nanoparticles. The present investigation clearly shows the effect of the synthesis method and possible relation between magnetic properties and microstructure of the prepared samples. Increase in nonmagnetic Zn 2+ content in cobalt ferrite nanoparticles is followed by decrease in n B , M s and other magnetic parameters. Squareness ratio for the Co-ferrite was 1.096 at room temperature. - Highlights: • Co–Zn nanoparticles are prepared by sol–gel auto-combustion method. • Structural properties were characterized by XRD, SEM, and FTIR. • Compositional stoichiometry was confirmed by EDAX analysis. • Magnetic parameters were measured by the pulse field hysteresis loop technique

Effect of sintering temperature on magnetization and Mössbauer parameters of cobalt ferrite nanoparticles

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Chandra, Grish, E-mail: grishphysics@gmail.com [Department of Physics, DSB Campus Kumaun University, Nainital 263002, Uttarakhand (India); Srivastava, R.C. [Department of Physics, GB Pant University of Agriculture and Technology, Pantnagar, Uttarakhand (India); Reddy, V.R. [UGC-DAE CSR, Khandwa Road, DAVV Campus, Indore 452017, Madhya Pradesh (India); Agrawal, H.M. [Department of Physics, GB Pant University of Agriculture and Technology, Pantnagar, Uttarakhand (India)

2017-04-01

Nanoparticles of cobalt ferrite of different particle size were prepared using sol-gel method. Powder X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and Mössbauer spectroscopy techniques were employed for characterization of nanoparticles for structural and magnetic properties. The particle size and saturation magnetization increase with the increase of sintering temperature. The saturation magnetization increases from 53 to 85 emu/g as the sintering temperature increases from 300 to 900 °C. The remanence increases while the coercivity decreases slightly with the increase of sintering temperature. Mössbauer spectra show the ferrimagnetic nature of all the samples and the cation distribution strictly depends on the sintering temperature. The stoichiometry of the cobalt ferrite formed was estimated to be (Co{sup 2+}{sub x}Fe{sup 3+}{sub 1−x})[Co{sup 2+}{sub 1−x}Fe{sup 3+}{sub 1+x}]O{sub 4}, based on our Mössbauer analysis. The inverse spinel structure gradually transforms towards the normal spinel structure as the sintering temperature increases. - Highlights: • After 500 °C sintering the cobalt ferrite shows complete crystallization. • An inversion sintering temperature between 900 °C and 1200 °C is proposed where the Fe{sup +3} again starts migration from B site to A site. • Sintering temperature is one of the prime factors which effect the magnetization and cation distribution between two sites A and B.

Synthesis of surfactant-coated cobalt ferrite nanoparticles for adsorptive removal of acid blue 45 dye

Science.gov (United States)

Waheed Mushtaq, Muhammad; Kanwal, Farah; Imran, Muhammad; Ameen, Naila; Batool, Madeeha; Batool, Aisha; Bashir, Shahid; Mustansar Abbas, Syed; Rehman, Ata ur; Riaz, Saira; Naseem, Shahzad; Ullah, Zaka

2018-03-01

Cobalt ferrite (CoFe2O4) nanoparticles (NPs) are synthesized by wet chemical coprecipitation method using metal chlorides as precursors and potassium hydroxide (KOH) as a precipitant. The tergitol-1x (T-1x) and didecyldimethyl ammonium bromide (DDAB) are used as capping agents and their effect is investigated on particle size, size distribution and morphology of cobalt ferrite nanoparticles (CFNPs). The Fourier transform infrared spectroscopy confirms the synthesis of CFNPs and formation of metal-oxygen (M-O) bond. The spinel phase structure, morphology, polydispersity and magnetic properties of ferrite nanoparticles are investigated by x-ray diffraction, scanning electron microscopy, dynamic light scattering and vibrating sample magnetometry analyses, respectively. The addition of capping agents effects the secondary growth of CFNPs and reduces their particle size, as is investigated by dynamic light scattering and atomic force microscopy. The results evidence that the DDAB is more promising surfactant to control the particle size (∼13 nm), polydispersity and aggregation of CFNPs. The synthesized CFNPs, CFNPs/T-1x and CFNPs/DDAB are used to study their adsorption potential for removal of acid blue 45 dye, and a maximum adsorptive removal of 92.25% is recorded by 0.1 g of CFNPs/DDAB at pH 2.5 and temperature 20 ± 1 °C. The results show that the dye is physically adsorbed by magnetic NPs and follows the Langmuir isotherm model.

Synthesis, structural investigation and magnetic properties of Zn{sup 2+} substituted cobalt ferrite nanoparticles prepared by the sol–gel auto-combustion technique

Energy Technology Data Exchange (ETDEWEB)

Raut, A.V., E-mail: nano9993@gmail.com [Vivekanand Arts and Sardar Dalipsingh Commerce and Science College, Aurangabad, 431004 Maharastra (India); Barkule, R.S.; Shengule, D.R. [Vivekanand Arts and Sardar Dalipsingh Commerce and Science College, Aurangabad, 431004 Maharastra (India); Jadhav, K.M., E-mail: drjadhavkm@gmail.com [Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad, 431004 Maharastra (India)

2014-05-01

Structural morphology and magnetic properties of the Co{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} (0.0≤x≥1.0) spinel ferrite system synthesized by the sol–gel auto-combustion technique using nitrates of respective metal ions have been studied. The ratio of metal nitrates to citric acid was taken at 1:3. The as prepared powder of cobalt zinc ferrite was sintered at 600 °C for 12 h after TG/DTA thermal studies. Compositional stoichiometry was confirmed by energy dispersive analysis of the X-ray (EDAX) technique. Single phase cubic spinel structure of Co–Zn nanoparticles was confirmed by XRD data. The average crystallite size (t), lattice constant (a) and other structural parameters of zinc substituted cobalt ferrite nanoparticles were calculated from XRD followed by SEM and FTIR. It is observed that the sol–gel auto-combustion technique has many advantages for the synthesis of technologically applicable Co–Zn ferrite nanoparticles. The present investigation clearly shows the effect of the synthesis method and possible relation between magnetic properties and microstructure of the prepared samples. Increase in nonmagnetic Zn{sup 2+} content in cobalt ferrite nanoparticles is followed by decrease in n{sub B}, M{sub s} and other magnetic parameters. Squareness ratio for the Co-ferrite was 1.096 at room temperature. - Highlights: • Co–Zn nanoparticles are prepared by sol–gel auto-combustion method. • Structural properties were characterized by XRD, SEM, and FTIR. • Compositional stoichiometry was confirmed by EDAX analysis. • Magnetic parameters were measured by the pulse field hysteresis loop technique.

Influence of aging time of oleate precursor on the magnetic relaxation of cobalt ferrite nanoparticles synthesized by the thermal decomposition method

International Nuclear Information System (INIS)

Herrera, Adriana P.; Polo-Corrales, Liliana; Chavez, Ermides; Cabarcas-Bolivar, Jari; Uwakweh, Oswald N.C.; Rinaldi, Carlos

2013-01-01

Cobalt ferrite nanoparticles are of interest because of their room temperature coercivity and high magnetic anisotropy constant, which make them attractive in applications such as sensors based on the Brownian relaxation mechanism and probes to determine the mechanical properties of complex fluids at the nanoscale. These nanoparticles can be synthesized with a narrow size distribution by the thermal decomposition of an iron–cobalt oleate precursor in a high boiling point solvent. We studied the influence of aging time of the iron–cobalt oleate precursor on the structure, chemical composition, size, and magnetic relaxation of cobalt ferrite nanoparticles synthesized by the thermal decomposition method. The structure and thermal behavior of the iron–cobalt oleate was studied during the aging process. Infrared spectra indicated a shift in the coordination state of the oleate and iron/cobalt ions from bidentate to bridging coordination. Aging seemed to influence the thermal decomposition of the iron–cobalt oleate as determined from thermogravimmetric analysis and differential scanning calorimetry, where shifts in the temperatures corresponding to decomposition events and a narrowing of the endotherms associated with these events were observed. Aging promoted formation of the spinel crystal structure, as determined from X-ray diffraction, and influenced the nanoparticle magnetic properties, resulting in an increase in blocking temperature and magnetocrystalline anisotropy. Mossbauer spectra also indicated changes in the magnetic properties resulting from aging of the precursor oleate. Although all samples exhibited some degree of Brownian relaxation, as determined from complex susceptibility measurements in a liquid medium, aging of the iron–cobalt oleate precursor resulted in crossing of the in-phase χ′and out-of-phase χ″ components of the complex susceptibility at the frequency of the Brownian magnetic relaxation peak, as expected for nanoparticles

FTIR and structural properties of co-precipitated cobalt ferrite nano particles

International Nuclear Information System (INIS)

Hutamaningtyas, E.; Utari; Suharyana; Purnama, B.; Wijayanta, A. T.

2016-01-01

The FTIR and structural properties in co-precipitated cobalt ferrite (CoFe 2 O 4 ) nanoparticles are discussed in this paper. The synthesis was conducted at temperatures of 75°C and 95°C following post annealing at 1200°C for 5 hours. Other modification samples were synthesis at temperature of 95°C and then annealing at temperature of 1000°C and 1200°C for 5 hours. For both modification of synthesis and annealing temperature, FTIR result showed a metal oxide at a wave number of 590 cm -1 which indicated cobalt ferrite nanoparticles. The crystalline structure was confirmed using x-ray diffraction that the high purity of cobalt ferrite was realized. Calculation of the cation distribution by using comparison I 220 /I 222 and I 422 /I 222 show that the synthesis and annealing temperature succesfully modify cation occupy the site octahedral and tetrahedral. (paper)

Synthesis, characterization and thermal analysis of polyimide-cobalt ferrite nanocomposites

International Nuclear Information System (INIS)

Mazuera, David; Perales, Oscar; Suarez, Marcelo; Singh, Surinder

2010-01-01

Research highlights: · Polyimide-cobalt ferrite nanocomposites were successfully produced. · Produced nanocomposites are suitable for use at temperatures below 80 deg. C. · Magnetic properties of nanocomposites were no sensitive to particle agglomeration. · Good distribution of clustered nanoparticles was achieved in produced composites. - Abstract: Cobalt ferrite nanocrystals were synthesized under size-controlled conditions in aqueous phase and incorporated into a polyimide matrix at various volumetric loads. Synthesized 20 nm cobalt ferrite single crystals, which exhibited a room-temperature coercivity of 2.9 kOe, were dispersed in polyimide precursor using two techniques: homogenizer and ball milling. These suspensions were then cured to develop the polyimide structure in the resulting nanocomposites. Produced films were characterized by Fourier transform infrared spectroscopy, X-ray diffraction and vibrating sample magnetometry, which confirmed the formation of the desired phases. As expected, the saturation magnetization in the nanocomposites varied according to the polyimide/ferrite weight ratio, while coercivity remained at the value corresponding to pure cobalt ferrite nanocrystals. Thermal degradation, thermal stability and dynamic mechanical analyses tests were also carried out to assess the effect of the concentration of the ferrite disperse phase on the thermo-mechanical behavior of the corresponding nanocomposites as well as the used dispersion techniques.

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

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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.

Chemical modification of cobalt ferrite nanoparticles with possible application as asphaltene flocculant agent

Energy Technology Data Exchange (ETDEWEB)

Oliveira, G.E.; Clarindo, J.E.S.; Santo, K.S.E., E-mail: geiza.oliveira@ufes.br [Universidade Federal do Espirito Santo (CCE/DQUI/UFES), Vitoria, ES (Brazil). Centro de Ciencias Exatas. Dept. de Quimica; Souza Junior, F.G. [Universidade Federal do Rio de Janeiro (IMA/UFRJ), Rio de Janeiro, RJ (Brazil). Instituto de Macromoleculas

2013-11-01

Asphaltenes can cause enormous losses in the oil industry, because they are soluble only in aromatic solvents. Therefore, they must be removed from the petroleum before it is refined, using flocculant agents. Aiming to find new materials that can work as flocculant agents to asphaltenes, cobalt ferrite nanoparticles were chemically modified through acid-base reactions using dodecylbenzene sulfonic acid (DBSA) to increase their lipophilicity. Nanoparticle synthesis was performed using the co-precipitation method followed by annealing of these nanoparticles, aiming to change the structural phase. Modified and unmodified nanoparticles were tested by FTIR-ATR, XRD and TGA/DTA. In addition, precipitation onset of the asphaltenes was performed using modified and unmodified nanoparticles. These tests showed that modified nanoparticles have a potential application as flocculant agents used to remove asphaltenes before oil refining, since the presence of nanoparticles promotes the asphaltene precipitation onset with the addition of a small amount of non-solvent (author)

Chemical modification of cobalt ferrite nanoparticles with possible application as asphaltene flocculant agent

International Nuclear Information System (INIS)

Oliveira, G.E.; Clarindo, J.E.S.; Santo, K.S.E.; Souza Junior, F.G.

2013-01-01

Asphaltenes can cause enormous losses in the oil industry, because they are soluble only in aromatic solvents. Therefore, they must be removed from the petroleum before it is refined, using flocculant agents. Aiming to find new materials that can work as flocculant agents to asphaltenes, cobalt ferrite nanoparticles were chemically modified through acid-base reactions using dodecylbenzene sulfonic acid (DBSA) to increase their lipophilicity. Nanoparticle synthesis was performed using the co-precipitation method followed by annealing of these nanoparticles, aiming to change the structural phase. Modified and unmodified nanoparticles were tested by FTIR-ATR, XRD and TGA/DTA. In addition, precipitation onset of the asphaltenes was performed using modified and unmodified nanoparticles. These tests showed that modified nanoparticles have a potential application as flocculant agents used to remove asphaltenes before oil refining, since the presence of nanoparticles promotes the asphaltene precipitation onset with the addition of a small amount of non-solvent (author)

Evidence of exchange-coupled behavior in chromium-cobalt ferrite nanoparticles

Science.gov (United States)

Tanbir, Kamar; Sharma, Lalit Kumar; Aakash; Singh, Rakesh Kumar; Choubey, Ravi Kant; Mukherjee, Samrat

2018-06-01

Cr doped cobalt ferrite nanoparticles were synthesized with the generic formula Co1-xCrxFe2O4 (x = 0, 0.05, 0.15, 0.25) through standard chemical co-precipitation method. XRD studies confirmed the pure spinel cubic structure belonging to Fd 3 bar m space group. From the Williamson-Hall plots, crystallite sizes were found to lie within the range (42 ± 1) nm for the different doped samples. The lattice parameter was found to decrease linearly with increase in the concentration of Cr3+ ion. The magnetic behavior of the samples was determined by M-H studies at 300 K, field cooled (5 T) at 5 K and temperature dependent studies. The M-H at 300 K show soft magnetic behavior whereas the M-H plots at 5 K predict the existence of in-homogeneity of the exchange interactions due to strong exchange coupling between the spins at the core and the surface of the nanoparticles.

Synthesis and characterization of graphene quantum dots/cobalt ferrite nanocomposite

Science.gov (United States)

Ramachandran, Shilpa; Sathishkumar, M.; Kothurkar, Nikhil K.; Senthilkumar, R.

2018-02-01

A facile method has been developed for the synthesis of a graphene quantum dots/cobalt ferrite nanocomposite. Graphene quantum dots (GQDs) were synthesized by a simple bottom-up method using citric acid, followed by the co-precipitation of cobalt ferrite nanoparticles on the graphene quantum dots. The morphology, structural analysis, optical properties, magnetic properties were investigated using transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-vis absorption spectroscopy, fluorescence spectroscopy, vibrating sample magnetometry (VSM) measurements. The synthesized nanocomposite showed good fluorescence and superparamagnetic properties, which are important for biomedical applications.

Size-dependent antimicrobial properties of the cobalt ferrite nanoparticles

Science.gov (United States)

Žalnėravičius, Rokas; Paškevičius, Algimantas; Kurtinaitiene, Marija; Jagminas, Arūnas

2016-10-01

The growing resistance of bacteria to conventional antibiotics elicited considerable interest to non-typical drugs. In this study, antimicrobial investigations were performed on low-size dispersion cobalt ferrite nanoparticles (Nps) fabricated by co-precipitation approach in several average sizes, in particular, 15.0, 5.0, and 1.65 nm. A variety of experimental tests demonstrated that the size of these Nps is determinant for antimicrobial efficiency against S. cerevisiae and several Candida species, in particular, C. parapsilosis, C. krusei, and C. albicans. The small and ultra-small fractions of CoFe2O4 Nps possess especially strong antimicrobial activity against all tested microorganisms. The possible reasons are discussed. Nps were characterized by means of transmission and high-resolution transmission electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and atomic force microscopy, chemical analysis and magnetic measurements.

Size-dependent antimicrobial properties of the cobalt ferrite nanoparticles

International Nuclear Information System (INIS)

Žalnėravičius, Rokas; Paškevičius, Algimantas; Kurtinaitiene, Marija; Jagminas, Arūnas

2016-01-01

The growing resistance of bacteria to conventional antibiotics elicited considerable interest to non-typical drugs. In this study, antimicrobial investigations were performed on low-size dispersion cobalt ferrite nanoparticles (Nps) fabricated by co-precipitation approach in several average sizes, in particular, 15.0, 5.0, and 1.65 nm. A variety of experimental tests demonstrated that the size of these Nps is determinant for antimicrobial efficiency against S. cerevisiae and several Candida species, in particular, C. parapsilosis, C. krusei, and C. albicans. The small and ultra-small fractions of CoFe_2O_4 Nps possess especially strong antimicrobial activity against all tested microorganisms. The possible reasons are discussed. Nps were characterized by means of transmission and high-resolution transmission electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and atomic force microscopy, chemical analysis and magnetic measurements.Graphical Abstract

Variation in band gap energy and electrical analysis of double doped cobalt ferrite

Science.gov (United States)

Parveen, Azra; Agrawal, Shraddha; Azam, Ameer

2018-05-01

The Ca and Cr doped cobalt ferrite nanoparticles (Co0.9Ca0.1) (Fe0.8 Cr0.2)2O4 were synthesized by microwave gel combustion method. Microstructural studies were carried out by XRD and SEM. Structural studies suggest that the crystal system remains spinal even with the doping of calcium and chromium. The SEM image shows the spherical morphology of surface of the sample. Optical properties of Ca and Cr doped cobalt ferrite were studied by UV-visible technique in the range of 400-600 nm. The electrical conductivity of pure and doped cobalt ferrite were studied as a function of frequency and were explained on the basis of electron hopping.

Structural and magnetic properties of cobalt-doped iron oxide nanoparticles prepared by solution combustion method for biomedical applications.

Science.gov (United States)

Venkatesan, Kaliyamoorthy; Rajan Babu, Dhanakotti; Kavya Bai, Mane Prabhu; Supriya, Ravi; Vidya, Radhakrishnan; Madeswaran, Saminathan; Anandan, Pandurangan; Arivanandhan, Mukannan; Hayakawa, Yasuhiro

2015-01-01

Cobalt-doped iron oxide nanoparticles were prepared by solution combustion technique. The structural and magnetic properties of the prepared samples were also investigated. The average crystallite size of cobalt ferrite (CoFe2O4) magnetic nanoparticle was calculated using Scherrer equation, and it was found to be 16±5 nm. The particle size was measured by transmission electron microscope. This value was found to match with the crystallite size calculated by Scherrer equation corresponding to the prominent intensity peak (311) of X-ray diffraction. The high-resolution transmission electron microscope image shows clear lattice fringes and high crystallinity of cobalt ferrite magnetic nanoparticles. The synthesized magnetic nanoparticles exhibited the saturation magnetization value of 47 emu/g and coercivity of 947 Oe. The anti-microbial activity of cobalt ferrite nanoparticles showed better results as an anti-bacterial agent. The affinity constant was determined for the nanoparticles, and the cytotoxicity studies were conducted for the cobalt ferrite nanoparticles at different concentrations and the results are discussed.

Size-dependent antimicrobial properties of the cobalt ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Žalnėravičius, Rokas [State Research Institute Center for Physical Sciences and Technology (Lithuania); Paškevičius, Algimantas [Nature Research Centre, Laboratory of Biodeterioration Research (Lithuania); Kurtinaitiene, Marija; Jagminas, Arūnas, E-mail: arunas.jagminas@ftmc.lt [State Research Institute Center for Physical Sciences and Technology (Lithuania)

2016-10-15

The growing resistance of bacteria to conventional antibiotics elicited considerable interest to non-typical drugs. In this study, antimicrobial investigations were performed on low-size dispersion cobalt ferrite nanoparticles (Nps) fabricated by co-precipitation approach in several average sizes, in particular, 15.0, 5.0, and 1.65 nm. A variety of experimental tests demonstrated that the size of these Nps is determinant for antimicrobial efficiency against S. cerevisiae and several Candida species, in particular, C. parapsilosis, C. krusei, and C. albicans. The small and ultra-small fractions of CoFe{sub 2}O{sub 4} Nps possess especially strong antimicrobial activity against all tested microorganisms. The possible reasons are discussed. Nps were characterized by means of transmission and high-resolution transmission electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and atomic force microscopy, chemical analysis and magnetic measurements.Graphical Abstract.

Immobilization of cellulase on functionalized cobalt ferrite nanoparticles

International Nuclear Information System (INIS)

Bohara, Raghvendra Ashok; Thorat, Nanasaheb Devappa; Pawar, Shivaji Hariba

2016-01-01

Amine functionalized cobalt ferrite (AF-CoFe 2 O 4 ) magnetic nanoparticles (MNPs) were used for immobilization of cellulase enzyme via 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride (EDS) and N-hydroxysuccinimide (NHS) coupling reaction. The structural, morphological and magnetic properties of AF-CoFe 2 O 4 were determined. TEM micrograph revealed a mean diameter of -8 nm and showed that the AF-CoFe 2 O 4 remain distinct with no significant change in size after binding with cellulase. Fourier transform infrared (FT-IR) spectroscopy confirmed the binding of cellulase to AF-CoFe 2 O 4 . The properties of immobilized cellulase were investigated by optimizing binding efficiency, pH, temperature and reusability. The results showed that the immobilized cellulase has higher thermal stability than free cellulase, which might be due to covalent interaction between cellulase and AF-CoFe 2 O 4 surface. The immobilized cellulase also showed good reusability after recovery. Therefore, AF-CoFe 2 O 4 MNPs can be considered as promising candidate for enzyme immobilization.

Influence of synthesis method on structural and magnetic properties of cobalt ferrite nanoparticles

International Nuclear Information System (INIS)

Gyergyek, Saso; Makovec, Darko; Kodre, Alojz; Arcon, Iztok; Jagodic, Marko; Drofenik, Miha

2010-01-01

The Co-ferrite nanoparticles having a relatively uniform size distribution around 8 nm were synthesized by three different methods. A simple co-precipitation from aqueous solutions and a co-precipitation in an environment of microemulsions are low temperature methods (50 o C), whereas a thermal decomposition of organo-metallic complexes was performed at elevated temperature of 290 o C. The X-ray diffractometry (XRD) showed spinel structure, and the high-resolution transmission electron microscopy (HRTEM) a good crystallinity of all the nanoparticles. Energy-dispersive X-ray spectroscopy (EDS) showed the composition close to stoichiometric (∼CoFe 2 O 4 ) for both co-precipitated nanoparticles, whereas the nanoparticles prepared by the thermal decomposition were Co-deficient (∼Co 0.6 Fe 2.4 O 4 ). The X-ray absorption near-edge structure (XANES) analysis showed Co valence of 2+ in all the samples, Fe valence 3+ in both co-precipitated samples, but average Fe valence of 2.7+ in the sample synthesized by thermal decomposition. The variations in cation distribution within the spinel lattice were observed by structural refinement of X-ray absorption fine structure (EXAFS). Like the bulk CoFe 2 O 4 , the nanoparticles synthesized at elevated temperature using thermal decomposition displayed inverse spinel structure with the Co ions occupying predominantly octahedral lattice sites, whereas co-precipitated samples showed considerable proportion of cobalt ions occupying tetrahedral sites (nearly 1/3 for the nanoparticles synthesized by co-precipitation from aqueous solutions and almost 1/4 for the nanoparticles synthesized in microemulsions). Magnetic measurements performed at room temperature and at 10 K were in good agreement with the nanoparticles' composition and the cation distribution in their structure. The presented study clearly shows that the distribution of the cations within the spinel lattice of the ferrite nanoparticles, and consequently their magnetic

Homogeneous Precipitation Synthesis and Magnetic Properties of Cobalt Ferrite Nanoparticles

Directory of Open Access Journals (Sweden)

Zhigang Liu

2008-01-01

Full Text Available Magnetic nanoparticles (NPs of cobalt ferrite have been synthesized via a homogeneous precipitation route using hexamethylenetetramine (HMT as the precipitant. The particle size, crystal structure, and magnetic properties of the synthesized particles were investigated by X-ray diffraction, transmission electron microscopy, and vibrating sample magnetometer. The NPs are of cubic inverse spinel structure and nearly spherical shape. With the increase of oxidation time from 30 to 180 minutes in the reaction solution at 90∘C, the average particle size increases from ~30 nm to ~45 nm. The as-synthesized NPs ~30 nm in size show higher Ms (61.5 emu/g and moderate Hc (945 Oe and Mr/Ms (0.45 value compared with the materials synthesized by coprecipitation method using NaOH as precipitate at high pH value.

Magnetic and Structural Investigations of Nanocrystalline Cobalt-Ferrite

Directory of Open Access Journals (Sweden)

I. Sharifi

2012-10-01

Full Text Available Cobalt ferrite is an important magnetic material due to their large magneto-crystalline anisotropy, high cohercivity, moderate saturation magnetization and chemical stability.In this study, cobalt ferrites Nanoparticles have been synthesized by the co-precipitation method and a new microemulsion route. We examined the cation occupancy in the spinel structure based on the “Rietveld with energies” method. The Xray measurements revealed the production of a broad single ferrite cubic phase with the average particle sizes of about 12 nm and 7nm, for co-precipitation and micro-emulsion methods, respectively. The FTIR measurements between 400 and 4000 cm-1 confirmed the intrinsic cation vibrations of the spinelstructure for the two methods. Furthermore, the Vibrating Sample Magnetometer (VSM was carried out at room temperature to study the structural and magnetic properties. The results revealed that by changing the method from co-precipitation to the reverse micelle the material exhibits a softer magnetic behavior in such a way that both saturation magnetization and coercivity decrease from 58 to 29 emu/g and from 286 to 25 Oe, respectively.

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.

Immobilization of cellulase on functionalized cobalt ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Bohara, Raghvendra Ashok; Thorat, Nanasaheb Devappa; Pawar, Shivaji Hariba [Center for Interdisciplinary Research, D. Y. Patil University, Kolhapur (India)

2016-01-15

Amine functionalized cobalt ferrite (AF-CoFe{sub 2}O{sub 4}) magnetic nanoparticles (MNPs) were used for immobilization of cellulase enzyme via 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride (EDS) and N-hydroxysuccinimide (NHS) coupling reaction. The structural, morphological and magnetic properties of AF-CoFe{sub 2}O{sub 4} were determined. TEM micrograph revealed a mean diameter of -8 nm and showed that the AF-CoFe{sub 2}O{sub 4} remain distinct with no significant change in size after binding with cellulase. Fourier transform infrared (FT-IR) spectroscopy confirmed the binding of cellulase to AF-CoFe{sub 2}O{sub 4}. The properties of immobilized cellulase were investigated by optimizing binding efficiency, pH, temperature and reusability. The results showed that the immobilized cellulase has higher thermal stability than free cellulase, which might be due to covalent interaction between cellulase and AF-CoFe{sub 2}O{sub 4} surface. The immobilized cellulase also showed good reusability after recovery. Therefore, AF-CoFe{sub 2}O{sub 4} MNPs can be considered as promising candidate for enzyme immobilization.

Self-biased cobalt ferrite nanocomposites for microwave applications

International Nuclear Information System (INIS)

Hannour, Abdelkrim; Vincent, Didier; Kahlouche, Faouzi; Tchangoulian, Ardaches; Neveu, Sophie; Dupuis, Vincent

2014-01-01

Oriented CoFe 2 O 4 nanoparticles, dispersed in polymethyl methacrylate (PMMA) matrix, were fabricated by magnetophoretic deposition of functionalized nanocolloidal cobalt ferrite particles into porous alumina membrane. Their magnetic behavior exhibits an out-of-plane easy axis with a large remanent magnetization and coercitivity. This orientation allows high effective internal magnetic anisotropy that contributes to the permanent bias along the wire axis. The microwave studies reveal a ferromagnetic resonance at 46.5 and 49.5 GHz, depending on the filling ratio of the membrane. Ansoft High Frequency Structure Simulator (Ansoft HFSS) simulations are in good agreement with experimental results. Such nanocomposite is presented as one of the promising candidates for microwave devices (circulators, isolators, noise suppressors etc.). - Highlights: • Oriented magnetic CoFe 2 O 4 nanoparticles were fabricated by magnetophoretic deposition of functionalized cobalt ferrite particles into porous alumina membrane. • The nanocomposite obtained presents an out-of-plane easy axis with a large remanent magnetization and coercitivity. • The high effective internal magnetic anisotropy contributes to the permanent bias along the wire axis. • The frequency ferromagnetic resonance ranges from 46.5 to 49.5 GHz, depending on the filling ratio of the membrane. • We have obtained a good agreement between Ansoft High Frequency Structure Simulator simulations and experimental results

Effect of preparation conditions on physicochemical, surface and catalytic properties of cobalt ferrite prepared by coprecipitation

Energy Technology Data Exchange (ETDEWEB)

El-Shobaky, G.A., E-mail: elshobaky@yahoo.co [Physical Chemistry Department, National Research Center, Dokki, Cairo (Egypt); Turky, A.M.; Mostafa, N.Y.; Mohamed, S.K. [Chemistry Department, Faculty of Science, Suez Canal University, Ismailia 41522 (Egypt)

2010-03-18

Cobalt ferrite nanoparticles were prepared via thermal treatment of cobalt-iron mixed hydroxides at 400-600 {sup o}C. The mixed hydroxides were coprecipitated from their nitrates solutions using NaOH as precipitating agent. The effects of pH and temperature of coprecipitation and calcination temperature on the physicochemical, surface and catalytic properties of the prepared ferrites were studied. The prepared systems were characterized using TG, DTG, DTA, chemical analysis, atomic absorption spectroscopy (AAS), X-ray diffraction (XRD), energy dispersive X-ray (EDX) as well as surface and texture properties based on nitrogen adsorption-desorption isotherms. The prepared cobalt ferrites were found to be mesoporous materials that have crystallite size ranges between 8 and 45 nm. The surface and catalytic properties of the produced ferrite phase were strongly dependent on coprecipitation conditions of the mixed hydroxides and on their calcination temperature.

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.

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

International Nuclear Information System (INIS)

Ahmad, Rabia; Hussain Gul, Iftikhar; Zarrar, Muhammad; Anwar, Humaira; Khan Niazi, Muhammad Bilal; Khan, Azim

2016-01-01

Cadmium substituted cobalt ferrites with formula Cd x Co 1−x Fe 2 O 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 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 x Co 1−x Fe 2 O 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 2+ substituted Co-ferrites increases.

Structural and magnetic properties of cobalt-doped iron oxide nanoparticles prepared by solution combustion method for biomedical applications

Directory of Open Access Journals (Sweden)

Venkatesan K

2015-10-01

Full Text Available Kaliyamoorthy Venkatesan,1 Dhanakotti Rajan Babu,1 Mane Prabhu Kavya Bai,2 Ravi Supriya,2 Radhakrishnan Vidya,2 Saminathan Madeswaran,1 Pandurangan Anandan,3 Mukannan Arivanandhan,3 Yasuhiro Hayakawa3 1School of Advanced Sciences, 2School of Bio Sciences and Technology, VIT University, Vellore, Tamil Nadu, India; 3Research Institute of Electronics, Shizuoka University, Hamamatsu, Japan Abstract: Cobalt-doped iron oxide nanoparticles were prepared by solution combustion technique. The structural and magnetic properties of the prepared samples were also investigated. The average crystallite size of cobalt ferrite (CoFe2O4 magnetic nanoparticle was calculated using Scherrer equation, and it was found to be 16±5 nm. The particle size was measured by transmission electron microscope. This value was found to match with the crystallite size calculated by Scherrer equation corresponding to the prominent intensity peak (311 of X-ray diffraction. The high-resolution transmission electron microscope image shows clear lattice fringes and high crystallinity of cobalt ferrite magnetic nanoparticles. The synthesized magnetic nanoparticles exhibited the saturation magnetization value of 47 emu/g and coercivity of 947 Oe. The anti-microbial activity of cobalt ferrite nanoparticles showed better results as an anti-bacterial agent. The affinity constant was determined for the nanoparticles, and the cytotoxicity studies were conducted for the cobalt ferrite nanoparticles at different concentrations and the results are discussed. Keywords: cytotoxicity, HR-TEM, magnetic nanoparticles, VSM 

Self-biased cobalt ferrite nanocomposites for microwave applications

Energy Technology Data Exchange (ETDEWEB)

Hannour, Abdelkrim, E-mail: abdelkrim.hannour@hotmail.com [LT2C Laboratory, Jean-Monnet University, 25 rue Dr. Rémy Annino, F-42000, Saint-Etienne (France); Vincent, Didier; Kahlouche, Faouzi; Tchangoulian, Ardaches [LT2C Laboratory, Jean-Monnet University, 25 rue Dr. Rémy Annino, F-42000, Saint-Etienne (France); Neveu, Sophie; Dupuis, Vincent [UPMC Univ Paris 06, UMR 7195, PECSA, F-75005, Paris (France)

2014-03-15

Oriented CoFe{sub 2}O{sub 4} nanoparticles, dispersed in polymethyl methacrylate (PMMA) matrix, were fabricated by magnetophoretic deposition of functionalized nanocolloidal cobalt ferrite particles into porous alumina membrane. Their magnetic behavior exhibits an out-of-plane easy axis with a large remanent magnetization and coercitivity. This orientation allows high effective internal magnetic anisotropy that contributes to the permanent bias along the wire axis. The microwave studies reveal a ferromagnetic resonance at 46.5 and 49.5 GHz, depending on the filling ratio of the membrane. Ansoft High Frequency Structure Simulator (Ansoft HFSS) simulations are in good agreement with experimental results. Such nanocomposite is presented as one of the promising candidates for microwave devices (circulators, isolators, noise suppressors etc.). - Highlights: • Oriented magnetic CoFe{sub 2}O{sub 4} nanoparticles were fabricated by magnetophoretic deposition of functionalized cobalt ferrite particles into porous alumina membrane. • The nanocomposite obtained presents an out-of-plane easy axis with a large remanent magnetization and coercitivity. • The high effective internal magnetic anisotropy contributes to the permanent bias along the wire axis. • The frequency ferromagnetic resonance ranges from 46.5 to 49.5 GHz, depending on the filling ratio of the membrane. • We have obtained a good agreement between Ansoft High Frequency Structure Simulator simulations and experimental results.

Improvement of drug delivery by hyperthermia treatment using magnetic cubic cobalt ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Dey, Chaitali, E-mail: chaitalidey29@gmail.com [Centre for Research in Nanoscience & Nanotechnology, Block-JD-2, Sector-III, Salt Lake, Kolkata 700106 (India); Baishya, Kaushik [S.N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700106 (India); Ghosh, Arup [S.N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700106 (India); Department of Physics, Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune 411008 (India); Goswami, Madhuri Mandal, E-mail: madhuri@bose.res.in [S.N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700106 (India); Ghosh, Ajay [Dept. of Applied Optics and Photonics, University of Calcutta, Block-JD-2, Sector-III, Salt Lake, Kolkata 700106 (India); Mandal, Kalyan [S.N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700106 (India)

2017-04-01

In this study, we report a novel synthesis method, characterization and application of a new class of ferromagnetic cubic cobalt ferrite magnetic nanoparticles (MNPs) for hyperthermia therapy and temperature triggered drug release. The MNPs are characterized by XRD, TEM, FESEM, AC magnetic hysteresis and VSM. These MNPs were coated with folic acid and loaded with an anticancer drug. The drug release studies were done at two different temperatures (37 °C and 44 °C) with progress of time. It was found that higher release of drug took place at elevated temperature (44 °C). We have developed a temperature sensitive drug delivery system which releases the heat sensitive drug selectively as the particles are heated up under AC magnetic field and controlled release is possible by changing the external AC magnetic field.

In situ fabrication and characterization of cobalt ferrite nanorods/graphene composites

International Nuclear Information System (INIS)

Fu, Min; Jiao, Qingze; Zhao, Yun

2013-01-01

Cobalt ferrite nanorods/graphene composites were prepared by a one-step hydrothermal process using NaHSO 3 as the reducing agent and 1-propyl-3-hexadecylimidazolium bromide as the structure growth-directing template. The reduction of graphene oxide and the in situ formation of cobalt ferrite nanorods were accomplished in a one-step reaction. The structure and morphology of as-obtained composites were characterized by field emission scanning electron microscopy, transmission electron microscopy, high resolution transmission electron microscopy, atomic force microscope, X-ray diffractometer, Fourier transform infrared spectra, X-ray photoelectron spectroscopy and Raman spectroscopy. Uniform rod-like cobalt ferrites with diameters of about 100 nm and length of about 800 nm were homogeneously distributed on the graphene sheets. The hybrid materials showed a saturation magnetization of 42.5 emu/g and coercivity of 495.1 Oe at room temperature. The electromagnetic parameters were measured using a vector network analyzer. A minimum reflection loss (RL) of − 25.8 dB was observed at 16.1 GHz for the cobalt ferrite nanorods/graphene composites with a thickness of 2 mm, and the effective absorption frequency (RL < − 10 dB) ranged from 13.5 to 18.0 GHz. The composites exhibited better absorbing properties than the cobalt ferrite nanorods and the mixture of cobalt ferrite nanorods and graphene. - Highlights: • Reduction of GO and formation of ferrites were accomplished in a one-step reaction. • Ionic liquid was used to control 1D growth of ferrite nanorods for the first time. • Cobalt ferrite nanorods/graphene composites showed dielectric and magnetic loss. • Cobalt ferrite nanorods/graphene composites exhibited better absorbing properties

Hydrothermal synthesis of mixed zinc–cobalt ferrite nanoparticles: structural and magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Coppola, P. [Univ. de Brasília, Complex Fluids Group, Instituto de Química (Brazil); Silva, F. G. da [Univ. de Brasília, Laboratório de Nanociência Ambiental e Aplicada - LNAA, Faculdade UnB Planaltina (Brazil); Gomide, G.; Paula, F. L. O. [Univ. de Brasília, Complex Fluids Group, Instituto de Física (Brazil); Campos, A. F. C. [Univ. de Brasília, Laboratório de Nanociência Ambiental e Aplicada - LNAA, Faculdade UnB Planaltina (Brazil); Perzynski, R. [Sorbonne Universités, UPMC Univ. Paris 06, CNRS, Laboratoire PHENIX (France); Kern, C. [Univ. de Brasília, Complex Fluids Group, Instituto de Química (Brazil); Depeyrot, J. [Univ. de Brasília, Complex Fluids Group, Instituto de Física (Brazil); Aquino, R., E-mail: reaquino@unb.br [Univ. de Brasília, Laboratório de Nanociência Ambiental e Aplicada - LNAA, Faculdade UnB Planaltina (Brazil)

2016-05-15

We synthesize Zn-substituted cobalt ferrite (Zn{sub x}Co{sub 1−x}Fe{sub 2}O{sub 4}, with 0 ≤ x ≤ 1) magnetic nanoparticles by a hydrothermal co-precipitation method in alkaline medium. The chemical composition is evaluated by atomic absorption spectroscopy and energy-dispersive X-ray spectroscopy techniques. The structure and morphology of the nanopaticles are investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. XRD Rietveld refinements reveal the cation distribution among the tetrahedral (A) and octahedral (B) sites. It shows that up to x ~0.5 zinc ions occupy preferably A-sites, above which Zn ions begin also a gradual occupancy of B-sites. TEM images show nanoparticles with different shapes varying from spheres, cubes, to octahedrons. Hysteresis loop properties are studied at 300 and 5 K. These properties are strongly influenced by the Zn and Co proportion in the nanoparticle composition. At 300 K, only samples with high Co content present hysteresis. At 5 K, the reduced remanent magnetization ratio (M{sub R}/M{sub S}) and the coercivity (H{sub C}) suggest that nanoparticles with x < 0.5 have cubic anisotropy. A kink on the hysteresis loop, close to the remanence, is observed at low temperature. This feature is presumably associated to interplay between hard and soft anisotropy regimes in the powder samples.Graphical Abstract.

hermo-Physical and Mechanical Properties of Unsaturated Polyester /Cobalt Ferrite Composites

Directory of Open Access Journals (Sweden)

Lamees Salam Faiq

2017-04-01

Full Text Available Unsaturated polyester was used as a matrix which was filled with different percentages of cobalt ferrite using hand lay-up method. Cobalt ferrite was synthesized using solid state ceramic method with reagent of CoO and Fe2O3. Mechanical properties such tensile strength, Young's modulus and shore D hardness of the composite have been studied. All these properties have increased by 10% with increasing cobalt ferrite contents. Also the thermal properties such thermal conductivity and specific heat capacity are highly increased as the ferrite content increased, while the thermal diffusivity increased by 22 %. On the other hand dielectric strength of composite has been measured which increased by 50% by increasing the cobalt ferrite content.

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.

Manganese substituted cobalt ferrite magnetostrictive materials for magnetic stress sensor applications

OpenAIRE

Paulsen, J. A.; Ring, A. P.; Lo, C. C. H.; Snyder, John Evan; Jiles, David

2005-01-01

Metal bonded cobalt ferrite composites have been shown to be promising candidate materials for use in magnetoelastic stress sensors, due to their large magnetostriction and high sensitivity of magnetization to stress. However previous results have shown that below 60 °C the cobalt ferrite material exhibits substantial magnetomechanical hysteresis. In the current study, measurements indicate that substituting Mn for some of the Fe in the cobalt ferrite can lower the Curie temperature of the ma...

Impact of Nd{sup 3+} in CoFe{sub 2}O{sub 4} spinel ferrite nanoparticles on cation distribution, structural and magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Yadav, Raghvendra Singh, E-mail: yadav@fch.vutbr.cz [Materials Research Centre, Brno University of Technology, Purkyňova 464/118, 61200 Brno (Czech Republic); Havlica, Jaromir; Masilko, Jiri; Kalina, Lukas; Wasserbauer, Jaromir; Hajdúchová, Miroslava; Enev, Vojtěch [Materials Research Centre, Brno University of Technology, Purkyňova 464/118, 61200 Brno (Czech Republic); Kuřitka, Ivo; Kožáková, Zuzana [Centre of Polymer Systems, University Institute, Tomas Bata University in Zlín, Nad Ovčírnou 3685, 760 01 Zlín (Czech Republic)

2016-02-01

Nd{sup 3+} doped cobalt ferrite nanoparticles have been synthesized by starch-assisted sol–gel auto-combustion method. The significant role played by Nd{sup 3+} added to cobalt ferrite in changing cation distribution and further in influencing structural and magnetic properties, was explored and reported. The crystal structure formation and crystallite size were studied from X-ray diffraction studies. The microstructural features were investigated by field emission scanning electron microscopy and transmission electron microscopy that demonstrates the nanocrystalline grain formation with spherical morphology. An infrared spectroscopy study shows the presence of two absorption bands related to tetrahedral and octahedral group complexes within the spinel ferrite lattice system. The change in Raman modes in synthesized ferrite system were observed with Nd{sup 3+} substitution, particle size and cation redistribution. The impact of Nd{sup 3+} on cation distribution of Co{sup 2+} and Fe{sup 3+} at octahedral and tetrahedral sites in spinel ferrite cobalt ferrite nanoparticles was investigated by X-ray photoelectron spectroscopy. Room temperature magnetization measurements showed that the saturation magnetization and coercivity increase with addition of Nd{sup 3+} substitution in cobalt ferrite. - Highlights: • Nd{sup 3+} doped CoFe{sub 2}O{sub 4} nanoparticles by starch-assisted sol–gel auto-combustion method. • The change in Raman modes with Nd{sup 3+} substitution. • Presence of absorption infrared bands related to octahedral and tetrahedral site. • The impact of Nd{sup 3+} on cation distribution at octahedral and tetrahedral sites. • Influence of Nd{sup 3+} substitution in cobalt ferrite on magnetic properties.

Modified solvothermal synthesis of cobalt ferrite (CoFe2O4 magnetic nanoparticles photocatalysts for degradation of methylene blue with H2O2/visible light

Directory of Open Access Journals (Sweden)

Abul Kalam

2018-03-01

Full Text Available Different grads of magnetic nano-scaled cobalt ferrites (CoFe2O4 photocatalysts were synthesized by modified Solvothermal (MST process with and without polysaccharide. The indigenously synthesized photocatalysts were characterized by means of X-ray diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM, high-resolution transmission electron microscopy (HRTEM, thermo gravimetric analysis (TGA, Fourier transform infrared (FT-IR, UV–visible (UV–vis spectroscopy and N2 adsorption–desorption isotherm method. The Fourier transform infrared spectroscopy study showed the Fe-O stretching vibration 590–619 cm−1, confirming the formation of metal oxide. The crystallite size of the synthesized photocatalysts was found in the range between 20.0 and 30.0 nm. The surface area of obtained magnetic nanoparticles is found to be reasonably high in the range of 63.0–76.0 m2/g. The results shown that only MST-2 is the most active catalyst for photo-Fenton like scheme for fast photodegradation action of methylene blue dye, this is possible due to optical band gap estimated of 2.65 eV. Captivatingly the percentage of degradation efficiency increases up to 80% after 140 min by using MST-2 photocatalyst. Photocatalytic degradation of methylene blue (MB dye under visible light irradiation with cobalt ferrite magnetic nanoparticles followed first order kinetic constant and rate constant of MST-2 is almost 2.0 times greater than MST-1 photocatalyst. Keywords: Cobalt ferrite, Photocatalysis, Kinetics, Optical properties, Surface area studies

Field dependent transition to the non-linear regime in magnetic hyperthermia experiments: Comparison between maghemite, copper, zinc, nickel and cobalt ferrite nanoparticles of similar sizes

Directory of Open Access Journals (Sweden)

E. L. Verde

2012-09-01

Full Text Available Further advances in magnetic hyperthermia might be limited by biological constraints, such as using sufficiently low frequencies and low field amplitudes to inhibit harmful eddy currents inside the patient's body. These incite the need to optimize the heating efficiency of the nanoparticles, referred to as the specific absorption rate (SAR. Among the several properties currently under research, one of particular importance is the transition from the linear to the non-linear regime that takes place as the field amplitude is increased, an aspect where the magnetic anisotropy is expected to play a fundamental role. In this paper we investigate the heating properties of cobalt ferrite and maghemite nanoparticles under the influence of a 500 kHz sinusoidal magnetic field with varying amplitude, up to 134 Oe. The particles were characterized by TEM, XRD, FMR and VSM, from which most relevant morphological, structural and magnetic properties were inferred. Both materials have similar size distributions and saturation magnetization, but strikingly different magnetic anisotropies. From magnetic hyperthermia experiments we found that, while at low fields maghemite is the best nanomaterial for hyperthermia applications, above a critical field, close to the transition from the linear to the non-linear regime, cobalt ferrite becomes more efficient. The results were also analyzed with respect to the energy conversion efficiency and compared with dynamic hysteresis simulations. Additional analysis with nickel, zinc and copper-ferrite nanoparticles of similar sizes confirmed the importance of the magnetic anisotropy and the damping factor. Further, the analysis of the characterization parameters suggested core-shell nanostructures, probably due to a surface passivation process during the nanoparticle synthesis. Finally, we discussed the effect of particle-particle interactions and its consequences, in particular regarding discrepancies between estimated

Studies on structural and magnetic properties of ternary cobalt magnesium zinc (CMZ) Co{sub 0.6-x}Mg{sub x}Zn{sub 0.4} Fe{sub 2}O{sub 4} (x = 0.0, 0.2, 0.4, 0.6) ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Kaur, Manpreet, E-mail: manpreetchem@pau.edu; Jain, Palak; Singh, Mandeep

2015-07-15

In this paper we report the variation in structural and magnetic properties of ternary ferrite nanoparticles (NPs) having stoichiometery Co{sub 0.6-x}Mg{sub x}Zn{sub 0.4} Fe{sub 2}O{sub 4} (x = 0.0, 0.2, 0.4, 0.6) and pure spinel ferrites MFe{sub 2}O{sub 4} (M = Mg, Co). NPs with average particle diameter of 25–45 nm were synthesized employing self-propagating oxalyl dihydrazide - metal nitrate combustion method. The products were characterized using X-ray diffraction (XRD), Vibrating sample magnetometer (VSM), Transmission electron microscopy (TEM) and FT-IR spectroscopy. FT-IR spectral analysis revealed two bands centered at 560 and 440 cm{sup −1} for tetrahedral and octahedral metal–oxygen bond stretching. Zinc doping caused red shift in the frequency band of tetrahedral M−O stretching. XRD powder diffraction patterns confirmed the formation of spinel ferrite nanoparticles, expansion of the lattice on zinc doping and enhancement of spinel phase purity in the doped ferrites. Cobalt ferrite displayed lowering of the magnetic parameters on zinc doping which further decreased in ternary ferrites Co{sub 0.6-x}Mg{sub x}Zn{sub 0.4}Fe{sub 2}O{sub 4} on replacing cobalt ions with non-magnetic magnesium ions up to x = 0.4. At x = 0.6 reverse trend was observed and Ms was enhanced. Magnesium zinc ferrite Mg{sub 0.6}Zn{sub 0.4} Fe{sub 2}O{sub 4} with high value of Ms was obtained. Combustion process employed in the present studies serves as a low temperature facile route for the synthesis and structural analysis of ternary doped ferrite nanoparticles. - Highlights: • Ternary doped cobalt magnesium zinc ferrite nanoparticles are synthesized. • FT-IR displayed red shift in tetrahedral stretching band on Zinc doping. • Expansion of lattice and enhancement of spinel phase purity on zinc doping. • The variation in saturation magnetization (Ms) on doping is explained.

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.

Synthesis and magnetic properties of CoFe2O4 spinel ferrite nanoparticles doped with lanthanide ions

International Nuclear Information System (INIS)

Kahn, Myrtil L.; Zhang, Z. John

2001-01-01

Lanthanide ions have been doped into cobalt spinel ferrites using an oil-in-water micellar method to form CoLn 0.12 Fe 1.88 O 4 nanoparticles with Ln=Ce, Sm, Eu, Gd, Dy, or Er. Doping with lanthanide ions (Ln III ) modulates the magnetic properties of cobalt spinel ferrite nanoparticles. In particular cases of Gd 3+ or Dy 3+ ions, a dramatic increase in the blocking temperature and coercivity is observed. Indeed, the introduction of only 4% of Gd 3+ ions increases the blocking temperature ∼100 K and the coercivity 60%. Initial studies on the magnetic properties of these doped nanoparticles clearly demonstrate that the relationship between the modulation of magnetic properties and the nature of doped Ln III ions is interesting but very complex. [copyright] 2001 American Institute of Physics

Investigation of structure and magnetic properties of cobalt-nickel and manganese ferrites nanoparticles synthesized in direct micelles of sodium dodecyl sulphate system

International Nuclear Information System (INIS)

Fedosyuk, V.M.; Mirgorod, Yu.A.

2016-01-01

Results of investigation of the crystal structure and magnetic properties of the nanoparticles of transition metals ferrites (cobalt, nickel, manganese) synthesized by unified methods using direct sodium dodecyl sulfate micelles are presented. Crystal structure of the samples was investigated by X-ray diffraction on DRON-3M (in the CuKa-radiation). Particle size was investigated by transmission electron microscopy on microscope JEOL JEM-1011 (accelerating voltage 100 kV). All powders contain nanoparticles of the same size in the range 2-6 nm. Magnetic properties of the samples were estimated from temperature and field dependences of the magnetization. All samples exhibit properties of superparamagnets with different blocking temperatures below 45 K. (authors).

Characterization and magnetic properties of cobalt ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Swatsitang, Ekaphan [Integrated Nanotechnology Research Center and Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen, 40002 (Thailand); Phokha, Sumalin, E-mail: sumalinphokha@gmail.com [Department of Physics, Faculty of Science, Udon Thani Rajabhat University, Udon Thani, 41000 Thailand (Thailand); Hunpratub, Sitchai; Usher, Brian [Department of Physics, Faculty of Science, Udon Thani Rajabhat University, Udon Thani, 41000 Thailand (Thailand); Bootchanont, Atipong [Division of Physics, Faculty of Science and Technology, Rajamangala University of Technology Thanyaburi (RMUTT), Pathumthani 12110 (Thailand); Maensiri, Santi [School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, 30000 Thailand (Thailand); Chindaprasirt, Prinya [Sustainable Infrastructure Research and Development Center, Department of Civil Engineering, Faculty of Engineering, Khon Kaen University, Khon Kaen, 40002 (Thailand)

2016-04-15

Inverse spinel cobalt ferrite (CoFe{sub 2}O{sub 4}) nanoparticles were synthesized by a polymer pyrolysis method and calcined at various temperatures from 800 to 1000 °C. The structure, morphology, valence states and magnetic properties of the calcined samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray absorption near edge structure (XANES) and vibrating sample magnetometer (VSM). All calcined samples had the cubic spinel type structure with average crystallite sizes increasing from 80 ± 2 to 100 ± 3 nm with increasing calcination temperature. The XANES spectra allowed the valence states of the Fe{sup 3+} and Co{sup 2+} ions in the samples to be established and simulation of the XANES spectra suggested that the site occupancy of Fe{sup 3+} and Co{sup 2+} ions was mixed, with the majority of Co{sup 2+} ions occupying octahedral sites and the majority of Fe{sup 3+} ions occupying tetrahedral sites within the spinel structure. All samples exhibited ferromagnetic behavior at room temperature with a maximum saturation magnetization (M{sub S}) of 3.42 μ{sub B} and a coercivity (H{sub C}) of 1100 Oe for crystallite sizes of 100 nm. The origin of the ferromagnetism is discussed in relation to the distribution of Fe{sup 3+} and Co{sup 2+} ions within the lattice and the crystallite sizes. - Graphical abstract: In Figure shows ferromagnetism (FM) at room temperature (RT), simulation of the XANES spectra of (a) Fe and (b) Co edges (inset in the right) and TEM image (inset in the left) of CoFe{sub 2}O{sub 4} nanoparticles prepared by polymer pyrolysis method. The bright field TEM image showed the aggregated particles. The simulation showed a cation combination with the majority of Co{sup 2+} ions occupying octahedral sites and the majority of Fe{sup 3+} ions occupying tetrahedral sites within the spinel structure. The distribution of Fe{sup 3+} and Co{sup 2+} ions within the lattice and the crystallite sizes is discussed on

Effect of rare earth substitution in cobalt ferrite bulk materials

International Nuclear Information System (INIS)

Bulai, G.; Diamandescu, L.; Dumitru, I.; Gurlui, S.; Feder, M.; Caltun, O.F.

2015-01-01

The study was focused on the influence of small amounts of rare earth (RE=La, Ce, Sm, Gd, Dy, Ho, Er, Yb) addition on the microstructure, phase content and magnetic properties of cobalt ferrite bulk materials. The X-Ray diffraction measurements confirmed the formation of the spinel structure but also the presence of secondary phases of RE oxides or orthoferrite in small percentages (up to 3%). Density measurements obtained by Archimedes method revealed a ~1 g cm −3 decrease for the RE doped cobalt ferrite samples compared with stoichiometric one. Both the Mössbauer and Fourier Transform Infrared Spectrocopy analysis results confirmed the formation of the spinel phase. The saturation magnetization and coercive field values of the doped samples obtained by Vibrating Sample Magnetometry were close to those of the pure cobalt ferrite. For magnetostrictive property studies the samples were analyzed using the strain gauge method. Higher maximum magnetostriction coefficients were found for the Ho, Ce, Sm and Yb doped cobalt ferrite bulk materials as related to the stoichiometric CoFe 2 O 4 sample. Moreover, improved strain derivative was observed for these samples but at higher magnetic fields due to the low increase of the coercive field values for doped samples. - Highlights: • Substitution by a large number of rare earth elements was investigated. • First reported results on magnetostriction measurements of RE doped cobalt ferrite. • The doped samples presented an increased porosity and a decreased grain size. • Increased magnetostrctive response was observed for several doped samples

Synthesis of nanocrystalline cobalt ferrite through soft chemistry methods: A green chemistry approach using sesame seed extract

Energy Technology Data Exchange (ETDEWEB)

Gingasu, Dana [Ilie Murgulescu Institute of Physical Chemistry, Romanian Academy, 202 Splaiul Independentei, 060021, Bucharest (Romania); Mindru, Ioana, E-mail: imandru@yahoo.com [Ilie Murgulescu Institute of Physical Chemistry, Romanian Academy, 202 Splaiul Independentei, 060021, Bucharest (Romania); Mocioiu, Oana Catalina; Preda, Silviu; Stanica, Nicolae; Patron, Luminita [Ilie Murgulescu Institute of Physical Chemistry, Romanian Academy, 202 Splaiul Independentei, 060021, Bucharest (Romania); Ianculescu, Adelina; Oprea, Ovidiu [Politehnica University of Bucharest, Faculty of Chemistry, 1-7 Polizu Street, 011061, Bucharest (Romania); Nita, Sultana; Paraschiv, Ileana [National Institute for Chemical Pharmaceutical Research and Development, 112 Calea Vitan, 031299, Bucharest (Romania); Popa, Marcela; Saviuc, Crina [University of Bucharest, Faculty of Biology, Microbiology Department, Research Institute of the University of Bucharest-ICUB, Life, Environmental and Earth Sciences Division, 91-95 Splaiul Independentei, Bucharest (Romania); Bleotu, Coralia [Stefan S. Nicolau Institute of Virology, Cellular and Molecular Pathology Department, 285 Mihai Bravu Avenue, Bucharest (Romania); Chifiriuc, Mariana Carmen [University of Bucharest, Faculty of Biology, Microbiology Department, Research Institute of the University of Bucharest-ICUB, Life, Environmental and Earth Sciences Division, 91-95 Splaiul Independentei, Bucharest (Romania)

2016-10-01

The nanocrystalline cobalt ferrites (CoFe{sub 2}O{sub 4}) were obtained through self-combustion and wet ferritization methods using aqueous extracts of sesame (Sesamum indicum L) seeds. The multimetallic complex compounds were characterized by Fourier transform infrared spectroscopy (FTIR), UV-VIS spectroscopy and thermal analysis. Phase identification, morphological evolution and magnetic properties of the obtained cobalt ferrites were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), FTIR and magnetic measurements. FE-SEM investigations revealed the particle size of CoFe{sub 2}O{sub 4} obtained by wet ferritization method ranged between 3 and 20.45 nm. Their antimicrobial, anti-biofilm and cytotoxic properties were evaluated. - Highlights: • CoFe{sub 2}O{sub 4} were obtained by two chemical synthesis methods. • Sesame seed extract was used as gelling or chelating agent. • The morphological features of CoFe{sub 2}O{sub 4} nanoparticles were evaluated. • CoFe{sub 2}O{sub 4} exhibited good microbicidal and anti-biofilm features.

Synthesis and characterization of diethylenetriaminepentaacetic acid-chitosan-coated cobalt ferrite core/shell nanostructures

Energy Technology Data Exchange (ETDEWEB)

Runhua, Qin [Department of Physics, North University of China, Taiyuan 030051 (China); National Special Superfine Powder Engineering Research Center, Nanjing University Science and Technology, Xiaolingwei 200, Nanjing 210094 (China); Li Fengsheng, E-mail: qinrunh@126.com [National Special Superfine Powder Engineering Research Center, Nanjing University Science and Technology, Xiaolingwei 200, Nanjing 210094 (China); Wei, Jiang; Mingyue, Chen [National Special Superfine Powder Engineering Research Center, Nanjing University Science and Technology, Xiaolingwei 200, Nanjing 210094 (China)

2010-08-01

Special diethylenetriaminepentaacetic acid (DTPA)-chitosan-coated cobalt ferrite core/shell nanoparticles have been synthesized via a novel zero-length emulsion crosslinking process and characterized via crosslinking degree, simultaneous thermogravimetric analysis and differential scanning calorimetry, X-ray diffractometry, Fourier transform infrared spectrometer, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and vibration sample magnetometry. The experimental results showed that the CoFe{sub 2}O{sub 4} nanoparticles were really encapsulated with a DTPA-chitosan hybrid layer and the nanocomposites were proved to be nearly superparamagnetic with saturation magnetization of 26.6 emu g{sup -1}.

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.

Tailoring the magnetic properties and magnetorheological behavior of spinel nanocrystalline cobalt ferrite by varying annealing temperature

Czech Academy of Sciences Publication Activity Database

Sedlacik, M.; Pavlinek, V.; Peer, Petra; Filip, Petr

2014-01-01

Roč. 18, č. 43 (2014), s. 6919-6924 ISSN 1477-9226 R&D Projects: GA ČR GA202/09/1626 Grant - others:GA MŠk(CZ) ED2.1.00/03.0111 Institutional support: RVO:67985874 Keywords : spinel nanocrystalline cobalt ferrite * nanoparticles * magnetorheological effect Subject RIV: BK - Fluid Dynamics Impact factor: 4.197, year: 2014

Synthesis, electrical and magnetic properties of sodium borosilicate glasses containing Co-ferrites nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Othman, H.A. [Department of Physics, Faculty of Science, Menoufia University, Shibin El-Kom 32511, Menoufia (Egypt); Eltabey, M.M. [Department of Basic Engineering Science, Faculty of Engineering, Menoufia University, Shibin El-Kom, Menoufia (Egypt); Department of Physics, Faculty of Science, Jazan University (Saudi Arabia); Ibrahim, Samia E.; El-Deen, L.M. Sharaf; Elkholy, M.M. [Department of Physics, Faculty of Science, Menoufia University, Shibin El-Kom 32511, Menoufia (Egypt)

2017-02-01

Co-ferrites nanoparticles that have been prepared by the co-precipitation method were added to sodium borosilicate (Na{sub 2}O–B{sub 2}O{sub 3}–SiO{sub 2}) glass matrix by the solid solution method and they were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and magnetization measurements. (XRD) revealed the formation of the Co-ferrite magnetic crystalline phase embedded in an amorphous matrix in all the samples. The investigated samples by (TEM) showed the formation of the cobalt ferrite nanoparticles with a spherical shape and highly monodispersed with an average size about 13 nm. IR data revealed that the BO{sub 3} and BO{sub 4} are the main structural units of these samples network. IR spectra of the investigated samples showed the characteristic vibration bands of Co-ferrite. Composition and frequency dependent dielectric properties of the prepared samples were measured at room temperature in the frequency range 100–100 kHz. The conductivity was found to increase with increasing cobalt ferrite content. The variations of conductivity and dielectric properties with frequency and composition were discussed. Magnetic hysteresis loops were traced at room temperature using VSM and values of saturation magnetization M{sub S} and coercive field H{sub C} were determined. The obtained results revealed that a ferrimagnetic behavior were observed and as Co-ferrite concentration increases the values of M{sub S} and H{sub C} increase from 2.84 to 8.79 (emu/g) and from 88.4 to 736.3 Oe, respectively.

Cobalt Ferrite Nanocrystallites for Sustainable Hydrogen Production Application

Directory of Open Access Journals (Sweden)

Rajendra S. Gaikwad

2011-01-01

Full Text Available Cobalt ferrite, CoFe2O4, nanocrystalline films were deposited using electrostatic spray method and explored in sustainable hydrogen production application. Reflection planes in X-ray diffraction pattern confirm CoFe2O4 phase. The surface scanning microscopy photoimages reveal an agglomeration of closely-packed CoFe2O4 nanoflakes. Concentrated solar-panel, a two-step water splitting process, measurement technique was preferred for measuring the hydrogen generation rate. For about 5 hr sustainable, 440 mL/hr, hydrogen production activity was achieved, confirming the efficient use of cobalt ferrite nanocrystallites film in hydrogen production application.

Structural, electrical, magnetic and dielectric properties of rare-earth substituted cobalt ferrites nanoparticles synthesized by the co-precipitation method

Energy Technology Data Exchange (ETDEWEB)

Nikumbh, A.K., E-mail: aknik@chem.unipune.ac.in; Pawar, R.A.; Nighot, D.V.; Gugale, G.S.; Sangale, M.D.; Khanvilkar, M.B.; Nagawade, A.V.

2014-04-15

Pure nanoparticles of the rare-earth substituted cobalt ferrites CoRE{sub x}Fe{sub 2−x}O{sub 4} (where RE=Nd, Sm and Gd and x=0.1 and 0.2) were prepared by the chemical co-precipitation method. X-ray diffraction, Transmission electron microscopy (TEM), d.c. electrical conductivity, Magnetic hysteresis and Thermal analysis are utilized in order to study the effect of variation in the rare-earth substitution and its impact on particle size, magnetic properties like M{sub S}, H{sub C} and Curie temperature. The phase identification of the materials by X-ray diffraction reveals the single-phase nature of the materials. The lattice parameter increased with rare-earth content for x≤0.2. The Transmission electron micrographs of Nd-, Sm- and Gd-substituted CoFe{sub 2}O{sub 4} exhibit the particle size 36.1 to 67.8 nm ranges. The data of temperature variation of the direct current electrical conductivity showed definite breaks, which corresponds to ferrimagnetic to paramagnetic transitions. The thermoelectric power for all compound are positive over the whole range of temperature. The dielectric constant decreases with frequency and rare-earth content for the prepared samples. The magnetic properties of rare-earth substituted cobalt ferrites showed a definite hysteresis loop at room temperature. The reduction of coercive force, saturation magnetization, ratio M{sub R}/M{sub S} and magnetic moments may be due to dilution of the magnetic interaction.

Synthesis and characterization of magnetic cobalt ferrite nanoparticles covered with 3-aminopropyltriethoxysilane for use as hybrid material in nano technology

International Nuclear Information System (INIS)

Camilo, Ruth Luqueze

2006-01-01

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 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)

Study of magnetic and structural properties of ferrofluids based on cobalt-zinc ferrite nanoparticles

International Nuclear Information System (INIS)

Lopez, J.; Gonzalez-Bahamon, L.F.; Prado, J.; Caicedo, J.C.; Zambrano, G.; Gomez, M.E.; Esteve, J.; Prieto, P.

2012-01-01

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 (1-x) Zn x Fe 2 O 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 (1-x) Zn x Fe 2 O 4 nanoparticles. X-ray diffraction patterns of Co (1-x) Zn x Fe 2 O 4 show the presence of the most intense peak corresponding to the (311) crystallographic orientation of the spinel phase of CoFe 2 O 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 (1-x) Zn x Fe 2 O 4 magnetic nanoparticles, the crystal and nanoparticle sizes determined by X-ray Diffraction and TEM

Evaluation of superparamagnetic and biocompatible properties of mesoporous silica coated cobalt ferrite nanoparticles synthesized via microwave modified Pechini method

Energy Technology Data Exchange (ETDEWEB)

Gharibshahian, M. [Faculty of New Sciences and Technologies, Semnan University, Semnan (Iran, Islamic Republic of); Mirzaee, O., E-mail: O_mirzaee@semnan.ac.ir [Faculty of Materials and Metallurgical Engineering, Semnan University, Semnan (Iran, Islamic Republic of); Nourbakhsh, M.S. [Faculty of New Sciences and Technologies, Semnan University, Semnan (Iran, Islamic Republic of)

2017-03-01

Cobalt ferrite nano particles were synthesized by Pechini sol-gel method and calcined at 700 °C in electrical and microwave furnace. The microwave calcined sample was coated with mesoporous silica by hydrothermal method. Characterization was performed by XRD, FESEM, TEM, VSM, BET and FTIR analysis. The cytotoxicity was evaluated by MTT assay with 3T3 fibroblast cells. The XRD and FTIR results confirmed spinal formation in both cases and verified the formation of silica coating on the nanoparticles. For microwave calcination, The XRD and SEM results demonstrated smaller and flat adhesion forms of nanoparticles with the average size of 15 nm. The VSM results demonstrated nearly superparamagnetic nanoparticles with significant saturation magnetization equal to 64 emu/g. By coating, saturation magnetization was decreased to 36 emu/g. Moreover, the BET results confirmed the formation of mesoporous coating with the average pore diameters of 2.8 nm and average pore volume of 0.82 cm{sup 3} g{sup −1}. Microwave calcined nanoparticles had the best structural and magnetic properties. - Highlights: • CoFe{sub 2}O{sub 4} nanoparticles were synthesized using the microwave modified Pechini method. • The Effect of calcination route and silica coating on NPs properties was studied. • The nearly superparamagnetic nanoparticles were achieved by microwave calcination. • MFC NPs had the best magnetic properties and MTT assay showed no toxicity for MFC-MSC NPs. • A useful scheme was designed to achieve biological superparamagnetic core/shell NPs.

Modified solvothermal synthesis of cobalt ferrite (CoFe2O4) magnetic nanoparticles photocatalysts for degradation of methylene blue with H2O2/visible light

Science.gov (United States)

Kalam, Abul; Al-Sehemi, Abdullah G.; Assiri, Mohammed; Du, Gaohui; Ahmad, Tokeer; Ahmad, Irfan; Pannipara, M.

2018-03-01

Different grads of magnetic nano-scaled cobalt ferrites (CoFe2O4) photocatalysts were synthesized by modified Solvothermal (MST) process with and without polysaccharide. The indigenously synthesized photocatalysts were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), thermo gravimetric analysis (TGA), Fourier transform infrared (FT-IR), UV-visible (UV-vis) spectroscopy and N2 adsorption-desorption isotherm method. The Fourier transform infrared spectroscopy study showed the Fe-O stretching vibration 590-619 cm-1, confirming the formation of metal oxide. The crystallite size of the synthesized photocatalysts was found in the range between 20.0 and 30.0 nm. The surface area of obtained magnetic nanoparticles is found to be reasonably high in the range of 63.0-76.0 m2/g. The results shown that only MST-2 is the most active catalyst for photo-Fenton like scheme for fast photodegradation action of methylene blue dye, this is possible due to optical band gap estimated of 2.65 eV. Captivatingly the percentage of degradation efficiency increases up to 80% after 140 min by using MST-2 photocatalyst. Photocatalytic degradation of methylene blue (MB) dye under visible light irradiation with cobalt ferrite magnetic nanoparticles followed first order kinetic constant and rate constant of MST-2 is almost 2.0 times greater than MST-1 photocatalyst.

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

Functional Magnetic Nanoparticles

Science.gov (United States)

Gass, James

Nanoparticle system research and characterization is the focal point of this research and dissertation. In the research presented here, magnetite, cobalt, and ferrite nanoparticle systems have been explored in regard to their magnetocaloric effect (MCE) properties, as well as for use in polymer composites. Both areas of study have potential applications across a wide variety of interdisciplinary fields. Magnetite nanoparticles have been successfully dispersed in a polymer. The surface chemistry of the magnetic nanoparticle proves critical to obtaining a homogenous and well separated high density dispersion in PMMA. Theoretical studies found in the literature have indicated that surface interface energy is a critical component in dispersion. Oleic acid is used to alter the surface of magnetite nanoparticles and successfully achieve good dispersion in a PMMA thin film. Polypyrrole is then coated onto the PMMA composite layer. The bilayer is characterized using cross-sectional TEM, cross-sectional SEM, magnetic characterization, and low frequency conductivity. The results show that the superparmagnetic properties of the as synthesized particles are maintained in the composite. With further study of the properties of these nanoparticles for real and functional uses, MCE is studied on a variety of magnetic nanoparticle systems. Magnetite, manganese zinc ferrite, and cobalt ferrite systems show significant broadening of the MCE and the ability to tune the peak temperature of MCE by varying the size of the nanoparticles. Four distinct systems are studied including cobalt, cobalt core silver shell nanoparticles, nickel ferrite, and ball milled zinc ferrite. The results demonstrate the importance of surface characteristics on MCE. Surface spin disorder appears to have a large influence on the low temperature magnetic and magnetocalorie characteristics of these nanoparticle systems.

Synthesis Characterization and Photocatalytic Studies of Cobalt Ferrite-Silica-Titania Nanocomposites

Directory of Open Access Journals (Sweden)

David Greene

2014-04-01

Full Text Available In this work, CoFe2O4@SiO2@TiO2 core-shell magnetic nanostructures have been prepared by coating of cobalt ferrite nanoparticles with the double SiO2/TiO2 layer using metallorganic precursors. The Transmission Electron Microscopy (TEM, Energy Dispersive X-Ray Analysis (EDX, Vibrational Sample Magnetometer (VSM measurements and Raman spectroscopy results confirm the presence both of the silica and very thin TiO2 layers. The core-shell nanoparticles have been sintered at 600 °C and used as a catalyst in photo-oxidation reactions of methylene blue under UV light. Despite the additional non-magnetic coatings result in a lower value of the magnetic moment, the particles can still easily be retrieved from reaction mixtures by magnetic separation. This retention of magnetism was of particular importance allowing magnetic recovery and re-use of the catalyst.

Tailoring the magnetic properties and magnetorheological behavior of spinel nanocrystalline cobalt ferrite by varying annealing temperature.

Science.gov (United States)

Sedlacik, Michal; Pavlinek, Vladimir; Peer, Petra; Filip, Petr

2014-05-14

Magnetic nanoparticles of spinel nanocrystalline cobalt ferrite were synthesized via the sol-gel method and subsequent annealing. The influence of the annealing temperature on the structure, magnetic properties, and magnetorheological effect was investigated. The finite crystallite size of the particles, determined by X-ray diffraction and the particle size observed via transmission electron microscopy, increased with the annealing temperature. The magnetic properties observed via a vibrating sample magnetometer showed that an increase in the annealing temperature leads to the increase in the magnetization saturation and, in contrast, a decrease in the coercivity. The effect of annealing on the magnetic properties of ferrite particles has been explained by the recrystallization process at high temperatures. This resulted in grain size growth and a decrease in an imposed stress relating to defects in the crystal lattice structure of the nanoparticles. The magnetorheological characteristics of suspensions of ferrite particles in silicone oil were measured using a rotational rheometer equipped with a magnetic field generator in both steady shear and small-strain oscillatory regimes. The magnetorheological performance expressed as a relative increase in the magnetoviscosity appeared to be significantly higher for suspensions of particles annealed at 1000 °C.

Dielectric properties of Al-substituted Co ferrite nanoparticles

Indian Academy of Sciences (India)

Administrator

The particle size, D, decreases with increase in Al-content. The lattice parameter, a ... a significant saving in time and energy consumption over the traditional methods. ... electrical, and magnetic properties of spinel ferrites. Cobalt ferrite based ...

Magnetic and magnetoelastic properties of M-substituted cobalt ferrites (M=Mn, Cr, Ga, Ge)

Energy Technology Data Exchange (ETDEWEB)

Song, Sang-Hoon [Iowa State Univ., Ames, IA (United States)

2007-12-15

Magnetic and magnetoelastic properties of a series of M-substituted cobalt ferrites, CoM_xFe_2-xO₄ (M=Mn, Cr, Ga; x=0.0 to 0.8) and Ge-substituted cobalt ferrites Co_1+xGe_xFe_2-2xO₄ (x=0.0 to 0.6) have been investigated.

Microstructural development of cobalt ferrite ceramics and its influence on magnetic properties

Science.gov (United States)

Kim, Gi-Yeop; Jeon, Jae-Ho; Kim, Myong-Ho; Suvorov, Danilo; Choi, Si-Young

2013-11-01

The microstructural evolution and its influence on magnetic properties in cobalt ferrite were investigated. The cobalt ferrite powders were prepared via a solid-state reaction route and then sintered at 1200 °C for 1, 2, and 16 h in air. The microstructures from sintered samples represented a bimodal distribution of grain size, which is associated with abnormal grain growth behavior. And thus, with increasing sintering time, the number and size of abnormal grains accordingly increased but the matrix grains were frozen with stagnant grain growth. In the sample sintered for 16 h, all of the matrix grains were consumed and the abnormal grains consequently impinged on each other. With the appearance of abnormal grains, the magnetic coercivity significantly decreased from 586.3 Oe (1 h sintered sample) to 168.3 Oe (16 h sintered sample). This is due to the magnetization in abnormal grains being easily flipped. In order to achieve high magnetic coercivity of cobalt ferrite, it is thus imperative to fabricate the fine and homogeneous microstructure.

Study of structural phase transformation and hysteresis behavior of inverse-spinel α-ferrite nanoparticles synthesized by co-precipitation method

Science.gov (United States)

Dabagh, Shadab; Chaudhary, Kashif; Haider, Zuhaib; Ali, Jalil

2018-03-01

Substitution of cobalt (Co2+) ions in cobalt ferrite (CoFe2O4) with copper (Cu2+) and aluminum (Al3+) ions allows variations in their electric and magnetic properties which can be optimized for specific applications. In this article, synthesis of inverse-spinel Co1-xCuxFe2-xAlxO4 (0.0 ≤ x ≤ 0.8) nanoparticles by substituting Cu2+ and Al3+ ions in CoFe2O4 via co-precipitation method is reported. By controlling copper and aluminum (Cu-Al) substituent ratio, the magnetic moment and coercivity of synthesized cobalt ferrite nanoparticles is optimized. The role of substituents on the structure, particle size, morphology, and magnetic properties of nano-crystalline ferrite is investigated. The Co1-xCuxFe2-xAlxO4 (0.0 ≤ x≤ 0.8) nanoparticles with crystallite size in the range of 23.1-26.5 nm are observed, 26.5 nm for x = 0.0-23.1 nm for x = 0.8. The inverse-spinel structure of synthesized Co1-xCuxFe2-xAlxO4 (0.0 ≤ x ≤ 0.8) nano-particles is confirmed by characteristic vibrational bands at tetrahedral and octahedral sites using Fourier transform infrared spectroscopy. A decreases in coercive field and magnetic moment is observed as Cu-Al contents are increased (x = 0.0-0.8). The positive anisotropy of synthesized particles Co1-xCuxFe2-xAlxO4 (0.0 ≤ x ≤ 0.8) is obtained in the range 1.96 × 105 J/m3 for x = 0.0 to 0.29 × 105 J/m3 for x = 0.8.

Synthesis of cobalt ferrite with enhanced magnetostriction properties by the sol−gel−hydrothermal route using spent Li-ion battery

International Nuclear Information System (INIS)

Yao, Lu; Xi, Yuebin; Xi, Guoxi; Feng, Yong

2016-01-01

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.

Comparison of drug delivery potentials of surface functionalized cobalt and zinc ferrite nanohybrids for curcumin in to MCF-7 breast cancer cells

International Nuclear Information System (INIS)

Sawant, V.J.; Bamane, S.R.; Shejwal, R.V.; Patil, S.B.

2016-01-01

The functionalization and surface engineering of CoFe 2 O 4 and ZnFe 2 O 4 nanoparticles were performed by coating with PEG and Chitosan respectively using simple wet co-precipitation. Then multiactive therapeutic drug curcumin was loaded to form drug delivery nanohybrids by precipitation. These nanohybrids were characterized separately using UV–vis, FTIR, PL spectroscopy, XRD, VSM, SEM and TEM analysis. The moderate antibacterial activities of the nanohybrids were elaborated by in vitro antibacterial screening on Escherichia coli and Staphylococcus aureus. The anticancer potentials, apoptotic effects and enhanced drug delivery properties of these nanohybrids were confirmed and compared on MCF-7 cells by in vitro MTT assay. The drug delivery activities for hydrophobic drug and anticancer effects of chitosan coated zinc ferrite functionalized nanoparticles were higher than PEG coated cobalt ferrite nanohybrids. - Highlights: • CoFe 2 O 4 and ZnFe 2 O 4 nanoparticles were surface functionalized with PEG and Chitosan respectively. • Hydrophobic multi therapeutic anticancer drug curcumin was loaded into these nanohybrids and their structure, morphologies were confirmed. • The effects of PEG and Chitosan coating over ferrites for curcumin release have been elaborated, and the Chitosan coated curcumin loaded Zinc ferrite nanohybrid exhibited higher drug delivery and anticancer effects.

Comparison of drug delivery potentials of surface functionalized cobalt and zinc ferrite nanohybrids for curcumin in to MCF-7 breast cancer cells

Energy Technology Data Exchange (ETDEWEB)

Sawant, V.J., E-mail: v11131@rediffmail.com [Department of Chemistry, Smt.K.W.College, Sangli, MS 416416 (India); Bamane, S.R. [Department of Chemistry, Raja Shripatrao Bhagwantrao College, Aundh, Satara, MS (India); Shejwal, R.V. [L.B.S. College, Satara, MS (India); Patil, S.B. [A.Birnale College of Pharmacy, Sangli, MS (India)

2016-11-01

The functionalization and surface engineering of CoFe{sub 2}O{sub 4} and ZnFe{sub 2}O{sub 4} nanoparticles were performed by coating with PEG and Chitosan respectively using simple wet co-precipitation. Then multiactive therapeutic drug curcumin was loaded to form drug delivery nanohybrids by precipitation. These nanohybrids were characterized separately using UV–vis, FTIR, PL spectroscopy, XRD, VSM, SEM and TEM analysis. The moderate antibacterial activities of the nanohybrids were elaborated by in vitro antibacterial screening on Escherichia coli and Staphylococcus aureus. The anticancer potentials, apoptotic effects and enhanced drug delivery properties of these nanohybrids were confirmed and compared on MCF-7 cells by in vitro MTT assay. The drug delivery activities for hydrophobic drug and anticancer effects of chitosan coated zinc ferrite functionalized nanoparticles were higher than PEG coated cobalt ferrite nanohybrids. - Highlights: • CoFe{sub 2}O{sub 4} and ZnFe{sub 2}O{sub 4} nanoparticles were surface functionalized with PEG and Chitosan respectively. • Hydrophobic multi therapeutic anticancer drug curcumin was loaded into these nanohybrids and their structure, morphologies were confirmed. • The effects of PEG and Chitosan coating over ferrites for curcumin release have been elaborated, and the Chitosan coated curcumin loaded Zinc ferrite nanohybrid exhibited higher drug delivery and anticancer effects.

Design and synthesis of ternary cobalt ferrite/graphene/polyaniline hierarchical nanocomposites for high-performance supercapacitors

Science.gov (United States)

Xiong, Pan; Huang, Huajie; Wang, Xin

2014-01-01

A ternary cobalt ferrite/graphene/polyaniline nanocomposite (CGP) is designed and fabricated via a facile two-step approach: cobalt ferrite nanoparticles dispersed on graphene sheets are achieved by a hydrothermal method, followed by coating with polyaniline (PANI) through in situ polymerization process. Electrochemical measurements demonstrate that the specific capacitance of the resulting ternary hybrid (CGP) is up to 1133.3 F g-1 at a scan rate of 1 mV s-1 and 767.7 F g-1 at a current density of 0.1 A g-1 using a three-electrode system, while 716.4 F g-1 at a scan rate of 1 mV s-1 and 392.3 F g-1 at a current density of 0.1 A g-1 using a two-electrode system, which are significantly higher than those of pure CoFe2O4, graphene and PANI, or binary CoFe2O4/graphene, CoFe2O4/PANI and graphene/PANI hybrids. In addition, over 96% of the initial capacitance can be retained after repeating test for 5000 cycles, demonstrating a high cycling stability. The extraordinary electrochemical performance of the ternary CGP nanocomposite can be attributed to its well-designed nanostructure and the synergistic effects of the individual components.

Harnessing microbial subsurface metal reduction activities to synthesize nanoscale cobalt ferrite with enhanced magnetic properties

International Nuclear Information System (INIS)

Coker, Victoria S.; Telling, Neil D.; van der Laan, Gerrit; Pattrick, Richard A.D.; Pearce, Carolyn I.; Arenholz, Elke; Tuna, Floriana; Winpenny, Richard E.P.; Lloyd, Jonathan R.

2009-01-01

Nanoscale ferrimagnetic particles have a diverse range of uses from directed cancer therapy and drug delivery systems to magnetic recording media and transducers. Such applications require the production of monodisperse nanoparticles with well-controlled size, composition, and magnetic properties. To fabricate these materials purely using synthetic methods is costly in both environmental and economical terms. However, metal-reducing microorganisms offer an untapped resource to produce these materials. Here, the Fe(III)-reducing bacterium Geobacter sulfurreducens is used to synthesize magnetic iron oxide nanoparticles. A combination of electron microscopy, soft X-ray spectroscopy, and magnetometry techniques was employed to show that this method of biosynthesis results in high yields of crystalline nanoparticles with a narrow size distribution and magnetic properties equal to the best chemically synthesized materials. In particular, it is demonstrated here that cobalt ferrite (CoFe 2 O 4 ) nanoparticles with low temperature coercivity approaching 8 kOe and an effective anisotropy constant of ∼ 10 6 erg cm -3 can be manufactured through this biotechnological route. The dramatic enhancement in the magnetic properties of the nanoparticles by the introduction of high quantities of Co into the spinel structure represents a significant advance over previous biomineralization studies in this area using magnetotactic bacteria. The successful production of nanoparticulate ferrites achieved in this study at high yields could open up the way for the scaled-up industrial manufacture of nanoparticles using environmentally benign methodologies. Production of ferromagnetic nanoparticles for pioneering cancer therapy, drug delivery, chemical sensors, catalytic activity, photoconductive materials, as well as more traditional uses in data storage embodies a large area of inorganic synthesis research. In particular, the addition of transition metals other than Fe into the structure

Harnessing microbial subsurface metal reduction activities to synthesise nanoscale cobalt ferrite with enhanced magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Coker, Victoria S.; Telling, Neil D.; van der Laan, Gerrit; Pattrick, Richard A.D.; Pearce, Carolyn I.; Arenholz, Elke; Tuna, Floriana; Winpenny, Richard E.P.; Lloyd, Jonathan R.

2009-03-24

Nanoscale ferrimagnetic particles have a diverse range of uses from directed cancer therapy and drug delivery systems to magnetic recording media and transducers. Such applications require the production of monodisperse nanoparticles with well-controlled size, composition, and magnetic properties. To fabricate these materials purely using synthetic methods is costly in both environmental and economical terms. However, metal-reducing microorganisms offer an untapped resource to produce these materials. Here, the Fe(III)-reducing bacterium Geobacter sulfurreducens is used to synthesize magnetic iron oxide nanoparticles. A combination of electron microscopy, soft X-ray spectroscopy, and magnetometry techniques was employed to show that this method of biosynthesis results in high yields of crystalline nanoparticles with a narrow size distribution and magnetic properties equal to the best chemically synthesized materials. In particular, it is demonstrated here that cobalt ferrite (CoFe{sub 2}O{sub 4}) nanoparticles with low temperature coercivity approaching 8 kOe and an effective anisotropy constant of {approx} 10{sup 6} erg cm{sup -3} can be manufactured through this biotechnological route. The dramatic enhancement in the magnetic properties of the nanoparticles by the introduction of high quantities of Co into the spinel structure represents a significant advance over previous biomineralization studies in this area using magnetotactic bacteria. The successful production of nanoparticulate ferrites achieved in this study at high yields could open up the way for the scaled-up industrial manufacture of nanoparticles using environmentally benign methodologies. Production of ferromagnetic nanoparticles for pioneering cancer therapy, drug delivery, chemical sensors, catalytic activity, photoconductive materials, as well as more traditional uses in data storage embodies a large area of inorganic synthesis research. In particular, the addition of transition metals other than

and aluminum-substituted cobalt ferrite prepared by co-precipitation

Indian Academy of Sciences (India)

Structural and magnetic properties of zinc- and aluminum-substituted cobalt ferrite prepared by co-precipitation method. S T ALONE1,∗ and K M JADHAV2. 1Shiv Chhatrapati College, Aurangabad 431 004, India. 2Department of Physics, Dr. B. A. Marathwada University, Aurangabad 431 004, India. ∗Corresponding author.

Synthesize and characterization of a novel anticorrosive cobalt ferrite nanoparticles dispersed in silica matrix (CoFe2O4-SiO2) to improve the corrosion protection performance of epoxy coating

International Nuclear Information System (INIS)

Gharagozlou, M.; Ramezanzadeh, B.; Baradaran, Z.

2016-01-01

Highlights: • An anticorrosive cobalt ferrite nanopigment dispersed in silica matrix was synthesized. • The nanopigment showed proper inhibition performance in solution study. • The nanopigment significantly improved the corrosion resistance of the epoxy coating. - Abstract: This study aimed at studying the effect of an anticorrosive nickel ferrite nanoparticle dispersed in silica matrix (NiFe 2 O 4 -SiO 2 ) on the corrosion protection properties of steel substrate. NiFe 2 O 4 and NiFe 2 O 4 -SiO 2 nanopigments were synthesized and then characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscope (TEM). Then, 1 wt.% of nanopigments was dispersed in an epoxy coating and the resultant nanocomposites were applied on the steel substrates. The corrosion inhibition effects of nanopigments were tested by an electrochemical impedance spectroscopy (EIS) and salt spray test. Results revealed that dispersing nickel ferrite nanoparticles in a silica matrix (NiFe 2 O 4 -SiO 2 ) resulted in the enhancement of the nanopigment dispersion in the epoxy coating matrix. Inclusion of 1 wt.% of NiFe 2 O 4 -SiO 2 nanopigment into the epoxy coating enhanced its corrosion protection properties before and after scratching.

Experimental demonstration of all-optical weak magnetic field detection using beam-deflection of single-mode fiber coated with cobalt-doped nickel ferrite nanoparticles.

Science.gov (United States)

Pradhan, Somarpita; Chaudhuri, Partha Roy

2015-07-10

We experimentally demonstrate single-mode optical-fiber-beam-deflection configuration for weak magnetic-field-detection using an optimized (low coercive-field) composition of cobalt-doped nickel ferrite nanoparticles. Devising a fiber-double-slit type experiment, we measure the surrounding magnetic field through precisely measuring interference-fringe yielding a minimum detectable field ∼100  mT and we procure magnetization data of the sample that fairly predicts SQUID measurement. To improve sensitivity, we incorporate etched single-mode fiber in double-slit arrangement and recorded a minimum detectable field, ∼30  mT. To further improve, we redefine the experiment as modulating fiber-to-fiber light-transmission and demonstrate the minimum field as 2.0 mT. The device will be uniquely suited for electrical or otherwise hazardous environments.

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...

Evaluation of humidity sensing properties of TMBHPET thin film embedded with spinel cobalt ferrite nanoparticles

International Nuclear Information System (INIS)

Zafar, Qayyum; Azmer, Mohamad Izzat; Al-Sehemi, Abdullah G.; Al-Assiri, Mohammad S.; Kalam, Abul; Sulaiman, Khaulah

2016-01-01

In this study, we report the enhanced sensing parameters of previously reported TMBHPET-based humidity sensor. Significant improved sensing performance has been demonstrated by coupling of TMBHPET moisture sensing thin film with cobalt ferrite nanoparticles (synthesized by eco-benign ultrasonic method). The mean size of CoFe_2O_4 nanoparticles has been estimated to be ~ 6.5 nm. It is assumed that the thin film of organic–ceramic hybrid matrix (TMBHPET:CoFe_2O_4) is a potential candidate for humidity sensing utility by virtue of its high specific surface area and porous surface morphology (as evident from TEM, FESEM, and AFM images). The hybrid suspension has been drop-cast onto the glass substrate with preliminary deposited coplanar aluminum electrodes separated by 40 µm distance. The influence of humidity on the capacitance of the hybrid humidity sensor (Al/TMBHPET:CoFe_2O_4/Al) has been investigated at three different frequencies of the AC applied voltage (V_r_m_s ~ 1 V): 100 Hz, 1 kHz, and 10 kHz. It has been observed that at 100 Hz, under a humidity of 99 % RH, the capacitance of the sensor increased by 2.61 times, with respect to 30 % RH condition. The proposed sensor exhibits significantly improved sensitivity ~560 fF/ % RH at 100 Hz, which is nearly 7.5 times as high as that of pristine TMBHPET-based humidity sensor. Further, the capacitive sensor exhibits improved dynamic range (30–99 % RH), small hysteresis (~2.3 %), and relatively quicker response and recovery times (~12 s, 14 s, respectively). It is assumed that the humidity response of the sensor is associated with the diffusion kinetics of water vapors and doping of the semiconductor nanocomposite by water molecules.

Effects of nickel and cobalt addition on creep strength and microstructure of the precipitation-strengthened 15Cr ferritic steels

Energy Technology Data Exchange (ETDEWEB)

Shibuya, Masachika; Toda, Yoshiaki; Sawada, Kota; Kushima, Hideaki; Kimura, Kazuhiro [National Inst. for Materials Science, Tsukuba, Ibaraki (Japan)

2010-07-01

Creep strength of 15Cr ferritic steel with ferrite matrix was increased by precipitation strengthening of intermetallic compounds. It was higher than those of 9-12Cr ferritic steels with a tempered martensitic microstructure strengthened by carbide and carbonitride. Addition of nickel was confirmed to improve Charpy impact toughness of the 15Cr steels, however, creep strength was slightly reduced by the addition of nickel. Microstructure of the 15Cr steel changes from ferrite single phase to dual phases of ferrite and martensite with the addition of nickel which is an austenite stabilizing element. The 15Cr steels investigated in the previous study, contain 3mass% of cobalt which is also an austenite stabilizing element, therefore, the influence of nickel and cobalt combination on mechanical properties and microstructure of the 15Cr-1Mo-6W-V-Nb steel is investigated in this study. Creep strength, Charpy impact toughness and microstructure of the steel were strongly influenced by the composition of nickel and cobalt. Design guideline of the 15Cr steel is discussed with respect to a role of microstructure and combination of nickel and cobalt addition. (orig.)

Control of carbon nanotube growth using cobalt nanoparticles as catalyst

International Nuclear Information System (INIS)

Huh, Yoon; Green, Malcolm L.H.; Kim, Young Heon; Lee, Jeong Yong; Lee, Cheol Jin

2005-01-01

We have controllably grown carbon nanotubes using uniformly distributed cobalt nanoparticles as catalyst. Cobalt nanoparticles with a uniform size were synthesized by chemical reaction and colloidal solutions including the cobalt nanoparticles were prepared. The cobalt nanoparticles were uniformly distributed on silicon substrates by a spin-coating method. Carbon nanotubes with a uniform diameter were synthesized on the cobalt nanoparticles by thermal chemical vapor deposition of acetylene gas. The density and vertical alignment of carbon nanotubes could be controlled by adjusting the density of cobalt (Co) nanoparticles

Remanence properties of Co-precipitated cobalt ferrite

International Nuclear Information System (INIS)

Bueno-Baques, D.; Medina-Boudri, Angela; Matutes-Aquino, J.

2001-01-01

Isothermal remanent magnetization (IRM) and DC demagnetization (DCD) curves of a co-precipitated cobalt ferrite sample were obtained. From the IRM and DCD data, the Henkel plot was obtained and analyzed in the Preisach model framework. The Henkel plot data are below the Wohlfarth line that indicates a dominant local disorder (demagnetizing-like effect). Forward and reverse switching field distribution curves were obtained from differentiation of the IRM and DCD curves. The peak values of these switching field distributions differ by a factor of about 2.7

Synthesis and characterization of structural and magnetic properties of polyaniline-cobalt ferrite (PA-CoFe) nanocomposites

Science.gov (United States)

Thakur, Sonika; Kaur, Parminder; Singh, Lakhwant

2018-05-01

The growing interest in the investigation of the properties of modified conducting polymers stems from their potential applications in various fields such as in sensing and catalytic devices. The present work reports the modification of conducting polymer polyaniline with cobalt ferrite (CoFe) nanoparticles, where CoFe nanoparticles are added in different successive weight percents. The composite samples were synthesized by in-situ chemical oxidative polymerization technique. The density of the samples has been found to increase with an increase in the CoFe content. Structural analysis of the synthesized sample has been done using X-ray diffraction studies. Perusal of the hysteresis curves of the prepared samples depicts that the introduction of CoFe into the polymer matrix leads to enhancement in the ferromagnetic behavior of the synthesized samples, suggesting that these nanocomposites have excellent microwave absorbing capacity.

Effect of Cr{sup 3+} substitution on electric and magnetic properties of cobalt ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Panda, R.K., E-mail: physics.panda@gmail.com [Department of Physics, National Institute of Technology, Rourkela, 769 008 (India); Muduli, R. [Department of Physics, National Institute of Technology, Rourkela, 769 008 (India); Jayarao, G. [Department of Ceramic Engineering, National Institute of Technology, Rourkela, 769 008 (India); Sanyal, D. [Variable Energy Cyclotron Centre, Kolkata, 700064 (India); Behera, D. [Department of Physics, National Institute of Technology, Rourkela, 769 008 (India)

2016-06-05

This work describes the effect of incorporation of Cr{sup 3+} into CoFe{sub 2}O{sub 4} nanoparticles on its magnetic and electric properties, prepared by auto combustion method. The samples of CoFe{sub 2-x}Cr{sub x}O4 (x = 0, 0.15, 0.3) series were characterized by x-ray diffraction and field emission scanning electron microscopy to find out the average particle size. The substitution of Cr{sup 3+} caused a significant reduction in particle size of the modified systems. Room temperature Moessbauer spectroscopy and magnetic characterization were performed. Analysis of extracted parameters concluded that Cr{sup 3+} replaced the Fe{sup 3+} at B-site (octahedral). The decrease in magnetization at B-site was found responsible for the observed reduced saturation magnetization and coercivity. Impedance spectroscopic analysis has revealed the suppression of electrode-sample surface conduction effect and enhancement of material resistivity. The latter was confirmed by dc resistivity measurement. All these results were explained on the basis of occupancy of Cr{sup 3+} at B-site, surface anisotropy potential and reduced particle size. - Highlights: • Cr substitution reduced the particle size in nano-cobalt ferrite. • Mossbauer study revealed that the Cr{sup 3+} replaced the Fe{sup 3+} at B-site. • Decrease in saturation magnetization and coercivity with the addition of Cr{sup 3+}. • Reduction of surface conduction and rise in resistance observed in modified systems.

Investigation of structural, magnetic and dielectric properties of Cr3+ substituted Cu0.75Co0.25Fe2-xO4 ferrite nanoparticles

Science.gov (United States)

Reddi, M. Sushma; Ramesh, M.; Sreenivasu, T.; Rao, G. S. N.; Samatha, K.

2018-05-01

Chromium doped Copper-Cobalt ferrite Nanoparticles were obtained by sol-gel auto-combustion method using citric acid as a fuel. The metal nitrates to citric acid ratio was taken as 1:1. The prepared powder of Cr3+ doped copper-cobalt ferrite nanoparticles is annealed at 600°C for 5 hrs and the same powder was used for characterization and investigations of structural properties. The phase composition, micro-structural, micro morphological and elemental analysis studies were carried out by X-ray diffraction (XRD), scanning electron microscope (SEM) technique and energy dispersive spectroscopy (EDS). The FTIR spectra of these samples are recorded to ensure the presence of the metallic compounds. The average crystallite size obtained by Scherrer's formula is of the order of 19.28 nm to 32.92 nm. The dielectric properties are investigated as a function of frequency at room temperature using LCR-Q meter. The saturation magnetization (Ms) of the Cr3+ substituted Cu-Co ferrite sintered at 1100°C lies in the range of 5.4136-28.9943 emu/g, the coercivity (Hc) dropped desperately from about 2091.3-778.53Oe as Cr3+ composition increases from 0.0 to 0.25.

Multifunctional metal ferrite nanoparticles for MR imaging applications

International Nuclear Information System (INIS)

Joshi, Hrushikesh M.

2013-01-01

Magnetic Resonance Imaging (MRI) is a very powerful non-invasive tool for in vivo imaging and clinical diagnosis. With rapid advancement in nanoscience and nanotechnology, there is rapid growth in nanoparticles-based contrast agents. Progress in synthetic protocols enable synthesis of multifunctional nanoparticles which facilitated efforts toward the development of multimodal contrast agents. In this review, recent developments in metal ferrite-based MR contrast agents have been described. Specifically, effect of size, shape, composition, assembly and surface modification of metal ferrite nanoparticles on their T 2 contrast have been discussed. The review further outlines the effect of leaching on MRI contrast and other various factors which affect the multimodal ability of the (T 1 –T 2 and T 2 -thermal activation) metal ferrite nanoparticles.

Water-assisted and surfactant-free synthesis of cobalt ferrite nanospheres via solvothermal method

Energy Technology Data Exchange (ETDEWEB)

Bi, Yiqing [CAS Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); Ren, Yanan [CAS Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190 (China); Bi, Feng [CAS Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); He, Tao, E-mail: het@nanoctr.cn [CAS Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190 (China)

2015-10-15

With ethylene glycol as the solvent, monodispersed cobalt ferrite nanospheres were prepared via a solvothermal method assisted by water. The samples were mainly characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscope. The size of as-prepared products ranges from 10 nm to 200 nm. Size distribution and chemical composition were controlled by the amount of water and pH value in the reaction system. More important, suitable amount of water can avoid the use of surfactant. - Highlights: • Cobalt ferrite nanospheres were synthesized via solvothermal method assisted by water. • An introduction of suitable amount of water can avoid the use of surfactant. • The pH value of the precursor can be used to adjust the product composition.

Modified ferrite core-shell nanoparticles magneto-structural characterization

Science.gov (United States)

Klekotka, Urszula; Piotrowska, Beata; Satuła, Dariusz; Kalska-Szostko, Beata

2018-06-01

In this study, ferrite nanoparticles with core-shell structures and different chemical compositions of both the core and shell were prepared with success. Proposed nanoparticles have in the first and second series magnetite core, and the shell is composed of a mixture of ferrites with Fe3+, Fe2+ and M ions (where M = Co2+, Mn2+ or Ni2+) with a general composition of M0.5Fe2.5O4. In the third series, the composition is inverted, the core is composed of a mixture of ferrites and as a shell magnetite is placed. Morphology and structural characterization of nanoparticles were done using Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), and Infrared spectroscopy (IR). While room temperature magnetic properties were measured using Mössbauer spectroscopy (MS). It is seen from Mössbauer measurements that Co always increases hyperfine magnetic field on Fe atoms at RT, while Ni and Mn have opposite influences in comparison to pure Fe ferrite, regardless of the nanoparticles structure.

Topotactic Synthesis of Porous Cobalt Ferrite Platelets from a Layered Double Hydroxide Precursor and Their Application in Oxidation Catalysis.

Science.gov (United States)

Ortega, Klaus Friedel; Anke, Sven; Salamon, Soma; Özcan, Fatih; Heese, Justus; Andronescu, Corina; Landers, Joachim; Wende, Heiko; Schuhmann, Wolfgang; Muhler, Martin; Lunkenbein, Thomas; Behrens, Malte

2017-09-12

Monocrystalline, yet porous mosaic platelets of cobalt ferrite, CoFe 2 O 4 , can be synthesized from a layered double hydroxide (LDH) precursor by thermal decomposition. Using an equimolar mixture of Fe 2+ , Co 2+ , and Fe 3+ during co-precipitation, a mixture of LDH, (Fe II Co II ) 2/3 Fe III 1/3 (OH) 2 (CO 3 ) 1/6 ⋅m H 2 O, and the target spinel CoFe 2 O 4 can be obtained in the precursor. During calcination, the remaining Fe II fraction of the LDH is oxidized to Fe III leading to an overall Co 2+ :Fe 3+ ratio of 1:2 as required for spinel crystallization. This pre-adjustment of the spinel composition in the LDH precursor suggests a topotactic crystallization of cobalt ferrite and yields phase pure spinel in unusual anisotropic platelet morphology. The preferred topotactic relationship in most particles is [111] Spinel ∥[001] LDH . Due to the anion decomposition, holes are formed throughout the quasi monocrystalline platelets. This synthesis approach can be used for different ferrites and the unique microstructure leads to unusual chemical properties as shown by the application of the ex-LDH cobalt ferrite as catalyst in the selective oxidation of 2-propanol. Compared to commercial cobalt ferrite, which mainly catalyzes the oxidative dehydrogenation to acetone, the main reaction over the novel ex-LDH cobalt is dehydration to propene. Moreover, the oxygen evolution reaction (OER) activity of the ex-LDH catalyst was markedly higher compared to the commercial material. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influence of the preparation route on the magnetic and structural properties of cobalt ferrites

International Nuclear Information System (INIS)

Revoredo Junior, Frederico Alves; Silva Junior, Jose Holanda da; Hernandez, Eduardo Padron

2014-01-01

Cobalt ferrite nanoparticles were produced using two methods of preparation, co-precipitation and reaction in the solid state. In synthesis made by solid state reaction was performed by heat treatment at 1200 ° C for four hours alternating with triturations to increase the efficiency of the process. The synthesis by coprecipitation was made with different flows of addition of alkali (NaOH). All samples were structurally characterized by X-ray diffraction and the average size of the crystals was obtained by Scherrer's formula and the Williamson-Hall method. The magnetic measurements were made as a function of applied magnetic field and temperature. Qualitative analyzes of energy dispersive spectroscopy defined the elements of sampling and analysis. Finally, Mössbauer spectroscopy analysis defined the magnetic character of the samples. (author)

Chemical bonding and magnetic properties of gadolinium (Gd) substituted cobalt ferrite

International Nuclear Information System (INIS)

Puli, Venkata Sreenivas; Adireddy, Shiva; Ramana, C.V.

2015-01-01

Graphical abstract: Room temperature Raman spectra of CoFe 2−x Gd x O 4 (CFGO, x = 0.0–0.3) compounds as a function of wavenumber (cm −1 ). - Highlights: • Gd substituted ferrites were synthesized under controlled concentration. • Gd ion induced lattice dynamical changes are significant. • Enhanced magnetization is observed upon Gd-incorporation in cobalt ferrite. • A correlation between lattice dynamics and magnetic properties is established. - Abstract: Polycrystalline gadolinium (Gd) substituted cobalt ferrites (CoFe 2−x Gd x O 4 ; x = 0–0.3, referred to CFGO) ceramics have been synthesized by solid state reaction method. Chemical bonding, crystal structure and magnetic properties of CFGO compounds have been evaluated as a function of Gd-content. X-ray diffraction (XRD) and Raman spectroscopic analyses confirmed the formation of inverse spinel cubic structure. However, a secondary ortho-ferrite phase (GdFeO 3 ) nucleates for higher values of Gd-content. A considerable increase in the saturation magnetization has been observed upon the initial substitution of Gd (x = 0.1). The saturation magnetization drastically decreases at higher Gd content (x ⩾ 0.3). No contribution from ortho-ferrite GdFeO 3 phase is noted to the magnetic properties. The increase in the magnetic saturation magnetization is attributed to the higher magnetic moment of Gd 3+ (4f 7 ) residing in octahedral sites is higher when compared to that of Fe 3+ (3d 5 ) and as well due to the migration of Co 2+ (3d 7 ) ions from the octahedral to the tetrahedral sites with a magnetic moment aligned anti-parallel to those of rare earth (RE 3+ ) ions in the spinel lattice. Increase in coercivity with increase in Gd 3+ is content is attributed to magnetic anisotropy in the ceramics

Preparation of cobalt-zinc ferrite (Co0.8Zn0.2Fe2O4) nanopowder via combustion method and investigation of its magnetic properties

International Nuclear Information System (INIS)

Yousefi, M.H.; Manouchehri, S.; Arab, A.; Mozaffari, M.; Amiri, Gh. R.; Amighian, J.

2010-01-01

Research highlights: → Cobalt-zinc ferrite was prepared by combustion method. → Properties of the sample were characterized by several techniques. → Curie temperature was determined to be 350 o C. -- Abstract: Cobalt-zinc ferrite (Co 0.8 Zn 0.2 Fe 2 O 4 ) was prepared by combustion method, using cobalt, zinc and iron nitrates. The crystallinity of the as-burnt powder was developed by annealing at 700 o C. Crystalline phase was investigated by XRD. Using Williamson-Hall method, the average crystallite sizes for nanoparticles were determined to be about 27 nm before and 37 nm after annealing, and residual stresses for annealed particles were omitted. The morphology of the annealed sample was investigated by TEM and the mean particle size was determined to be about 30 nm. The final stoichiometry of the sample after annealing showed good agreement with the initial stoichiometry using atomic absorption spectrometry. Magnetic properties of the annealed sample such as saturation magnetization, remanence magnetization, and coercivity measured at room temperature were 70 emu/g, 14 emu/g, and 270 Oe, respectively. The Curie temperature of the sample was determined to be 350 o C using AC-susceptibility technique.

Thermal effect on magnetic parameters of high-coercivity cobalt ferrite

Energy Technology Data Exchange (ETDEWEB)

Chagas, E. F., E-mail: efchagas@fisica.ufmt.br; Ponce, A. S.; Prado, R. J.; Silva, G. M. [Instituto de Física, Universidade Federal de Mato Grosso, 78060-900 Cuiabá-MT (Brazil); Bettini, J. [Laboratório Nacional de Nanotecnologia, Centro Nacional de Pesquisa em Energia e Materiais, 13083-970 Campinas (Brazil); Baggio-Saitovitch, E. [Centro Brasileiro de Pesquisas Físicas, Rua Xavier Sigaud 150 Urca. Rio de Janeiro (Brazil)

2014-07-21

We prepared very high-coercivity cobalt ferrite nanoparticles synthesized by a combustion method and using short-time high-energy mechanical milling to increase strain and the structural defects density. The coercivity (H{sub C}) of the milled sample reached 3.75 kOe—a value almost five times higher than that obtained for the non-milled material (0.76 kOe). To investigate the effect of the temperature on the magnetic behavior of the milled sample, we performed a thermal treatment on the milled sample at 300, 400, and 600 °C for 30 and 180 min. We analyzed the changes in the magnetic behavior of the nanoparticles due to the thermal treatment using the hysteresis curves, Williamson-Hall analysis, and transmission electron microscopy. The thermal treatment at 600 °C causes decreases in the microstructural strain and density of structural defects resulting in a significant decrease in H{sub C}. Furthermore, this thermal treatment increases the size of the nanoparticles and, as a consequence, there is a substantial increase in the saturation magnetization (M{sub S}). The H{sub C} of the samples treated at 600 °C for 30 and 180 min were 2.24 and 1.93 kOe, respectively, and the M{sub S} of these same samples increased from 57 emu/g to 66 and 70 emu/g, respectively. The H{sub C} and the M{sub S} are less affected by the thermal treatment at 300 and 400 °C.

Structural and magnetic properties of cobalt ferrite nanoparticles synthesized by co-precipitation at increasing temperatures

Science.gov (United States)

Stein, C. R.; Bezerra, M. T. S.; Holanda, G. H. A.; André-Filho, J.; Morais, P. C.

2018-05-01

This study reports on the synthesis and characterization of cobalt ferrite (CoFe2O4) nanoparticles (NPs) synthesized by chemical co-precipitation in alkaline medium at increasing temperatures in the range of 27 °C to 100 °C. High-quality samples in the size range of 5 to 10 nm were produced using very low stirring speed (250 rpm) and moderate alkaline aqueous solution concentration (4.8 mol/L). Three samples were synthesized and characterized by x-ray diffraction (XRD) and room-temperature (RT) magnetization measurements. All samples present superparamagnetic (SPM) behavior at RT and Rietveld refinements confirm the inverse cubic spinel structure (space group Fd-3m (227)) with minor detectable impurity phase. As the synthesis temperature increases, structural parameters such as lattice constant and grain size change monotonically from 8.385 to 8.383 Å and from 5.8 to 7.4 nm, respectively. Likewise, as the synthesis temperature increases the NPs' magnetic moment and saturation magnetization increases monotonically from 2.6 ×103 to 16×103 μB and from 37 to 66 emu/g, respectively. The RT magnetization (M) versus applied field (H) curves were analyzed by the first-order Langevin function averaged out by a lognormal distribution function of magnetic moments. The excellent curve-fitting of the M versus H data is credited to a reduced particle-particle interaction due to both the SPM behavior and the existence of a surface amorphous shell layer (dead layer), the latter reducing systematically as the synthesis temperature increases.

Green Synthesis Methods of CoFe_2O_4 and Ag-CoFe_2O_4 Nanoparticles Using Hibiscus Extracts and Their Antimicrobial Potential

International Nuclear Information System (INIS)

Gingasu, D.; Mindru, I.; Patron, L.; Caleron-Moreno, J.M.; Mocioiu, O.C.; Preda, S.; Stanica, N.; Nita, S.; Dobre, N.; Popa, M.; Gradisteanu, G.; Chifiriuc, M. C.

2016-01-01

The cobalt ferrite (CoFe_2O_4) and silver-cobalt ferrite (Ag-CoFe_2O_4) nanoparticles were obtained through self-combustion and wet ferritization methods using aqueous extracts of Hibiscus rosa-sinensis flower and leaf. X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and magnetic measurements were used for the characterization of the obtained oxide powders. The antimicrobial activity of the cobalt ferrite and silver-cobalt ferrite nanoparticles against Gram-positive and Gram-negative bacteria, as well as fungal strains, was investigated by qualitative and quantitative assays. The most active proved to be the Ag-CoFe_2O_4 nanoparticles, particularly those obtained through self-combustion using hibiscus leaf extract, which exhibited very low minimal inhibitory concentration values (0.031-0.062 mg/ml) against all tested microbial strains, suggesting their potential for the development of novel antimicrobial agents.

Green Synthesis Methods of CoFe2O4 and Ag-CoFe2O4 Nanoparticles Using Hibiscus Extracts and Their Antimicrobial Potential

Directory of Open Access Journals (Sweden)

Dana Gingasu

2016-01-01

Full Text Available The cobalt ferrite (CoFe2O4 and silver-cobalt ferrite (Ag-CoFe2O4 nanoparticles were obtained through self-combustion and wet ferritization methods using aqueous extracts of Hibiscus rosa-sinensis flower and leaf. X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and magnetic measurements were used for the characterization of the obtained oxide powders. The antimicrobial activity of the cobalt ferrite and silver-cobalt ferrite nanoparticles against Gram-positive and Gram-negative bacteria, as well as fungal strains, was investigated by qualitative and quantitative assays. The most active proved to be the Ag-CoFe2O4 nanoparticles, particularly those obtained through self-combustion using hibiscus leaf extract, which exhibited very low minimal inhibitory concentration values (0.031–0.062 mg/mL against all tested microbial strains, suggesting their potential for the development of novel antimicrobial agents.

Multiwalled Carbon Nanotubes Decorated with Cobalt Oxide Nanoparticles

Directory of Open Access Journals (Sweden)

D. G. Larrude

2012-01-01

Full Text Available Multiwalled carbon nanotubes (MWCNTs synthesized by spray pyrolysis were decorated with cobalt oxide nanoparticles using a simple synthesis route. This wet chemistry method yielded nanoparticles randomly anchored to the surface of the nanotubes by decomposition of cobalt nitrate hexahydrate diluted in acetone. Electron microscopy analysis indicated that dispersed particles were formed on the MWCNTs walls. The average size increased with the increasing concentration of cobalt nitrate in acetone in the precursor mixture. TEM images indicated that nanoparticles were strongly attached to the tube walls. The Raman spectroscopy results suggested that the MWCNT structure was slightly damaged after the nanoparticle growth.

Chemical synthesis of spinel cobalt ferrite (CoFe2O4) nano-flakes for supercapacitor application

International Nuclear Information System (INIS)

Kumbhar, V.S.; Jagadale, A.D.; Shinde, N.M.; Lokhande, C.D.

2012-01-01

Highlights: ► The first time preparation of cobalt ferrite material in thin film form, using chemical method at low temperature. ► A nano-flake like morphology of the cobalt ferrite thin film. ► An application of the film as an electrode in supercapacitor cell. - Abstract: The present paper reveals the formation of cobalt ferrite (CoFe 2 O 4 ) thin film on stainless steel substrate by simple chemical route from an alkaline bath containing Co 2+ and Fe 2+ ions. The films are characterised for structural, surface morphological and FT-IR properties. The XRD and FT-IR studies revealed formation of single phase of CoFe 2 O 4 . The formation of nano-flakes-like morphology is observed from scanning electron microscope. The electrochemical behaviour of CoFe 2 O 4 film has been studied using cyclic voltammetry in 1 M NaOH electrolyte. The maximum specific capacitance of 366 F g −1 is obtained at the scan rate of 5 mV s −1 . Using AC impedance technique equivalent series resistance (ESR) value is found to be 1.1 Ω.

Electrical and Magnetic Properties of Polyvinyl Alcohol-Cobalt ...

Indian Academy of Sciences (India)

7

synthesis methods of shape, size, magnetic properties of cobalt ferrite ... substance was then ground into a fine powder and calcined at 600oC for 10 hours and .... From the particles distribution pattern of CFO nanoparticles in Figure 2(a), it is.

Microstructure characterization and cation distribution of nanocrystalline cobalt ferrite

Energy Technology Data Exchange (ETDEWEB)

Abbas, Y.M., E-mail: ymabbas@live.com [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Mansour, S.A.; Ibrahim, M.H. [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Ali, Shehab E., E-mail: shehab_physics@yahoo.com [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt)

2011-11-15

Nanocrystalline cobalt ferrite has been synthesized using two different methods: ceramic and co-precipitation techniques. The nanocrystalline ferrite phase has been formed after 3 h of sintering at 1000 deg. C. The structural and microstructural evolutions of the nanophase have been studied using X-ray powder diffraction and the Rietveld method. The refinement result showed that the type of the cationic distribution over the tetrahedral and octahedral sites in the nanocrystalline lattice is partially an inverse spinel. The transmission electronic microscope analysis confirmed the X-ray results. The magnetic properties of the samples were characterized using a vibrating sample magnetometer. - Highlights: > The refinement result showed that the cationic distribution over the sites in the lattice is partially an inverse spinel. > The transmission electronic microscope analysis confirmed the X-ray results. > The magnetic properties of the samples were characterized using a vibrating sample magnetometer.

Influence of cobalt doping on structural and magnetic properties of BiFeO3 nanoparticles

Science.gov (United States)

Khan, U.; Adeela, N.; Javed, K.; Riaz, S.; Ali, H.; Iqbal, M.; Han, X. F.; Naseem, S.

2015-11-01

Nanocrystalline cobalt-doped bismuth ferrites with general formula of BiFe1- δ Co δ O3 (0 ≤ δ ≤ 0.1) have been synthesized using solution evaporation method. Structure and phase identification was performed with X-ray diffraction (XRD) technique. The results confirm the formation of rhombohedral-distorted Perovskite structure with R3c symmetry. A decrease in lattice parameters and an increase in X-ray density have been observed with increasing cobalt concentration in BiFeO3. Particle size determined by transmission electron microscope was in good agreement with XRD, i.e., 39 nm. Room-temperature coercivity and saturation magnetization of nanoparticles were increased up to 7.5 % of cobalt doping. Low-temperature magnetic measurements of selected sample showed increasing behavior in saturation magnetization, coercivity, effective magnetic moments, and anisotropy constant. An increase in coercivity with decrease in temperature followed theoretical model of Kneller's law, while modified Bloch's model was employed for saturation magnetization in temperature range of 5-300 K.

Chemical bonding and magnetic properties of gadolinium (Gd) substituted cobalt ferrite

Energy Technology Data Exchange (ETDEWEB)

Puli, Venkata Sreenivas, E-mail: vspuli@utep.edu [Department of Mechanical Engineering, University of Texas, El Paso, TX 79968 (United States); Adireddy, Shiva [Department of Physics and Engineering Physics, Tulane University, New Orleans, LA 70118 (United States); Ramana, C.V. [Department of Mechanical Engineering, University of Texas, El Paso, TX 79968 (United States)

2015-09-25

Graphical abstract: Room temperature Raman spectra of CoFe{sub 2−x}Gd{sub x}O{sub 4} (CFGO, x = 0.0–0.3) compounds as a function of wavenumber (cm{sup −1}). - Highlights: • Gd substituted ferrites were synthesized under controlled concentration. • Gd ion induced lattice dynamical changes are significant. • Enhanced magnetization is observed upon Gd-incorporation in cobalt ferrite. • A correlation between lattice dynamics and magnetic properties is established. - Abstract: Polycrystalline gadolinium (Gd) substituted cobalt ferrites (CoFe{sub 2−x}Gd{sub x}O{sub 4}; x = 0–0.3, referred to CFGO) ceramics have been synthesized by solid state reaction method. Chemical bonding, crystal structure and magnetic properties of CFGO compounds have been evaluated as a function of Gd-content. X-ray diffraction (XRD) and Raman spectroscopic analyses confirmed the formation of inverse spinel cubic structure. However, a secondary ortho-ferrite phase (GdFeO{sub 3}) nucleates for higher values of Gd-content. A considerable increase in the saturation magnetization has been observed upon the initial substitution of Gd (x = 0.1). The saturation magnetization drastically decreases at higher Gd content (x ⩾ 0.3). No contribution from ortho-ferrite GdFeO{sub 3} phase is noted to the magnetic properties. The increase in the magnetic saturation magnetization is attributed to the higher magnetic moment of Gd{sup 3+} (4f{sup 7}) residing in octahedral sites is higher when compared to that of Fe{sup 3+} (3d{sup 5}) and as well due to the migration of Co{sup 2+} (3d{sup 7}) ions from the octahedral to the tetrahedral sites with a magnetic moment aligned anti-parallel to those of rare earth (RE{sup 3+}) ions in the spinel lattice. Increase in coercivity with increase in Gd{sup 3+} is content is attributed to magnetic anisotropy in the ceramics.

Synthesis of cobalt boride nanoparticles using radio frequency thermal plasma

International Nuclear Information System (INIS)

Lapitan, Jr. Lorico DS.; Ying Ying Chen; Seesoek Choe; Watanabe, Takayuki

2012-01-01

Nano size cobalt boride particles were synthesized from vapor phase using a 30 kw-4 MHz radio frequency (RF) thermal plasma. Cobalt and boron powder mixtures used as precursors in different composition and feed rate were evaporated immediately in the high temperature plasma and cobalt boride nanoparticles were produced through the quenching process. The x-ray diffractometry (XRD) patterns of cobalt boride nanoparticles prepared from the feed powder ratio of 1:2 and 1:3 for Co: B showed peaks that are associated with the Co 2 B and CoB crystal phases of cobalt boride. The XRD analysis revealed that increasing the powder feed rate results in a higher mass fraction and a larger crystalline diameter of cobalt boride nanoparticles. The images obtained by field emission scanning electron microscopy (FE-SEM) revealed that cobalt boride nanoparticles have a spherical morphology. The crystallite size of the particles estimated with XRD was found to be 18-22 nm. (author)

Microstructure characterization and cation distribution of nanocrystalline cobalt ferrite

International Nuclear Information System (INIS)

Abbas, Y.M.; Mansour, S.A.; Ibrahim, M.H.; Ali, Shehab E.

2011-01-01

Nanocrystalline cobalt ferrite has been synthesized using two different methods: ceramic and co-precipitation techniques. The nanocrystalline ferrite phase has been formed after 3 h of sintering at 1000 deg. C. The structural and microstructural evolutions of the nanophase have been studied using X-ray powder diffraction and the Rietveld method. The refinement result showed that the type of the cationic distribution over the tetrahedral and octahedral sites in the nanocrystalline lattice is partially an inverse spinel. The transmission electronic microscope analysis confirmed the X-ray results. The magnetic properties of the samples were characterized using a vibrating sample magnetometer. - Highlights: → The refinement result showed that the cationic distribution over the sites in the lattice is partially an inverse spinel. → The transmission electronic microscope analysis confirmed the X-ray results. → The magnetic properties of the samples were characterized using a vibrating sample magnetometer.

Development of cobalt ferrite powder preparation employing the sol-gel technique and its structural characterization

International Nuclear Information System (INIS)

Sajjia, M.; Oubaha, M.; Prescott, T.; Olabi, A.G.

2010-01-01

Research highlights: This work focuses on the sol-gel process and the effects that the initial parameters have on the final product, which is the cobalt ferrite powder, in addition to the heat treatment. Particular interest is devoted to understand how the crosslinker and the chelating agent work and affect the final product. - Abstract: This work focuses on the development of a method to make cobalt ferrite powder using the sol-gel process. A particular emphasis is devoted to the understanding of the role of the chemical parameters involved in the sol-gel 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. X-ray 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 two standard samples to identify important reaction temperatures during the heat treatment. The average size of the nano crystallites was estimated for a sample by the full width at half maximum (FWHM) of the strongest X-ray diffraction (XRD) peak. 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.

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

International Nuclear Information System (INIS)

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

2016-01-01

(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, M"2"+ ion active sites were coordinated by −OH of the water molecules except for EDTA anions. The MFe_2O_4 magnetic nanoparticles exhibited enhanced magnetic properties when compared with nano-MFe_2O_4 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. - Graphical abstract: Schematic representation of the proposed model for MFe_2O_4 nanoparticle synthesis, starting from EDTA-chelated M"2"+ (M=Mg, Ca, or Ba) cations (left). High dispersion (Mg, Ca, Ba)-ferrite magnetic nanoparticles were prepared by a modified polyacrylamide gel route. Optimized utilization of polysaccharide, chelating agent, and sintering temperature allowed the formation of (Mg, Ca, Ba)-ferrite nanoparticles with a narrow diameter distribution. - Highlights: • We report a modified polyacrylamide gel route to synthesize (Mg, Ca, Ba)-ferrite magnetic nanoparticles. • Chelate mechanism of metal ions (Mg, Ca, Ba) and EDTA has been discussed. • Phase transformation process of (Mg, Ca, Ba)-ferrites has been discussed. • The preparation method increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles.

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.

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

Energy Technology Data Exchange (ETDEWEB)

Wang, S.F., E-mail: wangshifa2006@yeah.net [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Science and technology on vacuum technology and physics laboratory, Lanzhou Institute of Physics, Lanzhou 730000, Gansu (China); Li, Q. [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Zu, X.T., E-mail: xtzu@uestc.edu.cn [Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Xiang, X.; Liu, W. [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Li, S., E-mail: sean.li@unsw.edu.au [School of Material Science and Engineering, University of New South Wales, Sydney 2052 (Australia)

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, M{sup 2+} ion active sites were coordinated by −OH of the water molecules except for EDTA anions. The MFe{sub 2}O{sub 4} magnetic nanoparticles exhibited enhanced magnetic properties when compared with nano-MFe{sub 2}O{sub 4} 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. - Graphical abstract: Schematic representation of the proposed model for MFe{sub 2}O{sub 4} nanoparticle synthesis, starting from EDTA-chelated M{sup 2+} (M=Mg, Ca, or Ba) cations (left). High dispersion (Mg, Ca, Ba)-ferrite magnetic nanoparticles were prepared by a modified polyacrylamide gel route. Optimized utilization of polysaccharide, chelating agent, and sintering temperature allowed the formation of (Mg, Ca, Ba)-ferrite nanoparticles with a narrow diameter distribution. - Highlights: • We report a modified polyacrylamide gel route to synthesize (Mg, Ca, Ba)-ferrite magnetic nanoparticles. • Chelate mechanism of metal ions (Mg, Ca, Ba) and EDTA has been discussed. • Phase transformation process of (Mg, Ca, Ba)-ferrites has been discussed. • The preparation method increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles.

Chitosan-coated nickel-ferrite nanoparticles as contrast agents in magnetic resonance imaging

International Nuclear Information System (INIS)

Ahmad, Tanveer; Bae, Hongsub; Iqbal, Yousaf; Rhee, Ilsu; Hong, Sungwook; Chang, Yongmin; Lee, Jaejun; Sohn, Derac

2015-01-01

We report evidence for the possible application of chitosan-coated nickel-ferrite (NiFe 2 O 4 ) nanoparticles as both T 1 and T 2 contrast agents in magnetic resonance imaging (MRI). The coating of nickel-ferrite nanoparticles with chitosan was performed simultaneously with the synthesis of the nickel-ferrite nanoparticles by a chemical co-precipitation method. The coated nanoparticles were cylindrical in shape with an average length of 17 nm and an average width of 4.4 nm. The bonding of chitosan onto the ferrite nanoparticles was confirmed by Fourier transform infrared spectroscopy. The T 1 and T 2 relaxivities were 0.858±0.04 and 1.71±0.03 mM −1 s −1 , respectively. In animal experimentation, both a 25% signal enhancement in the T 1 -weighted mage and a 71% signal loss in the T 2 -weighted image were observed. This demonstrated that chitosan-coated nickel-ferrite nanoparticles are suitable as both T 1 and T 2 contrast agents in MRI. We note that the applicability of our nanoparticles as both T 1 and T 2 contrast agents is due to their cylindrical shape, which gives rise to both inner and outer sphere processes of nanoparticles. - Highlights: • Chitosan-coated nickel-ferrite (Ni-Fe 2 O 4 ) nanoparticles were synthesized in an aqueous system by chemical co-precipitation. • The characterization of bare and chitosan-coated nanoparticles were performed using various analytical tools, such as TEM, FTIR, XRD, and VMS. • We evaluated the coated particles as potential T 1 and T 2 contrast agents for MRI by measuring T 1 and T 2 relaxation times as a function of iron concentration. • Both T 1 and T 2 effects were also observed in animal experimentation

Ultradispersed Cobalt Ferrite Nanoparticles Assembled in Graphene Aerogel for Continuous Photo-Fenton Reaction and Enhanced Lithium Storage Performance.

Science.gov (United States)

Qiu, Bocheng; Deng, Yuanxin; Du, Mengmeng; Xing, Mingyang; Zhang, Jinlong

2016-07-04

The Photo-Fenton reaction is an advanced technology to eliminate organic pollutants in environmental chemistry. Moreover, the conversion rate of Fe(3+)/Fe(2+) and utilization rate of H2O2 are significant factors in Photo-Fenton reaction. In this work, we reported three dimensional (3D) hierarchical cobalt ferrite/graphene aerogels (CoFe2O4/GAs) composites by the in situ growing CoFe2O4 crystal seeds on the graphene oxide (GO) followed by the hydrothermal process. The resulting CoFe2O4/GAs composites demonstrated 3D hierarchical pore structure with mesopores (14~18 nm), macropores (50~125 nm), and a remarkable surface area (177.8 m(2 )g(-1)). These properties endowed this hybrid with the high and recyclable Photo-Fenton activity for methyl orange pollutant degradation. More importantly, the CoFe2O4/GAs composites can keep high Photo-Fenton activity in a wide pH. Besides, the CoFe2O4/GAs composites also exhibited excellent cyclic performance and good rate capability. The 3D framework can not only effectively prevent the volume expansion and aggregation of CoFe2O4 nanoparticles during the charge/discharge processes for Lithium-ion batteries (LIBs), but also shorten lithium ions and electron diffusion length in 3D pathways. These results indicated a broaden application prospect of 3D-graphene based hybrids in wastewater treatment and energy storage.

Magnetic and resonance properties of ferrihydrite nanoparticles doped with cobalt

Science.gov (United States)

Stolyar, S. V.; Yaroslavtsev, R. N.; Iskhakov, R. S.; Bayukov, O. A.; Balaev, D. A.; Dubrovskii, A. A.; Krasikov, A. A.; Ladygina, V. P.; Vorotynov, A. M.; Volochaev, M. N.

2017-03-01

Powders of undoped ferrihydrite nanoparticles and ferrihydrite nanoparticles doped with cobalt in the ratio of 5: 1 have been prepared by hydrolysis of 3 d-metal salts. It has been shown using Mössbauer spectroscopy that cobalt is uniformly distributed over characteristic crystal-chemical positions of iron ions. The blocking temperatures of ferrihydrite nanoparticles have been determined. The nanoparticle sizes, magnetizations, surface anisotropy constants, and bulk anisotropy constants have been estimated. The doping of ferrihydrite nanoparticles with cobalt leads to a significant increase in the anisotropy constant of a nanoparticle and to the formation of surface rotational anisotropy with the surface anisotropy constant K u = 1.6 × 10-3 erg/cm2.

Magnetoabsorption and magnetic hysteresis in Ni ferrite nanoparticles

Directory of Open Access Journals (Sweden)

Torres C.

2013-01-01

Full Text Available Nickel ferrite nanoparticles were prepared by a modified sol-gel technique employing coconut oil, and then annealed at different temperatures in 400-1200 °C range. This route of preparation has revealed to be one efficient and cheap technique to obtain high quality nickel ferrite nanosized powder. Sample particles sizes obtained with XRD data and Scherrer’s formula lie in 13 nm to 138 nm, with increased size with annealing temperature. Hysteresis loops have been obtained at room temperature with an inductive method. Magnetic field induced microwave absorption in nanoscale ferrites is a recent an active area of research, in order to characterize and explore potential novel applications. In the present work microwave magnetoabsorption data of the annealed nickel ferrite nanoparticles are presented. These data have been obtained with a system based on a network analyzer that operates in the frequency range 0 - 8.5 GHz. At fields up to 400 mT we can observe a peak according to ferromagnetic resonance theory. Sample annealed at higher temperature exhibits different absorption, coercivity and saturation magnetization figures, revealing its multidomain character.

Chitosan-coated nickel-ferrite nanoparticles as contrast agents in magnetic resonance imaging

Energy Technology Data Exchange (ETDEWEB)

Ahmad, Tanveer [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Department of Physics, Abdul Wali Khan University, Mardan (Pakistan); Bae, Hongsub; Iqbal, Yousaf [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Rhee, Ilsu, E-mail: ilrhee@knu.ac.kr [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Hong, Sungwook [Division of Science Education, Daegu University, Gyeongsan 712-714 (Korea, Republic of); Chang, Yongmin; Lee, Jaejun [Department of Diagnostic Radiology, College of Medicine, Kyungpook National University and Hospital, Daegu 700-721 (Korea, Republic of); Sohn, Derac [Department of Physics, Hannam University, Daejon (Korea, Republic of)

2015-05-01

We report evidence for the possible application of chitosan-coated nickel-ferrite (NiFe{sub 2}O{sub 4}) nanoparticles as both T{sub 1} and T{sub 2} contrast agents in magnetic resonance imaging (MRI). The coating of nickel-ferrite nanoparticles with chitosan was performed simultaneously with the synthesis of the nickel-ferrite nanoparticles by a chemical co-precipitation method. The coated nanoparticles were cylindrical in shape with an average length of 17 nm and an average width of 4.4 nm. The bonding of chitosan onto the ferrite nanoparticles was confirmed by Fourier transform infrared spectroscopy. The T{sub 1} and T{sub 2} relaxivities were 0.858±0.04 and 1.71±0.03 mM{sup −1} s{sup −1}, respectively. In animal experimentation, both a 25% signal enhancement in the T{sub 1}-weighted mage and a 71% signal loss in the T{sub 2}-weighted image were observed. This demonstrated that chitosan-coated nickel-ferrite nanoparticles are suitable as both T{sub 1} and T{sub 2} contrast agents in MRI. We note that the applicability of our nanoparticles as both T{sub 1} and T{sub 2} contrast agents is due to their cylindrical shape, which gives rise to both inner and outer sphere processes of nanoparticles. - Highlights: • Chitosan-coated nickel-ferrite (Ni-Fe{sub 2}O{sub 4}) nanoparticles were synthesized in an aqueous system by chemical co-precipitation. • The characterization of bare and chitosan-coated nanoparticles were performed using various analytical tools, such as TEM, FTIR, XRD, and VMS. • We evaluated the coated particles as potential T{sub 1} and T{sub 2} contrast agents for MRI by measuring T{sub 1} and T{sub 2} relaxation times as a function of iron concentration. • Both T{sub 1} and T{sub 2} effects were also observed in animal experimentation.

Influence of cobalt doping on structural and magnetic properties of BiFeO{sub 3} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Khan, U. [Chinese Academy of Sciences, Institute of Physics (China); Adeela, N., E-mail: adeela16@gmail.com [Centre for High Energy Physics, University of the Punjab (Pakistan); Javed, K. [Chinese Academy of Sciences, Institute of Physics (China); Riaz, S. [Centre for Solid State Physics, University of the Punjab (Pakistan); Ali, H. [Chinese Academy of Sciences, Institute of Physics (China); Iqbal, M. [Centre for High Energy Physics, University of the Punjab (Pakistan); Han, X. F. [Chinese Academy of Sciences, Institute of Physics (China); Naseem, S., E-mail: shahzad-naseem@yahoo.com [Centre for Solid State Physics, University of the Punjab (Pakistan)

2015-11-15

Nanocrystalline cobalt-doped bismuth ferrites with general formula of BiFe{sub 1−δ}Co{sub δ}O{sub 3} (0 ≤ δ ≤ 0.1) have been synthesized using solution evaporation method. Structure and phase identification was performed with X-ray diffraction (XRD) technique. The results confirm the formation of rhombohedral-distorted Perovskite structure with R3c symmetry. A decrease in lattice parameters and an increase in X-ray density have been observed with increasing cobalt concentration in BiFeO{sub 3}. Particle size determined by transmission electron microscope was in good agreement with XRD, i.e., 39 nm. Room-temperature coercivity and saturation magnetization of nanoparticles were increased up to 7.5 % of cobalt doping. Low-temperature magnetic measurements of selected sample showed increasing behavior in saturation magnetization, coercivity, effective magnetic moments, and anisotropy constant. An increase in coercivity with decrease in temperature followed theoretical model of Kneller’s law, while modified Bloch’s model was employed for saturation magnetization in temperature range of 5–300 K.Graphical Abstract.

Investigate the ultrasound energy assisted adsorption mechanism of nickel(II) ions onto modified magnetic cobalt ferrite nanoparticles: Multivariate optimization.

Science.gov (United States)

Mehrabi, Fatemeh; Alipanahpour Dil, Ebrahim

2017-07-01

In present study, magnetic cobalt ferrite nanoparticles modified with (E)-N-(2-nitrobenzylidene)-2-(2-(2-nitrophenyl)imidazolidine-1-yl) ethaneamine (CoFe 2 O 4 -NPs-NBNPIEA) was synthesized and applied as novel adsorbent for ultrasound energy assisted adsorption of nickel(II) ions (Ni 2+ ) from aqueous solution. The prepared adsorbent characterized by Fourier transforms infrared spectroscopy (FT-IR), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and X-ray diffraction (XRD). The dependency of adsorption percentage to variables such as pH, initial Ni 2+ ions concentration, adsorbent mass and ultrasound time were studied with response surface methodology (RSM) by considering the desirable functions. The quadratic model between the dependent and independent variables was built. The proposed method showed good agreement between the experimental data and predictive value, and it has been successfully employed to adsorption of Ni 2+ ions from aqueous solution. Subsequently, the experimental equilibrium data at different concentration of Ni 2+ ions and 10mg amount of adsorbent mass was fitted to conventional isotherm models like Langmuir, Freundlich, Tempkin, Dubinin-Radushkevich and it was revealed that the Langmuir is best model for explanation of behavior of experimental data. In addition, conventional kinetic models such as pseudo-first and second-order, Elovich and intraparticle diffusion were applied and it was seen that pseudo-second-order equation is suitable to fit the experimental data. Copyright © 2016 Elsevier B.V. All rights reserved.

Preparation and characterization of complex ferrite nanoparticles by a polymer-pyrolysis route

International Nuclear Information System (INIS)

Liu Xianming; Fu Shaoyun; Xiao Hongmei; Zhu Luping

2007-01-01

The polymer-pyrolysis route used in this work was to synthesize the copolymeric precursor of the mixed metallic ions and then to pyrolyze the precursor into complex spinel ferrite nanoparticles. Thermogravimetric analysis (TGA) showed that the complex ferrite nanoparticles could be obtained by calcination of their precursors at 500 deg. C. The structures, elemental analyses and particle morphology of the as-calcined products were characterized by powder X-ray diffraction (XRD), ICP-AES, transmission electron microscope (TEM) and electron diffraction (ED) pattern. The results revealed that the as-calcined powders were complex spinel ferrites and the size of those nanoparticles ranged from 10 to 20 nm. Magnetic measurements were carried out at room temperature using a vibrating sample magnetometer (VSM). The saturation magnetization of the Mn-Zn ferrites was related to the molar ratio of Mn to Zn and increased with the increase of Mn. The complex Co-Mn-Zn ferrite nanoparticles showed a high magnetization of 58 emu/g at the applied field of 10 kOe and a low coercivity of 30 Oe, which indicated that this materials exhibited characteristics of soft ferromagnetism

Magnetic behavior of nickel ferrite nanoparticles prepared by co-precipitation route

International Nuclear Information System (INIS)

Maaz, K.; Mashiatullah, A.; Javed, T.; Ali, G.; Karim, S.

2008-01-01

Magnetic nanoparticles of nickel ferrite (NiFe/sub 2/O/sub 4/) have been synthesized by co-precipitation route using stable ferric and nickel salts with sodium hydroxide as the precipitating agent and oleic acid as the surfactant. X-ray Diffraction (XRD) and Transmission Electron Microscope (TEM) analyses confirmed the formation of single phase nickel ferrite nanoparticles in the range 8-28 nm. The size of the particles was observed to be increasing linearly with increasing annealing temperature of the sample. Typical blocking effects were observed below -225 K for all the prepared samples. The superparamagnetic blocking temperature was found to be continuously increasing with increasing particle sizes that has been attributed to the increased effective anisotropy of the nanoparticles. The saturation moment of all the samples was found much below the bulk value of nickel ferrite that has been attributed to the disordered surface spins of these nanoparticles. (author)

Enhancement in surface area and magnetization of CoFe2O4 nanoparticles for targeted drug delivery application

Science.gov (United States)

Kale, Swati B.; Somvanshi, Sandeep B.; Sarnaik, M. N.; More, S. D.; Shukla, S. J.; Jadhav, K. M.

2018-05-01

This paper reports facile synthesis, characterizations by X-ray diffraction and scanning electron microscopy and magnetic behaviour of cobalt ferrite nanoparticles. Cobalt ferrite nanoparticles were prepared by sol-gel auto combustion technique using glycine as a fuel. Phase purity and nanocrystalline nature of the prepared sample was confirmed through X-ray diffraction technique. No extra peak other than cubic spinel structure was observed in the XRD pattern. The crystallite size calculated by using Scherrer's formula is of the order of 21.6 nm indicating the nanocrystalline nature of the prepared cobalt ferrite sample. The surface morphological studies were carried out using scanning electron microscope (SEM). SEM image shows homogeneous, agglomerated particles with sponge-like form. The saturation magnetization, coercivity and remenance magnetization obtained by hysteresis curve clearly gives the evidence of excellent and enhanced magnetic behaviour.

Dose-dependent cytotoxicity of clinically relevant cobalt nanoparticles and ions on macrophages in vitro

Energy Technology Data Exchange (ETDEWEB)

Kwon, Young-Min; Xia Zhidao; Glyn-Jones, Sion; Beard, David; Gill, Harinderjit S; Murray, David W, E-mail: young-min.kwon@ndos.ox.ac.u [Nuffield Department of Orthopaedic Surgery, University of Oxford, Oxford OX3 7LD (United Kingdom)

2009-04-15

Despite the satisfactory short-term implant survivorship of metal-on-metal hip resurfacing arthroplasty, periprosthetic soft-tissue masses such as pseudotumours are being increasingly reported. Cytotoxic effects of cobalt or chromium have been suggested to play a role in its aetiology. The aim of this study was to investigate the effects of clinically relevant metal nanoparticles and ions on the viability of macrophages in vitro. A RAW 264.7 murine macrophage cell line was cultured in the presence of either: (1) cobalt, chromium and titanium nanoparticles sized 30-35 nm; or (2) cobalt sulphate and chromium chloride. Two methods were used to quantify cell viability: Alamar Blue assay and Live/Dead assay. The cytotoxicity was observed only with cobalt. Cobalt nanoparticles and ions demonstrated dose-dependent cytotoxic effects on macrophages in vitro: the cytotoxic concentrations of nanoparticles and ions were 1 x 10{sup 12} particles ml{sup -1} and 1000 {mu}M, respectively. The high concentration of cobalt nanoparticles required for cytotoxicity of macrophages in vitro suggests that increased production of cobalt nanoparticles in vivo, due to excessive MoM implant wear, may lead to local adverse biological effects. Therefore, cytotoxicity of high concentrations of metal nanoparticles phagocytosed by macrophages located in the periprosthetic tissues may be an important factor in pathogenesis of pseudotumours.

Ferrite Nanoparticles, Films, Single Crystals, and Metamaterials: High Frequency Applications

International Nuclear Information System (INIS)

Harris, V.

2006-01-01

Ferrite materials have long played an important role in power conditioning, conversion, and generation across a wide spectrum of frequencies (up to ten decades). They remain the preferred magnetic materials, having suitably low losses, for most applications above 1 MHz, and are the only viable materials for nonreciprocal magnetic microwave and millimeter-wave devices (including tunable filters, isolators, phase shifters, and circulators). Recently, novel processing techniques have led to a resurgence of research interest in the design and processing of ferrite materials as nanoparticles, films, single crystals, and metamaterials. These latest developments have set the stage for their use in emerging technologies that include cancer remediation therapies such as magnetohyperthermia, magnetic targeted drug delivery, and magneto-rheological fluids, as well as enhanced magnetic resonance imaging. With reduced dimensionality of nanoparticles and films, and the inherent nonequilibrium nature of many processing schemes, changes in local chemistry and structure have profound effects on the functional properties and performance of ferrites. In this lecture, we will explore these effects upon the fundamental magnetic and electronic properties of ferrites. Density functional theory will be applied to predict the properties of these ferrites, with synchrotron radiation techniques used to elucidate the chemical and structural short-range order. This approach will be extended to study the atomic design of ferrites by alternating target laser-ablation deposition. Recently, this approach has been shown to produce ferrites that offer attractive properties not found in conventionally grown ferrites. We will explore the latest research developments involving ferrites as related to microwave and millimeter-wave applications and the attempt to integrate these materials with semiconductor materials platforms

Effect of cobalt ferrite (CoFe2O4) nanoparticles on the growth and development of Lycopersicon lycopersicum (tomato plants).

Science.gov (United States)

López-Moreno, Martha L; Avilés, Leany Lugo; Pérez, Nitza Guzmán; Irizarry, Bianca Álamo; Perales, Oscar; Cedeno-Mattei, Yarilyn; Román, Félix

2016-04-15

Nanoparticles (NPs) have been synthetized and studied to be incorporated in many industrial and medical applications in recent decades. Due to their different physical and chemical properties compared with bulk materials, researchers are focused to understand their interactions with the surroundings. Living organisms such as plants are exposed to these materials and they are able to tolerate different concentrations and types of NPs. Cobalt ferrite (CoFe2O4) NPs are being studied for their application in medical sciences because of their high coercivity, anisotropy, and large magnetostriction. These properties are desirable in magnetic resonance imaging, drug delivery, and cell labeling. This study is aimed to explore the tolerance of Solanum lycopersicum L. (tomato) plants to CoFe2O4 NPs. Tomato plants were grown in hydroponic media amended with CoFe2O4 nanoparticles in a range from 0 to 1000mgL(-1). Exposure to CoFe2O4 NPs did not affect germination and growth of plants. Uptake of Fe and Co inside plant tissues increased as CoFe2O4 nanoparticle concentration was increased in the media. Mg uptake in plant leaves reached its maximum level of 4.9mgg(-1) DW (dry weight) at 125mgL(-1) of CoFe2O4 NPs exposure and decreased at high CoFe2O4 NPs concentrations. Similar pattern was observed for Ca uptake in leaves where the maximum concentration found was 10mgg(-1) DW at 125mgL(-1) of CoFe2O4 NPs exposure. Mn uptake in plant leaves was higher at 62.5mgL(-1) of CoFe2O4 NPs compared with 125 and 250mgL(-1) treatments. Catalase activity in tomato roots and leaves decreased in plants exposed to CoFe2O4 NPs. Tomato plants were able to tolerate CoFe2O4 NPs concentrations up to 1000mgL(-1) without visible toxicity symptoms. Macronutrient uptake in plants was affected when plants were exposed to 250, 500 and 1000mgL(-1) of CoFe2O4 NPs. Published by Elsevier B.V.

Structural characterization of ferrite nanoparticles and composite materials using synchrotron radiation

International Nuclear Information System (INIS)

Albuquerque, A.S.; Macedo, W.A.A.; Plivelic, T.; Torriani, I.L.; Jimenez, J.A.L.; Saitovich, E.B.

2001-01-01

During the last decade nanocrystalline magnetic materials have been widely studied due to the multiple technological applications. Amongst the magnetic materials of major technological interest are the soft magnetic ferrites and the granular solids formed by ferrites dispersed in non-magnetic matrices. It is a well known fact that the magnetic properties of these materials, such as coercivity, magnetic saturation and magnetization, depend on the shape, size and size distribution of the nanoparticles. For this reason, the general purpose of this work was to obtain structural information on ferrite nanoparticles (NiFe 2 O 4 and NiZnFe 2 O 4 ) and granular solids obtained by dispersion of these particles in non magnetic matrices, like SiO 2 and SnO 2 . The ferrite samples were prepared by co-precipitation and heat treated between 300 and 600 deg. C at the Applied Physics Laboratory of tile CDTN. The granular solids, with 30% in volume concentration of ferrite, were obtained by mechanical alloying with milling times (t m ) varying between 1.25 and 10 h, at the CBPF

Distribution of cations in nanosize and bulk Co-Zn ferrites

Czech Academy of Sciences Publication Activity Database

Veverka, Miroslav; Jirák, Zdeněk; Kaman, Ondřej; Knížek, Karel; Maryško, Miroslav; Pollert, Emil; Závěta, K.; Lančok, Adriana; Dlouhá, M.; Vratislav, S.

2011-01-01

Roč. 22, č. 34 (2011), 345701/1-345701/7 ISSN 0957-4484 R&D Projects: GA ČR GAP204/10/0035; GA ČR(CZ) GAP108/11/0807 Institutional research plan: CEZ:AV0Z10100521; CEZ:AV0Z40320502 Keywords : cobalt zinc ferrites * nanoparticles distribution of cations Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.979, year: 2011

Magnetic Cobalt and Cobalt Oxide Nanoparticles in Hyperbranched Polyester Polyol Matrix

Directory of Open Access Journals (Sweden)

O. I. Medvedeva

2017-01-01

Full Text Available A series of cobalt (Co and its oxides based nanoparticles were synthesized by using hyperbranched polyester polyol Boltorn H20 as a platform and sodium borohydride as a reducing agent. UV, FT-IR, XRD, NTA, and TEM methods were employed to obtain physicochemical characteristics of the products. The average diameter of Co nanoparticles was approximately 8.2±3.4 nm. Their magnetic properties, including hysteresis loop, field-cooled, and zero field-cooled curves were investigated. The nanoparticles exhibit superparamagnetism at room temperature, accompanied by magnetic hysteresis below the blocking temperature.

Tuning the magnetism of ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Viñas, S. Liébana [Faculty of Physics and CENIDE, University Duisburg-Essen, Duisburg 47048 (Germany); Departamento de Física Aplicada, Universidade de Vigo, Vigo 36310 (Spain); Simeonidis, K. [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Li, Z.-A.; Ma, Z. [Faculty of Physics and CENIDE, University Duisburg-Essen, Duisburg 47048 (Germany); Myrovali, E.; Makridis, A.; Sakellari, D. [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Angelakeris, M., E-mail: agelaker@auth.gr [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Wiedwald, U.; Spasova, M. [Faculty of Physics and CENIDE, University Duisburg-Essen, Duisburg 47048 (Germany); Farle, M., E-mail: michael.farle@uni-due.de [Faculty of Physics and CENIDE, University Duisburg-Essen, Duisburg 47048 (Germany)

2016-10-01

The importance of magnetic interactions within an individual nanoparticle or between adjacent ones is crucial not only for the macroscopic collective magnetic behavior but for the AC magnetic heating efficiency as well. On this concept, single-(MFe{sub 2}O{sub 4} where M=Fe, Co, Mn) and core–shell ferrite nanoparticles consisting of a magnetically softer (MnFe{sub 2}O{sub 4}) or magnetically harder (CoFe{sub 2}O{sub 4}) core and a magnetite (Fe{sub 3}O{sub 4}) shell with an overall size in the 10 nm range were synthesized and studied for their magnetic particle hyperthermia efficiency. Magnetic measurements indicate that the coating of the hard magnetic phase (CoFe{sub 2}O{sub 4}) by Fe{sub 3}O{sub 4} provides a significant enhancement of hysteresis losses over the corresponding single-phase counterpart response, and thus results in a multiplication of the magnetic hyperthermia efficiency opening a novel pathway for high-performance, magnetic hyperthermia agents. At the same time, the existence of a biocompatible Fe{sub 3}O{sub 4} outer shell, toxicologically renders these systems similar to iron-oxide ones with significantly milder side-effects. - Highlights: • Magnetic hyperthermia is studied for 10 nm single and core/shell ferrite nanoparticles. • Maximum heating rate is observed for Fe{sub 3}O{sub 4}-coated CoFe{sub 2}O{sub 4} nanoparticles. • The increase is attributed to the interaction of phases with different anisotropy. • The presence of biocompatible Fe{sub 3}O{sub 4} shell potentially minimizes toxic side-effects.

Oxide nanoparticles in an Al-alloyed oxide dispersion strengthened steel: crystallographic structure and interface with ferrite matrix

Science.gov (United States)

Zhang, Zhenbo; Pantleon, Wolfgang

2017-07-01

Oxide nanoparticles are quintessential for ensuring the extraordinary properties of oxide dispersion strengthened (ODS) steels. In this study, the crystallographic structure of oxide nanoparticles, and their interface with the ferritic steel matrix in an Al-alloyed ODS steel, i.e. PM2000, were systematically investigated by high-resolution transmission electron microscopy. The majority of oxide nanoparticles were identified to be orthorhombic YAlO3. During hot consolidation and extrusion, they develop a coherent interface and a near cuboid-on-cube orientation relationship with the ferrite matrix in the material. After annealing at 1200 °C for 1 h, however, the orientation relationship between the oxide nanoparticles and the matrix becomes arbitrary, and their interface mostly incoherent. Annealing at 1300 °C leads to considerable coarsening of oxide nanoparticles, and a new orientation relationship of pseudo-cube-on-cube between oxide nanoparticles and ferrite matrix develops. The reason for the developing interfaces and orientation relationships between oxide nanoparticles and ferrite matrix under different conditions is discussed.

Enhanced magneto-optical Kerr effect in rare earth substituted nanostructured cobalt ferrite thin film prepared by sol–gel method

Energy Technology Data Exchange (ETDEWEB)

Avazpour, L.; Toroghinejad, M.R. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (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 13876-71557 (Iran, Islamic Republic of)

2016-11-30

Highlights: • The nanostructured rare earth doped Co-ferrite thin film was synthesized by the sol–gel method. • The coercivity of as high as 1.8 kOe is achieved for 20% substituted cobalt ferrite. • The average particle diameter of particulate film is decreasing by increasing substitute content. • Kerr spectra of films shifted to higher energies. • Kerr rotation angle increased to 1.65° for 0.1 Eu doped thin film. - Abstract: A series of rare-earth (RE)-doped nanocrystalline Co{sub x} RE{sub (1−x)} Fe{sub 2}O{sub 4} (x = 0, 0.1, 0.2 and RE: Nd, Eu) thin films were prepared on silicon substrates by a sol–gel process, and the influences of different RE{sup 3+} ions on the microstructure, magnetism and polar magneto-optical Kerr effect of the deposited films were investigated. Also this research presents the optimization process of cobalt ferrite thin films deposited via spin coating, by studying their structural and morphological properties at different thicknesses (200, 350 nm) and various heat treatment temperatures 300–850 °C. Nanoparticulate polycrystalline thin film were formed with heat treatment above 400 °C but proper magnetic properties due to well crystallization of the film were achieved at about 650 °C. AFM results indicated that the deposited thin films were crack-free exhibiting a dense nanogranular structure. The root-mean square (RMS) roughness of the thin films was in the range of 0.2–3.2 nm. The results revealed that both of the magnetism and magneto optical Kerr (MOKE) spectra of Co{sub x} RE{sub (1−x)} Fe{sub 2}O{sub 4} films could be mediated by doping with various RE ions. The Curie temperature of substituted samples was lower than pristine cobalt ferrite thin films. In MOKE spectra both dominant peaks were blue shifted with addition of RE ions. For low concentration dopant the inter-valence charge transfer related rotation was enhanced and for higher concentration dopant the crystal field rotation peak was enhanced

Studies on magnetic properties of chemically synthesized crystalline calcium ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Debnath, A., E-mail: debnathanimesh@gmail.com [Department of Civil Engineering, National Institute of Technology Agartala, Jirania, West Tripura, 799046 India (India); Bera, A.; Saha, B. [Department of Physics, National Institute of Technology Agartala, Jirania, West Tripura 799046 (India); Chattopadhyay, K. K. [Department of Physics, Jadavpur University, Kolkata 700 032 (India)

2016-05-23

Spinel-type ferrites have taken a very important role for modern electronic industry. Most of these ferrites exhibit low-loss dielectric properties, high resistivity, low eddy current and also high temperature ferromagnetism. Calcium ferrite is one such important metal oxide which is environmentally safe, chemically stable, low cost and greatly abundant. This outstanding material of calcium ferrite is synthesized by a simple chemical precipitation method using NaOH as the precipitating agent. Ferric chloride anhydrous (FeCl{sub 3}) and Calcium chloride dihydrate (CaCl{sub 2}.2H{sub 2}O) were used as iron and calcium sources respectively. The samples were heated at 200°C for 8h to obtain homogeneous powder of Calcium ferrite. The powders were characterized by using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Transmission electrical microscopy (TEM), and Fourier transform infrared spectroscopic (FTIR) measurements. The polycrystalline nature of the sample was confirmed by X-ray diffraction study. The magnetic properties of the sample were investigated by vibrating sample magnetometer (VSM) measurements. Magnetization curve of the prepared sample depicts that as synthesized calcium ferrite nanoparticles have saturation magnetic moment of 1.74 emu/g and the coercivity of 35.08 Oe with superparamagnetic behavior. The synthesized calcium ferrite nanoparticles with such magnetic properties will be a candidate material for different applications in electronics and exploring its functionality in the field of recently developing semiconductor device physics and spintronics.

Studies on magnetic properties of chemically synthesized crystalline calcium ferrite nanoparticles

International Nuclear Information System (INIS)

Debnath, A.; Bera, A.; Saha, B.; Chattopadhyay, K. K.

2016-01-01

Spinel-type ferrites have taken a very important role for modern electronic industry. Most of these ferrites exhibit low-loss dielectric properties, high resistivity, low eddy current and also high temperature ferromagnetism. Calcium ferrite is one such important metal oxide which is environmentally safe, chemically stable, low cost and greatly abundant. This outstanding material of calcium ferrite is synthesized by a simple chemical precipitation method using NaOH as the precipitating agent. Ferric chloride anhydrous (FeCl_3) and Calcium chloride dihydrate (CaCl_2.2H_2O) were used as iron and calcium sources respectively. The samples were heated at 200°C for 8h to obtain homogeneous powder of Calcium ferrite. The powders were characterized by using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Transmission electrical microscopy (TEM), and Fourier transform infrared spectroscopic (FTIR) measurements. The polycrystalline nature of the sample was confirmed by X-ray diffraction study. The magnetic properties of the sample were investigated by vibrating sample magnetometer (VSM) measurements. Magnetization curve of the prepared sample depicts that as synthesized calcium ferrite nanoparticles have saturation magnetic moment of 1.74 emu/g and the coercivity of 35.08 Oe with superparamagnetic behavior. The synthesized calcium ferrite nanoparticles with such magnetic properties will be a candidate material for different applications in electronics and exploring its functionality in the field of recently developing semiconductor device physics and spintronics.

Synthesis and characterization of cobalt/gold bimetallic nanoparticles

International Nuclear Information System (INIS)

Cheng, Guangjun; Hight Walker, Angela R.

2007-01-01

Cobalt/gold (Co/Au) bimetallic nanoparticles are prepared by chemically reducing gold (III) chloride to gold in the presence of pre-synthesized Co nanoparticles. Transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) absorption spectrometry, and a superconducting quantum interference device (SQUID) magnetometer have been used to characterize as-prepared bimetallic nanoparticles. Our findings demonstrate Au not only grows onto Co nanoparticles, forming a surface coating, but also diffuses into Co nanoparticles. The introduction of Au alters the crystalline structure of Co nanoparticles and changes their magnetic properties. Dodecanethiols induce a reorganization of as-prepared Co/Au bimetallic nanoparticles

Synthesis and controllable oxidation of monodisperse cobalt-doped wüstite nanoparticles and their core-shell stability and exchange-bias stabilization.

Science.gov (United States)

Chen, Chih-Jung; Chiang, Ray-Kuang; Kamali, Saeed; Wang, Sue-Lein

2015-09-14

Cobalt-doped wüstite (CWT), Co0.33Fe0.67O, nanoparticles were prepared via the thermal decomposition of CoFe2-oleate complexes in organic solvents. A controllable oxidation process was then performed to obtain Co0.33Fe0.67O/CoFe2O4 core-shell structures with different core-to-shell volume ratios and exchange bias properties. The oxidized core-shell samples with a ∼4 nm CoFe2O4 shell showed good resistance to oxygen transmission. Thus, it is inferred that the cobalt ferrite shell provides a better oxidation barrier performance than magnetite in the un-doped case. The hysteresis loops of the oxidized 19 nm samples exhibited a high exchange bias field (H(E)), an enhanced coercivity field (H(C)), and a pronounced vertical shift, thus indicating the presence of a strong exchange bias coupling effect. More importantly, the onset temperature of H(E) was found to be higher than 200 K, which suggests that cobalt doping increases the Néel temperature (T(N)) of the CWT core. In general, the results show that the homogeneous dispersion of Co in iron precursors improves the stability of the final CWT nanoparticles. Moreover, the CoFe2O4 shells formed following oxidation increase the oxidation resistance of the CWT cores and enhance their anisotropy energy.

Interaction effects in magnetic oxide nanoparticle systems

Indian Academy of Sciences (India)

The interaction effects in magnetic nanoparticle system were studied through a Monte Carlo simulation. The results of simulations were compared with two different magnetic systems, namely, iron oxide polymer nanocomposites prepared by polymerization over core and nanocrystalline cobalt ferrite thin films prepared by ...

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)

Characterization of a Porous Carbon Material Functionalized with Cobalt-Oxide/Cobalt Core-Shell Nanoparticles for Lithium Ion Battery Electrodes

KAUST Repository

Anjum, Dalaver H.; Rasul, Shahid; Roldan-Gutierrez, Manuel A.; Da Costa, Pedro M. F. J.

2016-01-01

A nanoporous carbon (C) material, functionalized with Cobalt-Oxide/Cobalt (CoO/Co) core-shell nanoparticles (NPs), was structurally and chemically characterized with transmission electron microcopy (TEM) while its electrochemical response

Cobalt nanoparticles as recyclable catalyst for aerobic oxidation of alcohols in liquid phase

Energy Technology Data Exchange (ETDEWEB)

Mondal, Arijit; Mukherjee, Debkumar, E-mail: debkumarmukherjee@rediffmail.com [Ramsaday College, Department of Chemistry (India); Adhikary, Bibhutosh, E-mail: adhikarybibhu@yahoo.com [Indian Institute of Engineering, Sciences and Technology, Shibpur, Department of Chemistry (India); Ahmed, Md Azharuddin [University of Calcutta, Department of Physics (India)

2016-05-15

Cobalt nanoparticles prepared at room temperature from cobalt sulphate and tetrabutyl ammonium bromide as surfactant have been found to be effective oxidation catalysts. Palladium and platinum nanoparticles (average size 4–6 nm) can also be prepared from PdCl{sub 2} and K{sub 2}PtCl{sub 4}, respectively, using the same surfactant but require high temperature (~120 °C) and much longer preparation time. Agglomeration of nanoparticles prepared from metals like palladium and platinum in common solvents, however, restricts their use as catalysts. It is therefore our endeavour to find the right combination of catalyst and solvent that will be beneficial from industrial point of view. Magnetic property measurement of cobalt nanoclusters was made using SQUID to identify their reusability nature. Herein, we report the use of cobalt nanoparticles (average size 90–95 nm) in dichloromethane solvent as effective reusable catalysts for aerobic oxidation of a variety of alcohols.Graphical Abstract.

Weak ferromagnetism and exchange biasing in cobalt oxide nanoparticle systems

NARCIS (Netherlands)

Tomou, A; Gournis, D; Panagiotopoulos, [No Value; Huang, Y; Hadjipanayis, GC; Kooi, BJ; Panagiotopoulos, I.

2006-01-01

Cobalt oxide nanoparticle systems have been prepared by wet chemical processing involving the encapsulation of the nanoparticles by an organic ligand shell (oleic acid and oleylamine). CoO nanoparticles were easily prepared by this method, while the synthesis of the CoPt/CoO nanocomposites was

Ferrite nanoparticles: Synthesis, characterisation and applications in electronic device

Energy Technology Data Exchange (ETDEWEB)

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

2017-01-15

Highlights: • Available synthesis methods of ferrite nanoparticles (FNPs) are briefly reviewed. • Summary of the advantage and limitation of FNPs synthesis techniques are presented. • The existing most common FNPs characterisation techniques are briefly reviewed. • Major application areas of FNPs in electronic materials are reviewed. - Abstract: Ferrite nanoparticles (FNPs) have attracted a great interest due to their wide applications in several areas such as biomedical, wastewater treatment, catalyst and electronic device. This review focuses on the synthesis, characterisation and application of FNPs in electronic device with more emphasis on the recently published works. The most commonly used synthesis techniques along with their advantages and limitations are discussed. The available characterisation techniques and their application in electronic materials such as sensors and biosensors, energy storage, microwave device, electromagnetic interference shielding and high-density recording media are briefly reviewed.

Morphology and composition tailoring of Co x Fe3 - x O4 nanoparticles

Science.gov (United States)

Fernandes de Medeiros, I. A.; Madigou, V.; Lopes-Moriyama, A. L.; Pereira de Souza, C.; Leroux, Ch.

2018-01-01

Nano-octahedra of cobalt ferrite Co x Fe3 - x O4 (1 ≤ x hydrothermal method using nitrates as precursors. For the first time, single-phased nano-octahedra of cobalt-rich ferrite Co x Fe3 - x O4 ( x = 1.5) were synthesized. The nano-octahedra are crystallized in a normal spinel structure, with tetrahedral sites occupied by Co2+. This specific octahedral shape was obtained with anionic, cationic, and nonionic surfactants. The nature of the surfactant influenced the chemical composition of the powder and the size of the nano-octahedra. The {100} truncation of the octahedra is more pronounced for the small particles. For the first time, single-phased nanoparticles with as much as x = 1.8 cobalt were synthesized with ethylene glycol as solvent. These nanoparticles, around 8 nm in size, have no specific shape and possess a lacunar spinel structure similar to maghemite. The samples were characterized by X-ray diffraction, transmission electron microscopy, and energy-dispersive spectroscopy.

Induction of apoptosis in cancer cells by NiZn ferrite nanoparticles through mitochondrial cytochrome C release

Directory of Open Access Journals (Sweden)

Al-Qubaisi MS

2013-10-01

Full Text Available Mothanna Sadiq Al-Qubaisi,1 Abdullah Rasedee,1,2 Moayad Husein Flaifel,3 Sahrim Hj Ahmad,3 Samer Hussein-Al-Ali,1 Mohd Zobir Hussein,4 Zulkarnain Zainal,4 Fatah H Alhassan,4 Yun H Taufiq-Yap,4 Eltayeb EM Eid,5 Ismail Adam Arbab,1 Bandar A Al-Asbahi,3 Thomas J Webster,6,7 Mohamed Ezzat El Zowalaty1,8,9 1Institute of Bioscience, 2Faculty of Veterinary Medicine, Universiti Putra Malaysia, 3Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 4Faculty of Science, Universiti Putra Malaysia, Selangor, Malaysia; 5College of Pharmacy, Qassim University, Buraidah, Saudi Arabia; 6Department of Chemical Engineering and Program in Bioengineering, Northeastern University, Boston, MA, USA; 7Center of Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah, Saudi Arabia; 8Faculty of Pharmacy, Zagazig University, Zagazig, Egypt; 9Faculty of Public Health and Tropical Medicine, Jazan University, Jazan, Saudi Arabia Abstract: The long-term objective of the present study was to determine the ability of NiZn ferrite nanoparticles to kill cancer cells. NiZn ferrite nanoparticle suspensions were found to have an average hydrodynamic diameter, polydispersity index, and zeta potential of 254.2 ± 29.8 nm, 0.524 ± 0.013, and -60 ± 14 mV, respectively. We showed that NiZn ferrite nanoparticles had selective toxicity towards MCF-7, HepG2, and HT29 cells, with a lesser effect on normal MCF 10A cells. The quantity of Bcl-2, Bax, p53, and cytochrome C in the cell lines mentioned above was determined by colorimetric methods in order to clarify the mechanism of action of NiZn ferrite nanoparticles in the killing of cancer cells. Our results indicate that NiZn ferrite nanoparticles promote apoptosis in cancer cells via caspase-3 and caspase-9, downregulation of Bcl-2, and upregulation of Bax and p53, with cytochrome C translocation. There was a concomitant collapse of the mitochondrial membrane potential in these cancer cells when treated

Evaluation of Antioxidant and Cytotoxicity Activities of Copper Ferrite (CuFe2O4 and Zinc Ferrite (ZnFe2O4 Nanoparticles Synthesized by Sol-Gel Self-Combustion Method

Directory of Open Access Journals (Sweden)

Samikannu Kanagesan

2016-08-01

Full Text Available Spinel copper ferrite (CuFe2O4 and zinc ferrite (ZnFe2O4 nanoparticles were synthesized using a sol-gel self-combustion technique. The structural, functional, morphological and magnetic properties of the samples were investigated by Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD, Transmission electron microscopy (TEM and vibrating sample magnetometry (VSM. XRD patterns conform to the copper ferrite and zinc ferrite formation, and the average particle sizes were calculated by using a transmission electron microscope, the measured particle sizes being 56 nm for CuFe2O4 and 68 nm for ZnFe2O4. Both spinel ferrite nanoparticles exhibit ferromagnetic behavior with saturation magnetization of 31 emug−1 for copper ferrite (50.63 Am2/Kg and 28.8 Am2/Kg for zinc ferrite. Both synthesized ferrite nanoparticles were equally effective in scavenging 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH free radicals. ZnFe2O4 and CuFe2O4 nanoparticles showed 30.57% ± 1.0% and 28.69% ± 1.14% scavenging activity at 125 µg/mL concentrations. In vitro cytotoxicity study revealed higher concentrations (>125 µg/mL of ZnFe2O4 and CuFe2O4 with increased toxicity against MCF-7 cells, but were found to be non-toxic at lower concentrations suggesting their biocompatibility.

Assessment of thyroid endocrine system impairment and oxidative stress mediated by cobalt ferrite (CoFe2 O4 ) nanoparticles in zebrafish larvae.

Science.gov (United States)

Ahmad, Farooq; Liu, Xiaoyi; Zhou, Ying; Yao, Hongzhou; Zhao, Fangfang; Ling, Zhaoxing; Xu, Chao

2016-12-01

Fascinating super paramagnetic uniqueness of iron oxide particles at nano-scale level make them extremely useful in the state of the art therapies, equipments, and techniques. Cobalt ferrite (CoFe 2 O 4 ) magnetic nanoparticles (MNPs) are extensively used in nano-based medicine and electronics, results in extensive discharge and accumulation into the environment. However, very limited information is available for their endocrine disrupting potential in aquatic organisms. In this study, the thyroid endocrine disrupting ability of CoFe 2 O 4 NPs in Zebrafish larvae for 168-h post fertilization (hpf) was evaluated. The results showed the elevated amounts of T4 and T3 hormones by malformation of hypothalamus pituitary axis in zebrafish larvae. These elevated levels of whole body THs leads to delayed hatching, head and eye malformation, arrested development, and alterations in metabolism. The influence of THs disruption on ROS production and change in activities of catalase (CAT), mu-glutathione s-transferase (mu-GST), and acid phosphatase (AP) were also studied. The production of significantly higher amounts of in vivo generation of ROS leads to membrane damage and oxidative stress. Presences of NPs and NPs agglomerates/aggregates were also the contributing factors in mechanical damaging the membranes and physiological structure of thyroid axis. The increased activities of CAT, mu-GST, and AP confirmed the increased oxidative stress, possible DNA, and metabolic alterations, respectively. The excessive production of in vivo ROS leads to severe apoptosis in head, eye, and heart region confirming that malformation leads to malfunctioning of hypothalamus pituitary axis. ROS-induced oxidative DNA damage by formation of 8-OHdG DNA adducts elaborates the genotoxicity potential of CoFe 2 O 4 NPs. This study will help us to better understand the risk and assessment of endocrine disrupting potential of nanoparticles. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 2068

Synthesis and magnetic characterization of nickel ferrite nanoparticles prepared by co-precipitation route

Science.gov (United States)

Maaz, K.; Karim, S.; Mumtaz, A.; Hasanain, S. K.; Liu, J.; Duan, J. L.

2009-06-01

Magnetic nanoparticles of nickel ferrite (NiFe 2O 4) have been synthesized by co-precipitation route using stable ferric and nickel salts with sodium hydroxide as the precipitating agent and oleic acid as the surfactant. X-ray diffraction (XRD) and transmission electron microscope (TEM) analyses confirmed the formation of single-phase nickel ferrite nanoparticles in the range 8-28 nm depending upon the annealing temperature of the samples during the synthesis. The size of the particles ( d) was observed to be increasing linearly with annealing temperature of the sample while the coercivity with particle size goes through a maximum, peaking at ˜11 nm and then decreases for larger particles. Typical blocking effects were observed below ˜225 K for all the prepared samples. The superparamagnetic blocking temperature ( T B) was found to be increasing with increasing particle size that has been attributed to the increased effective anisotropy energy of the nanoparticles. The saturation moment of all the samples was found much below the bulk value of nickel ferrite that has been attributed to the disordered surface spins or dead/inert layer in these nanoparticles.

Development and functionalization of magnetic nanoparticles as powerful and green catalysts for organic synthesis

Directory of Open Access Journals (Sweden)

Ahmed M. Abu-Dief

2018-03-01

Full Text Available Magnetic nanoparticles are a highly worthy reactant for the correlation of homogeneous inorganic and organic containing catalysts. This review deals with the very recent main advances in the development of various nano catalytic systems by the immobilization of homogeneous catalysts onto magnetic nanoparticles. Catalytic fields include the use of mainly cobalt, nickel, copper, and zinc ferrites, as well as their mixed-metal combinations with Cr, Cd, Mn and sometimes some lanthanides. The ferrite nanomaterials are obtained mainly by co-precipitation and hydrothermal methods, sometimes by the sonochemical technique, micro emulsion and flame spray synthesis route. Catalytic processes with application of ferrite nanoparticles include degradation (in particular photocatalytic, reactions of dehydrogenation, oxidation, alkylation, C–C coupling, among other processes. Ferrite nano catalysts can be easily recovered from reaction systems and reused up to several runs almost without loss of catalytic activity. Finally, we draw conclusions and present a futurity outlook for the further development of new catalytic systems which are immobilized onto magnetic nanoparticles.

Solubility of cobalt in primary circuit solutions

International Nuclear Information System (INIS)

Lambert, I.; Joyer, F.

1992-01-01

The solubility of cobalt ferrite (CoFe 2 O 4 ) was measured in PWR primary circuit conditions, in the temperature range 250-350 deg C, and the results were compared with the ones obtained on magnetite and nickel ferrite. As in the former cases, it was found that, in the prevailing primary circuit conditions, the solubility of the cobalt ferrite was minimum at temperatures around 300 deg C, for cobalt as well as for iron. The equilibrium iron concentration is significantly lower than in the case of magnetite. The results are discussed in relation with the POTHY code, based only on thermodynamic laws and data, used for the prediction of the primary circuit chemistry

Improvement of the oxidation stability of cobalt nanoparticles

Directory of Open Access Journals (Sweden)

Celin Dobbrow

2012-01-01

Full Text Available In order to enhance the resistance of cobalt nanoparticles to oxidation in air, the impact of different stabilization strategies on the isothermal oxidation of particle dispersions and powders was kinetically investigated and compared to as-prepared particle preparations. A post-synthesis treatment with different alcohols was employed, and we also investigate the influence of two different polymer shells on the oxidation process. We found a parabolic decrease of the magnetization for all particle charges, indicating that the process is dominated by a diffusion of oxygen to the cobalt core and a radial growth of the oxide layer from the particle surface to the core. A significant deceleration of the oxidation process was observed for all alcohol-passivated particle preparations, and this resulted finally in a stagnation effect. The stabilizing effect increases in the sequence Co@OA/MeOH < Co@OA/EtOH < Co@OA/iPrOH. For polymer-coated particle preparations Co@PCL and Co@PS, the deceleration was even more pronounced. The results demonstrate that cobalt nanoparticles can effectively be protected against oxidation in order to improve their mid- to longterm stability.

The superspin glass transition in zinc ferrite nanoparticles

Czech Academy of Sciences Publication Activity Database

Kaman, Ondřej; Kořínková, T.; Jirák, T.; Maryško, Miroslav; Veverka, Miroslav

2015-01-01

Roč. 117, č. 17 (2015), "17C706-1"-"17C706-4" ISSN 0021-8979 R&D Projects: GA ČR(CZ) GAP108/11/0807; GA ČR GAP204/10/0035 Institutional support: RVO:68378271 Keywords : superspin glass * zinc ferrite * doped magnetite * magnetic nanoparticles * thermal decomposition Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.101, year: 2015

Structural, dielectric and gas sensing behavior of Mn substituted spinel MFe2O4 (M=Zn, Cu, Ni, and Co) ferrite nanoparticles

Science.gov (United States)

Ranjith Kumar, E.; Siva Prasada Reddy, P.; Sarala Devi, G.; Sathiyaraj, S.

2016-01-01

Spinel ferrite (MnZnFe2O4, MnCuFe2O4, MnNiFe2O4 and MnCoFe2O4) nanoparticles have been prepared by evaporation method. The annealing temperature plays an important role on changing particle size of the spinel ferrite nanoparticles was found out by X-ray diffraction and transmission electron microscopy. The role of manganese substitution in the spinel ferrite nanoparticles were also analyzed for different annealing temperature. The substitution of Mn also creates a vital change in dielectric properties have been measured in the frequency range of 100 kHz to 5 MHz. These spinel ferrites are decomposed to α-Fe2O3 after annealing above 550 °C in air. Through the characterization of the prepared powder, the effect of annealing temperature, chemical composition and preparation technique on the microstructure, particle size and dielectric properties of the Mn substituted spinel ferrite nanoparticles are discussed. Furthermore, Conductance response of Mn substituted MFe2O4 ferrite nanoparticles were measured by exposing the materials to reducing gas like liquefied petroleum gas (LPG).

Controlling the size and magnetic properties of nano CoFe2O4 by microwave assisted co-precipitation method

Science.gov (United States)

Prabhakaran, T.; Mangalaraja, R. V.; Denardin, Juliano C.

2018-02-01

In this report, cobalt ferrite nanoparticles synthesized using microwave assisted co-precipitation method was reported. Efforts have been made to control the particles size, distribution, morphology and magnetic properties of cobalt ferrite nanoparticles by varying the concentration of NaOH solution and microwave irradiation time. It was observed that the rate of nucleation and crystal growth was influenced by the tuning parameters. In that way, the average crystallite size of single phase cobalt ferrite nanoparticles was controlled within 9-11 and 10-12 nm with an increase of base concentration and microwave irradiation time, respectively. A narrow size distribution of nearly spherical nanoparticles was achieved through the present procedure. A soft ferromagnetism at room temperature with the considerable saturation magnetization of 58.4 emu g-1 and coercivity of 262.7 Oe was obtained for the cobalt ferrites synthesized with 2.25 M of NaOH solution for 3 and 7 min of microwave irradiation time, respectively. The cobalt ferrite nanoparticles synthesized with a shorter reaction time of 3-7 min was found to be advantageous over other methods that involved conventional heating procedures and longer reaction time to achieve the better magnetic properties for the technological applications.

Magnetic nanoparticles studied by small angle X-ray scattering

International Nuclear Information System (INIS)

Oliveira, Cristiano Luis Pinto; Antonel, Soledad; Negri, Martin

2011-01-01

Full text: Magnetic nanoparticles have attracted much attention in the past decades because of their potential applications in high-density magnetic recording, magnetic fluids, data storage, spin-tronics, solar cells, sensors and catalysis. Among the magnetic nanoparticles, cobalt ferrite (CoFe 2 O 4 ) has been widely studied due to high electromagnetic performance, excellent chemical stability, mechanical hardness, and high cubic magnetocrystalline anisotropy. These properties make it a promising candidate for many applications in commercial electronics such as video, audio tapes, high-density digital recording media, and magnetic fluids. Other interesting application is the use of magnetic nanocompounds in the design of magneto elastomers. Magnetoelastomers are dispersions of magnetic particles into an elastomer polymer matrix. These materials are highly promising for applications in the development of sensors and actuators, mainly because of the possibility to optimize the quality parameters of the devices by systematically changing the chemical nature of both the inorganic particles and the organic polymeric matrix, with the consequent modification of the magnetic, electric and elastic properties. Moreover, nanoparticles of cobalt-iron oxides (cobalt ferrite, CoFe 2 O 4 ) appears as very interesting compounds for magnetoelasticity, not only because present magnetic anisotropy, moderate-high magnetization and high coercitivity at room temperature, but also because the possibility to modulate its magnetic properties by chemical synthesis, that is by synthesizing nanoparticles of different sizes having thus not only different magnetic parameters but also different magnetic behavior (superparamagnetism or ferromagnetism). That means that most of the magnetic properties of CoFe 2 O 4 ferrite strongly depend on the size and shape of the nanoparticles, which are closely related to the method of preparation. On the other hand, nickel nanoparticles are very interesting

Magnetic nanoparticles studied by small angle X-ray scattering

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Cristiano Luis Pinto [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica. Grupo de Fluidos Complexos; Antonel, Soledad; Negri, Martin [Universidad de Buenos Aires (UBA) (Argentina). Facultad de Ciencias Exactas y Naturales. Dept. de Quimica Inorganica, Analitica y Quimica Fisica

2011-07-01

Full text: Magnetic nanoparticles have attracted much attention in the past decades because of their potential applications in high-density magnetic recording, magnetic fluids, data storage, spin-tronics, solar cells, sensors and catalysis. Among the magnetic nanoparticles, cobalt ferrite (CoFe{sub 2}O{sub 4}) has been widely studied due to high electromagnetic performance, excellent chemical stability, mechanical hardness, and high cubic magnetocrystalline anisotropy. These properties make it a promising candidate for many applications in commercial electronics such as video, audio tapes, high-density digital recording media, and magnetic fluids. Other interesting application is the use of magnetic nanocompounds in the design of magneto elastomers. Magnetoelastomers are dispersions of magnetic particles into an elastomer polymer matrix. These materials are highly promising for applications in the development of sensors and actuators, mainly because of the possibility to optimize the quality parameters of the devices by systematically changing the chemical nature of both the inorganic particles and the organic polymeric matrix, with the consequent modification of the magnetic, electric and elastic properties. Moreover, nanoparticles of cobalt-iron oxides (cobalt ferrite, CoFe{sub 2}O{sub 4}) appears as very interesting compounds for magnetoelasticity, not only because present magnetic anisotropy, moderate-high magnetization and high coercitivity at room temperature, but also because the possibility to modulate its magnetic properties by chemical synthesis, that is by synthesizing nanoparticles of different sizes having thus not only different magnetic parameters but also different magnetic behavior (superparamagnetism or ferromagnetism). That means that most of the magnetic properties of CoFe{sub 2}O{sub 4} ferrite strongly depend on the size and shape of the nanoparticles, which are closely related to the method of preparation. On the other hand, nickel

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.

The role of pH on the particle size and magnetic consequence of cobalt ferrite

International Nuclear Information System (INIS)

Safi, Rohollah; Ghasemi, Ali; Shoja-Razavi, Reza; Tavousi, Majid

2015-01-01

Cobalt ferrite (CoFe 2 O 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 2 O 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 −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 2 O 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

Synthesis, characterization and adsorption capability for Congo red of CoFe2O4 ferrite nanoparticles

International Nuclear Information System (INIS)

Ding, Zui; Wang, Wei; Zhang, Yajun; Li, Feng; Liu, J. Ping

2015-01-01

Highlights: • CoFe 2 O 4 ferrite nanoparticles are synthesized by an ethanol-assisted hydrothermal method. • Suitable amount of ethanol can reduce the particle size and increase BET surface area. • The introduction of ethanol leads to the cation redistribution. • Using ethanol/water mixed solution greatly enhances their adsorption capacity for CR dyes. - Abstract: CoFe 2 O 4 ferrite nanoparticles are synthesized by an ethanol-assisted hydrothermal method, where the ethanol is mixed with water as the solution. In this synthesis, a rapid mixing of reducible metal cations with reducing agent and a simultaneous reduction process take place in a colloid mill. Synthesized ferrite samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and Raman spectroscopy. XRD patterns reveal the formation of CoFe 2 O 4 ferrites with single spinel phase. SEM and TEM images show that the as-synthesized samples are with narrow size distribution. Raman spectroscopy studies clearly indicate the cation distribution in nanosized particles. Here, it is worthy to note that, with increasing ethanol content in ethanol–water mixed solution, an obvious superparamagnetic behavior of as-synthesized nanoparticles at room temperature is observed. The adsorption capability of the as-synthesized ferrite nanoparticles for Congo Red (CR) is examined. Enhancement of adsorption capability for CR with adding ethanol as the mixing solution is shown. The adsorption mechanism is discussed. This investigation reveals that the composition of ethanol/water mixed solution has great effects on the microstructure and magnetic properties as well as adsorption capacity of Congo Red (CR) dye of the as-synthesized CoFe 2 O 4 ferrite samples

Influence of nanoparticle-membrane electrostatic interactions on membrane fluidity and bending elasticity.

Science.gov (United States)

Santhosh, Poornima Budime; Velikonja, Aljaž; Perutkova, Šarka; Gongadze, Ekaterina; Kulkarni, Mukta; Genova, Julia; Eleršič, Kristina; Iglič, Aleš; Kralj-Iglič, Veronika; Ulrih, Nataša Poklar

2014-02-01

The aim of this work is to investigate the effect of electrostatic interactions between the nanoparticles and the membrane lipids on altering the physical properties of the liposomal membrane such as fluidity and bending elasticity. For this purpose, we have used nanoparticles and lipids with different surface charges. Positively charged iron oxide (γ-Fe2O3) nanoparticles, neutral and negatively charged cobalt ferrite (CoFe2O4) nanoparticles were encapsulated in neutral lipid 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine and negatively charged 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine lipid mixture. Membrane fluidity was assessed through the anisotropy measurements using the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene. Though the interaction of both the types of nanoparticles reduced the membrane fluidity, the results were more pronounced in the negatively charged liposomes encapsulated with positively charged iron oxide nanoparticles due to strong electrostatic attractions. X-ray photoelectron spectroscopy results also confirmed the presence of significant quantity of positively charged iron oxide nanoparticles in negatively charged liposomes. Through thermally induced shape fluctuation measurements of the giant liposomes, a considerable reduction in the bending elasticity modulus was observed for cobalt ferrite nanoparticles. The experimental results were supported by the simulation studies using modified Langevin-Poisson-Boltzmann model. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Cobalt ferrite nanoparticles with improved aqueous colloidal stability and electrophoretic mobility

International Nuclear Information System (INIS)

Munjal, Sandeep; Khare, Neeraj

2016-01-01

We have synthesized CoFe 2 O 4 (CFO) nanoparticles of size ∼ 12.2 nm by hydrothermal synthesis method. To control the size of these CFO nanoparticles, oleic acid was used as a surfactant. The inverse spinel phase of the synthesized nanoparticles was confirmed by X-ray diffraction method. As synthesized oleic acid coated CFO (OA@CFO) nanoparticles has very less electrophoretic mobility in the water and are not water dispersible. These OA@CFO nanoparticles were successfully turned into water soluble phase with a better colloidal aqueous stability, through a chemical treatment using citric acid. The modified citric acid coated CFO (CA@CFO) nanoparticles were dispersible in water and form a stable aqueous solution with high electrophoretic mobility.

Fe3O4 nanoparticles decorated MWCNTs @ C ferrite nanocomposites and their enhanced microwave absorption properties

Science.gov (United States)

Zhang, Kaichuang; Gao, Xinbao; Zhang, Qian; Chen, Hao; Chen, Xuefang

2018-04-01

Fe3O4 nanoparticles decorated MWCNTs @ C ferrite nanocomposites were synthesized using a co-precipitation method and a calcination process. As one kind absorbing material, we researched the electromagnetic absorption properties of the composites that were mixed with a filler loading of 80 wt% paraffin. In addition, we studied the influence of the magnetic nanoparticle content on the absorbing properties. The results showed that the frequency corresponding to the maximum absorptions shifted to lower frequency when the magnetic nanoparticles content increased. The Fe3O4 nanoparticles decorated MWCNTs @ C ferrite nanocomposites with approximately 60% Fe3O4 nanoparticles showed the best electromagnetic absorption properties. The maximum reflection loss was -52.47 dB with a thickness of 2.0 mm at 10.4 GHz.

Magnesium ferrite nanoparticles: a rapid gas sensor for alcohol

Science.gov (United States)

Godbole, Rhushikesh; Rao, Pratibha; Bhagwat, Sunita

2017-02-01

Highly porous spinel MgFe2O4 nanoparticles with a high specific surface area have been successfully synthesized by a sintering free auto-combustion technique and characterized for their structural and surface morphological properties using XRD, BET, TEM and SEM techniques. Their sensing properties to alcohol vapors viz. ethanol and methanol were investigated. The site occupation of metal ions was investigated by VSM. The as-synthesized sample shows the formation of sponge-like porous material which is necessary for gas adsorption. The gas sensing characteristics were obtained by measuring the gas response as a function of operating temperature, concentration of the gas, and the response-recovery time. The response of magnesium ferrite to ethanol and methanol vapors was compared and it was revealed that magnesium ferrite is more sensitive and selective to ethanol vapor. The sensor operates at a substantially low vapor concentration of about 1 ppm of alcohol vapors, exhibits fantastic response reproducibility, long term reliability and a very fast response and recovery property. Thus the present study explored the possibility of making rapidly responding alcohol vapor sensor based on magnesium ferrite. The sensing mechanism has been discussed in co-relation with magnetic and morphological properties. The role of occupancy of Mg2+ ions in magnesium ferrite on its gas sensing properties has also been studied and is found to influence the response of magnesium ferrite ethanol sensor.

One-pot synthesis of graphene supported platinum–cobalt nanoparticles as electrocatalysts for methanol oxidation

International Nuclear Information System (INIS)

Kepenienė, V.; Tamašauskaitė-Tamašiūnaitė, L.; Jablonskienė, J.; Semaško, M.; Vaičiūnienė, J.; Vaitkus, R.; Norkus, E.

2016-01-01

In the present study the graphene supported platinum–cobalt nanoparticles were prepared via microwave synthesis. The composition of prepared catalysts was examined by Inductively Coupled Plasma Optical Emission Spectroscopy. The shape and size of catalyst particles were determined by Transmission Electron Microscopy. The electrocatalytic activity of the graphene supported platinum–cobalt nanoparticles was investigated towards the electro-oxidation of methanol in an alkaline medium. It has been found that the graphene supported platinum–cobalt nanoparticles having the Pt:Co molar ratio 1:7 show the highest activity towards the electro-oxidation of methanol among the catalysts with the Pt:Co molar ratios equal to 1:1 and 1:44, graphene supported bare Co and Pt/C catalysts. - Highlights: • Preparation of graphene supported Pt-Co nanoparticles by microwave synthesis. • Electrocatalysts for oxidation of methanol. • Higher activity of PtCo/graphene towards methanol oxidation.

One-pot synthesis of graphene supported platinum–cobalt nanoparticles as electrocatalysts for methanol oxidation

Energy Technology Data Exchange (ETDEWEB)

Kepenienė, V., E-mail: virginalisk@gmail.com [Department of Catalysis, Center for Physical Sciences and Technology, Vilnius LT 01108 (Lithuania); Tamašauskaitė-Tamašiūnaitė, L.; Jablonskienė, J.; Semaško, M.; Vaičiūnienė, J. [Department of Catalysis, Center for Physical Sciences and Technology, Vilnius LT 01108 (Lithuania); Vaitkus, R. [Faculty of Chemistry, Vilnius University, Vilnius LT 03225 (Lithuania); Norkus, E. [Department of Catalysis, Center for Physical Sciences and Technology, Vilnius LT 01108 (Lithuania)

2016-03-01

In the present study the graphene supported platinum–cobalt nanoparticles were prepared via microwave synthesis. The composition of prepared catalysts was examined by Inductively Coupled Plasma Optical Emission Spectroscopy. The shape and size of catalyst particles were determined by Transmission Electron Microscopy. The electrocatalytic activity of the graphene supported platinum–cobalt nanoparticles was investigated towards the electro-oxidation of methanol in an alkaline medium. It has been found that the graphene supported platinum–cobalt nanoparticles having the Pt:Co molar ratio 1:7 show the highest activity towards the electro-oxidation of methanol among the catalysts with the Pt:Co molar ratios equal to 1:1 and 1:44, graphene supported bare Co and Pt/C catalysts. - Highlights: • Preparation of graphene supported Pt-Co nanoparticles by microwave synthesis. • Electrocatalysts for oxidation of methanol. • Higher activity of PtCo/graphene towards methanol oxidation.

Influence of Cobalt Doping on the Physical Properties of Zn0.9Cd0.1S Nanoparticles

Directory of Open Access Journals (Sweden)

Gupta Hari Om

2009-01-01

Full Text Available Abstract Zn0.9Cd0.1S nanoparticles doped with 0.005–0.24 M cobalt have been prepared by co-precipitation technique in ice bath at 280 K. For the cobalt concentration >0.18 M, XRD pattern shows unidentified phases along with Zn0.9Cd0.1S sphalerite phase. For low cobalt concentration (≤0.05 M particle size, d XRDis ~3.5 nm, while for high cobalt concentration (>0.05 M particle size decreases abruptly (~2 nm as detected by XRD. However, TEM analysis shows the similar particle size (~3.5 nm irrespective of the cobalt concentration. Local strain in the alloyed nanoparticles with cobalt concentration of 0.18 M increases ~46% in comparison to that of 0.05 M. Direct to indirect energy band-gap transition is obtained when cobalt concentration goes beyond 0.05 M. A red shift in energy band gap is also observed for both the cases. Nanoparticles with low cobalt concentrations were found to have paramagnetic nature with no antiferromagnetic coupling. A negative Curie–Weiss temperature of −75 K with antiferromagnetic coupling was obtained for the high cobalt concentration.

Ultrasound assisted extraction of Maxilon Red GRL dye from water samples using cobalt ferrite nanoparticles loaded on activated carbon as sorbent: Optimization and modeling.

Science.gov (United States)

Mehrabi, Fatemeh; Vafaei, Azam; Ghaedi, Mehrorang; Ghaedi, Abdol Mohammad; Alipanahpour Dil, Ebrahim; Asfaram, Arash

2017-09-01

In this research, a selective, simple and rapid ultrasound assisted dispersive solid-phase micro-microextraction (UA-DSPME) was developed using cobalt ferrite nanoparticles loaded on activated carbon (CoFe 2 O 4 -NPs-AC) as an efficient sorbent for the preconcentration and determination of Maxilon Red GRL (MR-GRL) dye. The properties of sorbent are characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Vibrating sample magnetometers (VSM), Fourier transform infrared spectroscopy (FTIR), Particle size distribution (PSD) and Scanning Electron Microscope (SEM) techniques. The factors affecting on the determination of MR-GRL dye were investigated and optimized by central composite design (CCD) and artificial neural networks based on genetic algorithm (ANN-GA). CCD and ANN-GA were used for optimization. Using ANN-GA, optimum conditions were set at 6.70, 1.2mg, 5.5min and 174μL for pH, sorbent amount, sonication time and volume of eluent, respectively. Under the optimized conditions obtained from ANN-GA, the method exhibited a linear dynamic range of 30-3000ngmL -1 with a detection limit of 5.70ngmL -1 . The preconcentration factor and enrichment factor were 57.47 and 93.54, respectively with relative standard deviations (RSDs) less than 4.0% (N=6). The interference effect of some ions and dyes was also investigated and the results show a good selectivity for this method. Finally, the method was successfully applied to the preconcentration and determination of Maxilon Red GRL in water and wastewater samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Fabrication and analysis of ordered magnetic cobalt nanoparticles; Herstellung und Untersuchung geordneter magnetischer Kobaltnanoteilchen

Energy Technology Data Exchange (ETDEWEB)

Zuern, Klaus P.

2009-12-17

In the dissertation on hand monodisperse, wellordered magnetic cobalt and cobalt hydride nanoparticles have been produced and investigated magnetically. The preparation was achieved by diblock-copolymer-micelles filled with cobalt salt, from which nanoparticles of elementary cobalt respectively cobalt hydride were generated in different steps of the procedure. It was evident that the cobalthydride generated by the hydrogen plasma was surprisingly stable. It could even be taken into consideration as a hydrogen storage device for fuel cell. The magnetic properties of the particles has been investigated by x-ray magnetic circular dichroism (XMCD). In addition it was evident, that it was principally impossible to investigate a film layered on a substrate with a SQUID-magnetometer, if this film produces only a small signal as well absolutely as relatively to the magnetically measured total moment of the sample. (orig.)

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

International Nuclear Information System (INIS)

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

2017-01-01

Highlights: • Superparamagnetic nanoparticles of Gd doped Mn-Zn spinel ferrites synthesized by co-precipitation. • XRD and FTIR studies justify the formation of cubical spinel structure. • Maximum saturation magnetization and magnetic moment at x = 0.025. • PL spectra shows blue shift for x = 0.025, 0.075 and may be attributed to quantum confinement. - Abstract: 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 Mn 0.5 Zn 0.5 Gd x Fe 2-x O 4 (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 Gd 3+ 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.

Spin Hall magnetoresistance at the interface between platinum and cobalt ferrite thin films with large magnetic anisotropy

Directory of Open Access Journals (Sweden)

Takeshi Tainosho

2017-05-01

Full Text Available The recently discovered spin Hall magnetoresistance (SMR effect is a useful means to obtain information on the magnetization process at the interface between a nonmagnetic metal and ferromagnetic insulators. We report the SMR measurements at the interface between platinum and cobalt ferrite thin films for samples with two different preferential directions of magnetization (out-of-plane and in-plane. The directional difference of the magnetic easy axis does not seem to influence the value of SMR.

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.

Some of Physical Properties of Nanostructured (Mg1-xCoxFe2O4 Ferrites Prepared by Sol-Gel Method

Directory of Open Access Journals (Sweden)

Muhammad Abdul Ammer Alsherefi

2018-01-01

Full Text Available Sol-gel auto combustion technique was used to prepare nanoparticles of magnesium-cobalt ferrites with the chemical formula Mg1-xCoxFe2O4 for  (x=0, 0.2, 0.4, 0.6, 0.8, 1, where x added as weight  percentages, and sintering  at temperature (1100 oC. The X-ray patterns of prepared powder has confirmed the structure of cubic spinel structure (fcc. The prepared samples were composed of nearly spherical nano particles .An average particle size of  magnesium-cobalt ferrite  were  calculated  using  Debye Scherer’s relation is equal 53.12 nm. The surface structure of the samples was investigated by Scanning Electron Microscope(SEM. The electromagnetic properties for prepared samples were investigated using Vector Network Analyzer (VNA in X-band microwave region.

Effect of gamma irradiation on the structural and magnetic properties of Co–Zn spinel ferrite nanoparticles

International Nuclear Information System (INIS)

Raut, Anil V.; Kurmude, D.V.; Shengule, D.R.; Jadhav, K.M.

2015-01-01

Highlights: • Co–Zn ferrite nanoparticles were examined before and after γ-irradiation. • Single phase cubic spinel structure of Co–Zn was confirmed by XRD data. • The grain size was reported in the range of 52–62 nm after γ-irradiation. • Ms, Hc, n B were reported to be increased after gamma irradiation. - Abstract: In this work, the structural and magnetic properties of Co 1−x Zn x Fe 2 O 4 (0.0 ≤ x ≤ 1.0) ferrite nanoparticles were studied before and after gamma irradiation. The as-synthesized samples of Co–Zn ferrite nanoparticles prepared by sol–gel auto-combustion technique were analysed by XRD which suggested the single phase; cubic spinel structure of the material. Crystal defects produced in the spinel lattice were studied before and after Co 60 γ-irradiation in a gamma cell with a dose rate of 0.1 Mrad/h in order to report the changes in structural and magnetic properties of the Co–Zn ferrite nanoparticles. The average crystallite size (t), lattice parameter (α) and other structural parameters of gamma-irradiated and un-irradiated Co 1−x Zn x Fe 2 O 4 spinel ferrite system was calculated from XRD data. The morphological characterizations were performed using scanning electron microscopy (SEM). The magnetic properties were measured using pulse field hysteresis loop tracer by applying magnetic field of 1000 Oe, and the analysis of data obtained revealed that the magnetic property such as saturation magnetization (Ms), coecivity (Hc), magneton number (n B ) etc. magnetic parameters were increased after irradiation

Synthesis of nanoparticles of vanadium carbide in the ferrite of nodular cast iron

CERN Document Server

Fras, E; Guzik, E; Lopez, H

2005-01-01

The synthesis method of nanoparticles of vanadium carbide in nodular cast iron is presented. After introduction of this method, the nanoparticles with 10-70 nm of diameter was obtained in the ferrite. The diffraction investigations confirmed that these particles are vanadium carbides of type V/sub 3/C/sub 4/.

Synthesis and properties of nickel cobalt boron nanoparticles

Science.gov (United States)

Patel, J.; Pankhurst, Q. A.; Parkin, I. P.

2005-01-01

Amorphous cobalt nickel boride nanoparticles were synthesised by chemical reduction synthesis in aqueous solution. Careful control of synthesis conditions and post reaction oxidation enabled the nanoparticles to be converted into a core-shell structure comprising of an amorphous Co-Ni-B core and an outer metal oxide sheet. These particles had interesting magnetic properties including saturation magnetisations and coercivities of the order of 80 emu/g and 170 Oe respectively, making them suitable for a potential use as an exchange-pinned magnetic material.

Study the effect of calcination temperature on physical and magnetic properties of bare Cobalt nanoparticles and that coated with silica shell

International Nuclear Information System (INIS)

Arabi, H.; Pourarian, F.; Chahkandinejad, R.

2012-01-01

In this paper, in order to investigate the effect of calcination temperature on the structural and magnetic properties of cobalt nanoparticles, samples have been prepared by Co-precipitation method at different calcination temperature. Cobalt nanoparticles have been prepared by Co-precipitation method at room temperature using hydrazine as reducing in ethanol hydrazine alkaline environment. This agent reduces cobalt salts to Cobalt nanoparticles in FCC and HCP phases. Phase analysis and investigation of Structural properties of the samples using X-ray diffraction patterns (XRD) confirm the formation of hexagonal phases of Co nanoparticles. Transmission electron microscopy was used for determining the size and shape morphology of nanoparticles. Magnetic properties of these nanoparticles have been investigated using a Vibrating sample magnetometer. The results indicate that these nanoparticles are ferromagnetic at room temperature. In addition, in this paper Co nanoparticles coated with silica shell have been prepared by the wet chemical method. Transmission electron microscopy images showed the cobalt core with average diameter of 17-20 nm coated by a silica shell with thickness of 5-7 nm. Hysteresis Loop of these Co nanoparticles coated by silica shell illustrates 16.9 emu/gr for saturation magnetization at 10000 (Oe), which is much less than that of Cobalt nanoparticles

Magnetic Properties of Copper Doped Nickel Ferrite Nanoparticles Synthesized by Co Precipitation Method

Science.gov (United States)

Anjana, V.; John, Sara; Prakash, Pooja; Nair, Amritha M.; Nair, Aravind R.; Sambhudevan, Sreedha; Shankar, Balakrishnan

2018-02-01

Nickel ferrite nanoparticles with copper atoms as dopant have been prepared using co-precipitation method with general formula Ni1-xCuxFe2O4 (x=0.2, 0.4, 0.6, 0.8 and 1) and are sintered at quite ambient temperature. Structural and magnetic properties were examined using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction method (XRD) and Vibrating Sample Magnetometer (VSM) to study the influence of copper doping in nickel ferrite magnetic nanoparticles. X-ray studies proves that the particles are possessing single phase spinel structure with an average particle size calculated using Debye Scherer formula. Magnetic measurements reveal that saturation magnetization value (Ms) decreases while magnetic coercivity (Hc) increases upon doping.

Synthesis of Ni-Zn ferrite nanoparticles in radiofrequency thermal plasma reactor and their use for purification of histidine-tagged proteins

International Nuclear Information System (INIS)

Feczko, Tivadar; Muskotal, Adel; Gal, Lorand; Szepvoelgyi, Janos; Sebestyen, Anett; Vonderviszt, Ferenc

2008-01-01

Superparamagnetic Ni-Zn ferrite nanoparticles were synthesized in radiofrequency thermal plasma reactor from aqueous solutions of Ni- and Zn-nitrates. The nanoparticles were studied for protein purification performance in both quantitative and qualitative terms. For comparison, experiments were also performed by Ni-charged affinity chromatography. It was proved that the Ni-Zn ferrite nanoparticles effectively purified histidine-tagged proteins with a maximum protein binding capacity of about 7% (w/w). Gel electrophoresis demonstrated better purification characteristics for magnetic nanoparticles than for affinity chromatography.

Effect of gamma irradiation on the structural and magnetic properties of Co–Zn spinel ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Raut, Anil V., E-mail: nano9993@gmail.com [Vivekanand Arts, Sardar Dalipsingh Commerce and Science College, Aurangabad 431004, (M.S.) India (India); Kurmude, D.V. [Milind College of Science, Aurangabad 431004, (M.S.) India (India); Shengule, D.R. [Vivekanand Arts, Sardar Dalipsingh Commerce and Science College, Aurangabad 431004, (M.S.) India (India); Jadhav, K.M. [Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431004, (M.S.) India (India)

2015-03-15

Highlights: • Co–Zn ferrite nanoparticles were examined before and after γ-irradiation. • Single phase cubic spinel structure of Co–Zn was confirmed by XRD data. • The grain size was reported in the range of 52–62 nm after γ-irradiation. • Ms, Hc, n{sub B} were reported to be increased after gamma irradiation. - Abstract: In this work, the structural and magnetic properties of Co{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} (0.0 ≤ x ≤ 1.0) ferrite nanoparticles were studied before and after gamma irradiation. The as-synthesized samples of Co–Zn ferrite nanoparticles prepared by sol–gel auto-combustion technique were analysed by XRD which suggested the single phase; cubic spinel structure of the material. Crystal defects produced in the spinel lattice were studied before and after Co{sup 60} γ-irradiation in a gamma cell with a dose rate of 0.1 Mrad/h in order to report the changes in structural and magnetic properties of the Co–Zn ferrite nanoparticles. The average crystallite size (t), lattice parameter (α) and other structural parameters of gamma-irradiated and un-irradiated Co{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} spinel ferrite system was calculated from XRD data. The morphological characterizations were performed using scanning electron microscopy (SEM). The magnetic properties were measured using pulse field hysteresis loop tracer by applying magnetic field of 1000 Oe, and the analysis of data obtained revealed that the magnetic property such as saturation magnetization (Ms), coecivity (Hc), magneton number (n{sub B}) etc. magnetic parameters were increased after irradiation.

Investigations on structural, optical and magnetic properties of Dy-doped zinc ferrite nanoparticles

Science.gov (United States)

Vinosha, P. Annie; Deepapriya, S.; Rodney, John. D.; Das, S. Jerome

2018-04-01

A persuasive and thriftily feasible homogeneous co-precipitation route was adopted to fabricate dysprosium (Dy) doped zinc ferrite (Zn1-xDyxFe2O4)nanoparticles in order to examine their structural, optical and magnetic properties. Theas-synthesized Zn1-xDyxFe2O4 was studied for its momentous applications in photo-degradation of organic Methylene Blue (MB) dye. The paper marksthe connotation of zinc ferrite nanocatalyst in Photo-Fenton degradation. The chemical composition of dysprosium has a decisive feature of this research work. From X-ray diffraction analysis (XRD), spinel phase formation of theas-synthesized Zn1-xDyxFe2O4 nanoparticles was observedand the crystallite size was foundto increase as the doping concentration increased. Theabsorption bands peaked between 600-400 cm-l waspragmatic by Fourier Transform Infrared spectral analysis (FTIR). Transmission Electron Microscopy (TEM) micrograph elucidated the morphology and the speck size of as-synthesized nanoparticles. Surface area and pore size were determined by Brunauer-Emmett-Teller (BET) technique.

A biosensor system using nickel ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Singh, Prachi, E-mail: prachi.singh@st.niituniversity.in; Rathore, Deepshikha, E-mail: deep.nano@gmail.com [NIIT University, Neemrana, NH-8, Alwar, Rajasthan, India, 301705 (India)

2016-05-06

NiFe{sub 2}O{sub 4} ferrite nanoparticles were synthesized by chemical co-precipitation method and the structural characteristics were investigated using X-ray diffraction technique, where single cubic phase formation of nanoparticles was confirmed. The average particle size of NiFe{sub 2}O{sub 4} was found to be 4.9 nm. Nanoscale magnetic materials are an important source of labels for biosensing due to their strong magnetic properties which are not found in biological systems. This property of the material was exploited and the fabrication of the NiFe{sub 2}O{sub 4} nanoparticle based biosensor was done in the form of a capacitor system, with NiFe{sub 2}O{sub 4} as the dielectric material. The biosensor system was tested towards different biological materials with the help of electrochemical workstation and the same was analysed through Cole-Cole plot of NiFe{sub 2}O{sub 4}. The performance of the sensor was determined based on its sensitivity, response time and recovery time.

The structural evolution and diffusion during the chemical transformation from cobalt to cobalt phosphide nanoparticles

KAUST Repository

Ha, Don-Hyung

2011-01-01

We report the structural evolution and the diffusion processes which occur during the phase transformation of nanoparticles (NPs), ε-Co to Co 2P to CoP, from a reaction with tri-n-octylphosphine (TOP). Extended X-ray absorption fine structure (EXAFS) investigations were used to elucidate the changes in the local structure of cobalt atoms which occur as the chemical transformation progresses. The lack of long-range order, spread in interatomic distances, and overall increase in mean-square disorder compared with bulk structure reveal the decrease in the NP\\'s structural order compared with bulk structure, which contributes to their deviation from bulk-like behavior. Results from EXAFS show both the Co2P and CoP phases contain excess Co. Results from EXAFS, transmission electron microscopy, X-ray diffraction, and density functional theory calculations reveal that the inward diffusion of phosphorus is more favorable at the beginning of the transformation from ε-Co to Co2P by forming an amorphous Co-P shell, while retaining a crystalline cobalt core. When the major phase of the sample turns to Co 2P, the diffusion processes reverse and cobalt atom out-diffusion is favored, leaving a hollow void, characteristic of the nanoscale Kirkendall effect. For the transformation from Co2P to CoP theory predicts an outward diffusion of cobalt while the anion lattice remains intact. In real samples, however, the Co-rich nanoparticles continue Kirkendall hollowing. Knowledge about the transformation method and structural properties provides a means to tailor the synthesis and composition of the NPs to facilitate their use in applications. © 2011 The Royal Society of Chemistry.

Structural, dielectric and gas sensing behavior of Mn substituted spinel MFe{sub 2}O{sub 4} (M=Zn, Cu, Ni, and Co) ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Ranjith Kumar, E., E-mail: ranjueaswar@gmail.com [Department of Physics, Dr. NGP Institute of Technology, Coimbatore 641048, Tamil Nadu (India); Siva Prasada Reddy, P.; Sarala Devi, G. [Inorganic and Physical Chemistry Division, Indian Institute Chemical Technology, Hyderabad 500607 (India); Sathiyaraj, S. [Department of Chemistry, Dr. NGP Institute of Technology, Coimbatore 641048, Tamil Nadu (India)

2016-01-15

Spinel ferrite (MnZnFe{sub 2}O{sub 4}, MnCuFe{sub 2}O{sub 4}, MnNiFe{sub 2}O{sub 4} and MnCoFe{sub 2}O{sub 4}) nanoparticles have been prepared by evaporation method. The annealing temperature plays an important role on changing particle size of the spinel ferrite nanoparticles was found out by X-ray diffraction and transmission electron microscopy. The role of manganese substitution in the spinel ferrite nanoparticles were also analyzed for different annealing temperature. The substitution of Mn also creates a vital change in dielectric properties have been measured in the frequency range of 100 kHz to 5 MHz. These spinel ferrites are decomposed to α-Fe{sub 2}O{sub 3} after annealing above 550 °C in air. Through the characterization of the prepared powder, the effect of annealing temperature, chemical composition and preparation technique on the microstructure, particle size and dielectric properties of the Mn substituted spinel ferrite nanoparticles are discussed. Furthermore, Conductance response of Mn substituted MFe{sub 2}O{sub 4} ferrite nanoparticles were measured by exposing the materials to reducing gas like liquefied petroleum gas (LPG). - Highlights: • The egg white support to achieve sample with shorter reaction time. • Manganese plays a significant role in sensor response. • Nature of the ferrites was affected with increasing annealing temperature.

Temperature dependent and applied field strength dependent magnetic study of cobalt nickel ferrite nano particles: Synthesized by an environmentally benign method

Science.gov (United States)

Sontu, Uday Bhasker; G, Narsinga Rao; Chou, F. C.; M, V. Ramana Reddy

2018-04-01

Spinel ferrites have come a long way in their versatile applications. The ever growing applications of these materials demand detailed study of material properties and environmental considerations in their synthesis. In this article, we report the effect of temperature and applied magnetic field strength on the magnetic behavior of the cobalt nickel ferrite nano powder samples. Basic structural properties of spinel ferrite nano particles, that are synthesized by an environmentally benign method of auto combustion, are characterized through XRD, TEM, RAMAN spectroscopy. Diffuse Reflectance Spectroscopy (DRS) is done to understand the nickel substitution effect on the optical properties of cobalt ferrite nano particles. Thermo magnetic studies using SQUID in the temperature range 5 K to 400 K and room temperature (300 K) VSM studies are performed on these samples. Fields of 0Oe (no applied field: ZF), 1 kOe (for ZFC and FC curves), 5 kOe (0.5 T), 50 kOe (5T) (for M-H loop study) are used to study the magnetic behavior of these nano particles. The XRD,TEM analysis suggest 40 nm crystallites that show changes in the cation distribution and phase changes in the spinel structure with nickel substitution. Raman micrographs support phase purity changes and cation redistributions with nickel substitution. Diffuse reflectance study on powder samples suggests two band gap values for nickel rich compounds. The Magnetic study of these sample nano particles show varied magnetic properties from that of hard magnetic, positive multi axial anisotropy and single-magnetic-domain structures at 5 K temperature to soft magnetic core shell like structures at 300 K temperature. Nickel substitution effect is non monotonous. Blocking temperature of all the samples is found to be higher than the values suggested in the literature.

Structural, Magnetic and Microwave Properties of Nanocrystalline Ni-Co-Gd Ferrites

Science.gov (United States)

Nikzad, Alireza; Parvizi, Roghaieh; Rezaei, Ghasem; Vaseghi, Behrooz; Khordad, Reza

2018-02-01

A series of Co- and Gd-substituted NiFe2O4 ferrite nanoparticles with the formula Ni1- x Co x Fe2- y Gd y O4 (where x = 0.0-1.0 and y = 0.0-0.1) have been successfully synthesized using a hydrothermal method. X-ray diffraction and field emission scanning electron microscopy results indicated that a highly crystallized spherical ferrite nanoparticle structure was obtained along with an increase in the lattice parameters. Compositional analysis of the prepared nanoferrite powders has been carried out using energy-dispersive x-ray (EDX) spectra. The EDX analysis reveals the presence of Ni, Co, Gd and Fe elements in the specimens. Magnetization and the coercive field improved dramatically with an increase in the amount of cobalt and gadolinium added, attributed to the redistribution of cations in the spinel nanoferrite structure. Saturation magnetization and coercivity values up to 99 emu/g and 918 Oe, respectively, were measured using a vibration sample magnetometer at room temperature. Comparative microwave absorption experiments demonstrated that the reflection loss (RL) properties enhanced with increasing substitution of cations in the Ni-ferrite spinel structure for an absorber thickness of 1.8 mm. A maximum RL of - 26.7 dB was obtained for substituted Ni-Co-Gd nanoferrite with x = 1.0 and y = 0.1 at a frequency of 9.4 GHz with a bandwidth of 3.6 GHz (RL ≤ - 10 dB). Experimental results revealed that the synthesized nanoparticles possessed great potential in microwave absorption applications.

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.

Deposition of Lanthanum Strontium Cobalt Ferrite (LSCF) Using Suspension Plasma Spraying for Oxygen Transport Membrane Applications

Science.gov (United States)

Fan, E. S. C.; Kesler, O.

2015-08-01

Suspension plasma spray deposition was utilized to fabricate dense lanthanum strontium cobalt ferrite oxygen separation membranes (OSMs) on porous metal substrates for mechanical support. The as-sprayed membranes had negligible and/or reversible material decomposition. At the longer stand-off distance (80 mm), smooth and dense membranes could be manufactured using a plasma with power below approximately 81 kW. Moreover, a membrane of 55 μm was observed to have very low gas leakage rates desirable for OSM applications. This thickness could potentially be decreased further to improve oxygen diffusion by using metal substrates with finer surface pores.

Gd{sup 3+} doped Mn-Zn soft ferrite nanoparticles: Superparamagnetism and its correlation with other physical properties

Energy Technology Data Exchange (ETDEWEB)

Thakur, Prashant; Sharma, Rohit; Sharma, Vineet; Barman, P.B. [Department of Physics & Materials Science, Jaypee University of Information Technology, Waknaghat, Solan, Himachal Pradesh 173234 (India); Kumar, Manoj [Department of Physics & Materials Science, Jaypee Institute of Information Technology, Noida 201307 (India); Barman, Dipto [Gwangju Institute of Science & Technology, Gwangju (Korea, Republic of); Department of Computer Science & Engineering, Jaypee University of Information Technology, Waknaghat, Solan, Himachap Pradesh 173234 (India); Katyal, S.C. [Department of Physics & Materials Science, Jaypee Institute of Information Technology, Noida 201307 (India); Sharma, Pankaj, E-mail: pankaj.sharma@juit.ac.in [Department of Physics & Materials Science, Jaypee University of Information Technology, Waknaghat, Solan, Himachal Pradesh 173234 (India)

2017-06-15

Highlights: • Superparamagnetic nanoparticles of Gd doped Mn-Zn spinel ferrites synthesized by co-precipitation. • XRD and FTIR studies justify the formation of cubical spinel structure. • Maximum saturation magnetization and magnetic moment at x = 0.025. • PL spectra shows blue shift for x = 0.025, 0.075 and may be attributed to quantum confinement. - Abstract: 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 Mn{sub 0.5}Zn{sub 0.5}Gd{sub x}Fe{sub 2-x}O{sub 4} (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 Gd{sup 3+} 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.

Cobalt nanoparticles as reusable catalysts for reduction of 4 ...

Indian Academy of Sciences (India)

33

active and ordered structures of cobalt nanoparticles. The air stable ... same surfactant was found to reduce p-nitrophenol but lose their catalytic efficiency after recovery. Based on chemical and ... industrial sources.11-13 The US Environmental Protection Agency has reported nitrophenols as one of the most hazardous and ...

Encapsulation of cobalt nanoparticles in cross-linked-polymer cages

Energy Technology Data Exchange (ETDEWEB)

Hatamie, Shadie [Department of Electronic-Science, Fergusson College, Pune 411 004 (India); Dhole, S.D. [Department of Physics, University of Pune, Pune 411 007 (India); Ding, J. [Department of Materials Science and Engineering, National University of Singapore, 7, Engineering Drive 1, Singapore 117574 (Singapore); Kale, S.N. [Department of Electronic-Science, Fergusson College, Pune 411 004 (India)], E-mail: sangeetakale2004@gmail.com

2009-07-15

Nanoparticles embedded in polymeric cages give rise to interesting applications ranging from nanocatalysis to drug-delivery systems. In this context, we report on synthesis of cobalt (Co) nanoparticles trapped in polyvinyl alcohol (PVA) matrix to yield self-supporting magnetic films in PVA slime. A 20 nm, Co formed in FCC geometry encapsulated with a weak citrate coat when caged in PVA matrix exhibited persistence of magnetism and good radio-frequency response. Cross-linking of PVA chains to form cage-like structures to arrest Co nanoparticles therein, is believed to be the reason for oxide-free nature of Co, promising applications in biomedicine as well as in radio-frequency shielding.

Synthesis, characterization and adsorption capability for Congo red of CoFe{sub 2}O{sub 4} ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Ding, Zui [State Key Laboratory of Chemical Resource Engineering and School of Science, Beijing University of Chemical Technology, Beijing 100029 (China); Beijing Key Laboratory of Environmentally Harmful Chemical Analysis, Beijing University of Chemical Technology, Beijing 100029 (China); Wang, Wei, E-mail: wangwei@mail.buct.edu.cn [State Key Laboratory of Chemical Resource Engineering and School of Science, Beijing University of Chemical Technology, Beijing 100029 (China); Beijing Key Laboratory of Environmentally Harmful Chemical Analysis, Beijing University of Chemical Technology, Beijing 100029 (China); Zhang, Yajun [Institute of Plastics Machinery and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Li, Feng [State Key Laboratory of Chemical Resource Engineering and School of Science, Beijing University of Chemical Technology, Beijing 100029 (China); Liu, J. Ping [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States)

2015-08-15

Highlights: • CoFe{sub 2}O{sub 4} ferrite nanoparticles are synthesized by an ethanol-assisted hydrothermal method. • Suitable amount of ethanol can reduce the particle size and increase BET surface area. • The introduction of ethanol leads to the cation redistribution. • Using ethanol/water mixed solution greatly enhances their adsorption capacity for CR dyes. - Abstract: CoFe{sub 2}O{sub 4} ferrite nanoparticles are synthesized by an ethanol-assisted hydrothermal method, where the ethanol is mixed with water as the solution. In this synthesis, a rapid mixing of reducible metal cations with reducing agent and a simultaneous reduction process take place in a colloid mill. Synthesized ferrite samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and Raman spectroscopy. XRD patterns reveal the formation of CoFe{sub 2}O{sub 4} ferrites with single spinel phase. SEM and TEM images show that the as-synthesized samples are with narrow size distribution. Raman spectroscopy studies clearly indicate the cation distribution in nanosized particles. Here, it is worthy to note that, with increasing ethanol content in ethanol–water mixed solution, an obvious superparamagnetic behavior of as-synthesized nanoparticles at room temperature is observed. The adsorption capability of the as-synthesized ferrite nanoparticles for Congo Red (CR) is examined. Enhancement of adsorption capability for CR with adding ethanol as the mixing solution is shown. The adsorption mechanism is discussed. This investigation reveals that the composition of ethanol/water mixed solution has great effects on the microstructure and magnetic properties as well as adsorption capacity of Congo Red (CR) dye of the as-synthesized CoFe{sub 2}O{sub 4} ferrite samples.

Hydrothermal synthesis, characterization, and magneticproperties of cobalt chromite nanoparticles

Czech Academy of Sciences Publication Activity Database

Zákutná, Dominika; Repko, A.; Matulková, I.; Nižňanský, Daniel; Ardu, A.; Cannas, C.; Mantlíková, Alice; Vejpravová, Jana

2014-01-01

Roč. 16, č. 2 (2014), 1-14 ISSN 1388-0764 R&D Projects: GA ČR GAP108/10/1250 Institutional support: RVO:68378271 ; RVO:61388980 Keywords : cobalt chromite * hydrothermal method * nanoparticles * size effect * multiferroic materials Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.184, year: 2014

An Efficient and Recyclable Nanoparticle-Supported Cobalt Catalyst for Quinoxaline Synthesis

Directory of Open Access Journals (Sweden)

Fatemeh Rajabi

2015-11-01

Full Text Available The syntheses of quinoxalines derived from 1,2-diamine and 1,2-dicarbonyl compounds under mild reaction conditions was carried out using a nanoparticle-supported cobalt catalyst. The supported nanocatalyst exhibited excellent activity and stability and it could be reused for at least ten times without any loss of activity. No cobalt contamination could be detected in the products by AAS measurements, pointing to the excellent activity and stability of the Co nanomaterial.

Dynamic magnetoelectric effects in bulk and layered composites of cobalt zinc ferrite and lead zirconate titanate

Energy Technology Data Exchange (ETDEWEB)

Srinivasan, G.; Hayes, R.; DeVreugd, C.P. [Oakland University, Physics Department, Rochester, MI (United States); Laletsin, V.M.; Paddubnaya, N. [National Academy of Sciences, Institute of Technical Acoustics, Vitebsk (Belarus)

2005-02-01

Low-frequency magnetoelectric (ME) coupling is investigated in bulk samples and multilayers of cobalt zinc ferrite, Co{sub 1-x}Zn{sub x}Fe{sub 2}O{sub 4} (x=0-0.6), and lead zirconate titanate. In bulk samples, the transverse and longitudinal couplings are weak and of equal magnitude. A substantial strengthening of ME interactions is evident in layered structures, with the ME voltage coefficient a factor of 10-30 higher than in bulk samples. Important findings of our studies of layered composites are as follows. (i) The transverse coupling is stronger than the longitudinal coupling. (ii) The strength of ME interactions is dependent on Zn substitution, with a maximum for x=0.4. (iii) A weak coupling exists at the ferromagnetic-piezoelectric interface, as revealed by an analysis of the volume and static magnetic field dependence of ME voltage coefficients. (iv) The interface coupling k increases with Zn substitution and the k versus x profile shows a maximum centered at x=0.4. (v) The Zn-assisted enhancement can be attributed to efficient magneto-mechanical coupling in the ferrite. (orig.)

Synthesis and structural characterization of magnetic cadmium sulfide-cobalt ferrite nanocomposite, and study of its activity for dyes degradation under ultrasound

Science.gov (United States)

Farhadi, Saeed; Siadatnasab, Firouzeh

2016-11-01

Cadmium sulfide-cobalt ferrite (CdS/CFO) nanocomposite was easily synthesized by one-step hydrothermal decomposition of cadmium diethyldithiocarbamate complex on the CoFe2O4 nanoparticles at 200 °C. Spectroscopic techniques of powder X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), UV-visible spectroscopy, field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET), and magnetic measurements were applied for characterizing the structure and morphology of the product. The results of FT-IR, XRD and EDX indicated that the CdS/CFO was highly pure. SEM and TEM results revealed that the CdS/CFO nanocomposite was formed from nearly uniform and sphere-like nanoparticles with the size of approximately 20 nm. The UV-vis absorption spectrum of the CdS/CFO nanocomposite showed the band gap of 2.21 eV, which made it suitable for sono-/photo catalytic purposes. By using the obtained CdS/CFO nanocomposite, an ultrasound-assisted advanced oxidation process (AOP) has been developed for catalytic degradation of methylene blue (MB), Rhodamine B (RhB), and methyl orange (MO)) in the presence of H2O2 as a green oxidant. CdS/CFO nanocomposite exhibited excellent sonocatalytic activity, so that, dyes were completely degraded in less than 10 min. The influences of crucial factors such as the H2O2 amount and catalyst dosage on the degradation efficiency were evaluated. The as-prepared CdS/CFO nanocomposite exhibited higher catalytic activity than pure CdS nanoparticles. Moreover, the magnetic property of CoFe2O4 made the nanocomposite recyclable.

Structure of Oxide Nanoparticles in Fe-16Cr MA/ODS Ferritic Steel

Energy Technology Data Exchange (ETDEWEB)

Hsiung, L; Fluss, M; Kimura, A

2010-04-06

Oxide nanoparticles in Fe-16Cr ODS ferritic steel fabricated by mechanical alloying (MA) method have been examined using high-resolution transmission electron microscopy (HRTEM) techniques. A partial crystallization of oxide nanoparticles was frequently observed in as-fabricated ODS steel. The crystal structure of crystalline oxide particles is identified to be mainly Y{sub 4}Al{sub 2}O{sub 9} (YAM) with a monoclinic structure. Large nanoparticles with a diameter larger than 20 nm tend to be incoherent and have a nearly spherical shape, whereas small nanoparticles with a diameter smaller than 10 nm tend to be coherent or semi-coherent and have faceted boundaries. The oxide nanoparticles become fully crystallized after prolonged annealing at 900 C. These results lead us to propose a three-stage formation mechanism of oxide nanoparticles in MA/ODS steels.

Structural, optical, Induced ferromagnetism and anti-ferromagnetism in SnO2 nanoparticles by varying cobalt concentration

International Nuclear Information System (INIS)

Ali, Atif; Sarfraz, A.K.; Ali, Kashif; Mumtaz, A.

2015-01-01

The SnO 2 nanoparticles were prepared with different cobalt concentrations (0.0%, 0.5%, 1%, 3% and 4%) by chemical co-precipitation method. The NH 4 OH was used as precipitating agent; the pH value, reaction time and reaction temperature were optimized during synthesis. The x-ray diffraction (XRD) pattern reveals the formation of single phase tetragonal structure of undoped and cobalt doped SnO 2 nanoparticles which lies in the range of 19–22 nm calculated by De-Bye Scherrer's formula. The optical properties were studied by measuring the reflectance spectroscopy which shows that band gap energy decreases with increase in cobalt concentration. The magnetic characterization was performed by Quantum Design Physical property measurement system (PPMS). Interestingly magnetic measurements show that ferromagnetism in a Co doped SnO 2 becomes visible for x=0.5% and diminishes with further increasing of cobalt concentration. - Highlights: • SnO 2 nanoparticles were prepared with different cobalt concentrations (0.0 % 0.5%, 1%, 3% and 4%) by the chemical co-precipitation method. • Structure was confirmed through x-ray diffraction (XRD) analysis. • The optical properties were studied by measuring the reflectance spectroscopy. • The magnetic characterization was performed

Synthesis and magnetic properties of cobalt-iron/cobalt-ferrite soft/hard magnetic core/shell nanowires

Science.gov (United States)

Leandro Londoño-Calderón, César; Moscoso-Londoño, Oscar; Muraca, Diego; Arzuza, Luis; Carvalho, Peterson; Pirota, Kleber Roberto; Knobel, Marcelo; Pampillo, Laura Gabriela; Martínez-García, Ricardo

2017-06-01

A straightforward method for the synthesis of CoFe2.7/CoFe2O4 core/shell nanowires is described. The proposed method starts with a conventional pulsed electrodeposition procedure on alumina nanoporous template. The obtained CoFe2.7 nanowires are released from the template and allowed to oxidize at room conditions over several weeks. The effects of partial oxidation on the structural and magnetic properties were studied by x-ray spectrometry, magnetometry, and scanning and transmission electron microscopy. The results indicate that the final nanowires are composed of 5 nm iron-cobalt alloy nanoparticles. Releasing the nanowires at room conditions promoted surface oxidation of the nanoparticles and created a CoFe2O4 shell spinel-like structure. The shell avoids internal oxidation and promotes the formation of bi-magnetic soft/hard magnetic core/shell nanowires. The magnetic properties of both the initial single-phase CoFe2.7 nanowires and the final core/shell nanowires, reveal that the changes in the properties from the array are due to the oxidation more than effects associated with released processes (disorder and agglomeration).

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.

Small-angle neutron scattering investigations of Co-doped iron oxide nanoparticles. Preliminary results

Science.gov (United States)

Creanga, Dorina; Balasoiu, Maria; Soloviov, Dmitro; Balasoiu-Gaina, Alexandra-Maria; Puscasu, Emil; Lupu, Nicoleta; Stan, Cristina

2018-03-01

Preliminary small-angle neutron scattering investigations on aqueous suspensions of several cobalt doped ferrites (CoxFe3-xO4, x=0; 0.5; 1) nanoparticles prepared by chemical co-precipitation method, are reported. The measurements were accomplished at the YuMO instrument in function at the IBR-2 reactor. Results of intermediary data treatment are presented and discussed.

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

Energy Technology Data Exchange (ETDEWEB)

El-Sayed, H.M. [Physics Department, Faculty of Science, Ain Shams University, Cairo (Egypt); Ali, I.A.; Azzam, A. [Nuclear Physics Department, Nuclear Research Center, Atomic Energy Authority (Egypt); Sattar, A.A. [Physics Department, Faculty of Science, Ain Shams University, Cairo (Egypt)

2017-02-15

Nanoparticle ferrite with chemical formula Mg{sub (1−x)}Zn{sub x}Fe{sub 2}O{sub 4} (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. - Highlights: • Synthesis of Mg-Zn nanoparticle ferrite by sol-gel technique. • Methods of dead layer thickness calculation. • Magnetic behaviour explanation. • Relation between the Specific Absorption Rate, dead layer thickness and particle size.

Reaction pathway towards formation of cobalt single chain magnets and nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Balaji, G.; Desilva, Rohini M.; Palshin, V. [Center for Advanced Microstructures and Devices, Louisiana State University, 6980 Jefferson Highway, Baton Rouge, LA 70806 (United States); Desilva, N. [Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803 (United States); Palmer, G. [Department of Biochemistry and Cell Biology, Rice University, MS 140, 6100 Main street, Houston, TX 77251 (United States); Kumar, Challa S.S.R., E-mail: ckumar1@lsu.ed [Center for Advanced Microstructures and Devices, Louisiana State University, 6980 Jefferson Highway, Baton Rouge, LA 70806 (United States)

2010-03-15

With the advent of molecular magnets the quest for suitable high density magnetic storage materials has fuelled further research in this area. Here in this report, we present a detailed mechanistic investigation of thermal decomposition of cyclopentadienyl cobalt [CoCp(CO){sub 2}] precursor where Cp is the cyclopentadienyl moiety. The reaction revealed the formation of cobalt nanoparticles (Co-NPs) through an isolable reaction intermediate characterized as a Single Chain Magnet (SCM), [Co(Cp){sub 2}]{sub 2}CoCl{sub 4} (1). The SQUID magnetic measurements showed the presence of very strong antiferromagnetic interactions between Co{sup 2+} ions. The zero-field cooled (ZFC) and field cooled (FC) magnetization curves branch out below 5 K and there is evidence for frequency dependent complex susceptibility along with a maximum observed around 2.5 K. The optical studies indicated that the Co{sup 2+} d-d transition is influenced by the polarity of the solvents. The cobalt nanoparticles (Co-NPs) were obtained, either directly from 1 or from its precursor. They are spherical in shape with a mean size 15 nm, have fcc crystal structure and were found to be ferromagnetic at room temperature.

The cellular magnetic response and biocompatibility of biogenic zinc- and cobalt-doped magnetite nanoparticles

Science.gov (United States)

Moise, Sandhya; Céspedes, Eva; Soukup, Dalibor; Byrne, James M.; El Haj, Alicia J.; Telling, Neil D.

2017-01-01

The magnetic moment and anisotropy of magnetite nanoparticles can be optimised by doping with transition metal cations, enabling their properties to be tuned for different biomedical applications. In this study, we assessed the suitability of bacterially synthesized zinc- and cobalt-doped magnetite nanoparticles for biomedical applications. To do this we measured cellular viability and activity in primary human bone marrow-derived mesenchymal stem cells and human osteosarcoma-derived cells. Using AC susceptibility we studied doping induced changes in the magnetic response of the nanoparticles both as stable aqueous suspensions and when associated with cells. Our findings show that the magnetic response of the particles was altered after cellular interaction with a reduction in their mobility. In particular, the strongest AC susceptibility signal measured in vitro was from cells containing high-moment zinc-doped particles, whilst no signal was observed in cells containing the high-anisotropy cobalt-doped particles. For both particle types we found that the moderate dopant levels required for optimum magnetic properties did not alter their cytotoxicity or affect osteogenic differentiation of the stem cells. Thus, despite the known cytotoxicity of cobalt and zinc ions, these results suggest that iron oxide nanoparticles can be doped to sufficiently tailor their magnetic properties without compromising cellular biocompatibility.

Synthesis of ferrite nanoparticle by milling process for preparation of single domain magnet

International Nuclear Information System (INIS)

Suryadi; Hasbiyallah; Agus S W; Nurul TR; Budhy Kurniawan

2009-01-01

Study of ferrite nanoparticle synthesis for preparation of single domain magnet by milling of scrap magnet material have been done. Sample preparation were done using disk mill continued with high energy milling (HEM). Some powder were taken after 5, 10 dan 20 hours milling using HEM-E3D. The powder were then characterized using X-Ray Fluorescence (XRF), X-Ray Diffractometer (XRD) and Scanning Electron Microscope (SEM). XRF characterization result, confirmed by XRD analysis result, showed that the sample are of Strontium ferrite phase. Microstructure analysis result showed the occurrence of grain refining process of ferrite particle with increasing of milling time. Particle having size of nanometers successfully obtained, although in unhomogeneous distribution. Magnetic properties characterization result showed the increasing of hysteresis curve area of sample for longer milling time and sintering process. (author)

Oxide nanoparticles in an Al-alloyed oxide dispersion strengthened steel: crystallographic structure and interface with ferrite matrix

DEFF Research Database (Denmark)

Zhang, Zhenbo; Pantleon, Wolfgang

2017-01-01

Oxide nanoparticles are quintessential for ensuring the extraordinary properties of oxide dispersion strengthened (ODS) steels. In this study, the crystallographic structure of oxide nanoparticles, and their interface with the ferritic steel matrix in an Al-alloyed ODS steel, i.e. PM2000, were...

Pulsed electrodeposition of cobalt nanoparticles on copper: influence of the operating parameters on size distribution and morphology

International Nuclear Information System (INIS)

Pagnanelli, Francesca; Altimari, Pietro; Bellagamba, Marco; Granata, Giuseppe; Moscardini, Emanuela; Schiavi, Pier Giorgio; Toro, Luigi

2015-01-01

Cobalt nanoparticles were synthesized by pulsed electrodeposition on copper substrate. Scanning electron microscopy and image analysis were used to determine morphology and particle size distribution of nanoparticle populations obtained in different operating conditions. After preliminary tests, t on and t off were set at 50 and 300 ms respectively to obtain distinct nanoparticles and avoid dendritic structures. Experimental tests were performed according to two partially superimposed factorial designs with two factors at two levels. First factorial design investigated the effect of current density (I = 10 and 50 mA/cm 2 ) and discharged cobalt (Q = 2.5 × 10 −3 and 1.0 × 10 −2 C); second factorial design investigated the effect of cobalt concentration (C 0 = 0.01 and 0.1 M) for the same two levels of Q. For optimized value of t on /t off , square and hexagonal shaped nanoparticles were obtained. Statistical analysis evidenced that, for C 0 = 0.1 mol/L, current density is the most influencing factor on mean size: increasing I from 10 to 50 mA/cm 2 determined a diminution of mean size of 240 nm. For the same cobalt concentration, increasing the deposition time (Q) determined an increase of mean size of 60 nm. Diminishing the initial cobalt concentration from 0.1 to 0.01 mol/L determined an increase of mean size from 10 nm to 36 nm. For C 0 = 0.01 mol/L nanoparticles grow reaching an optimal size (36 nm) and then, increasing the time of deposition, optimal sized subunits tend to aggregate. As for polydispersity of nanoparticles, statistical tests denoted that increasing I determined significant reduction of variance, while increasing the time of deposition determined a significant increase of variance

Highly stable silica-coated manganese ferrite nanoparticles as high-efficacy T2 contrast agents for magnetic resonance imaging

Science.gov (United States)

Ahmad, Ashfaq; Bae, Hongsub; Rhee, Ilsu

2018-05-01

Highly stable silica-coated manganese ferrite nanoparticles were fabricated for application as magnetic resonance imagining (MRI) contrast agents. The manganese ferrite nanoparticles were synthesized using a hydrothermal technique and coated with silica. The particle size was investigated using transmission electron microscopy and was found to be 40-60 nm. The presence of the silica coating on the particle surface was confirmed by Fourier transform infrared spectroscopy. The crystalline structure was investigated by X-ray diffraction, and the particles were revealed to have an inverse spinel structure. Superparamagnetism was confirmed by the magnetic hysteresis curves obtained using a vibrating sample magnetometer. The efficiency of the MRI contrast agents was investigated by using aqueous solutions of the particles in a 4.7 T MRI scanner. The T1 and T2 relaxivities of the particles were 1.42 and 60.65 s-1 mM-1, respectively, in water. The ratio r2/r1 was 48.91, confirming that the silica-coated manganese ferrite nanoparticles were suitable high-efficacy T2 contrast agents.

Synthesis and characterization of cobalt sulfide nanoparticles by sonochemical method

Science.gov (United States)

Muradov, Mustafa B.; Balayeva, Ofeliya O.; Azizov, Abdulsaid A.; Maharramov, Abel M.; Qahramanli, Lala R.; Eyvazova, Goncha M.; Aghamaliyev, Zohrab A.

2018-03-01

Convenient and environmentally friendly synthesis of Co9S8/PVA, CoxSy/EG and CoxSy/3-MPA nanocomposites were carried out in the presence of ultrasonic irradiation by the liquid phase synthesis of the sonochemical method. For the synthesis, cobalt acetate tetrahydrate [Co(CH3COO)2·4H2O] and sodium sulfide (Na2S·9H2O) were used as a cobalt and sulfur precursor, respectively. Polyvinyl alcohol (PVA), ethylene glycol (EG) and 3-mercaptopropionic acid (3-MPA) were used as a capping agent and surfactant. The structural, optical properties and morphology of nanocomposites were characterized using X-ray diffractometer (XRD), Ultraviolet/Visible Spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The optical band gap of Co9S8/PVA is 1.81 eV and for CoxSy/EG is 2.42 eV, where the direct band gap of bulk cobalt sulfide is (0.78-0.9 eV). The wide band gap indicates that synthesised nanocomposites can be used in the fabrication of optical and photonic devices. The growth mechanisms of the Co9S8, CoS2 and Co3S4 nanoparticles were discussed by the reactions. The effects of sonication time and annealing temperature on the properties of the nanoparticles have been studied in detail.

Characterization of a Cobalt-Tungsten Interconnect

DEFF Research Database (Denmark)

Harthøj, Anders; Holt, Tobias; Caspersen, Michael

2012-01-01

is to act both as a diffusion barrier for chromium and provide better protection against high temperature oxidation than a pure cobalt coating. This work presents a characterization of a cobalt-tungsten alloy coating electrodeposited on the ferritic steel Crofer 22 H which subsequently was oxidized in air......A ferritic steel interconnect for a solid oxide fuel cell must be coated in order to prevent chromium evaporation from the steel substrate. The Technical University of Denmark and Topsoe Fuel Cell have developed an interconnect coating based on a cobalt-tungsten alloy. The purpose of the coating...... for 300 h at 800 °C. The coating was characterized with Glow Discharge Optical Spectroscopy (GDOES), Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). The oxidation properties were evaluated by measuring weight change of coated samples of Crofer 22 H and Crofer 22 APU as a function...

Effect of annealing on properties of Mg doped Zn-ferrite nanoparticles

Directory of Open Access Journals (Sweden)

K. Nadeem

2015-04-01

Full Text Available A comparison of structural and magnetic properties of as-prepared and annealed (900 °C Mg doped Zn ferrite nanoparticles (Zn1−xMgxFe2O4, with x=0, 0.1, 0.2, 0.3, 0.4 and 0.5 is presented. X-ray diffraction (XRD studies confirmed the cubic spinel structure for both the as-prepared and annealed nanoparticles. The average crystallite size and lattice parameter were increased by annealing. Scanning electron microscopy (SEM images also showed that the average particle size increased after annealing. Fourier transform infrared spectroscopy (FTIR also confirmed the spinel structure for both series of nanoparticles. For both annealed and as-prepared nanoparticles, the O–Mtet.–O vibrational band shifts towards higher wave numbers with increased Mg concentration due to cationic rearrangement on the lattice sites. Magnetization studies revealed an anomalous decreasing magnetization for the annealed nanoparticles which is also ascribed to cationic rearrangement on the lattice sites after annealing. The measurement of coercivity showed a decreasing trend by annealing due to the increased nanoparticle size and better crystallinity.

Structural, morphological and dielectric studies of zirconium substituted CoFe2O4 nanoparticles

Directory of Open Access Journals (Sweden)

S. Anand

2017-12-01

Full Text Available In this work, the influence of zirconium substitution in cubic spinel nanocrystalline CoFe2O4 on the structural, morphological and dielectric properties are reported. Zirconium substituted cobalt ferrite Co1-xZrxFe2O4 (x = 0.7 nanoparticles were synthesized by sol-gel route. The structural and morphological investigations using powder X-ray diffraction and high resolution scanning electron microscope (HRSEM analysis are reported. Scherrer plot, Williamson–Hall analysis and Size-strain plot method were used to calculate the crystallite size and lattice strain of the samples. High purity chemical composition of the sample was confirmed by energy dispersive X-ray analysis. The atoms vibration modes of as synthesized nanoparticles were recorded using Fourier transform infrared (FTIR spectrometer in the range of 4000–400 cm-1. The temperature-dependent dielectric properties of zirconium substituted cobalt ferrite nanoparticles were also carried out. Relative dielectric permittivity, loss tangent and AC conductivity were measured in the frequency range 50 Hz to 5 MHz at temperatures between 323 K and 473 K. The dielectric constant and dielectric loss values of the sample decreased with increasing in the frequency of the applied signal.

Spin canting phenomenon in cadmium doped cobalt ferrites ...

Indian Academy of Sciences (India)

2016-08-26

Aug 26, 2016 ... Abstract. Synthesis of non-collinear (spin canted) ferrites having the formula, CoCdFe2−O4 ( = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0), has been carried out using the sol–gel auto combustion method. The ferrite samples show an interesting magnetic transition from Neel to Yafet–Kittel configuration, as the Cd2+ ...

In situ TEM observation of the Boudouard reaction: Multi-layered graphene formation from CO on cobalt nanoparticles at atmospheric pressure

NARCIS (Netherlands)

Bremmer, G.M.; Zacharaki, E.; Sjåstad, A.O.; Navarro, V.; Frenken, J.W.M.; Kooyman, P.J.

2017-01-01

Using a MEMS nanoreactor in combination with a specially designed in situ Transmission Electron Microscope (TEM) holder and gas supply system, we imaged the formation of multiple layers of graphene encapsulating a cobalt nanoparticle, at 1 bar CO:N2 (1:1) and 500 °C. The cobalt nanoparticle was

Effects of Mn partitioning on nanoscale precipitation and mechanical properties of ferritic steels strengthened by NiAl nanoparticles

International Nuclear Information System (INIS)

Jiao, Z.B.; Luan, J.H.; Miller, M.K.; Yu, C.Y.; Liu, C.T.

2015-01-01

The critical role of Mn partitioning in the formation of ordered NiAl nanoparticles in ferritic steels has been examined through a combination of atom probe tomography (APT) and thermodynamic and first-principles calculations. Our APT study reveals that Mn partitions to the NiAl nanoparticles, and dramatically increases the particle number density by more than an order of magnitude, leading to a threefold enhancement in strengthening. Atomistic structural analyses reveal that Mn is energetically favored to partition to the NiAl nanoparticles by preferentially occupying the Al sublattice, which not only increases the driving force, but also reduces the strain energy for nucleation, thereby significantly decreasing the critical energy for formation of the NiAl nanoparticles in ferritic steels. In addition, the effects of Mn on the precipitation strengthening mechanisms were quantitatively evaluated in terms of chemical strengthening, coherency strengthening, modulus strengthening and order strengthening

X-ray imaging and spectroscopy of individual cobalt nanoparticles using photoemission electron microscopy

International Nuclear Information System (INIS)

Fraile Rodriguez, A.; Nolting, F.; Bansmann, J.; Kleibert, A.; Heyderman, L.J.

2007-01-01

Photoemission electron microscopy (PEEM) was employed for X-ray imaging and absorption spectroscopy of individual cobalt nanoparticles as small as 8 nm grown using an arc ion cluster source. Using lithographic markers on the samples we were able to identify the same particles with PEEM and scanning electron microscopy. Significant variations in the shape of the X-ray absorption spectra between different cobalt particles were detected. Furthermore, our data suggest that distinctive spectral information about the individual particles, such as the quenching of oxide-related features and changes in the cobalt L 3 -edge intensity, cancel out and cannot be detected in the measurement over an ensemble of particles

Synthesis and Magnetic Properties of Nearly Monodisperse CoFe2O4Nanoparticles Through a Simple Hydrothermal Condition

Directory of Open Access Journals (Sweden)

Li Xing-Hua

2010-01-01

Full Text Available Abstract Nearly monodisperse cobalt ferrite (CoFe2O4 nanoparticles without any size-selection process have been prepared through an alluring method in an oleylamine/ethanol/water system. Well-defined nanospheres with an average size of 5.5 nm have been synthesized using metal chloride as the law materials and oleic amine as the capping agent, through a general liquid–solid-solution (LSS process. Magnetic measurement indicates that the particles exhibit a very high coercivity at 10 K and perform superparamagnetism at room temperature which is further illuminated by ZFC/FC curves. These superparamagnetic cobalt ferrite nanomaterials are considered to have potential application in the fields of biomedicine. The synthesis method is possible to be a general approach for the preparation of other pure binary and ternary compounds.

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.

HRTEM Study of the Role of Nanoparticles in ODS Ferritic Steel

Energy Technology Data Exchange (ETDEWEB)

Hsiung, L; Tumey, S; Fluss, M; Serruys, Y; Willaime, F

2011-08-30

Structures of nanoparticles and their role in dual-ion irradiated Fe-16Cr-4.5Al-0.3Ti-2W-0.37Y{sub 2}O{sub 3} (K3) ODS ferritic steel produced by mechanical alloying (MA) were studied using high-resolution transmission electron microscopy (HRTEM) techniques. The observation of Y{sub 4}Al{sub 2}O{sub 9} complex-oxide nanoparticles in the ODS steel imply that decomposition of Y{sub 2}O{sub 3} in association with internal oxidation of Al occurred during mechanical alloying. HRTEM observations of crystalline and partially crystalline nanoparticles larger than {approx}2 nm and amorphous cluster-domains smaller than {approx}2 nm provide an insight into the formation mechanism of nanoparticles/clusters in MA/ODS steels, which we believe involves solid-state amorphization and re-crystallization. The role of nanoparticles/clusters in suppressing radiation-induced swelling is revealed through TEM examinations of cavity distributions in (Fe + He) dual-ion irradiated K3-ODS steel. HRTEM observations of helium-filled cavities (helium bubbles) preferably trapped at nanoparticle/clusters in dual-ion irradiated K3-ODS are presented.

Chitosan doped with nanoparticles of copper, nickel and cobalt.

Science.gov (United States)

Cárdenas-Triviño, Galo; Elgueta, Carolina; Vergara, Luis; Ojeda, Javier; Valenzuela, Ariel; Cruzat, Christian

2017-11-01

Metal colloids in 2 propanol using nanoparticles (NPs) of copper, nickel and cobalt were prepared by Chemical Liquid Deposition (CLD) method. The resulting colloidal dispersions were characterized by Transmission Electron Microscopy (TEM). The colloids were supported in chitosan. Then, microbiological assays were performed using E. coli and S. aureus in order to determine the bactericide/bacteriostatic activity of nanoparticles (NPs) trapped or chelated with chitosan. Finally, the toxicity of the metal colloids Cu, Ni and Co was tested. Bio-assays were conducted in three different animal species. First of all on earth warms (Eisenia foetida) to evaluate the toxicity and the biocompatibility of chitosan in lactic acid (1% and 0.5%). Secondly bio-assay done in fishes (rainbow trout), the liver toxicity of NPs in vivo was evaluated. Finally, a bio-assay was conducted in Sprange-Dawley rats of 100g weight, which were injected intraperitoneally with different solutions of chitosan metal colloids. Then, the minimum and maximum concentration were determined for copper, nickel and cobalt. The purpose of the use of chitosan was acting as a carrier for some magnetic NPs, which toxicity would allow to obtain new polymeric materials with potential applications as magnet future drugs carrier. Copyright © 2017 Elsevier B.V. All rights reserved.

Heat generation in agglomerated ferrite nanoparticles in an alternating magnetic field

International Nuclear Information System (INIS)

Lima, E Jr; De Biasi, E; Mansilla, M Vasquez; Saleta, M E; Granada, M; Troiani, H E; Zysler, R D; Effenberger, F B; Rossi, L M; Rechenberg, H R

2013-01-01

The role of agglomeration and magnetic interparticle interactions in heat generation of magnetic ferrofluids in an ac magnetic field is still unclear, with apparent discrepancy between the results presented in the literature. In this work, we measured the heat generating capability of agglomerated ferrite nanoparticles in a non-invasive ac magnetic field with f = 100 kHz and H 0 = 13 kA m -1 . The nanoparticles were morphologically and magnetically characterized, and the specific absorption rate (SAR) for our ac magnetic field presents a clear dependence on the diameter of the nanoparticles, with a maximum SAR = 48 W g -1 for 15 nm. Our agglomerated nanoparticles have large hydrodynamic diameters, thus the mechanical relaxation can be neglected as a heat generation mechanism. Therefore, we present a model that simulates the SAR dependence of the agglomerated samples on the diameter of the nanoparticles based on the hysteresis losses that is valid for the non-linear region (with H 0 comparable to the anisotropy field). Our model takes into account the magnetic interactions among the nanoparticles in the agglomerate. For comparison, we also measured the SAR of non-agglomerated nanoparticles in a similar diameter range, in which Néel and Brown relaxations dominate the heat generation.

Ferromagnetic resonance parameters of ball-milled Ni-Zn ferrite nanoparticles

International Nuclear Information System (INIS)

Rao, B. Parvatheeswara; Caltun, Ovidiu; Dumitru, Ioan; Spinu, Leonard

2006-01-01

Ferrite nanoparticles of the size about 6 nm have been made by using high-energy ball mill on the sintered pellets of the system Ni 0.65 Zn 0.375 In x Ti 0.025 Fe 1.95- x O 4 . XRD, VSM and FMR techniques were used for structural and magnetic characterizations of the samples. The magnetic characteristics of indium-doped samples are compared with those for bulk samples. The differences are discussed in terms of the particle size and small-particle magnetism

Cyclodextrin-PEG conjugate-wrapped magnetic ferrite nanoparticles for enhanced drug loading and release

Science.gov (United States)

Enoch, Israel V. M. V.; Ramasamy, Sivaraj; Mohiyuddin, Shanid; Gopinath, Packirisamy; Manoharan, R.

2018-05-01

Magnetic nanoparticles are envisaged to overcome the impediments in the methods of targeted drug delivery and hence cure cancer effectively. We report herein, manganese ferrite nanoparticles, coated with β-cyclodextrin-modified polyethylene glycol as a carrier for the drug, camptothecin. The particles are of the size of 100 nm and they show superparamagnetic behaviour. The saturation magnetization does not get diminished on polymer coverage of the nanoparticles. The β-cyclodextrin-polyethylene glycol conjugates are characterized using NMR and mass spectrometric techniques. By coating the magnetic nanoparticles with the cyclodextrin-tethered polymer, the drug-loading capacity is enhanced and the observed release of the drug is slow and sustained. The cell viability of HEK293 and HCT15 cells is evaluated and the cytotoxicity is enhanced when the drug is loaded in the polymer-coated magnetic nanoparticles. The noncovalent-binding based and enhanced drug loading on the nanoparticles and the sustained release make the nanocarrier a promising agent for carrying the payload to the target.

Dispersible cobalt chromite nanoparticles: facile synthesis and size driven collapse of magnetism

Czech Academy of Sciences Publication Activity Database

Zákutná, D.; Matulková, I.; Kentzinger, E.; Medlín, R.; Su, Y.; Nemkovski, K.; Disch, S.; Vejpravová, Jana; Nižňanský, D.

2016-01-01

Roč. 6, č. 109 (2016), s. 107659-107668 ISSN 2046-2069 R&D Projects: GA ČR(CZ) GA15-01953S Institutional support: RVO:68378271 Keywords : cobalt chromite * nanoparticle * multiferoic Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.108, year: 2016

Iron-based soft magnetic composites with Mn-Zn ferrite nanoparticles coating obtained by sol-gel method

Science.gov (United States)

Wu, Shen; Sun, Aizhi; Xu, Wenhuan; Zhang, Qian; Zhai, Fuqiang; Logan, Philip; Volinsky, Alex A.

2012-11-01

This paper focuses on iron-based soft magnetic composites which were synthesized by utilizing Mn-Zn ferrite nanoparticles to coat iron powder. The nanocrystalline iron powders, with an average particle diameter of 20 nm, were obtained via the sol-gel method. Scanning electron microscopy, energy dispersive X-ray spectroscopy and distribution maps show that the iron particle surface is covered with a thin layer of Mn-Zn ferrites. Mn-Zn ferrite uniformly coated the surface of the powder particles, resulting in a reduced imaginary permeability, increased electrical resistivity and a higher operating frequency of the synthesized magnets. Mn-Zn ferrite coated samples have higher permeability and lower magnetic loss when compared with the non-magnetic epoxy resin coated compacts. The real part of permeability increases by 33.5% when compared with the epoxy resin coated samples at 10 kHz. The effects of heat treatment temperature on crystalline phase formation and on the magnetic properties of the Mn-Zn ferrite were investigated via X-ray diffraction and a vibrating sample magnetometer. Ferrites decomposed to FeO and MnO after annealing above 400 °C in nitrogen; thus it is the optimum annealing temperature to attain the desired permeability.

Layer-by-Layer Self-Assembled Ferrite Multilayer Nanofilms for Microwave Absorption

Directory of Open Access Journals (Sweden)

Jiwoong Heo

2015-01-01

Full Text Available We demonstrate a simple method for fabricating multilayer thin films containing ferrite (Co0.5Zn0.5Fe2O4 nanoparticles, using layer-by-layer (LbL self-assembly. These films have microwave absorbing properties for possible radar absorbing and stealth applications. To demonstrate incorporation of inorganic ferrite nanoparticles into an electrostatic-interaction-based LbL self-assembly, we fabricated two types of films: (1 a blended three-component LbL film consisting of a sequential poly(acrylic acid/oleic acid-ferrite blend layer and a poly(allylamine hydrochloride layer and (2 a tetralayer LbL film consisting of sequential poly(diallyldimethylammonium chloride, poly(sodium-4-sulfonate, bPEI-ferrite, and poly(sodium-4-sulfonate layers. We compared surface morphologies, thicknesses, and packing density of the two types of ferrite multilayer film. Ferrite nanoparticles (Co0.5Zn0.5Fe2O4 were prepared via a coprecipitation method from an aqueous precursor solution. The structure and composition of the ferrite nanoparticles were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy, and scanning electron microscopy. X-ray diffraction patterns of ferrite nanoparticles indicated a cubic spinel structure, and energy dispersive X-ray spectroscopy revealed their composition. Thickness growth and surface morphology were measured using a profilometer, atomic force microscope, and scanning electron microscope.

Structural variation study of cobalt nanoparticles synthesized by co-precipitation method using 59Co NMR

Science.gov (United States)

Manjunatha, M.; Kumar, Rajeev; B. M., Siddesh; Sahoo, Balaram; Damle, R.; Ramesh, K. P.

2018-04-01

We have synthesized cobalt nanoparticles using co-precipitation method. Further, the two phases of the cobalt is monitored by varying the synthesis parameters. 59Co NMR and XRD are used as characterization tools to study the phase variation in the cobalt samples. XRD and NMR results show a remarkable correlation in the two samples (Co-1 and Co-2). Co-2 has predominant fcc and hcp phases, whereas, Co-1 has fcc phase with lower amount of hcp. Both the samples show same saturation magnetization (Ms) but there is a remarkable difference in the phase composition. Thus, 59Co NMR appears to be a good tool to identify the phase purity of the ferromagnetic cobalt samples.

Comparative Cytogenetic Study on the Toxicity of Magnetite and Zinc Ferrite Nanoparticles in Sunflower Root Cells

Science.gov (United States)

Foca-nici, Ecaterina; Capraru, Gabriela; Creanga, Dorina

2010-12-01

In this experimental study the authors present their results regarding the cellular division rate and the percentage of chromosomal aberrations in the root meristematic cells of Helianthus annuus cultivated in the presence of different volume fractions of magnetic nanoparticle suspensions, ranging between 20 and 100 microl/l. The aqueous magnetic colloids were prepared from chemically co-precipitated ferrites coated in sodium oleate. Tissue samples from the root meristeme of 2-3 day old germinated seeds were taken to prepare microscope slides following Squash method combined with Fuelgen techniques. Microscope investigation (cytogenetic tests) has resulted in the evaluation of mitotic index and chromosomal aberration index that appeared diminished and respectively increased following the addition of magnetic nanoparticles in the culture medium of the young seedlings. Zinc ferrite toxic influence appeared to be higher than that of magnetite, according to both cytogenetic parameters.

Cobalt oxide polymorph growth on electrostatic self-assembled nanoparticle arrays for dually tunable nano-textures

International Nuclear Information System (INIS)

Bulliard, Xavier; Benayad, Anass; Lee, Kwang-Hee; Choi, Yun-Hyuk; Lee, Jae Cheol; Park, Jong-Jin; Kim, Jong-Min

2011-01-01

We report on a method for surface nano-texturing on a plastic substrate. Nano-objects with a silica nanoparticle core and a textured cobalt oxide crown are created with selectable density on the plastic substrate. The resulting dual morphology is easily tuned over large areas, either by changing the parameters directing nanoparticle deposition through electrostatic self-arrangement for nano-object density control, or the parameter directing cobalt oxide deposition for shape control. The entire process takes place at room temperature, with no chemicals harmful to the plastic substrate. The ready modulation of the dual morphology is used to control the wettability properties of the plastic film, which is covered by nano-objects.

Microwave dielectric properties of nanostructured nickel ferrite

Indian Academy of Sciences (India)

Wintec

Abstract. 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.

Carbon-encapsulated nickel-cobalt alloys nanoparticles fabricated via new post-treatment strategy for hydrogen evolution in alkaline media

Science.gov (United States)

Guo, Hailing; Youliwasi, Nuerguli; Zhao, Lei; Chai, Yongming; Liu, Chenguang

2018-03-01

This paper addresses a new post-treatment strategy for the formation of carbon-encapsulated nickel-cobalt alloys nanoparticles, which is easily controlled the performance of target products via changing precursor composition, calcination conditions (e.g., temperature and atmosphere) and post-treatment condition. Glassy carbon electrode (GCE) modified by the as-obtained carbon-encapsulated mono- and bi-transition metal nanoparticles exhibit excellent electro-catalytic activity for hydrogen production in alkaline water electrolysis. Especially, Ni0.4Co0.6@N-Cs800-b catalyst prepared at 800 °C under an argon flow exhibited the best electrocatalytic performance towards HER. The high HER activity of the Ni0.4Co0.6@N-Cs800-b modified electrode is related to the appropriate nickel-cobalt metal ratio with high crystallinity, complete and homogeneous carbon layers outside of the nickel-cobalt with high conductivity and the synergistic effect of nickel-cobalt alloys that also accelerate electron transfer process.

Ultrafine Cobalt Sulfide Nanoparticles Encapsulated Hierarchical N-doped Carbon Nanotubes for High-performance Lithium Storage

International Nuclear Information System (INIS)

Li, Xiaoyan; Fu, Nianqing; Zou, Jizhao; Zeng, Xierong; Chen, Yuming; Zhou, Limin; Lu, Wei; Huang, Haitao

2017-01-01

Graphical abstract: Ultrafine cobalt sulfide nanoparticles encapsulated in hierarchical N-doped carbon nanotubes show exceptional lithium ion storage as anodes. - Abstract: Nanostructured cobalt sulfide based materials with rational design are attractive for high-performance lithium-ion batteries. In this work, we report a multistep method to synthesize ultrafine cobalt sulfide nanoparticles encapsulated in hierarchical N-doped carbon nanotubes (CoS x @HNCNTs). Co-based zeolitic imidazolate framework (ZIF-67) nanotubes are obtained from the reaction between electrospun polyacrylonitrile/cobalt acetate and 2-methylimidazole, followed by the dissolution of template. Next, a combined calcination and sulfidation process is employed to convert the ZIF-67 nanotubes to CoS x @HNCNTs. Benefited from the compositional and structural features, the as-prepared nanostructured hybrid materials deliver superior lithium storage properties with high capacity of 1200 mAh g −1 at 0.25 A g −1 . More importantly, a remarkable capacity of 1086 mAh g −1 can be maintained after 100 cycles at the current density of 0.5 A g −1 . Even at a high rate of 5 A g −1 , a reversible capacity of 592 mAh g −1 after 1600 cycles can still be achieved.

Effect of annealing on particle size, microstructure and gas sensing properties of Mn substituted CoFe{sub 2}O{sub 4} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Kumar, E. Ranjith, E-mail: ranjueaswar@gmail.com [Department of Physics, Dr. NGP Institute of Technology, Coimbatore 641048, Tamil Nadu (India); Kamzin, A.S. [Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg 194021 (Russian Federation); Janani, K. [Department of Physics, Kongunadu Arts and Science College, Coimbatore, Tamil Nadu (India)

2016-11-01

Microstructure, morphological and gas sensor studies of Mn substituted cobalt ferrite nanoparticles synthesized by a simple evaporation method and auto- combustion method. The influence of heat treatment on phase and particle size of spinel ferrite nanoparticles were determined by X-ray diffraction and Mossbauer spectroscopy. The XRD study reveals that the lattice constant and crystallite size of the samples increases with the increase of annealing temperature. Last one was confirmed by Mossbauer data. The lowest size of particles of MnCoFe{sub 2}O{sub 4} (~3 nm) is obtained by auto combustion method. The spherical shaped nanoparticles are recorded by TEM. Furthermore, conductance response of Mn–Co ferrite nanomaterial was measured by exposing the material to reducing gas like liquefied petroleum gas (LPG) which showed a sensor response of ~0.19 at an optimum operating temperature of 250 °C. - Highlights: • ~3 nm sized particles were prepared by auto combustion method. • Mossbauer study was analyzed for different annealed samples. • The size of the particles increased with increasing annealing temperature.

Magnetic properties and morphology of manganese ferrite nanoparticles in glasses

International Nuclear Information System (INIS)

Edelman, I; Ivanova, O; Ivantsov, I; Velikanov, D; Petrakovskaja, E; Artemenko, A; Curély, J; Kliava, J; Zaikovskiy, V; Stepanov, S

2011-01-01

Static magnetization (SM), magnetic circular dichroism (MCD) and electron magnetic resonance (EMR) studies are reported of borate glasses 22.5 K 2 O-22.5 Al 2 O 3 -55 B 2 O 3 co-doped with iron and manganese oxides. In as-prepared glasses the paramagnetic ions usually are in diluted state; however, if the ratio of the iron and manganese oxides in the charge is 3/2, magnetic nanoparticles are found already in as-prepared glass. After additional thermal treatment all glasses show magnetic behaviour, MCD and EMR due to the presence of magnetic nanoparticles with characteristics close to those of manganese ferrite. By computer simulating the EMR spectra at variable temperatures, their morphological characteristics are deduced: relatively broad size and shape distribution with average diameter of ca. 3-4 nm. The characteristic temperature-dependent shift of the apparent resonance field is explained by a strong temperature dependence of the magnetocrystalline anisotropy in the nanoparticles. The potassium-alumina-borate glasses containing magnetic nanoparticles represent a novel class of materials: t ransparent magnets . Indeed, they remain transparent in a part of visible and near infrared spectral range while showing magnetic and magneto-optical properties characteristic of magnetically ordered materials.

Effect of PVP as a capping agent in single reaction synthesis of nanocomposite soft/hard ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Ahmad, H.A. [Department of Physics, Faculty of Science, Universiti Putra Malaysia, UPM, 43400 Serdang, Selangor (Malaysia); Saiden, N.M., E-mail: nlaily@upm.edu.my [Department of Physics, Faculty of Science, Universiti Putra Malaysia, UPM, 43400 Serdang, Selangor (Malaysia); Saion, E.; Azis, R.S.; Mamat, M.S. [Department of Physics, Faculty of Science, Universiti Putra Malaysia, UPM, 43400 Serdang, Selangor (Malaysia); Hashim, M. [Advanced Material and Nanotechnology Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, UPM, 43400 Serdang, Selangor (Malaysia)

2017-04-15

Nanocomposite magnets consist of soft and hard ferrite phases are known as an exchange spring magnet when they are sufficiently spin exchange coupled. Hard and soft ferrites offer high value of coercivity, H{sub c} and saturation magnetization, M{sub s} respectively. In order to obtain a better permanent magnet, both soft and hard ferrite phases need to be “exchange coupled”. The nanoparticles were prepared by a simple one-pot technique of 80% soft phase and 20% hard phase. This technique involves a single reaction mixture of metal nitrates and aqueous solution of varied amounts of polyvinylpyrrolidone (PVP). The heat treatment applied was at 800 °C for 3 h. The synthesized composites were characterized by Transmission Electron Microscope (TEM), Fourier Transform Infra-red (FT-IR), Energy Dispersive X-Ray (EDX), X-ray diffraction (XRD) and Vibrating sample magnetometer (VSM). The coexistence of two phases, Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and SrFe{sub 12}O{sub 19} were observed by XRD patterns. It also verified by the EDX that no impurities detected. The magnetic properties of nanocomposite ferrites for 0.06 g/ml PVP gives a better properties of H{sub c} 932 G and M{sub s} 39.0 emu/g with average particle size obtained from FESEM was 49.2 nm. The concentration of PVP used gives effect on the magnetic properties of the samples. - Highlights: • Amount of PVP play important roles in controlling the particle size distribution and magnetic properties. • This is a novel technique to produce nanocomposite ferrites effectively. • This study contributes better understanding on magnetic properties in nanoparticle composite magnets.

Observation and manipulation of magnetic domains in sol gel derived thin films of spinel ferrites

Science.gov (United States)

Datar, Ashwini A.; Mathe, Vikas L.

2017-12-01

Thin films of spinel ferrites, namely zinc substituted nickel, cobalt ferrite, and manganese substituted cobalt ferrite, were synthesized using sol-gel derived spin-coating techniques. The films were characterized using x-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy techniques for the analysis of structural, morphological and vibrational band transition properties, which confirm the spinel phase formation of the films. The magnetic force microscopy (MFM) technique was used to observe the magnetic domain structure present in the synthesized films. Further, the films were subjected to an external DC magnetic field of 2 kG to orient the magnetic domains and analyzed using an ex situ MFM technique.

Electromagnetic properties of NiZn ferrite nanoparticles and their polymer composites

Energy Technology Data Exchange (ETDEWEB)

Parsons, P. [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, Aberdeen Proving Ground, Maryland 21005 (United States); Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States); Duncan, K. [U.S. Army, Communications-Electronics Research, Development and Engineering Center, Space and Terrestrial Communications Directorate, Aberdeen Proving Ground, Maryland 21005 (United States); Giri, A. K. [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, Aberdeen Proving Ground, Maryland 21005 (United States); Bowhead Science and Technology, LLC, Belcamp, Maryland 21017 (United States); Xiao, J. Q. [Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States); Karna, S. P., E-mail: shashi.p.karna.civ@mail.mil [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, Aberdeen Proving Ground, Maryland 21005 (United States)

2014-05-07

The magnetic properties of polycrystalline NiZn ferrite nanoparticles synthesized using a polyol-reduction and coprecipitation reaction methods have been investigated. The effects on magnetization of synthesis approach, chemical composition, processing conditions, and on the size of nanoparticles on magnetization have been investigated. The measured room-temperature magnetization for the as-prepared magnetic nanoparticles (MNP) synthesized via polyol-reduction and coprecipitation is 69 Am{sup 2} kg{sup −1} and 14 Am{sup 2} kg{sup −1}, respectively. X-ray diffraction measurements confirm spinel structure of the particles with an estimated grain size of ∼80 nm obtained from the polyol-reduction and 28 nm obtained from these coprecipitation techniques. Upon calcination under atmospheric conditions at different temperatures between 800 °C and 1000 °C, the magnetization, M, of the coprecipitated MNP increases to 76 Am{sup 2} kg{sup −1} with an estimated grain size of 90 nm. The MNP-polymer nanocomposites made from the synthesized MNP in various loading fraction and high density polyethylene exhibit interesting electromagnetic properties. The measured permeability and permittivity of the magnetic nanoparticle-polymer nanocomposites increases with the loading fractions of the magnetic nanoparticles, suggesting control for impedance matching for antenna applications.

Large scale solvothermal synthesis and a strategy to obtain stable Langmuir–Blodgett film of CoFe2O4 nanoparticles

International Nuclear Information System (INIS)

Thampi, Arya; Babu, Keerthi; Verma, Seema

2013-01-01

Highlights: • Large scale, monodisperse CoFe 2 O 4 nanoparticles by solvothermal route. • LB technique to obtain stable film of CoFe 2 O 4 nanoparticles over a large area. • Hydrophobicity of substrate was enhanced utilizing LB films of cadmium arachidate. • P–A isotherm and AFM cross sectional height profile analysis confirms stability. • Large scale organization of nanoparticles for surface pressure higher than 15 mN/m. -- Abstract: Nearly monodisperse oleic acid coated cobalt ferrite nanoparticles were synthesized in large scale by a simple solvothermal method utilizing N-methyl 2-Pyrrolidone (NMP) as a high boiling solvent. The magnetic oxide was further investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer (VSM). Langmuir–Blodgett (LB) technique is discussed to obtain a 2D assembly of oleic acid coated CoFe 2 O 4 nanoparticles over a large area. We describe a method to obtain stable, condensed three layers of cadmium arachidate on a piranha treated glass substrate. The hydrophobic surface thus obtained was subsequently used for forming a stable monolayer of oleic acid stabilized cobalt ferrite nanoparticles at the air–water interface. The stability of the LB films at the air–water interface was studied by pressure–area isotherm curves and atomic force microscopy (AFM) cross sectional height profile analysis. 2D organization of the magnetic nanoparticles at different surface pressures was studied by TEM. Preparation of large area LB films of CoFe 2 O 4 nanoparticles is reported for a surface pressure more than 15 mN/m

Iron-based soft magnetic composites with Mn–Zn ferrite nanoparticles coating obtained by sol–gel method

International Nuclear Information System (INIS)

Wu, Shen; Sun, Aizhi; Xu, Wenhuan; Zhang, Qian; Zhai, Fuqiang; Logan, Philip; Volinsky, Alex A.

2012-01-01

This paper focuses on iron-based soft magnetic composites which were synthesized by utilizing Mn–Zn ferrite nanoparticles to coat iron powder. The nanocrystalline iron powders, with an average particle diameter of 20 nm, were obtained via the sol–gel method. Scanning electron microscopy, energy dispersive X-ray spectroscopy and distribution maps show that the iron particle surface is covered with a thin layer of Mn–Zn ferrites. Mn–Zn ferrite uniformly coated the surface of the powder particles, resulting in a reduced imaginary permeability, increased electrical resistivity and a higher operating frequency of the synthesized magnets. Mn–Zn ferrite coated samples have higher permeability and lower magnetic loss when compared with the non-magnetic epoxy resin coated compacts. The real part of permeability increases by 33.5% when compared with the epoxy resin coated samples at 10 kHz. The effects of heat treatment temperature on crystalline phase formation and on the magnetic properties of the Mn–Zn ferrite were investigated via X-ray diffraction and a vibrating sample magnetometer. Ferrites decomposed to FeO and MnO after annealing above 400 °C in nitrogen; thus it is the optimum annealing temperature to attain the desired permeability. - Highlights: ► Uniformly coated Mn–Zn ferrite powder increased the operating frequency of SMCs. ► Compared with epoxy coated, the permeability of SMCs increased by 33.5% at 10 kHz. ► 400 °C is the optimum annealing temperature to attain the desired permeability.

Structural and DC electrical resistivity, magnetic properties of Co0.5M0.5Fe2O4 (M= Ni, Zn, and Mg) ferrite nanoparticles

Science.gov (United States)

Ramakrishna, A.; Murali, N.; Mammo, Tulu Wegayehu; Samatha, K.; Veeraiah, V.

2018-04-01

Inverse spinel structured nanoparticles of cobalt ferrite partially substituted by divalent cations of Ni, Zn, and Mg have been synthesized through sol-gel auto combustion route. Structural parameters are studied by powder X-ray diffraction at the diffraction angle range of 10-80°; and FT-IR spectroscopy in the wavenumber range of 1600-400 cm-1. Lattice parameters were calculated from the (hkl) values of the diffraction planes and interplanar spacing and found to be in the range of 8.3659-8.4197 Å. The surface morphology and crystalline nature are studied using scanning electron microscopy and also using HRTEM. The magnetic properties are analyzed through vibrating sample magnetometer. High saturation magnetization of 90.12 emu/g has been achieved from Co-Zn sample whereas high coercive force of 883.45 Oe is achieved in Co-Ni sample. A two-probe DC resistivity was measured in temperature ranges of 300-450 K.

Nitrogen-Doped Carbon Encapsulated Nickel/Cobalt Nanoparticle Catalysts for Olefin Migration of Allylarenes

DEFF Research Database (Denmark)

Kramer, Søren; Mielby, Jerrik Jørgen; Buss, Kasper Spanggård

2017-01-01

Olefin migration of allylarenes is typically performed with precious metal-based homogeneous catalysts. In contrast, very limited progress has been made using cheap, earth-abundant base metals as heterogeneous catalysts for these transformations - in spite of the obvious economic and environmental...... advantages. Herein, we report on the use of an easily prepared heterogeneous catalyst material for the migration of olefins, in particular allylarenes. The catalyst material consists of nickel/cobalt alloy nanoparticles encapsulated in nitrogen-doped carbon shells. The encapsulated nanoparticles are stable...

Viscometric characterization of cobalt nanoparticle-based magnetorheological fluids using genetic algorithms

International Nuclear Information System (INIS)

Chaudhuri, Anirban; Wereley, Norman M.; Kotha, Sanjay; Radhakrishnan, Ramachandran; Sudarshan, Tirumalai S.

2005-01-01

The rheological flow curves (shear stress vs. shear rate) of a nanoparticle cobalt-based magnetorheological fluid can be modeled using Bingham-plastic and Herschel-Bulkley constitutive models. Steady-state rheological flow curves were measured using a parallel disk rheometer for constant shear rates as a function of applied magnetic field. Genetic algorithms were used to identify constitutive model parameters from the flow curve data

Magnetic nickel ferrite nanoparticles as highly durable catalysts for catalytic transfer hydrogenation of bio-based aldehydes

DEFF Research Database (Denmark)

He, Jian; Yang, Song; Riisager, Anders

2018-01-01

Magnetic nickel ferrite (NiFe2O4) nanoparticles were exploited as stable and easily separable heterogeneous catalysts for catalytic transfer hydrogenation (CTH) of furfural to furfuryl alcohol with 2-propanol as both the hydrogen source and the solvent providing 94% product yield at 180 degrees C...

Neutron diffraction studies on cobalt substituted BiFeO3

Science.gov (United States)

Ray, J.; Biswal, A. K.; Acharya, S.; Babu, P. D.; Siruguri, V.; Vishwakarma, P. N.

2013-02-01

A dilute concentration of single phase Cobalt substituted Bismuth ferrite, BiFe1-XCoXO3; (x=0, 0.02) is prepared by sol-gel auto combustion method. Room temperature neutron diffraction patterns show no change in the crystal and magnetic structure upon cobalt doping. The calculation of magnetic moments shows 3.848 μB for Fe+ and 2.85 μB for Co3+. The cobalt is found to be in intermediate spin state.

Zinc ferrite nanoparticles as perspective functional materials for applications in casting technologies

Directory of Open Access Journals (Sweden)

A. Kmita

2017-01-01

Full Text Available In this article it discuss on possible application of magnetic oxide nanoparticles, namely non-stoichiometric zinc ferrite nanoparticles as a functionalizing agent in foundry processes. Thermal analysis showed a weight loss of the sample at 1 273 K in an amount of 7,7 %, which is a result of the following processes taking place in different temperature ranges. Upon its thermal treatment Zn0,4Fe2,6O4 decomposes to zinc oxide and iron (III oxide (first stage and next to iron (II,III oxide and oxygen (second stage. The degree of decomposition was expressed as Fe2+ / Fetotal. Mössbauer spectroscopy showed that the over 30 % of Fe3+ present in starting material was reduced to Fe2+.

In situ preparation of cobalt nanoparticles decorated in N-doped carbon nanofibers as excellent electromagnetic wave absorbers.

Science.gov (United States)

Liu, Huihui; Li, Yajing; Yuan, Mengwei; Sun, Genban; Li, Huifeng; Ma, Shulan; Liao, Qingliang; Zhang, Yue

2018-06-11

The electrospinning and annealing methods is applied to prepare cobalt nanoparticles decorated in N-doped carbon nanofibers (Co/N-C NFs) with solid and macroporous structures. In detail, the nanocomposites are synthesized by carbonization of as-electrospun polyacrylonitrile (PAN)/cobalt acetylacetonate nanofibers in an argon atmosphere. The solid Co/N-C NFs has lengths up to dozens of microns with the average diameter of ca. 500 nm and possess abundant cobalt nanoparticles on both the surface and within the fibers, and the cobalt nanoparticles size is about 20 nm. The macroporous Co/N-C NFs possess a hierarchical pore structure, and there are macropores (500 nm) and mesopores (2-50 nm) existed in this material. The saturation magnetization (Ms) and coercivity (Hc) of the solid Co/N-C NFs are 28.4 emu g-1 and 661 Oe, respectively. And those of the macroporous Co/N-C NFs are 23.3 emu g-1 and 580 Oe, respectively. The solid Co/N-C NFs exhibits excellent electromagnetic wave absorbability, a minimum reflection loss (RL) value of -25.7 dB is achieved with a matching thickness of 2 mm for solid Co/N-C NFs when the filler loading is 5 wt%, and the effective bandwidth (BW) (RL≤-10 dB) is 4.3 GHz. Moreover, the effective microwave absorption can be achieved in the whole range of 1-18 GHz by adjusting the thickness of the sample layer and content of the dopant sample.

Large scale solvothermal synthesis and a strategy to obtain stable Langmuir–Blodgett film of CoFe{sub 2}O{sub 4} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Thampi, Arya; Babu, Keerthi; Verma, Seema, E-mail: sa.verma@iiserpune.ac.in

2013-07-05

Highlights: • Large scale, monodisperse CoFe{sub 2}O{sub 4} nanoparticles by solvothermal route. • LB technique to obtain stable film of CoFe{sub 2}O{sub 4} nanoparticles over a large area. • Hydrophobicity of substrate was enhanced utilizing LB films of cadmium arachidate. • P–A isotherm and AFM cross sectional height profile analysis confirms stability. • Large scale organization of nanoparticles for surface pressure higher than 15 mN/m. -- Abstract: Nearly monodisperse oleic acid coated cobalt ferrite nanoparticles were synthesized in large scale by a simple solvothermal method utilizing N-methyl 2-Pyrrolidone (NMP) as a high boiling solvent. The magnetic oxide was further investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer (VSM). Langmuir–Blodgett (LB) technique is discussed to obtain a 2D assembly of oleic acid coated CoFe{sub 2}O{sub 4} nanoparticles over a large area. We describe a method to obtain stable, condensed three layers of cadmium arachidate on a piranha treated glass substrate. The hydrophobic surface thus obtained was subsequently used for forming a stable monolayer of oleic acid stabilized cobalt ferrite nanoparticles at the air–water interface. The stability of the LB films at the air–water interface was studied by pressure–area isotherm curves and atomic force microscopy (AFM) cross sectional height profile analysis. 2D organization of the magnetic nanoparticles at different surface pressures was studied by TEM. Preparation of large area LB films of CoFe{sub 2}O{sub 4} nanoparticles is reported for a surface pressure more than 15 mN/m.

Magnetic liposomes based on nickel ferrite nanoparticles for biomedical applications.

Science.gov (United States)

Rodrigues, Ana Rita O; Gomes, I T; Almeida, Bernardo G; Araújo, J P; Castanheira, Elisabete M S; Coutinho, Paulo J G

2015-07-21

Nickel ferrite nanoparticles with superparamagnetic behavior at room temperature were synthesized using a coprecipitation method. These magnetic nanoparticles were either covered with a lipid bilayer, forming dry magnetic liposomes (DMLs), or entrapped in liposomes, originating aqueous magnetoliposomes (AMLs). A new and promising method for the synthesis of DMLs is described. The presence of the lipid bilayer in DMLs was confirmed by FRET (Förster Resonance Energy Transfer) measurements between the fluorescent-labeled lipids NBD-C12-HPC (NBD acting as a donor) included in the second lipid layer and rhodamine B-DOPE (acceptor) in the first lipid layer. An average donor-acceptor distance of 3 nm was estimated. Assays of the non-specific interactions of magnetoliposomes with biological membranes (modeled using giant unilamellar vesicles, GUVs) were performed. Membrane fusion between both aqueous and dry magnetoliposomes and GUVs was confirmed by FRET, which is an important result regarding applications of these systems both as hyperthermia agents and antitumor drug nanocarriers.

A study of magnetoplumbite-type (M-type) cobalt-titanium-substituted barium ferrite, BaCoxTixFe12-2xO19 (x = 1-6)

International Nuclear Information System (INIS)

Teh, G.B.; Saravanan, N.; Jefferson, D.A.

2007-01-01

Cobalt(II)-titanium(IV)-substituted barium ferrite forming the chemical formula of BaCo x Ti x Fe 12-2x O 19 (x = 1-6) have been investigated using X-ray diffraction spectroscopy (XRD), Superconducting Quantum Interference Device (SQUID) and high-resolution transmission electron microscopy (HRTEM). The specimen of magnetoplumbite (M-type) Co-Ti-substituted BaFe 12 O 19 were synthesised via sol-gel method using ethylene glycol as precursor. Significant increase in line broadening of the XRD patterns were observed indicating the decrease of particle sizes due to the Co(II)-Ti(IV) substitution. BaCo 3 Ti 3 Fe 6 O 19 showed the highest coercivity but moderate saturation and remnant magnetisations. HRTEM imaging showed that Co(II)-Ti(IV) substitution in the system of BaCo x Ti x Fe 12-2x O 19 (x = 1-6) produced no drastic change in the structure of the M-type ferrites. Most of the M-types crystals examined by HRTEM displayed a long axis perpendicular to the c-axis of the M-type structure. Disordered crystals showing the intergrowth between Co-Ti-substituted barium ferrite and the spinel-structured iron oxide were detected

A novel solution combustion synthesis of cobalt oxide nanoparticles as negative-electrode materials for lithium ion batteries

International Nuclear Information System (INIS)

Wen Wei; Wu Jinming; Tu Jiangping

2012-01-01

Highlights: ► We examine the electrochemical performance of cobalt oxides fabricated by solution combustion synthesis for rechargeable lithium-ion battery applications. ► The additive of NaF in precursor results in an eruption combustion mode. ► The eruption combustion leads to fluffy networks with smaller grains and more macroporous voids. ► The network contributes to higher discharge capacity, higher initial coulombic efficiency, and better cycling performance for rechargeable lithium-ion batteries. - Abstract: Low cost mass production of cobalt oxide nanoparticles with high electrochemical performance is of practical interest for rechargeable lithium-ion batteries. In this report, cobalt oxide nanoparticles were fabricated by solution combustion synthesis, with the introduction of NaF into the precursor to alter the combustion mode. The novel eruption combustion resulted in fluffy networks with smaller particles and more macroporous voids, which contributed to the higher discharge capacity, higher initial coulombic efficiency, and better cycling performance when compared with that achieved by the conventional combustion mode.

Magnetic properties of Co-ferrite-doped hydroxyapatite nanoparticles having a core/shell structure

International Nuclear Information System (INIS)

Petchsang, N.; Pon-On, W.; Hodak, J.H.; Tang, I.M.

2009-01-01

The magnetic properties of Co-ferrite-doped hydroxyapatite (HAP) nanoparticles of composition Ca 10-3x Fe 2x Co x (PO 4 ) 6 (OH) 2 (where x=0, 0.1, 0.2, 0.3, 0.4 and 0.5% mole) are studied. Transmission electron microscope micrograms show that the 90 nm size nanoparticles annealed at 1250 o C have a core/shell structure. Their electron diffraction patterns show that the shell is composed of the hydroxyapatite and the core is composed of the Co-ferrite, CoFe 2 O 4 . Electron spin resonance measurements indicate that the Co 2+ ions are being substituted into the Ca(1) sites in HAP lattice. X-ray diffraction studies show the formation of impurity phases as higher amounts of the Fe 3+ /Co 2+ ions which are substituted into the HAP host matrix. The presence of two sextets (one for the A-site Fe 3+ and the other for the B-site Fe 3+ ) in the Moessbauer spectrum for all the doped samples clearly indicates that the CoFe 2 O 4 .cores are in the ferromagnetic state. Evidence of the impurity phases is seen in the appearance of doublet patterns in the Moessbauer spectrums for the heavier-doped (x=0.4 and 0.5) specimens. The decrease in the saturation magnetizations and other magnetic properties of the nanoparticles at the higher doping levels is consistent with some of the Fe 3+ and Co 2+ which being used to form the CoO and Fe 2 O 3 impurity phase seen in the XRD patterns.

Process optimization and properties of magnetically hard cobalt carbide nanoparticles via modified polyol method

International Nuclear Information System (INIS)

Zamanpour, Mehdi; Bennett, Steven P.; Majidi, Leily; Chen, Yajie; Harris, Vincent G.

2015-01-01

Highlights: • High-coercivity cobalt carbides were synthesized by polyol method. • No rare earth elements were used during synthesis process. • Process parameters (reaction temperature, precursors’ concentrations, surfactants and reaction duration) were studied/optimized. • Process was scaled-up to synthesis more than 5 g powders per batch. - Abstract: Cobalt carbide magnetic nanoparticles were successfully synthesized via a modified polyol process without using a rare-earth catalyst during the synthesis process. The present results show admixtures of Co 2 C and Co 3 C phases possessing magnetization values exceeding 47 emu/g and coercivity values exceeding 2.3 kOe at room temperature. Moreover, these experiments have illuminated the important role of the reaction temperature, hydroxyl ion concentrations and the reaction duration on the crystallographic structure and magnetic properties of the nanoparticles. The crystallographic structure and particle size of the Co x C nanoparticles were characterized by X-ray diffractometry and scanning electron microscopy. Vibrating sample magnetometry was used to determine magnetic properties. Scale-up of synthesis to more than 5 g per batch was demonstrated with no significant degradation of magnetic properties

Process optimization and properties of magnetically hard cobalt carbide nanoparticles via modified polyol method

Energy Technology Data Exchange (ETDEWEB)

Zamanpour, Mehdi; Bennett, Steven P. [Center for Microwave Magnetic Materials and Integrated Circuits (CM3IC), Northeastern University, Boston, MA 02115 (United States); Majidi, Leily [Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA 02115 (United States); Chen, Yajie [Center for Microwave Magnetic Materials and Integrated Circuits (CM3IC), Northeastern University, Boston, MA 02115 (United States); Harris, Vincent G. [Center for Microwave Magnetic Materials and Integrated Circuits (CM3IC), Northeastern University, Boston, MA 02115 (United States); Department of Electrical and Computer Engineering, Northeastern University, Boston, MA 02115 (United States)

2015-03-15

Highlights: • High-coercivity cobalt carbides were synthesized by polyol method. • No rare earth elements were used during synthesis process. • Process parameters (reaction temperature, precursors’ concentrations, surfactants and reaction duration) were studied/optimized. • Process was scaled-up to synthesis more than 5 g powders per batch. - Abstract: Cobalt carbide magnetic nanoparticles were successfully synthesized via a modified polyol process without using a rare-earth catalyst during the synthesis process. The present results show admixtures of Co{sub 2}C and Co{sub 3}C phases possessing magnetization values exceeding 47 emu/g and coercivity values exceeding 2.3 kOe at room temperature. Moreover, these experiments have illuminated the important role of the reaction temperature, hydroxyl ion concentrations and the reaction duration on the crystallographic structure and magnetic properties of the nanoparticles. The crystallographic structure and particle size of the Co{sub x}C nanoparticles were characterized by X-ray diffractometry and scanning electron microscopy. Vibrating sample magnetometry was used to determine magnetic properties. Scale-up of synthesis to more than 5 g per batch was demonstrated with no significant degradation of magnetic properties.

Phase equilibria in the iron oxide-cobalt oxide-phosphorus oxide system

Science.gov (United States)

De Guire, Mark R.; Prasanna, T. R. S.; Kalonji, Gretchen; O'Handley, Robert C.

1987-01-01

Two novel ternary compounds are noted in the present study of 1000 C solid-state equilibria in the Fe-Co-P-O system's Fe2O3-FePO4-Co3(Po4)2-CoO region: CoFe(PO4)O, which undergoes incongruent melting at 1130 C, and Co3Fe4(PO4)6, whose incongruent melting occurs at 1080 C. The liquidus behavior-related consequences of rapidly solidified cobalt ferrite formation from cobalt ferrite-phosphate melts are discussed with a view to spinel formation. It is suggested that quenching from within the spinel-plus-liquid region may furnish an alternative to quenching a homogeneous melt.

Thermomagnetic characterization of organic-based ferrofluids prepared with Ni ferrite nanoparticles

International Nuclear Information System (INIS)

Arana, Mercedes; Bercoff, Paula G.; Jacobo, Silvia E.

2017-01-01

Highlights: • Kerosene-based ferrofluids of Ni-ferrite NPs from high energy ball milling. • Thermomagnetic characterization of organic-based ferrofluids. • Measured thermal variables enhancements of ferrofluid vs. magnetic field. • Curves successfully fitted by a gas-compression model of nanoaggregates. - Abstract: In this work, a thermomagnetic characterization of kerosene-based ferrofluids (FFs) prepared with Ni-ferrite nanoparticles (NPs) is performed by measuring their thermal conductivity and diffusivity coefficient enhancements. The particles were synthesized by high-energy ball milling, as an alternative to the most commonly chosen NPs synthesis methods for FFs. The action of an applied magnetic field on the FF increases the thermal conductivity and diffusivity due to cooperation between the NPs, as it agglomerates them favoring chain-like and clusters formations. It was found that the heat capacity of the studied FFs decreases under the application of a magnetic field. The obtained results for thermal conductivity of FFs under magnetic fields were fitted by a gas-compression model that considers NPs agglomerates in the fluid.

Thermomagnetic characterization of organic-based ferrofluids prepared with Ni ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Arana, Mercedes, E-mail: mercedes.arana@labh2.coppe.ufrj.br [Facultad de Matemática, Astronomía, Física y Computación (FaMAF), Universidad Nacional de Córdoba, IFEG, CONICET, Medina Allende s/n, Ciudad Universitaria, Córdoba (Argentina); Bercoff, Paula G. [Facultad de Matemática, Astronomía, Física y Computación (FaMAF), Universidad Nacional de Córdoba, IFEG, CONICET, Medina Allende s/n, Ciudad Universitaria, Córdoba (Argentina); Jacobo, Silvia E. [DiQuiMMAI, Facultad de Ingeniería, Universidad de Buenos Aires, INTECIN, CONICET, Av. Paseo Colón 850, Buenos Aires (Argentina)

2017-01-15

Highlights: • Kerosene-based ferrofluids of Ni-ferrite NPs from high energy ball milling. • Thermomagnetic characterization of organic-based ferrofluids. • Measured thermal variables enhancements of ferrofluid vs. magnetic field. • Curves successfully fitted by a gas-compression model of nanoaggregates. - Abstract: In this work, a thermomagnetic characterization of kerosene-based ferrofluids (FFs) prepared with Ni-ferrite nanoparticles (NPs) is performed by measuring their thermal conductivity and diffusivity coefficient enhancements. The particles were synthesized by high-energy ball milling, as an alternative to the most commonly chosen NPs synthesis methods for FFs. The action of an applied magnetic field on the FF increases the thermal conductivity and diffusivity due to cooperation between the NPs, as it agglomerates them favoring chain-like and clusters formations. It was found that the heat capacity of the studied FFs decreases under the application of a magnetic field. The obtained results for thermal conductivity of FFs under magnetic fields were fitted by a gas-compression model that considers NPs agglomerates in the fluid.

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.

Mn-Zn ferrite nanoparticles with silica and titania coatings: synthesis, transverse relaxivity and cytotoxicity

Czech Academy of Sciences Publication Activity Database

Kaman, Ondřej; Kuličková, Jarmila; Maryško, Miroslav; Veverka, Pavel; Herynek, V.; Havelek, R.; Královec, K.; Kubániová, D.; Kohout, J.; Dvořák, P.; Jirák, Zdeněk

2017-01-01

Roč. 53, č. 11 (2017), s. 1-8, č. článku 5300908. ISSN 0018-9464 R&D Projects: GA ČR GA16-04340S Institutional support: RVO:68378271 Keywords : amorphous titania * silica * magnetic nanoparticles * Mn-Zn ferrite * transverse relaxivity * cytotoxicity Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.243, year: 2016

Cobalt doped antimony oxide nano-particles based chemical sensor and photo-catalyst for environmental pollutants

Energy Technology Data Exchange (ETDEWEB)

Jamal, Aslam [Centre for Advanced Materials and Nano-Engineering (CAMNE) and Department of Chemistry, Faculty of Sciences and Arts, Najran University, P. O. Box 1988, Najran 11001 (Saudi Arabia); Rahman, Mohammed M. [Center of Excellence for Advanced Materials Research (CEAMR), King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); Chemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); Khan, Sher Bahadar, E-mail: drkhanmarwat@gmail.com [Center of Excellence for Advanced Materials Research (CEAMR), King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); Chemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); Faisal, Mohd. [Centre for Advanced Materials and Nano-Engineering (CAMNE) and Department of Chemistry, Faculty of Sciences and Arts, Najran University, P. O. Box 1988, Najran 11001 (Saudi Arabia); Akhtar, Kalsoom [Division of Nano Sciences and Department of Chemistry, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Rub, Malik Abdul; Asiri, Abdullah M.; Al-Youbi, Abdulrahman O. [Center of Excellence for Advanced Materials Research (CEAMR), King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); Chemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia)

2012-11-15

Graphical abstract: A dichloromethane chemical sensor using cobalt antimony oxides has been fabricated. This sensor showed high sensitivity and will be a useful candidate for environmental and health monitoring. Also it showed high photo-catalytic activity and can be a good candidate as a photo-catalyst for organic hazardous materials. Highlights: Black-Right-Pointing-Pointer Reusable chemical sensor. Black-Right-Pointing-Pointer Green environmental and eco-friendly chemi-sensor. Black-Right-Pointing-Pointer High sensitivity. Black-Right-Pointing-Pointer Good candidate for environmental and health monitoring. - Abstract: Cobalt doped antimony oxide nano-particles (NPs) have been synthesized by hydrothermal process and structurally characterized by utilizing X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and Fourier transforms infrared spectrophotometer (FT-IR) which revealed that the synthesized cobalt antimony oxides (CoSb{sub 2}O{sub 6}) are well crystalline nano-particles with an average particles size of 26 {+-} 10 nm. UV-visible absorption spectra ({approx}286 nm) were used to investigate the optical properties of CoSb{sub 2}O{sub 6}. The chemical sensing of CoSb{sub 2}O{sub 6} NPs have been primarily investigated by I-V technique, where dichloromethane is used as a model compound. The analytical performance of dichloromethane chemical sensor exhibits high sensitivity (1.2432 {mu}A cm{sup -2} mM{sup -1}) and a large linear dynamic range (1.0 {mu}M-0.01 M) in short response time (10 s). The photo catalytic activity of the synthesized CoSb{sub 2}O{sub 6} nano-particles was evaluated by degradation of acridine orange (AO), which degraded 58.37% in 200 min. These results indicate that CoSb{sub 2}O{sub 6} nano-particles can play an excellent research impact in the environmental field.

Preparation of Mn-Zn ferrite nanoparticles and their silica-coated clusters: magnetic properties and transverse relaxivity

Czech Academy of Sciences Publication Activity Database

Kaman, Ondřej; Kuličková, Jarmila; Herynek, Vít; Koktan, Jakub; Maryško, Miroslav; Dědourková, T.; Knížek, Karel; Jirák, Zdeněk

2017-01-01

Roč. 427, Apr (2017), s. 251-257 ISSN 0304-8853 Institutional support: RVO:68378271 ; RVO:68378041 Keywords : magnetic nanoparticles * Mn-Zn ferrite * hydrothermal synthesis * magnetic resonance imaging * transverse relaxivity Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.630, year: 2016

Characterization of a Porous Carbon Material Functionalized with Cobalt-Oxide/Cobalt Core-Shell Nanoparticles for Lithium Ion Battery Electrodes

KAUST Repository

Anjum, Dalaver H.

2016-04-18

A nanoporous carbon (C) material, functionalized with Cobalt-Oxide/Cobalt (CoO/Co) core-shell nanoparticles (NPs), was structurally and chemically characterized with transmission electron microcopy (TEM) while its electrochemical response for Lithium ion battery (LIB) applications was evaluated as well. The results herein show that the nanoporous C material was uniformly functionalized with the CoO/Co core-shell NPs. Further the NPs were crystalline with fcc-Type lattice on the Co2+ oxide shell and hcp-Type core of metallic Co0. The electrochemical study was carried out by using galvanostatic charge/discharge cycling at a current density of 1000 mA g-1. The potential of this hybrid material for LIB applications was confirmed and it is attributed to the successful dispersion of the Co2+/ Co0 NPs in the C support.

Formation of DNA-network embedding ferromagnetic Cobalt nano-particles

Science.gov (United States)

Kanki, Teruo; Tanaka, Hidekazu; Shirakawa, Hideaki; Sacho, Yu; Taniguchi, Masateru; Lee, Hea-Yeon; Kawai, Tomoji; Kang, Nam-Jung; Chen, Jinwoo

2002-03-01

Formation of DNA-network embedding ferromagnetic Cobalt nano-particles T. Kanki, Hidekazu. Tanaka, H. Shirakawa, Y. Sacho, M. Taniguchi, H. Lee, T. Kawai The Institute of Scientific and Industrial Research, Osaka University, Japan and Nam-Jung Kang, Jinwoo Chen Korea Advanced Institute of Science and Technology (KAIST), Korea DNA can be regarded as a naturally occurring and highly specific functional biopolymer and as a fine nano-wire. Moreover, it was found that large-scale DNA networks can be fabricated on mica surfaces. By using this network structure, we can expect to construct nano-scale assembly of functional nano particle, for example ferromagnetic Co nano particles, toward nano scale spin-electronics based on DNA circuits. When we formed DNA network by 250mg/ml DNA solution of poly(dG)-poly(dC) including ferromagnetic Co nano particles (diameter of 12nm), we have conformed the DNA network structure embedding Co nano-particles (height of about 12nm) by atomic force microscopy. On the other hand, we used 100mg/ml DNA solution, DNA can not connect each other, and many Co nano-particles exist without being embedded.

Microemulsion synthesis and magnetic properties of hydroxyapatite-encapsulated nano CoFe{sub 2}O{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Foroughi, Firoozeh [Department of Materials Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Isfahan (Iran, Islamic Republic of); Hassanzadeh-Tabrizi, S.A., E-mail: tabrizi1980@gmail.com [Young Researchers and Elite Club, Najafabad Branch, Islamic Azad University, Najafabad, Isfahan (Iran, Islamic Republic of); Amighian, Jamshid [Department of Materials Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Isfahan (Iran, Islamic Republic of)

2015-05-15

Hydroxyapatite-encapsulated cobalt ferrite (CoFe{sub 2}O{sub 4}) nanopowders were synthesized by one step microemulsion method. The powders were characterized by X-ray Diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometer. TEM results showed that nanoparticles calcined at 700 °C have core–shell morphology. It was found that the resultant phases, morphology and magnetic properties of the samples depend on calcining temperature. The synthesized nanoparticles showed a maximum saturation magnetization of 7.8 emu/g with a wasp-waisted hysteresis loop. The magnetion was reduced by increasing calcining temperature to 900 °C. This reduction is due to the reaction of cobalt ferrite with hydroxyapatite which leads to CaFe{sub 12}(PO{sub 4}){sub 8}(OH){sub 12} phase. - Highlights: • Hydroxyapatite-encapsulated cobalt ferrite nanopowders were synthesized by a microemulsion method. • The characterization of nanoparticles was performed using various analytical tools, such as TEM, FE-SEM, FTIR, XRD and VSM. • The nanoparticles showed a maximum saturation magnetization of 7.8 emu/g. • The samples indicated a wasp-waisted hysteresis loop.

Comparative cytotoxic response of nickel ferrite nanoparticles in human liver HepG2 and breast MFC-7 cancer cells.

Science.gov (United States)

Ahamed, Maqusood; Akhtar, Mohd Javed; Alhadlaq, Hisham A; Khan, M A Majeed; Alrokayan, Salman A

2015-09-01

Nickel ferrite nanoparticles (NPs) have received much attention for their potential applications in biomedical fields such as magnetic resonance imaging, drug delivery and cancer hyperthermia. However, little is known about the toxicity of nickel ferrite NPs at the cellular and molecular levels. In this study, we investigated the cytotoxic responses of nickel ferrite NPs in two different types of human cells (i.e., liver HepG2 and breast MCF-7). Nickel ferrite NPs induced dose-dependent cytotoxicity in both types of cells, which was demonstrated by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazoliumbromide (MTT), neutral red uptake (NRU) and lactate dehydrogenase (LDH) assays. Nickel ferrite NPs were also found to induce oxidative stress, which was evident by the depletion of glutathione and the induction of reactive oxygen species (ROS) and lipid peroxidation. The mitochondrial membrane potential due to nickel ferrite NP exposure was also observed. The mRNA levels for the tumor suppressor gene p53 and the apoptotic genes bax, CASP3 and CASP9 were up-regulated, while the anti-apoptotic gene bcl-2 was down-regulated following nickel ferrite NP exposure. Furthermore, the activities of apoptotic enzymes (caspase-3 and caspase-9) were also higher in both types of cells treated with nickel ferrite NPs. Cytotoxicity induced by nickel ferrite was efficiently prevented by N-acetyl cysteine (ROS scavenger) treatment, which suggested that oxidative stress might be one of the possible mechanisms of nickel ferrite NP toxicity. We also observed that MCF-7 cells were slightly more susceptible to nickel ferrite NP exposure than HepG2 cells. This study warrants further investigation to explore the potential mechanisms of different cytotoxic responses of nickel ferrite NPs in different cell lines. Copyright © 2015 Elsevier Ltd. All rights reserved.

Preparation and microwave-infrared absorption of reduced graphene oxide/Cu-Ni ferrite/Al2O3 composites

Science.gov (United States)

De-yue, Ma; Xiao-xia, Li; Yu-xiang, Guo; Yu-run, Zeng

2018-01-01

Reduced graphene oxide (RGO)/Cu-Ni ferrite/Al2O3 composite was prepared by solvothermal method, and its properties were characterized by SEM, x-ray diffraction, energy-dispersive x-ray spectroscopy and FTIR. The electromagnetic parameters in 2-18 GHz and mid-infrared (IR) spectral transmittance of the composite were measured, respectively. The results show that Cu0.7Ni0.3Fe2O4 nanoparticles with an average size of tens nanometers adsorb on surface of RGO, and meanwhile, Al2O3 nanoparticles adhere to the surface of Cu0.7Ni0.3Fe2O4 nanoparticles and RGO. The composite has both dielectric and magnetic loss mechanism. Its reflection loss is lower than -19 dB in 2-18 GHz, and the maximum of -23.2 dB occurs at 15.6 GHz. With the increasing of Al2O3 amount, its reflection loss becomes lower and the maximum moves towards low frequency slightly. Compared with RGO/Cu-Ni ferrite composites, its magnetic loss and reflection loss slightly reduce with the increasing of Al2O3 amount, and the maximum of reflection loss shifts from a low frequency to a high one. However, its broadband IR absorption is significantly enhanced owing to nano-Al2O3. Therefore, RGO/Cu-Ni ferrite/Al2O3 composites can be used as excellent broadband microwave and IR absorbing materials, and maybe have broad application prospect in electromagnetic shielding, IR absorbing and coating materials.

Synthesis and cytotoxicity study of magnesium ferrite-gold core-shell nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Nonkumwong, Jeeranan [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Pakawanit, Phakkhananan [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Wipatanawin, Angkana [Division of Biochemistry and Biochemical Technology, Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Jantaratana, Pongsakorn [Department of Physics, Faculty of Science, Kasetsart University, Bangkok 11900 (Thailand); Ananta, Supon [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Srisombat, Laongnuan, E-mail: slaongnuan@yahoo.com [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

2016-04-01

In this work, the core-magnesium ferrite (MgFe{sub 2}O{sub 4}) nanoparticles were prepared by hydrothermal technique. Completed gold (Au) shell coating on the surfaces of MgFe{sub 2}O{sub 4} 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 MgFe{sub 2}O{sub 4} 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 MgFe{sub 2}O{sub 4} 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 MgFe{sub 2}O{sub 4}-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 MgFe{sub 2}O{sub 4}-Au core-shell nanoparticles still exhibit superparamagnetism with lower saturation magnetization value, compared with MgFe{sub 2}O{sub 4} core. Both of MgFe{sub 2}O{sub 4} and MgFe{sub 2}O{sub 4}-Au core-shell also showed in vitro non-cytotoxicity to mouse areola fibroblast (L-929) cell line. - Highlights: • Synthesis of MgFe{sub 2}O{sub 4}-Au core-shell nanoparticles with particle size < 100 nm • Complete Au shell coating on the surfaces of MgFe{sub 2}O{sub 4} nanoparticles • In vitro cytotoxicity study of complete coated MgFe{sub 2}O{sub 4}-Au core

Synthesis and cytotoxicity study of magnesium ferrite-gold core-shell nanoparticles

International Nuclear Information System (INIS)

Nonkumwong, Jeeranan; Pakawanit, Phakkhananan; Wipatanawin, Angkana; Jantaratana, Pongsakorn; Ananta, Supon; Srisombat, Laongnuan

2016-01-01

In this work, the core-magnesium ferrite (MgFe_2O_4) nanoparticles were prepared by hydrothermal technique. Completed gold (Au) shell coating on the surfaces of MgFe_2O_4 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 MgFe_2O_4 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 MgFe_2O_4 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 MgFe_2O_4-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 MgFe_2O_4-Au core-shell nanoparticles still exhibit superparamagnetism with lower saturation magnetization value, compared with MgFe_2O_4 core. Both of MgFe_2O_4 and MgFe_2O_4-Au core-shell also showed in vitro non-cytotoxicity to mouse areola fibroblast (L-929) cell line. - Highlights: • Synthesis of MgFe_2O_4-Au core-shell nanoparticles with particle size < 100 nm • Complete Au shell coating on the surfaces of MgFe_2O_4 nanoparticles • In vitro cytotoxicity study of complete coated MgFe_2O_4-Au core-shell nanoparticles

Synthesis and Characterization of Chitosan Coated Manganese Zinc Ferrite Nanoparticles as MRI Contrast Agents

Directory of Open Access Journals (Sweden)

M. Zahraei

2015-04-01

Full Text Available Manganese zinc ferrite nanoparticles (MZF NPs were synthesized by using a direct, efficient and environmental friendly hydrothermal method. To improve the colloidal stability of MZF NPs for biomedical applications, NPs were coated with chitosan by ionic gelation technique using sodium tripolyphosphate (TPP as crosslinker. The synthesized NPs were characterized by X ray diffraction (XRD analysis, inductively coupled plasma optical emission spectrometry (ICP-OES, fourier transform infrared (FTIR spectroscopy, transmission electron microscopy (TEM, vibrating sample magnetometer (VSM and the dynamic light scattering (DLS methods. The results confirmed the spinel ferrite phase formation without any calcination process after synthesis. Mean particle size of bare NPs was around 14 nm. Moreover, certain molar ratio of chitosan to TPP was required for encapsulation of NPs in chitosan. Coated NPs showed hydrodynamic size of 300 nm and polydispersity index about 0.3.

Influence of calcination temperature on Cd{sub 0.3}Co{sub 0.7}Fe{sub 2}O{sub 4} nanoparticles: Structural, thermal and magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Reddy, Ch.Venkata, E-mail: cvrphy@gmail.com [School of Mechanical Engineering, Yeungnam University, 214-1, Dae-dong, Gyeongsan-si, Gyeongsangbuk-do 712-749 (Korea, Republic of); PrabhakarVattikuti, S.V. [School of Mechanical Engineering, Yeungnam University, 214-1, Dae-dong, Gyeongsan-si, Gyeongsangbuk-do 712-749 (Korea, Republic of); Ravikumar, R.V.S.S.N. [Department of Physics, Acharya Nagarjuna University, AP 522510 (India); Moon, Sang Jun, E-mail: nanobiomems@dgist.ac.kr [Cybernetics Laboratory, Daegu Gyeongbuk Institute of Science and Technology (DGIST) (Korea, Republic of); Shim, Jaesool, E-mail: jshim@ynu.ac.kr [School of Mechanical Engineering, Yeungnam University, 214-1, Dae-dong, Gyeongsan-si, Gyeongsangbuk-do 712-749 (Korea, Republic of)

2015-11-15

Cadmium substituted cobalt ferrite nanoparticles are synthesis using the chemical method. The as-prepared ferrite nanoparticles are calcinated at 300 °C and 600 °C respectively. The samples are studied using; Powder XRD, SEM with EDX, TEM, FT-IR, TG-DTA and vibrating sample magnetometer (VSM) in order to study the calcination temperature effect on structural, morphological and magnetic properties. The magnetic properties, like saturation magnetization and coercivity increases with increasing the calcination temperature. This enhancement is attributed to the transition from amulti-domain to a single-domain nature. The absorption bands observed at 588 cm{sup −1} (ν{sub 1}) and 440 cm{sup −1} (ν{sub 2}) are attributed to the vibrations of tetrahedral and octahedral complexes. The TG-DTA curves reveal the thermal stability of the prepared ferrite nanoparticles. The calcination temperature influences the magnetic properties, surface morphology and crystalline size. - Highlights: • Cd{sub 0.3}Co{sub 0.7}Fe{sub 2}O{sub 4} nanoparticles synthesized using the chemical co-precipitation. • The magnetization, coercivity values increases with increasing the calcination temperature. • The calcination temperature influences the magnetic properties and crystallite size. • The FTIR spectra results confirmed the vibrations of tetrahedral and octahedral complexes.

Effect of Synthesis Parameters on the Structure and Magnetic Properties of Magnetic Manganese Ferrite/Silver Composite Nanoparticles Synthesized by Wet Chemistry Method

DEFF Research Database (Denmark)

Huy, L.T.; Tam, L.T.; Phan, V.N.

2016-01-01

In the present work, magnetic manganese ferrite/silver (MnFe2O4-Ag) composite nanoparticles were synthesized by wet chemistry method. This synthesis process consists of two steps: first, the seed of manganese ferrite nanoparticles (MnFe2O4 NPs) was prepared by a coprecipitationmethod; second......, growth of silver nanoparticles (AgNPs) on the MnFe2O4 seed by modified photochemical reaction. We have conducted systematically the effects of synthesis parameters such as pH value, synthesis time, precursor salts concentration, mass ratio and stabilizing agents on the structure and magnetic properties......-prepared MnFe2O4-Ag magnetic nanocomposites display excellent properties of high crystallinity, long-term aggregation stability in aqueous medium, large saturation magnetization in the range of 15-20 emu/g, and small sizes of Ag-NPs similar to 20 nm. These exhibited properties made the MnFe2O4-Ag...

Cu{sup 2+}-modified physical properties of Cobalt-Nickel ferrite

Energy Technology Data Exchange (ETDEWEB)

Rajasekhar Babu, K.; Rao, K. Rama [Department of Physics, Andhra University, Visakhapatnam, Andhra Pradesh 530003 (India); Rajesh Babu, B., E-mail: rajeshbabu.bitra@gmail.com [Department of Physics, GVP College of Engineering for Women, Visakhapatnam, Andhra Pradesh 530048 (India)

2017-07-15

Highlights: • In this work, Influence of Cu and cation redistribution is discussed in detail. • Theoretical and experimental results related to distribution, lattice constant are found to be consistent. • Substitution of Cu significantly modifies the magnetization, permeability, grain size and resistivity. - Abstract: The present study focused on structural, magnetic and electrical properties of Cu substituted Co-Ni ferrite nanoparticles synthesized by sol-gel combustion method. X-ray diffraction, Fourier Transform infra-red spectroscopy (FTIR), magnetization, magnetic permeability and resistivity measurements were carried out to study the structural, magnetic and electrical properties. X-ray diffraction pattern confirms single phase spinel formation. Crystallite size determined from Scherer’s method increases with Cu concentration. Distribution of cations was estimated from X-ray line intensity calculations, suggest that the majority of Cu{sup 2+} ions occupy octahedral (B) site. Saturation magnetization exhibit increasing trend from 40 emu/g (x = 0.0) to 60 emu/g (x = 0.4) with Cu concentration, though higher magnetic moment Ni ions are replaced by lower magnetic moment Cu ions. Magnetic permeability increases with increasing Cu concentration and shows a flat profile in the frequency range 1–50 MHz. Significant modification in DC electrical resistivity and activation energy are explained on the basis of hopping mechanism.

Spin canting phenomenon in cadmium doped cobalt ferrites ...

Indian Academy of Sciences (India)

O4 ( = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0), has been carried out using the sol–gel auto combustion method. The ferrite samples show an interesting magnetic transition from Neel to Yafet–Kittel configuration, as the Cd2+ concentration is increased ...

Fluid Dynamics of Magnetic Nanoparticles in Simulated Blood Vessels

Science.gov (United States)

Blue, Lauren; Sewell, Mary Kathryn; Brazel, Christopher S.

2008-11-01

Magnetic nanoparticles (MNPs) can be used to locally target therapies and offer the benefit of using an AC magnetic field to combine hyperthermia treatment with the triggered release of therapeutic agents. Here, we investigate localization of MNPs in a simulated environment to understand the relationship between magnetic field intensity and bulk fluid dynamics to determine MNP retention in a simulated blood vessel. As MNPs travel through blood vessels, they can be slowed or trapped in a specific area by applying a magnetic field. Magnetic cobalt ferrite nanoparticles were synthesized and labeled with a fluorescent rhodamine tag to visualize patterns in a flow cell, as monitored by a fluorescence microscope. Particle retention was determined as a function of flow rate, concentration, and magnetic field strength. Understanding the relationship between magnetic field intensity, flow behavior and nanoparticle characteristics will aid in the development of therapeutic systems specifically targeted to diseased tissue.

Silica-coated manganite and Mn-based ferrite nanoparticles: a comparative study focused on cytotoxicity

Czech Academy of Sciences Publication Activity Database

Kaman, Ondřej; Dědourková, T.; Koktan, Jakub; Kuličková, Jarmila; Maryško, Miroslav; Veverka, Pavel; Havelek, R.; Královec, K.; Turnovcová, Karolína; Jendelová, Pavla; Schröfel, A.; Svoboda, L.

2016-01-01

Roč. 18, č. 4 (2016), 1-18, č. článku 100. ISSN 1388-0764 R&D Projects: GA ČR GA15-10088S Institutional support: RVO:68378271 ; RVO:68378041 Keywords : magnetic nanoparticles * manganite * ferrite * in vitro toxicity * stem cells Subject RIV: BM - Solid Matter Physics ; Magnetism; EB - Genetics ; Molecular Biology (UEM-P) OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.); Acoustics (UEM-P) Impact factor: 2.020, year: 2016

Electrophoretic deposition of nickel zinc ferrite nanoparticles into microstructured patterns

Directory of Open Access Journals (Sweden)

Stefan J. Kelly

2016-05-01

Full Text Available Using DC electric fields, nickel-zinc ferrite (Ni0.5Zn0.5Fe2O4 nanoparticles (Dh =16.6 ± 3.6 nm are electrophoretically deposited onto silicon substrates to form dense structures defined by photoresist molds. Parameters such as electric field, bath composition, and deposition time are tuned to produce films ranging in thickness from 177 to 805 nm. The deposited films exhibit soft magnetic properties with a saturation magnetization of 60 emu/g and a coercivity of 2.6 kA/m (33 Oe. Additionally, the influence of the photoresist mold on the deposit profile is studied, and patterned films with different shapes (lines, squares, circles, etc. are demonstrated with feature sizes down to 5 μm.

Comparison effects and electron spin resonance studies of α-Fe2O4 spinel type ferrite nanoparticles.

Science.gov (United States)

Bayrakdar, H; Yalçın, O; Cengiz, U; Özüm, S; Anigi, E; Topel, O

2014-11-11

α-Fe2O4 spinel type ferrite nanoparticles have been synthesized by cetyltrimethylammonium bromide (CTAB) and ethylenediaminetetraacetic acid (EDTA) assisted hydrothermal route by using NaOH solution. Electron spin resonance (ESR/EPR) measurements of α-Fe2O4 nanoparticles have been performed by a conventional x-band spectrometer at room temperature. The comparison effect of nanoparticles prepared by using CTAB and EDTA in different α-doping on the structural and morphological properties have been investigated in detail. The effect of EDTA-assisted synthesis for α-Fe2O4 nanoparticles are refined, and thus the spectroscopic g-factor are detected by using ESR signals. These samples can be considered as great benefits for magnetic recording media, electromagnetic and drug delivery applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of particle size on degree of inversion in ferrites

International Nuclear Information System (INIS)

Siddique, M.; Butt, N.M.

2012-01-01

Ferrites with the spinel structure are important materials because of their structural, magnetic and electrical properties. The suitability of these materials depends on both the intrinsic behavior of the material and the effects of the grain size. Moessbauer spectroscopy was employed to investigate the cation distribution and degree of inversion in bulk and nano sized particles of CuFe/sub 2/O/sub 4/, MnFe/sub 2/O/sub 4/ and NiFe/sub 2/O/sub 4/ ferrites. The Moessbauer spectra of all bulk ferrites showed complete magnetic behavior, whereas nanoparticle ferrites showed combination of ferromagnetic and superparamagnetic components. Moreover, the cation distribution in nanoparticle materials was also found to be different to that of their bulk counterparts indicating the particle size dependency. The inversion of Cu and Ni ions in bulk sample was greater than that of nanoparticles; whereas the inversion of Mn ions was less in bulk material as compared to the nanoparticles. Hence the degree of inversion decreased in CuFe/sub 2/O/sub 4/ and NiFe/sub 2/O/sub 4/ samples whereas, it increased in MnFe/sub 2/O/sub 4/ as the particle size decreased and thus showed the anomalous behavior in this case. The nanoparticle samples also showed paramagnetic behaviour due to superparamagnetism and this effect is more prominent in MnFe/sub 2/O/sub 4/. Moessbauer spectra of bulk and nanoparticles CuFe/sub 2/O/sub 4/ is shown. (Orig./A.B.)

Fabrication of Lanthanum Strontium Cobalt Ferrite-Gadolinium-Doped Ceria Composite Cathodes Using a Low-Price Inkjet Printer.

Science.gov (United States)

Han, Gwon Deok; Choi, Hyung Jong; Bae, Kiho; Choi, Hyeon Rak; Jang, Dong Young; Shim, Joon Hyung

2017-11-15

In this work, we have successfully fabricated lanthanum strontium cobalt ferrite (LSCF)-gadolinium-doped ceria (GDC) composite cathodes by inkjet printing and demonstrated their functioning in solid oxide fuel cells (SOFCs). The cathodes are printed using a low-cost HP inkjet printer, and the LSCF and GDC source inks are synthesized with fluidic properties optimum for inkjet printing. The composition and microstructure of the LSCF and GDC layers are successfully controlled by controlling the color level in the printed images and the number of printing cycles, respectively. Anode-support type SOFCs with optimized LSCF-GDC composite cathodes synthesized by our inkjet printing method have achieved a power output of over 570 mW cm -2 at 650 °C, which is comparable to the performance of a commercial SOFC stack. Electrochemical impedance analysis is carried out to establish a relationship between the cell performance and the compositional and structural characteristics of the printed LSCF-GDC composite cathodes.

Influence of synthesis approach on structural and magnetic properties of lithium ferrite nanoparticles

International Nuclear Information System (INIS)

Dar, M. Abdullah; Shah, Jyoti; Siddiqui, W.A.; Kotnala, R.K.

2012-01-01

Highlights: ► Nanocrystalline Li 0.5 Fe 2.5 O 4 ferrites were synthesized with an average crystallite size of 12.3 nm and 5.7 nm by chemical co-precipitation and reverse microemulsion technique respectively. ► The non-saturated M–H loops, absence of hysteresis, remanence and coercivity at room temperature is indicative of the presence of superparamagnetic and single-domain particles for both the materials. ► The blocking temperature T B shifts to lower temperature with the increase of applied field, which is attributed to the reduction of magnetocrystalline anisotropy constant. ► At high temperature, microemulsion synthesized nanoparticles are observed to show a maxima immediately below the Curie temperature which is attributed to the cumulative effect of the anisotropy variation of temperature and particle size growth during the measurement. - Abstract: Nanocrystalline Li 0.5 Fe 2.5 O 4 ferrite particles were synthesized with an average crystallite size of 12.3 nm and 5.7 nm by chemical coprecipitation and reverse microemulsion technique respectively. Zero-field cooled (ZFC) and field cooled (FC) magnetization measurements at different magnetic fields and magnetic hysteresis loops at different temperatures have been measured. The non-saturation of M–H loops with a very low coercivity and remenance at room temperature confirms the presence of superparamagnetic (SPM) nature and single-domain ferrite particles. The blocking temperature (T B ) has been found to shift towards the lower temperature region with the increase in applied magnetic field. It has been attributed to the reduction of magnetocrystalline anisotropy constant and blocking temperature dereases from 145 K to 110 K with increase in field from 50 Oe to 1000 Oe in the samples synthesized by microemulsion method. At high temperature, microemulsion synthesized nanoparticles show a maximum in magnetization versus temperature plot just below the Curie temperature (T C ) which has been attributed

Nitrogen and Sulfur Co-doped Graphene Supported Cobalt Sulfide Nanoparticles as an Efficient Air Cathode for Zinc-air Battery

International Nuclear Information System (INIS)

Ganesan, Pandian; Ramakrishnan, Prakash; Prabu, Moni; Shanmugam, Sangaraju

2015-01-01

Highlights: • CoS 2 nanoparticles supported on a nitrogen and sulfur co-doped graphene oxide is described. • Improved round trip efficiency was observed for CoS 2 (400)/N,S-GO. • CoS 2 (400)/N,S-GO possess improved durability with low over-potential. • CoS 2 (400)/N,S-GO is a promising air cathode for zinc-air battery. - ABSTRACT: Zinc-air battery is considered as one of the promising energy storage devices due to their low cost, eco-friendly and safe. Here, we present a simple approach to the preparation of cobalt sulfide nanoparticles supported on a nitrogen and sulfur co-doped graphene oxide surface. Cobalt sulfide nanoparticles dispersed on graphene oxide hybrid was successfully prepared by solid state thermolysis approach at 400 °C, using cobalt thiourea and graphene oxide. X-ray diffraction study revealed that hybrid electrode prepared at 400 °C results in pure CoS 2 phase. The hybrid CoS 2 (400)/N,S-GO electrode exhibits low over-potential gap about 0.78 V vs. Zn after 70 cycles with remarkable and robust charge and discharge profile. And also the CoS 2 (400)/N,S-GO showing deep discharge behavior with stability up to 7.5 h.

HRTEM Study of Oxide Nanoparticles in K3-ODS Ferritic Steel Developed for Radiation Tolerance

Energy Technology Data Exchange (ETDEWEB)

Hsiung, L; Fluss, M; Tumey, S; Kuntz, J; El-Dasher, B; Wall, M; Choi, W; Kimura, A; Willaime, F; Serruys, Y

2009-11-02

Crystal and interfacial structures of oxide nanoparticles and radiation damage in 16Cr-4.5Al-0.3Ti-2W-0.37 Y{sub 2}O{sub 3} ODS ferritic steel have been examined using high-resolution transmission electron microscopy (HRTEM) techniques. Oxide nanoparticles with a complex-oxide core and an amorphous shell were frequently observed. The crystal structure of complex-oxide core is identified to be mainly monoclinic Y{sub 4}Al{sub 2}O{sub 9} (YAM) oxide compound. Orientation relationships between the oxide and the matrix are found to be dependent on the particle size. Large particles (> 20 nm) tend to be incoherent and have a spherical shape, whereas small particles (< 10 nm) tend to be coherent or semi-coherent and have a faceted interface. The observations of partially amorphous nanoparticles and multiple crystalline domains formed within a nanoparticle lead us to propose a three-stage mechanism to rationalize the formation of oxide nanoparticles containing core/shell structures in as-fabricated ODS steels. Effects of nanoparticle size and density on cavity formation induced by (Fe{sup 8+} + He{sup +}) dual-beam irradiation are briefly addressed.

Fabrication and electromagnetic properties of flake ferrite particles based on diatomite

International Nuclear Information System (INIS)

Zhang Deyuan; Zhang Wenqiang; Cai Jun

2011-01-01

Hexagonal ferrite BaZn 1.1 Co 0.9 Fe 16 O 27 coated surfaces of diatomite flakes of low density were synthesized by a sol-gel method. The phase structures, morphologies, particle size and chemical compositions of the composites were characterized by X-ray diffraction, scanning electron microscope and energy dispersive X-ray spectroscopy. The results show that hexagonal ferrite coated diatomite flakes can be achieved, and that the coating consisted of BaZn 1.1 Co 0.9 Fe 16 O 27 nanoparticles. The vibranting sample magnetometer results reveal that the flake ferrite particles have static magnetic properties. The complex permeability and permittivity of the composites were measured in the frequency range of 1-18 GHz. The microwave absorption properties of these ferrite particles are discussed. The results indicate that the flake ferrites have the potential to be used as a lightweight broad band microwave absorber. - Highlights: → We synthesize the flake ferrite particles using diatomite as a template. → Flake ferrite particles' coating layers are constituted by BaZn 1.1 Co 0.9 Fe 16 O 27 nanoparticles. → Flake ferrite particles have good static magnetic properties.→ Flake ferrites are a kind lightweight broad band microwave absorber.

Fabrication and electromagnetic properties of flake ferrite particles based on diatomite

Energy Technology Data Exchange (ETDEWEB)

Zhang Deyuan [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China); Zhang Wenqiang, E-mail: zwqzwqzwqzwq@126.com [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China); Cai Jun, E-mail: jun_cai@buaa.edu.cn [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China)

2011-09-15

Hexagonal ferrite BaZn{sub 1.1}Co{sub 0.9}Fe{sub 16}O{sub 27} coated surfaces of diatomite flakes of low density were synthesized by a sol-gel method. The phase structures, morphologies, particle size and chemical compositions of the composites were characterized by X-ray diffraction, scanning electron microscope and energy dispersive X-ray spectroscopy. The results show that hexagonal ferrite coated diatomite flakes can be achieved, and that the coating consisted of BaZn{sub 1.1}Co{sub 0.9}Fe{sub 16}O{sub 27} nanoparticles. The vibranting sample magnetometer results reveal that the flake ferrite particles have static magnetic properties. The complex permeability and permittivity of the composites were measured in the frequency range of 1-18 GHz. The microwave absorption properties of these ferrite particles are discussed. The results indicate that the flake ferrites have the potential to be used as a lightweight broad band microwave absorber. - Highlights: > We synthesize the flake ferrite particles using diatomite as a template. > Flake ferrite particles' coating layers are constituted by BaZn{sub 1.1}Co{sub 0.9}Fe{sub 16}O{sub 27} nanoparticles. > Flake ferrite particles have good static magnetic properties. > Flake ferrites are a kind lightweight broad band microwave absorber.

Comparative studies on structural properties and antimicrobial potential of spinel ferrite nanoparticles synthesized using various methods

Science.gov (United States)

Baraliya, Jagdish D.; Rakhashiya, Purvi M.; Patel, Pooja P.; Thaker, Vrinda S.; Joshi, Hiren H.

2017-05-01

In this study, novel multifunctional magnetic iron-based nanoparticles (CoFe2O4) coated with silica, silica-DEG (diethylene glycol), PEG (polyethylene glycol) were synthesized using Auto Combustion Method (ACM), Co-precipitation Method (COPM), Citrate Precursor Method (CPM), Flash Combustion Method (FCM). These spinel ferrite nanoparticles also contain very high antibacterial properties to fulfill the requirements of a drug delivery system so that the antibiotic concentration could be minimized. A potential delivery system could be based on a ferromagnetic fluid. The effects of various preparation methods on the physical properties of the nanoparticles were examined. The nanoparticles were also tested against four human pathogenic bacteria (Gram negative E.coli, P. aeruginosa, Gram positive S. aureus, S. pyogenus) and two fungi (C. albicans, A.niger). It was revealed that a nanoparticle has strong antibacterial activity as compared to antifungal. Further, Gram positive bacteria are more affected than Gram negative bacteria. It was also clear that different methods of coating have great influence on the antimicrobial properties. It was observed that these nanoparticles have significantly different but potentially very high antimicrobial activities against the tested organisms than found elsewhere by other nanoparticles on the same organisms.

Bioinspired synthesis of magnetic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

David, Anand [Iowa State Univ., Ames, IA (United States)

2009-01-01

The synthesis of magnetic nanoparticles has long been an area of active research. Magnetic nanoparticles can be used in a wide variety of applications such as magnetic inks, magnetic memory devices, drug delivery, magnetic resonance imaging (MRI) contrast agents, and pathogen detection in foods. In applications such as MRI, particle uniformity is particularly crucial, as is the magnetic response of the particles. Uniform magnetic particles with good magnetic properties are therefore required. One particularly effective technique for synthesizing nanoparticles involves biomineralization, which is a naturally occurring process that can produce highly complex nanostructures. Also, the technique involves mild conditions (ambient temperature and close to neutral pH) that make this approach suitable for a wide variety of materials. The term 'bioinspired' is important because biomineralization research is inspired by the naturally occurring process, which occurs in certain microorganisms called 'magnetotactic bacteria'. Magnetotactic bacteria use biomineralization proteins to produce magnetite crystals having very good uniformity in size and morphology. The bacteria use these magnetic particles to navigate according to external magnetic fields. Because these bacteria synthesize high quality crystals, research has focused on imitating aspects of this biomineralization in vitro. In particular, a biomineralization iron-binding protein found in a certain species of magnetotactic bacteria, magnetospirillum magneticum, AMB-1, has been extracted and used for in vitro magnetite synthesis; Pluronic F127 gel was used to increase the viscosity of the reaction medium to better mimic the conditions in the bacteria. It was shown that the biomineralization protein mms6 was able to facilitate uniform magnetite synthesis. In addition, a similar biomineralization process using mms6 and a shorter version of this protein, C25, has been used to synthesize cobalt ferrite

Boron-capped tris(glyoximato) cobalt clathrochelate as a precursor for the electrodeposition of nanoparticles catalyzing H2 evolution in water.

Science.gov (United States)

Anxolabéhère-Mallart, Elodie; Costentin, Cyrille; Fournier, Maxime; Nowak, Sophie; Robert, Marc; Savéant, Jean-Michel

2012-04-11

Electrochemical investigation of a boron-capped tris(glyoximato)cobalt clathrochelate complex in the presence of acid reveals that the catalytic activity toward hydrogen evolution results from an electrodeposition of cobalt-containing nanoparticles on the electrode surface at a modest cathodic potential. The deposited particles act as remarkably active catalysts for H(2) production in water at pH 7. © 2012 American Chemical Society

Correlation of reactivity with structural factors in a series of Fe(II) substituted cobalt ferrites

International Nuclear Information System (INIS)

Sileo, Elsa E.; Garcia Rodenas, Luis; Paiva-Santos, Carlos O.; Stephens, Peter W.; Morando, Pedro J.; Blesa, Miguel A.

2006-01-01

A series of powdered cobalt ferrites, Co x Fe 3- x O 4 with 0.66≤x II , were synthesized by a mild procedure, and their Fe and Co site occupancies and structural characteristics were explored using X-ray anomalous scattering and the Rietveld refinement method. The dissolution kinetics, measured in 0.1 M oxalic acid aqueous solution at 70 deg. C, indicate in all cases the operation of a contracting volume rate law. The specific rates increased with the Fe II content following approximately a second-order polynomial expression. This result suggests that the transfer of Fe III controls the dissolution rate, and that the leaching of a first layer of ions Co II and Fe II leaves exposed a surface enriched in slower dissolving octahedral Fe III ions. Within this model, inner vicinal lattice Fe II accelerates the rate of Fe III transfer via internal electron hopping. A chain mechanism, involving successive electron transfers, fits the data very well. - Graphical abstract: The electron exchange between octahedral Fe II and Fe III ions has important consequences on the specific dissolution rates. Display Omitted

Use of magnetic nanoparticles to enhance bioethanol production in syngas fermentation.

Science.gov (United States)

Kim, Young-Kee; Lee, Haryeong

2016-03-01

The effect of two types of nanoparticles on the enhancement of bioethanol production in syngas fermentation by Clostridium ljungdahlii was examined. Methyl-functionalized silica and methyl-functionalized cobalt ferrite-silica (CoFe2O4@SiO2-CH3) nanoparticles were used to improve syngas-water mass transfer. Of these, CoFe2O4@SiO2-CH3 nanoparticles showed better enhancement of syngas mass transfer. The nanoparticles were recovered using a magnet and reused five times to evaluate reusability, and it was confirmed that their capability for mass transfer enhancement was maintained. Both types of nanoparticles were applied to syngas fermentation, and production of biomass, ethanol, and acetic acid was enhanced. CoFe2O4@SiO2-CH3 nanoparticles were more efficient for the productivity of syngas fermentation due to improved syngas mass transfer. The biomass, ethanol, and acetic acid production compared to a control were increased by 227.6%, 213.5%, and 59.6%, respectively by addition of CoFe2O4@SiO2-CH3 nanoparticles. The reusability of the nanoparticles was confirmed by reuse of recovered nanoparticles for fermentation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Water dispersible superparamagnetic Cobalt iron oxide nanoparticles for magnetic fluid hyperthermia

Energy Technology Data Exchange (ETDEWEB)

Salunkhe, Ashwini B. [Centre for advanced materials research, Department of Physics, Savitribai Phule Pune University, Pune 411007 (India); Soft matter and molecular biophysics group, Department of Applied Physics, University of Santiago de Compostela, Santiago de Compostela (Spain); Khot, Vishwajeet M. [Department of Physics and Astronomy, University College London (United Kingdom); Ruso, Juan M. [Soft matter and molecular biophysics group, Department of Applied Physics, University of Santiago de Compostela, Santiago de Compostela (Spain); Patil, S.I., E-mail: patil@physics.unipune.ac.in [Centre for advanced materials research, Department of Physics, Savitribai Phule Pune University, Pune 411007 (India)

2016-12-01

Superparamagnetic nanoparticles of Cobalt iron oxide (CoFe{sub 2}O{sub 4}) are synthesized chemically, and dispersed in an aqueous suspension for hyperthermia therapy application. Different parameters such as magnetic field intensity, particle concentration which regulates the competence of CoFe{sub 2}O{sub 4} nanoparticle as a heating agents in hyperthermia are investigated. Specific absorption rate (SAR) decreases with increase in the particle concentration and increases with increase in applied magnetic field intensity. Highest value of SAR is found to be 91.84 W g{sup −1} for 5 mg. mL{sup −1} concentration. Oleic acid conjugated polyethylene glycol (OA-PEG) coated CoFe{sub 2}O{sub 4} nanoparticles have shown superior cyto-compatibility over uncoated nanoparticles to L929 mice fibroblast cell lines for concentrations below 2 mg. mL{sup −1}. Present work provides the underpinning for the use of CoFe{sub 2}O{sub 4} nanoparticles as a potential heating mediator for magnetic fluid hyperthermia. - Highlights: • Superparamagnetic, water dispersible CoFe{sub 2}O{sub 4} NPs were synthesized by simple and cost effective Co precipitation route. • Effect of coating on various physical and chemical properties of CoFe{sub 2}O{sub 4} NPs were studied. • The effect of coating on induction heating as well as biocompatibility of NPs were studied.

Synthesis and magnetic properties of Co.sub.1-x./sub.Zn.sub.x./sub.Fe.sub.2./sub.O.sub.4+γ./sub. nanoparticles as materials for magnetic fluid hyperthermia

Czech Academy of Sciences Publication Activity Database

Veverka, Miroslav; Veverka, Pavel; Jirák, Zdeněk; Kaman, Ondřej; Knížek, Karel; Maryško, Miroslav; Pollert, Emil; Závěta, Karel

2010-01-01

Roč. 322, č. 16 (2010), s. 2386-2389 ISSN 0304-8853 R&D Projects: GA AV ČR KAN200200651; GA AV ČR KJB100100701; GA MŠk MEB090901 Institutional research plan: CEZ:AV0Z10100521 Keywords : magnetic nanoparticle * cobalt zinc ferrite * precipitation * magnetic behavior * magnetic fluid hyperthermia Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.689, year: 2010

Antimicrobial Lemongrass Essential Oil—Copper Ferrite Cellulose Acetate Nanocapsules

Directory of Open Access Journals (Sweden)

Ioannis L. Liakos

2016-04-01

Full Text Available Cellulose acetate (CA nanoparticles were combined with two antimicrobial agents, namely lemongrass (LG essential oil and Cu-ferrite nanoparticles. The preparation method of CA nanocapsules (NCs, with the two antimicrobial agents, was based on the nanoprecipitation method using the solvent/anti-solvent technique. Several physical and chemical analyses were performed to characterize the resulting NCs and to study their formation mechanism. The size of the combined antimicrobial NCs was found to be ca. 220 nm. The presence of Cu-ferrites enhanced the attachment of LG essential oil into the CA matrix. The magnetic properties of the combined construct were weak, due to the shielding of Cu-ferrites from the polymeric matrix, making them available for drug delivery applications where spontaneous magnetization effects should be avoided. The antimicrobial properties of the NCs were significantly enhanced with respect to CA/LG only. This work opens novel routes for the development of organic/inorganic nanoparticles with exceptional antimicrobial activities.

Antimicrobial Lemongrass Essential Oil-Copper Ferrite Cellulose Acetate Nanocapsules.

Science.gov (United States)

Liakos, Ioannis L; Abdellatif, Mohamed H; Innocenti, Claudia; Scarpellini, Alice; Carzino, Riccardo; Brunetti, Virgilio; Marras, Sergio; Brescia, Rosaria; Drago, Filippo; Pompa, Pier Paolo

2016-04-20

Cellulose acetate (CA) nanoparticles were combined with two antimicrobial agents, namely lemongrass (LG) essential oil and Cu-ferrite nanoparticles. The preparation method of CA nanocapsules (NCs), with the two antimicrobial agents, was based on the nanoprecipitation method using the solvent/anti-solvent technique. Several physical and chemical analyses were performed to characterize the resulting NCs and to study their formation mechanism. The size of the combined antimicrobial NCs was found to be ca. 220 nm. The presence of Cu-ferrites enhanced the attachment of LG essential oil into the CA matrix. The magnetic properties of the combined construct were weak, due to the shielding of Cu-ferrites from the polymeric matrix, making them available for drug delivery applications where spontaneous magnetization effects should be avoided. The antimicrobial properties of the NCs were significantly enhanced with respect to CA/LG only. This work opens novel routes for the development of organic/inorganic nanoparticles with exceptional antimicrobial activities.

The intrinsic antimicrobial activity of citric acid-coated manganese ferrite nanoparticles is enhanced after conjugation with the antifungal peptide Cm-p5

Science.gov (United States)

Lopez-Abarrategui, Carlos; Figueroa-Espi, Viviana; Lugo-Alvarez, Maria B; Pereira, Caroline D; Garay, Hilda; Barbosa, João ARG; Falcão, Rosana; Jiménez-Hernández, Linnavel; Estévez-Hernández, Osvaldo; Reguera, Edilso; Franco, Octavio L; Dias, Simoni C; Otero-Gonzalez, Anselmo J

2016-01-01

Diseases caused by bacterial and fungal pathogens are among the major health problems in the world. Newer antimicrobial therapies based on novel molecules urgently need to be developed, and this includes the antimicrobial peptides. In spite of the potential of antimicrobial peptides, very few of them were able to be successfully developed into therapeutics. The major problems they present are molecule stability, toxicity in host cells, and production costs. A novel strategy to overcome these obstacles is conjugation to nanomaterial preparations. The antimicrobial activity of different types of nanoparticles has been previously demonstrated. Specifically, magnetic nanoparticles have been widely studied in biomedicine due to their physicochemical properties. The citric acid-modified manganese ferrite nanoparticles used in this study were characterized by high-resolution transmission electron microscopy, which confirmed the formation of nanocrystals of approximately 5 nm diameter. These nanoparticles were able to inhibit Candida albicans growth in vitro. The minimal inhibitory concentration was 250 µg/mL. However, the nanoparticles were not capable of inhibiting Gram-negative bacteria (Escherichia coli) or Gram-positive bacteria (Staphylococcus aureus). Finally, an antifungal peptide (Cm-p5) from the sea animal Cenchritis muricatus (Gastropoda: Littorinidae) was conjugated to the modified manganese ferrite nanoparticles. The antifungal activity of the conjugated nanoparticles was higher than their bulk counterparts, showing a minimal inhibitory concentration of 100 µg/mL. This conjugate proved to be nontoxic to a macrophage cell line at concentrations that showed antimicrobial activity. PMID:27563243

Manganese ferrite-based nanoparticles induce ex vivo, but not in vivo, cardiovascular effects

Directory of Open Access Journals (Sweden)

Nunes ADC

2014-07-01

Full Text Available Allancer DC Nunes,1 Laylla S Ramalho,2 Álvaro PS Souza,1 Elizabeth P Mendes,1,3 Diego B Colugnati,1 Nícholas Zufelato,2 Marcelo H Sousa,4 Andris F Bakuzis,2 Carlos H Castro1,3 1Department of Physiological Sciences, 2Physics Institute, Federal University of Goiás, Goiânia, Brazil; 3National Institute of Science and Technology in Nanobiopharmaceutics, Belo Horizonte, Brazil; 4Faculty of Ceilândia, University of Brasília, Brasília-DF, Brazil Abstract: Magnetic nanoparticles (MNPs have been used for various biomedical applications. Importantly, manganese ferrite-based nanoparticles have useful magnetic resonance imaging characteristics and potential for hyperthermia treatment, but their effects in the cardiovascular system are poorly reported. Thus, the objectives of this study were to determine the cardiovascular effects of three different types of manganese ferrite-based magnetic nanoparticles: citrate-coated (CiMNPs; tripolyphosphate-coated (PhMNPs; and bare magnetic nanoparticles (BaMNPs. The samples were characterized by vibrating sample magnetometer, X-ray diffraction, dynamic light scattering, and transmission electron microscopy. The direct effects of the MNPs on cardiac contractility were evaluated in isolated perfused rat hearts. The CiMNPs, but not PhMNPs and BaMNPs, induced a transient decrease in the left ventricular end-systolic pressure. The PhMNPs and BaMNPs, but not CiMNPs, induced an increase in left ventricular end-diastolic pressure, which resulted in a decrease in a left ventricular end developed pressure. Indeed, PhMNPs and BaMNPs also caused a decrease in the maximal rate of left ventricular pressure rise (+dP/dt and maximal rate of left ventricular pressure decline (–dP/dt. The three MNPs studied induced an increase in the perfusion pressure of isolated hearts. BaMNPs, but not PhMNPs or CiMNPs, induced a slight vasorelaxant effect in the isolated aortic rings. None of the MNPs were able to change heart

Preparation of Mn-Zn ferrite nanoparticles and their silica-coated clusters: Magnetic properties and transverse relaxivity

Energy Technology Data Exchange (ETDEWEB)

Kaman, Ondřej, E-mail: kamano@seznam.cz [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic); Kuličková, Jarmila [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic); Herynek, Vít [Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, 140 21 Praha 4 (Czech Republic); Koktan, Jakub [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic); University of Chemistry and Technology, Prague, Technická 5, 166 28 Praha 6 (Czech Republic); Maryško, Miroslav [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic); Dědourková, Tereza [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic); University of Pardubice, Doubravice 41, 532 10 Pardubice (Czech Republic); Knížek, Karel; Jirák, Zdeněk [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic)

2017-04-01

Hydrothermal synthesis of Mn{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} nanoparticles followed by direct encapsulation of the as-grown material into silica is demonstrated as a fast and facile method for preparation of efficient negative contrast agents based on clusters of ferrite crystallites. At first, the hydrothermal procedure is optimized to achieve strictly single-phase magnetic nanoparticles of Mn-Zn ferrites in the compositional range of x≈0.2–0.6 and with the mean size of crystallites ≈10 nm. The products are characterized by powder X-ray diffraction, X-ray fluorescence spectroscopy, and SQUID magnetometry, and the composition close to x=0.4 is selected for the preparation of silica-coated clusters with the mean diameter of magnetic cores ≈25 nm. Their composite structure is studied by means of transmission electron microscopy combined with detailed image analysis and magnetic measurements in DC fields. The relaxometric studies, performed in the magnetic field of B{sub 0}=0.5 T, reveal high transverse relaxivity (r{sub 2}(20 °C)=450 s{sup −1} mmol(Me{sub 3}O{sub 4}){sup −1} L) with a pronounced temperature dependence, which correlates with the observed temperature dependence of magnetization and is ascribed to a mechanism of transverse relaxation similar to the motional averaging regime. - Highlights: • Mn-Zn ferrite particles with size of ≈10 nm are synthesized by hydrothermal method. • Their structure and magnetic properties are analysed in dependence on composition. • Silica-coated clusters with the size ≈26 nm are prepared as contrast agent for MRI. • Their transverse relaxivity shows strong temperature dependence.

Magnetic properties of Co{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} spinel ferrite nanoparticles synthesized by starch-assisted sol–gel autocombustion method and its ball milling

Energy Technology Data Exchange (ETDEWEB)

Yadav, Raghvendra Singh, E-mail: yadav@fch.vutbr.cz [Materials Research Centre, Brno University of Technology, Purkyňova 464/118, 61200 Brno (Czech Republic); Havlica, Jaromir [Materials Research Centre, Brno University of Technology, Purkyňova 464/118, 61200 Brno (Czech Republic); Hnatko, Miroslav; Šajgalík, Pavol [Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, SK-845 36 Bratislava (Slovakia); Alexander, Cigáň [Institute of Measurement Science, Slovak Academy of Sciences, Dúbravská cesta 9, SK-841 04 Bratislava (Slovakia); Palou, Martin; Bartoníčková, Eva; Boháč, Martin; Frajkorová, Františka; Masilko, Jiri; Zmrzlý, Martin; Kalina, Lukas; Hajdúchová, Miroslava; Enev, Vojtěch [Materials Research Centre, Brno University of Technology, Purkyňova 464/118, 61200 Brno (Czech Republic)

2015-03-15

In this article, Co{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} (x=0.0 and 0.5) spinel ferrite nanoparticles were achieved at 800 °C by starch-assisted sol–gel autocombustion method. To further reduce the particle size, these synthesized ferrite nanoparticles were ball-milled for 2 h. X-ray diffraction patterns demonstrated single phase formation of Co{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} (x=0.0 and 0.5) spinel ferrite nanoparticles. FE-SEM analysis indicated the nanosized spherical particles formation with spherical morphology. The change in Raman modes and relative intensity were observed due to ball milling and consequently decrease of particle size and cationic redistribution. An X-ray Photoelectron Spectroscopy (XPS) result indicated that Co{sup 2+}, Zn{sup 2+} and Fe{sup 3+} exist in octahedral and tetrahedral sites. The cationic redistribution of Zn{sup 2+} and consequently Fe{sup 3+} occurred between octahedral and tetrahedral sites after ball-milling. The change in saturation magnetization (M{sub s}) and coercivity (H{sub c}) with decrease of nanocrystalline size and distribution of cations in spinel ferrite were observed. - Highlights: • Co{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} spinel ferrite nanoparticles. • Starch-assisted sol–gel auto-combustion method. • Effect of ball-milling on particle size and cation distribution. • Magnetic property dependent on cations and particle size.

Structural, morphological and magnetic properties of Eu-doped CoFe2O4 nano-ferrites

Directory of Open Access Journals (Sweden)

Aiman Zubair

Full Text Available Europium (Eu doped spinel cobalt ferrites having composition CoEuxFe2−xO4 where x = 0.00, 0.03, 0.06, 0.09, 0.12 were fabricated by co-precipitation route. In order to observe the phase development of the ferrite samples, thermo-gravimetric analysis was carried out. The synthesized samples were subjected to X-ray diffraction analysis for structural investigation. All the samples were found to constitute face centered cubic (FCC spinel structure belonging to Fd3m space group. Scanning electron microscopy revealed the formation of nanocrystalline grains with spherical shape. Energy dispersive X-ray spectra confirmed the presence of Co, Eu, Fe and O elements with no existence of any impurity. The magnetic hysteresis curves measured at room temperature exhibited ferrimagnetic behavior with maximum saturation magnetization (Ms of 65 emu/g and coercivity (Hc of 966 Oe. The origin of ferrimagnetism in Eu doped cobalt ferrites was discussed in detail with reverence to the allocation of Co2+ and Fe3+ ions within the spinel lattice. The overall coercivity was increased (944–966 Oe and magnetization was decreased (65–46 emu/g with the substitution of Eu3+. The enhancement of former is ascribed to the transition from multi domain to single domain state and reduction in lateral is attributed to the incorporation of nonmagnetic Eu ions for Fe, resulting in weak superexchange interactions. Keywords: Europium doped cobalt ferrites, Co-precipitation, X-ray diffraction, Scanning electron microscopy, Magnetic properties

Attainment of barium hexa ferrite nanoparticles by a Pechini method

International Nuclear Information System (INIS)

Galvao, Sheila B.; Timoteo, Flavio Junior J.; Machado, Tercio G.; Souto, Kesia K.O.; Floreoto, Neide T.; Paskocimas, Carlos A.

2009-01-01

The barium hexa ferrites (BaFe 12 O 19 ) are used as a compound of materials applied in electronic devices, as medical devices, satellites, dada servers systems, wireless systems and others. The general properties are strongly related to the microstructure and morphology, and the particles size decrease results in advantages to the majority applications, mainly the high-tech thumbnail devices. These magnetic ceramic materials, with perovskite structure, are traditionally prepared my conventional oxide mixture synthesis. In this work was studied the nanoparticle synthesis of BaFe 12 O 19 by the precursors polymeric method (Pechini), using as precursors the barium carbonate and the iron nitrate, under different thermal treatment conditions. The samples were characterized by XRD, Raman spectroscopy, SEM, BET, DTA and TGA. The results presented the attainment of a monophasic powder with particles size around 100 nm. (author)

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.

Structural and magnetic properties of Ni0.8M0.2Fe2O4 (M = Cu, Co) nano-crystalline ferrites

Science.gov (United States)

Vijaya Babu, K.; Satyanarayana, G.; Sailaja, B.; Santosh Kumar, G. V.; Jalaiah, K.; Ravi, M.

2018-06-01

Nano-crystalline nickel ferrites are interesting materials due to their large physical and magnetic properties. In the present work, two kinds of spinel ferrites Ni0.8M0.2Fe2O4 (M = Cu, Co) are synthesized by using sol-gel auto-combustion method and the results are compared with NiFe2O4. The structural properties of synthesized ferrites are determined by using X-ray powder diffraction; scanning electron microscope and Fourier transform infrared spectroscopy. The cation distribution obtained from X-ray diffraction show that cobalt/copper occupies only tetrahedral site in spinel lattice. The lattice constant increases with the substitution of cobalt/copper. The structural parameters like bond lengths, tetrahedral and octahedral edges have been varied with the substitution. The microstructural study is carried out by using SEM technique and the average grain size is increased with nickel ferrite. The initial permeability (μi) is improving with the substitution. The observed g-value from ESR is approximately equal to standard value.

Preparation of single-crystal copper ferrite nanorods and nanodisks

International Nuclear Information System (INIS)

Du Jimin; Liu Zhimin; Wu Weize; Li Zhonghao; Han Buxing; Huang Ying

2005-01-01

This article, for the first time, reports the preparation of single-crystal copper ferrite nanorods and nanodisks. Using amorphous copper ferrite nanoparticles synthesized by reverse micelle as reaction precursor, single-crystal copper ferrite nanorods were synthesized via hydrothermal method in the presence of surfactant polyethylene glycol (PEG), however, copper ferrite nanodisks were prepared through the same procedures except the surfactant PEG. The resulting nanomaterials have been characterized by powder X-ray diffraction (XRD), selected electron area diffraction (SEAD), and transmission electron microscopy (TEM). The bulk composition of the samples was determined by means of X-ray photoelectron spectroscopy (XPS)

Atomistic structure of cobalt-phosphate nanoparticles for catalytic water oxidation.

Science.gov (United States)

Hu, Xiao Liang; Piccinin, Simone; Laio, Alessandro; Fabris, Stefano

2012-12-21

Solar-driven water splitting is a key photochemical reaction that underpins the feasible and sustainable production of solar fuels. An amorphous cobalt-phosphate catalyst (Co-Pi) based on earth-abundant elements has been recently reported to efficiently promote water oxidation to protons and dioxygen, a main bottleneck for the overall process. The structure of this material remains largely unknown. We here exploit ab initio and classical atomistic simulations combined with metadynamics to build a realistic and statistically meaningful model of Co-Pi nanoparticles. We demonstrate the emergence and stability of molecular-size ordered crystallites in nanoparticles initially formed by a disordered Co-O network and phosphate groups. The stable crystallites consist of bis-oxo-bridged Co centers that assemble into layered structures (edge-sharing CoO(6) octahedra) as well as in corner- and face-sharing cubane units. These layered and cubane motifs coexist in the crystallites, which always incorporate disordered phosphate groups at the edges. Our computational nanoparticles, although limited in size to ~1 nm, can contain more than one crystallite and incorporate up to 18 Co centers in the cubane/layered structures. The crystallites are structurally stable up to high temperatures. We simulate the extended X-ray absorption fine structure (EXAFS) of our nanoparticles. Those containing several complete and incomplete cubane motifs-which are believed to be essential for the catalytic activity-display a very good agreement with the experimental EXAFS spectra of Co-Pi grains. We propose that the crystallites in our nanoparticles are reliable structural models of the Co-Pi catalyst surface. They will be useful to reveal the origin of the catalytic efficiency of these novel water-oxidation catalysts.

Generation of Transparent Oxygen Evolution Electrode Consisting of Regularly Ordered Nanoparticles from Self-Assembly Cobalt Phthalocyanine as a Template

KAUST Repository

Ziani, Ahmed; Shinagawa, Tatsuya; Stegenburga, Liga; Takanabe, Kazuhiro

2016-01-01

of the nanoparticles, and transparency of the catalysts. In this study, we present a systematic study of the structural and optical properties, surface morphologies, and electrochemical oxygen evolution reaction (OER) performance of cobalt oxide prepared from a

Rhodamine B removal on A-rGO/cobalt oxide nanoparticles composite by adsorption from contaminated water

Science.gov (United States)

Alwan, Salam H.; Alshamsi, Hassan A. Habeeb; Jasim, Layth S.

2018-06-01

Cobalt oxide nanoparticles@rGO composite is prepared by using graphene oxide (GO) as a supporting substance. GO is first treated with ascorbic acid to form rGO. Finally, cobalt oxide nanoparticles reaction with rGO sheets and using as the adsorbent to removal Rh.B dye from wastewater. The morphology and chemical structure of prepared samples were characterized by FTIR, X-ray spectroscopy, SEM-EDX, TEM, AFM and TGA. The adsorption of Rh.B dye on the A-rGO/Co3O4 composite was accomplished under different conditions that are equilibrium time, pH solution, ionic strength, and temperature. The adsorption isotherms of Rh.B dye on the A-rGO/Co3O4 composite could be illustrated well by the Langmuir, Freundlich and Tempkin model. The thermodynamic factors (ΔHo, ΔSo, and ΔGo) estimated from the temperature-dependent isotherms revealed that the adsorption reaction of Rh.B dye on the A-rGO/Co3O4 composite was an endothermic and spontaneous process.

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.

Generation of Transparent Oxygen Evolution Electrode Consisting of Regularly Ordered Nanoparticles from Self-Assembly Cobalt Phthalocyanine as a Template

KAUST Repository

Ziani, Ahmed

2016-11-04

The decoration of (photo)electrodes for efficient photoresponse requires the use of electrocatalysts with good dispersion and high transparency for efficient light absorption by the photoelectrode. As a result of the ease of thermal evaporation and particulate self-assembly growth, the phthalocyanine molecular species can be uniformly deposited layer-by-layer on the surface of substrates. This structure can be used as a template to achieve a tunable amount of catalysts, high dispersion of the nanoparticles, and transparency of the catalysts. In this study, we present a systematic study of the structural and optical properties, surface morphologies, and electrochemical oxygen evolution reaction (OER) performance of cobalt oxide prepared from a phthalocyanine metal precursor. Cobalt phthalocyanine (CoPc) films with different thicknesses were deposited by thermal evaporation on different substrates. The films were annealed at 400 °C in air to form a material with the cobalt oxide phase. The final Co oxide catalysts exhibit high transparency after thermal treatment. Their OER measurements demonstrate well expected mass activity for OER. Thermally evaporated and treated transition metal oxide nanoparticles are attractive for the functionalization of (photo)anodes for water oxidation.

Structural, dielectric and magnetic properties of cobalt ferrite prepared using auto combustion and ceramic route

International Nuclear Information System (INIS)

Murugesan, C.; Perumal, M.; Chandrasekaran, G.

2014-01-01

Cobalt ferrite is synthesized by using low temperature auto combustion and high temperature ceramic methods. The prepared samples have values of lattice constant equal to 8.40 Å and 8.38 Å for auto combustion and ceramic methods respectively. The FTIR spectrum of samples of the auto combustion method shows a high frequency vibrational band at 580 cm −1 assigned to tetrahedral site and a low frequency vibrational band at 409 cm −1 assigned to octahedral site which are shifted to 590 cm −1 and 412 cm −1 for the ceramic method sample. SEM micrographs of samples show a substantial difference in surface morphology and size of the grains between the two methods. The frequency dependent dielectric constant and ac conductivity of the samples measured from 1 Hz to 2 MHz at room temperature are reported. The room temperature magnetic hysteresis parameters of the samples are measured using VSM. The measured values of saturation magnetization, coercivity and remanent magnetization are 42 emu/g, 1553 Oe, 18.5 emu/g for the auto combustion method, 66.7 emu/g, 379.6 Oe, and 17.3 emu/g for the ceramic method, respectively. The difference in preparation methods and size of the grains causes interesting changes in electrical and magnetic properties

Cellulose-precursor synthesis of nanocrystalline Co0.5Cu0.5Fe2O4 spinel ferrites

International Nuclear Information System (INIS)

Ounnunkad, Kontad; Phanichphant, Sukon

2012-01-01

Highlights: ► Synthesis of spinel copper cobalt nanoferrite particles from a cellulose precursor for the first time. Control of nanosize and properties of nanoferrites can take place by varying the calcining temperature. The simple, low cost, easy cellulose process is a choice of nanoparticle processing technology. -- Abstract: Nanocrystalline Cu 0.5 Co 0.5 Fe 2 O 4 powders were prepared via a metal-cellulose precursor synthetic route. Cellulose was used as a fuel and a dispersing agent. The resulting precursors were calcined in the temperature range of 450–600 °C. The phase development of the samples was determined by using Fourier transform infrared (FT-IR) spectroscopy and powder X-ray diffraction (XRD). The field-dependent magnetizations of the nanopowders were measured by vibrating sample magnetometer (VSM). All XRD patterns are of a spinel ferrite with cubic symmetry. Microstructure of the ferrites showed irregular shapes and uniform particles with agglomeration. From XRD data, the crystallite sizes are in range of 16–42 nm. Saturation magnetization and coercivity increased with increasing calcining temperature due to enhancement of crystallinity and reduction of oxygen vacancies.

Functionalized bismuth ferrite harmonic nanoparticles for cancer cells labeling and imaging

Energy Technology Data Exchange (ETDEWEB)

Passemard, Solène; Staedler, Davide; Sonego, Giona [Ecole Polytechnique Fédérale de Lausanne, Institute of Chemical Sciences and Engineering (Switzerland); Magouroux, Thibaud [Université de Genève, GAP-Biophotonics (Switzerland); Schneiter, Guillaume Stéphane [Ecole Polytechnique Fédérale de Lausanne, Institute of Chemical Sciences and Engineering (Switzerland); Juillerat-Jeanneret, Lucienne [University Institute of Pathology, CHUV-UNIL (Switzerland); Bonacina, Luigi [Université de Genève, GAP-Biophotonics (Switzerland); Gerber-Lemaire, Sandrine, E-mail: Sandrine.Gerber@epfl.ch [Ecole Polytechnique Fédérale de Lausanne, Institute of Chemical Sciences and Engineering (Switzerland)

2015-10-15

Bismuth ferrite (BFO) harmonic nanoparticles (NPs) display high nonlinear optical efficiency and excellent biocompatibility profile which make them attractive for the development of diagnostic applications as contrast agents. In this study, we present a general method for the functionalization of this material with chemical ligands targeting cancer molecular biomarkers. In particular, a conjugation protocol based on click reaction between alkynyl-containing targeting ligands and poly(ethylene glycol)-coated BFO NPs (67.7 nm) displaying surface reactive azido groups was developed. Copper-free click reaction allowed fast and efficient conjugation of a covalent inhibitor of prolyl-specific endopeptidases to coated BFO NPs. The ability of these functionalized nanomaterials (134.2 nm) to act as imaging probes for cancer cells was demonstrated by the selective labeling of human lung cancer cells.

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.

Hyperthermic effect of magnetic nanoparticles under electromagnetic field

Directory of Open Access Journals (Sweden)

Giovanni Baldi

2009-06-01

Full Text Available Magnetic nanoparticles have attracted increasingly attention due to their potential applications in many industrial fields, even extending their use in biomedical applications. In the latter contest the main features of magnetic nanoparticles are the possibility to be driven by external magnetic fields, the ability to pass through capillaries without occluding them and to absorb and convert electromagnetic radiation in to heat (Magnetic Fluid Hyperthermia. The main challenges of the current works on hyperthermia deal with the achievement of highly efficiency magnetic nanoparticles, the surface grafting with ligands able to facilitate their specific internalisation in tumour cells and the design of stealth nanocomposites able to circulate in the blood compartment for a long time. This article presents the synthesis of cobalt ferrite nanoparticles dispersed in diethylene glycol via the so called polyol strategy and the crystal size control through successive synthesis steps. Preliminary heat dissipation evaluations on the prepared samples were carried out and the question of how particles sizes affect their magnetic and hyperthermic properties was addressed as well. Furthermore we will present how surface chemistry can be modified in order to change the dispersity of the product without affecting magnetic and hyperthermic properties.

Influence of multiwalled carbon nanotube addition on the magnetic and reflection-loss characteristics of Mn–Sn–Ti substituted strontium ferrite nanoparticles

International Nuclear Information System (INIS)

Jamalian, Majid; Ghasemi, Ali; Paimozd, Ebrahim

2014-01-01

Highlights: • Structural properties of nanocomposites were investigated. • The microwave absorbing characteristics were studied. • The synthesized materials are proper candidates for electromagnetic wave absorber. - Abstract: In this work, Mn–Sn–Ti substituted strontium ferrite (Sr-ferrite:SrM) nanoparticles were attached on the outer surface of varied multi-walled carbon nanotubes volume fraction with the amount of 10, 15, 20, 25 and 30, by employing of the sol–gel method. The phase identification and morphologies of the nanocomposites were characterized by X-ray diffraction and field emission scanning microscopy respectively. The obtained results showed that the single phase SrFe 9.5 (Mn 1.25 Sn 0.625 Ti 0.625 ) O 19 nanoparticles were decorated on MWCNTs can be obtained at 900 °C. Fourier transform infrared revealed that both the stretching and the bending modes are formed in the citrate complex in the ferrite and hydroxyl and carboxyl groups on the external surface of MWCNTs. The Magnetic properties were measured by a vibrating sample magnetometer. It was found that saturation magnetization, remanent magnetization and coercivity decrease by an increase in the MWCNTs content from 10 to 30 vol%. The reflection loss measurement of the prepared absorber which contain the ratio of 70–30 mass% for the nanocomposite to the polyvinyl chloride, done by the vector network analyzer, proved that the prepared nanocomposites have the maximum reflection loss of −28 dB at the frequency of 8.8 GHz for Mn–Ti–Sn substituted strontium ferrite −30 vol% MWCNT nanocomposite with a bandwidth of 4 GHz (RL > −10 dB)

Influence of multiwalled carbon nanotube addition on the magnetic and reflection-loss characteristics of Mn–Sn–Ti substituted strontium ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Jamalian, Majid, E-mail: mjscience@yahoo.com; Ghasemi, Ali; Paimozd, Ebrahim

2014-08-01

Highlights: • Structural properties of nanocomposites were investigated. • The microwave absorbing characteristics were studied. • The synthesized materials are proper candidates for electromagnetic wave absorber. - Abstract: In this work, Mn–Sn–Ti substituted strontium ferrite (Sr-ferrite:SrM) nanoparticles were attached on the outer surface of varied multi-walled carbon nanotubes volume fraction with the amount of 10, 15, 20, 25 and 30, by employing of the sol–gel method. The phase identification and morphologies of the nanocomposites were characterized by X-ray diffraction and field emission scanning microscopy respectively. The obtained results showed that the single phase SrFe{sub 9.5} (Mn{sub 1.25}Sn{sub 0.625}Ti{sub 0.625}) O{sub 19} nanoparticles were decorated on MWCNTs can be obtained at 900 °C. Fourier transform infrared revealed that both the stretching and the bending modes are formed in the citrate complex in the ferrite and hydroxyl and carboxyl groups on the external surface of MWCNTs. The Magnetic properties were measured by a vibrating sample magnetometer. It was found that saturation magnetization, remanent magnetization and coercivity decrease by an increase in the MWCNTs content from 10 to 30 vol%. The reflection loss measurement of the prepared absorber which contain the ratio of 70–30 mass% for the nanocomposite to the polyvinyl chloride, done by the vector network analyzer, proved that the prepared nanocomposites have the maximum reflection loss of −28 dB at the frequency of 8.8 GHz for Mn–Ti–Sn substituted strontium ferrite −30 vol% MWCNT nanocomposite with a bandwidth of 4 GHz (RL > −10 dB)

Influence of La3+ Substitution on Structure, Morphology and Magnetic Properties of Nanocrystalline Ni-Zn Ferrite.

Directory of Open Access Journals (Sweden)

Y K Dasan

Full Text Available Lanthanum substituted Ni-Zn ferrite nanoparticles (Ni0.5Zn0.5LaxFe1-xO4; 0.00 ≤x≤ 1.00 synthesized by sol-gel method were presented. X-ray diffraction patterns reveal the typical single phase spinel cubic ferrite structure, with the traces of secondary phase for lanthanum substituted nanocrystals. In addition, the structural analysis also demonstrates that the average crystallite size varied in the range of 21-25 nm. FTIR spectra present the two prominent absorption bands in the range of 400 to 600 cm-1 which are the fingerprint region of all ferrites. Surface morphology of both substituted and unsubstituted Ni-Zn ferrite nanoparticle samples was studied using FESEM technique and it indicates a significant increase in the size of spherical shaped particles with La3+ substitution. Magnetic properties of all samples were analyzed using vibrating sample magnetometer (VSM. The results revealed that saturation magnetization (Ms and coercivity (Hc of La3+ substituted samples has decreased as compared to the Ni-Zn ferrite samples. Hence, the observed results affirm that the lanthanum ion substitution has greatly influenced the structural, morphology and magnetic properties of Ni-Zn ferrite nanoparticles.

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.

Acid-functionalized nanoparticles for biomass hydrolysis

Science.gov (United States)

Pena Duque, Leidy Eugenia

Cellulosic ethanol is a renewable source of energy. Lignocellulosic biomass is a complex material composed mainly of cellulose, hemicellulose, and lignin. Biomass pretreatment is a required step to make sugar polymers liable to hydrolysis. Mineral acids are commonly used for biomass pretreatment. Using acid catalysts that can be recovered and reused could make the process economically more attractive. The overall goal of this dissertation is the development of a recyclable nanocatalyst for the hydrolysis of biomass sugars. Cobalt iron oxide nanoparticles (CoFe2O4) were synthesized to provide a magnetic core that could be separated from reaction using a magnetic field and modified to carry acid functional groups. X-ray diffraction (XRD) confirmed the crystal structure was that of cobalt spinel ferrite. CoFe2O4 were covered with silica which served as linker for the acid functions. Silica-coated nanoparticles were functionalized with three different acid functions: perfluoropropyl-sulfonic acid, carboxylic acid, and propyl-sulfonic acid. Transmission electron microscope (TEM) images were analyzed to obtain particle size distributions of the nanoparticles. Total carbon, nitrogen, and sulfur were quantified using an elemental analyzer. Fourier transform infra-red spectra confirmed the presence of sulfonic and carboxylic acid functions and ion-exchange titrations accounted for the total amount of catalytic acid sites per nanoparticle mass. These nanoparticles were evaluated for their performance to hydrolyze the beta-1,4 glycosidic bond of the cellobiose molecule. Propyl-sulfonic (PS) and perfluoropropyl-sulfonic (PFS) acid functionalized nanoparticles catalyzed the hydrolysis of cellobiose significantly better than the control. PS and PFS were also evaluated for their capacity to solubilize wheat straw hemicelluloses and performed better than the control. Although PFS nanoparticles were stronger acid catalysts, the acid functions leached out of the nanoparticle during

Transforming single domain magnetic CoFe_2O_4 nanoparticles from hydrophobic to hydrophilic by novel mechanochemical ligand exchange

International Nuclear Information System (INIS)

Munjal, Sandeep; Khare, Neeraj

2017-01-01

Single-phase uniform-sized (~9 nm) cobalt ferrite (CFO) nanoparticles have been synthesized by hydrothermal synthesis using oleic acid as a surfactant. The as-synthesized oleic acid-coated CFO (OA-CFO) nanoparticles were well dispersible in nonpolar solvents but not dispersible in water. The OA-CFO nanoparticles have been successfully transformed to highly water-dispersible citric acid-coated CFO (CA-CFO) nanoparticles using a novel single-step ligand exchange process by mechanochemical milling, in which small chain citric acid molecules replace the original large chain oleic acid molecules available on CFO nanoparticles. The OA-CFO nanoparticle’s hexane solution and CA-CFO nanoparticle’s water solution remain stable even after 6 months and show no agglomeration and their dispersion stability was confirmed by zeta-potential measurements. The contact angle measurement shows that OA-CFO nanoparticles are hydrophobic whereas CA-CFO nanoparticles are superhydrophilic in nature. The potentiality of as-synthesized OA-CFO and mechanochemically transformed CA-CFO nanoparticles for the demulsification of highly stabilized water-in-oil and oil-in-water emulsions has been demonstrated.

and aluminum-substituted cobalt ferrite prepared by co-precipitation ...

Indian Academy of Sciences (India)

Spinal ferrites having the general formula Co1-ZnFe2-AlO4 ( = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) were prepared using the wet chemical co-operation technique. The samples were annealed at 800°C for 12 h and were studied by means of X-ray diffraction, magnetization and low field AC susceptibility measurements.

The filler powders laser welding of ODS ferritic steels

Energy Technology Data Exchange (ETDEWEB)

Liang, Shenyong, E-mail: s_y_liang@126.com; Lei, Yucheng; Zhu, Qiang

2015-01-15

Laser welding was performed on Oxide Dispersion Strengthened (ODS) ferritic steel with the self-designed filler powders. The filler powders were added to weld metal to produce nano-particles (Y–M–O and TiC), submicron particles (Y–M–O) and dislocation rings. The generated particles were evenly distributed in the weld metal and their forming mechanism and behavior were analyzed. The results of the tests showed that the nano-particles, submicron particles and dislocation rings were able to improve the micro-hardness and tensile strength of welded joint, and the filler powders laser welding was an effective welding method of ODS ferritic steel.

Correlation of electronic and magnetic properties of thin polymer layers with cobalt nanoparticles

DEFF Research Database (Denmark)

Kharchenko, A.; Lukashevich, M.; Popok, Vladimir

2013-01-01

Nanoparticles (NPs) of cobalt are synthesized in shallow layers of polyimide using 40 keV implantation of Co+ ions with a few different fluences at various ion current densities. Nucleation of individual NPs at low fluencies and their percolation at high fluencies are crucial processes governing...... of the magnetoresistance on the applied magnetic field allows to suggest spin-dependent domain wall scattering affecting the electron transport. The samples implanted with low fluencies demonstrate superparamagnetic behavior down to very low blocking temperatures. While for high fluence (1.25x1017 cm-2) the transition...

A study of magnetoplumbite-type (M-type) cobalt-titanium-substituted barium ferrite, BaCo{sub x}Ti{sub x}Fe{sub 12-2x}O{sub 19} (x = 1-6)

Energy Technology Data Exchange (ETDEWEB)

Teh, G.B. [Department of Bioscience and Chemistry, Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, 53300 Kuala Lumpur (Malaysia)], E-mail: tehgb@mail.utar.edu.my; Saravanan, N. [Department of Bioscience and Chemistry, Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, 53300 Kuala Lumpur (Malaysia); Jefferson, D.A. [Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom)

2007-10-15

Cobalt(II)-titanium(IV)-substituted barium ferrite forming the chemical formula of BaCo{sub x}Ti{sub x}Fe{sub 12-2x}O{sub 19} (x = 1-6) have been investigated using X-ray diffraction spectroscopy (XRD), Superconducting Quantum Interference Device (SQUID) and high-resolution transmission electron microscopy (HRTEM). The specimen of magnetoplumbite (M-type) Co-Ti-substituted BaFe{sub 12}O{sub 19} were synthesised via sol-gel method using ethylene glycol as precursor. Significant increase in line broadening of the XRD patterns were observed indicating the decrease of particle sizes due to the Co(II)-Ti(IV) substitution. BaCo{sub 3}Ti{sub 3}Fe{sub 6}O{sub 19} showed the highest coercivity but moderate saturation and remnant magnetisations. HRTEM imaging showed that Co(II)-Ti(IV) substitution in the system of BaCo{sub x}Ti{sub x}Fe{sub 12-2x}O{sub 19} (x = 1-6) produced no drastic change in the structure of the M-type ferrites. Most of the M-types crystals examined by HRTEM displayed a long axis perpendicular to the c-axis of the M-type structure. Disordered crystals showing the intergrowth between Co-Ti-substituted barium ferrite and the spinel-structured iron oxide were detected.

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.

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

Transforming single domain magnetic CoFe{sub 2}O{sub 4} nanoparticles from hydrophobic to hydrophilic by novel mechanochemical ligand exchange

Energy Technology Data Exchange (ETDEWEB)

Munjal, Sandeep; Khare, Neeraj, E-mail: nkhare@physics.iitd.ernet.in [Indian Institute of Technology Delhi, Department of Physics (India)

2017-01-15

Single-phase uniform-sized (~9 nm) cobalt ferrite (CFO) nanoparticles have been synthesized by hydrothermal synthesis using oleic acid as a surfactant. The as-synthesized oleic acid-coated CFO (OA-CFO) nanoparticles were well dispersible in nonpolar solvents but not dispersible in water. The OA-CFO nanoparticles have been successfully transformed to highly water-dispersible citric acid-coated CFO (CA-CFO) nanoparticles using a novel single-step ligand exchange process by mechanochemical milling, in which small chain citric acid molecules replace the original large chain oleic acid molecules available on CFO nanoparticles. The OA-CFO nanoparticle’s hexane solution and CA-CFO nanoparticle’s water solution remain stable even after 6 months and show no agglomeration and their dispersion stability was confirmed by zeta-potential measurements. The contact angle measurement shows that OA-CFO nanoparticles are hydrophobic whereas CA-CFO nanoparticles are superhydrophilic in nature. The potentiality of as-synthesized OA-CFO and mechanochemically transformed CA-CFO nanoparticles for the demulsification of highly stabilized water-in-oil and oil-in-water emulsions has been demonstrated.

Cobalt magnetic nanoparticles embedded in carbon matrix: biofunctional validation

Energy Technology Data Exchange (ETDEWEB)

Krolow, Matheus Z., E-mail: matheuskrolow@ifsul.edu.br [Universidade Federal de Pelotas, Engenharia de Materiais, Centro de Desenvolvimento Tecnologico (Brazil); Monte, Leonardo G.; Remiao, Mariana H.; Hartleben, Claudia P.; Moreira, Angela N.; Dellagostin, Odir A. [Universidade Federal de Pelotas, Nucleo de Biotecnologia, Centro de Desenvolvimento Tecnologico (Brazil); Piva, Evandro [Universidade Federal de Pelotas, Faculdade de Odontologia (Brazil); Conceicao, Fabricio R. [Universidade Federal de Pelotas, Nucleo de Biotecnologia, Centro de Desenvolvimento Tecnologico (Brazil); Carreno, Neftali L. V. [Universidade Federal de Pelotas, Engenharia de Materiais, Centro de Desenvolvimento Tecnologico (Brazil)

2012-09-15

Carbon nanostructures and nanocomposites display versatile allotropic morphologies, physico-chemical properties and have a wide range of applications in mechanics, electronics, biotechnology, structural material, chemical processing, and energy management. In this study we report the synthesis, characterization, and biotechnological application of cobalt magnetic nanoparticles, with diameter approximately 15-40 nm, embedded in carbon structure (Co/C-MN). A single-step chemical process was used in the synthesis of the Co/C-MN. The Co/C-MN has presented superparamagnetic behavior at room temperature an essential property for immunoseparation assays carried out here. To stimulate interactions between proteins and Co/C-MN, this nanocomposite was functionalized with acrylic acid (AA). We have showed the bonding of different proteins onto Co/C-AA surface using immunofluorescence assay. A Co/C-AA coated with monoclonal antibody anti-pathogenic Leptospira spp. was able to capture leptospires, suggesting that it could be useful in immunoseparation assays.

Effect of pH value on electromagnetic loss properties of Co–Zn ferrite prepared via coprecipitation method

International Nuclear Information System (INIS)

Huang, Xiaogu; Zhang, Jing; Wang, Wei; Sang, Tianyi; Song, Bo; Zhu, Hongli; Rao, Weifeng; Wong, Chingping

2016-01-01

In this paper, the cobalt zinc ferrite was prepared by coprecipitation method at different pH conditions. The influence of pH values on the coprecipitation reaction was theoretically analyzed at first. The calculated results showed that the pH values should be controlled in the range of 9–11 to form the stable precipitation. The XRD investigation was used to further confirm the formation of the composite on specific pH values. In addition, the morphological study revealed that the average particle size of the composite decreased from 40 nm to 30 nm when the pH value increased from 9–11. The variation of microstructure plays a critical role in controlling the electromagnetic properties. From the electromagnetic analysis, the dielectric loss factor was 0.02–0.07 and magnetic loss factor was 0.2–0.5 for the composite synthesized at pH of 9, which presents dramatically improved dielectric loss and magnetic loss properties than the samples prepared at pH of 10 and 11. The as-prepared cobalt zinc ferrite are highly promising to be used as microwave absorption materials. - Highlights: • Co–Zn ferrite was prepared by coprecipitation method with different pH values. • To obtain pure Co–Zn ferrite, the theoretical pH values were 9–11. • Microstructure and electromagnetic properties can be tuned by varying pH values. • Co–Zn ferrite prepared with pH=9 performed well electromagnetic loss properties.

Mössbauer effect studies and X-ray diffraction analysis of cobalt ...

Indian Academy of Sciences (India)

Home; Journals; Bulletin of Materials Science; Volume 26; Issue 5. Mössbauer effect studies and X-ray diffraction analysis of cobalt ferrite prepared in powder form by thermal decomposition method. M D Joseph Sebastian B Rudraswamy M C Radhakrishna Ramani. Magnetic Materials Volume 26 Issue 5 August 2003 pp ...

Spectra study and size control of cobalt nanoparticles passivated with oleic acid and triphenylphosphine

International Nuclear Information System (INIS)

Su Yikun; Ouyang Xing; Tang Jiaoning

2010-01-01

This paper compares the performance of two surfactants-triphenylphosphine (TPP) and oleic acid (OA) as a pair of capping agents in the synthesis of magnetic Co nanoparticles (NPs). Magnetic colloids of cobalt NPs are prepared by reducing solute cobalt chloride in the presence of stabilizing agents at a high temperature and characterized by TEM. Infrared spectra reveal that a chemical bond can be formed between O of C=O band and Co atoms while a coordinate bond forms between P and Co atoms around the NPs on the surface. OA binds strongly to the particle surface during synthesis that hinders the particle from growing; the TPP reversibly coordinates neutral metal surface sites that favor rapid growth. We studied the influence of changing the TPP/OA concentration ratio on the particle size distribution and crystallinity of Co NPs. Our results indicate the presence of TPP/OA is able to control particle growth, stabilize the colloidal suspension and prevent the final product from oxidation by air.

Cobalt nanoparticles deposited and embedded in AlN: Magnetic, magneto-optical, and morphological properties

International Nuclear Information System (INIS)

Huttel, Y.; Gomez, H.; Clavero, C.; Cebollada, A.; Armelles, G.; Navarro, E.; Ciria, M.; Benito, L.; Arnaudas, J.I.; Kellock, A.J.

2004-01-01

We present a structural, morphological, magnetic, and magneto-optical study of cobalt nanoparticles deposited on 50 A ring AlN/c-sapphire substrates and embedded in an AlN matrix. The dependence of the properties of Co nanoclusters deposited on AlN with growth temperature and amount of deposited Co are studied and discussed. Also we directly compare the properties of as grown and AlN embedded Co nanoclusters and show that the AlN matrix has a strong impact on their magnetic and magneto-optical properties

Competitive Adsorption-Assisted Formation of One-Dimensional Cobalt Nanochains with High CO Hydrogenation Activity

Energy Technology Data Exchange (ETDEWEB)

Liang, Xin [State; Ren, Zhibo [State; Institute; Zhu, Xiaolin [State; Zhang, Qinwei [State; Mei, Donghai [Institute; Chen, Biaohua [State

2017-10-31

In the present work, cobalt nanochains have been successfully synthesized by a novel co assisted self-assembling formation strategy. A dramatic morphology transformation from cobalt nanoparticles to nanochains are observed when co molecules were introduced into the synthetic system. DFT calculations further confirm that competitive co-adsorbed co and oleylamine over the cobalt nanoparticles facilitates the formation of cobalt nanochains, which show higher co hydrogenation performance. The present work provides a new strategic and promising method for controllable synthesis of catalyst nanomaterials with the preferred surface structure and morphology.

Curcumin drug delivery by vanillin-chitosan coated with calcium ferrite hybrid nanoparticles as carrier.

Science.gov (United States)

Kamaraj, Sriram; Palanisamy, Uma Maheswari; Kadhar Mohamed, Meera Sheriffa Begum; Gangasalam, Arthanareeswaran; Maria, Gover Antoniraj; Kandasamy, Ruckmani

2018-04-30

The aim of the present investigation is the development, optimization and characterization of curcumin-loaded hybrid nanoparticles of vanillin-chitosan coated with super paramagnetic calcium ferrite. The functionally modified vanillin-chitosan was prepared by the Schiff base reaction to enhance the hydrophobic drug encapsulation efficiency. Calcium ferrite (CFNP) nano particles were added to the vanillin modified chitosan to improve the biocompatibility. The vanillin-chitosan-CFNP, hybrid nanoparticle carrier was obtained by ionic gelation method. Characterizations of the hybrid materials were performed by XRD, FTIR, 1 H NMR, TGA, AFM and SEM techniques to ensure the modifications on the chitosan material. Taguchi method was applied to optimize the drug (curcumin) encapsulation efficiency by varying the drug to chitosan-vanillin, CFNP to chitosan-vanillin and TPP (sodium tripolyphospate) to chitosan-vanillin ratios. The maximum encapsulation efficiency was obtained as 98.3% under the conditions of 0.1, 0.75 and 1.0 for the drug to chitosan-vanillin, CFNP to chitosan-vanillin and TPP to chitosan-vanillin ratios, respectively. The curcumin release was performed at various pH, initial drug loading concentrations and magnetic fields. The drug release mechanism was predicted by fitting the experimental kinetic data with various drug release models. The drug release profiles showed the best fit with Higuchi model under the most of conditions. The drug release mechanism followed both non-Fickian diffusion and case II transport mechanism for chitosan, however the non-Fickian diffusion mechanism was followed for the vanillin modified chitosan. The biocompatibility of the hybrid material was tested using L929 fibroblast cells. The cytotoxicity test was performed against MCF-7 breast cancer cell line to check the anticancer property of the hybrid nano carrier with the curcumin drug. Copyright © 2018 Elsevier B.V. All rights reserved.

Opto-electrochemical In Situ Monitoring of the Cathodic Formation of Single Cobalt Nanoparticles.

Science.gov (United States)

Brasiliense, Vitor; Clausmeyer, Jan; Dauphin, Alice L; Noël, Jean-Marc; Berto, Pascal; Tessier, Gilles; Schuhmann, Wolfgang; Kanoufi, Fréderic

2017-08-21

Single-particle electrochemistry at a nanoelectrode is explored by dark-field optical microscopy. The analysis of the scattered light allows in situ dynamic monitoring of the electrodeposition of single cobalt nanoparticles down to a radius of 65 nm. Larger sub-micrometer particles are directly sized optically by super-localization of the edges and the scattered light contains complementary information concerning the particle redox chemistry. This opto-electrochemical approach is used to derive mechanistic insights about electrocatalysis that are not accessible from single-particle electrochemistry. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

As-grown enhancement of spinodal decomposition in spinel cobalt ferrite thin films by Dynamic Aurora pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Debnath, Nipa [Graduate School of Science and Technology, Shizuoka University, Hamamatsu 432-8561 (Japan); Department of Physics, Jagannath University, Dhaka 1100 (Bangladesh); Kawaguchi, Takahiko; Kumasaka, Wataru [Department of Electronics and Materials Science, Shizuoka University, Hamamatsu 432-8561 (Japan); Das, Harinarayan [Materials Science Division, Atomic Energy Centre, Dhaka 1000 (Bangladesh); Shinozaki, Kazuo [School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo 152-8550 (Japan); Sakamoto, Naonori [Department of Electronics and Materials Science, Shizuoka University, Hamamatsu 432-8561 (Japan); Research Institute of Electronics, Shizuoka University, Hamamatsu 432-8561 (Japan); Suzuki, Hisao [Graduate School of Science and Technology, Shizuoka University, Hamamatsu 432-8561 (Japan); Department of Electronics and Materials Science, Shizuoka University, Hamamatsu 432-8561 (Japan); Research Institute of Electronics, Shizuoka University, Hamamatsu 432-8561 (Japan); Wakiya, Naoki, E-mail: wakiya.naoki@shizuoka.ac.jp [Graduate School of Science and Technology, Shizuoka University, Hamamatsu 432-8561 (Japan); Department of Electronics and Materials Science, Shizuoka University, Hamamatsu 432-8561 (Japan); Research Institute of Electronics, Shizuoka University, Hamamatsu 432-8561 (Japan)

2017-06-15

Highlights: • As-grown enhancement of spinodal decomposition (SD) in Co{sub x}Fe{sub 3−x}O{sub 4} film is observed. • Magnetic-field-induced ion-impingement enhances SD without any post-annealing. • The enhancement of SD is independent of the lattice-mismatch-induced strain. • This approach can promote SD in any thin film without post-deposition annealing. - Abstract: Cobalt ferrite Co{sub x}Fe{sub 3−x}O{sub 4} thin films with composition within the miscibility gap were grown using Dynamic Aurora pulsed laser deposition. X-ray diffraction patterns reveal as-grown phase separation to Fe-rich and Co-rich phases with no post-deposition annealing. The interconnected surface microstructure of thin film shows that this phase separation occurs through spinodal decomposition enhanced by magnetic-field-induced ion-impingement. The lattice parameter variation of the thin films with the magnetic field indicates that the composition fluctuations can be enhanced further by increasing the magnetic field. Results show that spinodal decomposition enhancement by magnetic-field-induced ion-impingement is independent of the lattice-mismatch-induced strain. This approach can promote spinodal decomposition in any thin film with no post-deposition annealing process.

Composition tunable cobalt–nickel and cobalt–iron alloy nanoparticles below 10 nm synthesized using acetonated cobalt carbonyl

International Nuclear Information System (INIS)

Schooneveld, Matti M. van; Campos-Cuerva, Carlos; Pet, Jeroen; Meeldijk, Johannes D.; Rijssel, Jos van; Meijerink, Andries; Erné, Ben H.; Groot, Frank M. F. de

2012-01-01

A general organometallic route has been developed to synthesize Co x Ni 1−x and Co x Fe 1−x alloy nanoparticles with a fully tunable composition and a size of 4–10 nm with high yield. In contrast to previously reported synthesis methods using dicobalt octacarbonyl (Co 2 (CO) 8 ), here the cobalt–cobalt bond in the carbonyl complex is first broken with anhydrous acetone. The acetonated compound, in the presence of iron carbonyl or nickel acetylacetonate, is necessary to obtain small composition tunable alloys. This new route and insights will provide guidelines for the wet-chemical synthesis of yet unmade bimetallic alloy nanoparticles.

Structural, electrical and magnetic properties of Sc{sup 3+} doped Mn-Zn ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Angadi, V. Jagdeesha [Department of Physics, Bangalore University, Bangalore 560056 (India); Choudhury, Leema [Department of Physics, K.G. Reddy College of Engineering & Technology, Moinabad, 501504 Ranga Reddy, Telangana (India); Sadhana, K. [Department of Physics, University College of Science, Osmania University, Saifabad, Hyderabad 500004 (India); Liu, Hsiang-Lin [Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan (China); Sandhya, R. [Department of Physics, University College of Science, Osmania University, Hyderabad 500007 (India); Matteppanavar, Shidaling; Rudraswamy, B.; Pattar, Vinayak; Anavekar, R.V. [Department of Physics, Bangalore University, Bangalore 560056 (India); Praveena, K., E-mail: praveenaou@gmail.com [Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan (China)

2017-02-15

Sc{sup 3+} doped Mn{sub 0.5}Zn{sub 0.5}Sc{sub y}Fe{sub 2−y}O{sub 4} (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{sup −1} and 540 cm{sup −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 (Sc{sup 3+}) on the characteristic properties of Mn-Zn ferrites. Further, the frequency dependent dielectric constant and dielectric loss were found to decrease with increasing multiple Sc{sup 3+} concentration. Nyquist plot in the complex impedance spectra suggest the existence of multiple electrical responses. Magnetic measurements reveals that saturation magnetization (M{sub s}), remnant magnetization (M{sub r}), magnetic moment (η{sub B}) and magnetic particle size (D{sub m}) increase with Sc{sup 3+} ion concentration up to x=0.03 and then decrease. The values of spin canting angle (α{sub Y-K}) and the magnetic particle size (D{sub m}) are found to be in the range of 68–75° and 10–19 nm respectively with Sc{sup 3+} 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

Cobalt magnetic nanoparticles embedded in carbon matrix: biofunctional validation

International Nuclear Information System (INIS)

Krolow, Matheus Z.; Monte, Leonardo G.; Remião, Mariana H.; Hartleben, Cláudia P.; Moreira, Ângela N.; Dellagostin, Odir A.; Piva, Evandro; Conceição, Fabricio R.; Carreño, Neftalí L. V.

2012-01-01

Carbon nanostructures and nanocomposites display versatile allotropic morphologies, physico-chemical properties and have a wide range of applications in mechanics, electronics, biotechnology, structural material, chemical processing, and energy management. In this study we report the synthesis, characterization, and biotechnological application of cobalt magnetic nanoparticles, with diameter approximately 15–40 nm, embedded in carbon structure (Co/C-MN). A single-step chemical process was used in the synthesis of the Co/C-MN. The Co/C-MN has presented superparamagnetic behavior at room temperature an essential property for immunoseparation assays carried out here. To stimulate interactions between proteins and Co/C-MN, this nanocomposite was functionalized with acrylic acid (AA). We have showed the bonding of different proteins onto Co/C-AA surface using immunofluorescence assay. A Co/C-AA coated with monoclonal antibody anti-pathogenic Leptospira spp. was able to capture leptospires, suggesting that it could be useful in immunoseparation assays.

Magnetic properties of nickel nanowires decorated with cobalt nanoparticles fabricated by two step electrochemical deposition technique

Energy Technology Data Exchange (ETDEWEB)

Maaz, K., E-mail: maaz@impcas.ac.cn [Materials Research Center, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); Nanomaterials Research Group, Physics Division, PINSTECH, Nilore, 45650, Islamabad (Pakistan); Duan, J.L. [Materials Research Center, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); Karim, S. [Nanomaterials Research Group, Physics Division, PINSTECH, Nilore, 45650, Islamabad (Pakistan); Chen, Y.H.; Yao, H.J.; Mo, D.; Sun, Y.M. [Materials Research Center, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); Liu, J., E-mail: j.liu@impcas.ac.cn [Materials Research Center, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China)

2016-10-01

We demonstrate fabrication and magnetic characterization of novel nanostructures composed of Ni nanowires decorated with Co nanoparticles by two step etching and electrochemical deposition in polycarbonate template. Structural analysis confirmed the formation of nickel nanowires with diameter of 62 nm which are surrounded by cobalt nanoparticles of about 15 nm in diameter. By electron microscopy analyses it is evident that the nanoparticles are distributed on the surface of the nanowires. Analysis of magnetization data indicates that ferromagnetic Ni nanowires exhibit an easy axis of magnetization parallel to the wire long-axis while the angular dependence of coercivity indicates that magnetization reversal occurs through the curling process in these nanowires. An exchange bias accompanied by vertical shift in magnetization was observed below ∼20 K, measured under a cooling field of 1 kOe, which is attributed to the spin interactions between the spin-glass like surface layer and ferromagnetic core of the nanowires and nanoparticles. - Highlights: • Co-decorated Ni nanowires were fabricated by two-step electrodeposition technique. • The nanoparticles are distributed on the surface of nanowires. • Magnetization reversal occurs through the curling process in the nanowires. • Temperature dependent coercivity follows thermal activation model.

Extraction and preconcentration of trace levels of cobalt using functionalized magnetic nanoparticles in a sequential injection lab-on-valve system with detection by electrothermal atomic absorption spectrometry

International Nuclear Information System (INIS)

Wang Yang; Luo Xiaoyu; Tang Jie; Hu Xiaoya; Xu Qin; Yang Chun

2012-01-01

Graphical abstract: An approach to performing extraction and preconcentration employing functionalized magnetic particles for the determination of cobalt in the sequential injection lab-on-valve system using detection by electrothermal atomic absorption spectrometry. Highlights: ► New SPE method for cobalt separation/preconcentration was reported. ► Functionalized magnetic nanoparticles were used as adsorbent. ► Extraction, elution, and detection procedures were performed in the LOV system. ► This automatic extraction technique provided a good platform for metal analysis. - Abstract: A new approach to performing extraction and preconcentration employing functionalized magnetic nanoparticles for the determination of trace metals is presented. Alumina-coated iron oxide nanoparticles were synthesized and used as the solid support. The nanoparticles were functionalized with sodium dodecyl sulfate and used as adsorbents for solid phase extraction of the analyte. Extraction, elution, and detection procedures were performed sequentially in the sequential injection lab-on-valve (SI-LOV) system followed by electrothermal atomic absorption spectrometry (ETAAS). Mixtures of hydrophobic analytes were successfully extracted from solution using the synthesized magnetic adsorbents. The potential use of the established scheme was demonstrated by taking cobalt as a model analyte. Under the optimal conditions, the calibration curve showed an excellent linearity in the concentration range of 0.01–5 μg L −1 , and the relative standard deviation was 2.8% at the 0.5 μg L −1 level (n = 11). The limit of detection was 6 ng L −1 with a sampling frequency of 18 h −1 . The present method has been successfully applied to cobalt determination in water samples and two certified reference materials.

Influence of lanthanum on the optomagnetic properties of zinc ferrite prepared by combustion method

International Nuclear Information System (INIS)

Tholkappiyan, R.; Vishista, K.

2014-01-01

Pure and lanthanum doped zinc ferrite nanoparticles were synthesized by a combustion method using glycine as fuel. The mechanism of formation of these nanoferrites is discussed briefly. The prepared nanoparticles characterized using powder X-ray diffraction analysis (XRD) revealed the formation of cubic spinel phase with high crystallinity. Average crystallite size, X-ray density and bulk density were found to decrease with an increase in La 3+ concentration. The chemical elements and states on the surface of these ferrites were determined using X-ray photoelectron spectroscopy (XPS). The detailed core level spectra of the photoelectron peaks of Zn 2p, Fe 2p, La 3d and O 1s were analyzed. The magnetic behavior of these nanoparticles was studied using a vibrating sample magnetometer (VSM) and corresponding changes in the saturation magnetization (Ms), coercivity (Hc) and remanent magnetization (Mr) were analyzed. The optical behavior of these ferrite nanoparticles was characterized by UV–Diffuse reflectance studies (UV–DRS). From the UV–DRS studies, the optical band gap was found to be in the range of 1.87–1.97 eV. The combustion method significantly produces large amount of products within a short time. Therefore, this method is potentially suitable for manufacturing industries for preparing the magnetic nanoparticles

Metal/Carbon Hybrid Nanostructures Produced from Plasma-Enhanced Chemical Vapor Deposition over Nafion-Supported Electrochemically Deposited Cobalt Nanoparticles

Directory of Open Access Journals (Sweden)

Mohammad Islam

2018-04-01

Full Text Available In this work, we report development of hybrid nanostructures of metal nanoparticles (NP and carbon nanostructures with strong potential for catalysis, sensing, and energy applications. First, the etched silicon wafer substrates were passivated for subsequent electrochemical (EC processing through grafting of nitro phenyl groups using para-nitrobenzene diazonium (PNBT. The X-ray photoelectron spectroscope (XPS and atomic force microscope (AFM studies confirmed presence of few layers. Cobalt-based nanoparticles were produced over dip or spin coated Nafion films under different EC reduction conditions, namely CoSO4 salt concentration (0.1 M, 1 mM, reduction time (5, 20 s, and indirect or direct EC reduction route. Extensive AFM examination revealed NP formation with different attributes (size, distribution depending on electrochemistry conditions. While relatively large NP with >100 nm size and bimodal distribution were obtained after 20 s EC reduction in H3BO3 following Co2+ ion uptake, ultrafine NP (<10 nm could be produced from EC reduction in CoSO4 and H3BO3 mixed solution with some tendency to form oxides. Different carbon nanostructures including few-walled or multiwalled carbon nanotubes (CNT and carbon nanosheets were grown in a C2H2/NH3 plasma using the plasma-enhanced chemical vapor deposition technique. The devised processing routes enable size controlled synthesis of cobalt nanoparticles and metal/carbon hybrid nanostructures with unique microstructural features.

Magnetic Properties of (Nia-ZnbX Cu1-X Ferrite Nanoparticle Fabricated by Sol-Gel Process

Directory of Open Access Journals (Sweden)

Yang S.

2017-06-01

Full Text Available In future, more mobile devices with different frequencies will be used at the same time. Therefore, it is expected that the trouble caused by wave interference between devices will be further intensified. In order to prevent this trouble, investigation of selective frequency transmission or absorption material is required. In this paper, magnetic properties of nickel-zinc-copper ferrite nano powder was researched as wave absorber. (Nia-ZnbxCu1-xFe2O4(NZCF nanoparticles were fabricated by the sol-gel method. The influence of copper substitution on lattice parameter change was analyzed by X-ray diffraction (XRD, particle size was analyzed by scanning electron microscopy (SEM, and Magnetic properties analyzed by vibrating sample magnetometer (VSM. The NZCF and Nickel-zinc ferrite (NZF lattice parameter difference was 0.028 Å and particle size was calculated as 30 nm with the XRD peak. The VSM results of (Ni0.3-Zn0.30.6Cu1-0.6Fe2O4 annealed sample at 700°C for 3hous were 58.5 emu/g (Ms, 22.8 Oe (Hc. It was the most suitable magnetic properties for wave absorber in this investigation.

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.

Synthesis and Adsorption Property of SiO2@Co(OH2 Core-Shell Nanoparticles

Directory of Open Access Journals (Sweden)

Yongde Meng

2015-04-01

Full Text Available Silica nanoparticles were directly coated with cobalt hydroxide by homogeneous precipitation of slowly decomposing urea in cobalt nitrate solution. The cobalt hydroxide was amorphous, and its morphology was nanoflower-like. The BET (Brunauer-Emmett-Teller surface area of the core-shell composite was 221 m2/g. Moreover, the possible formation procedure is proposed: the electropositive cobalt ions were first adsorbed on the electronegative silica nanoparticles surface, which hydrolyzed to form cobalt hydroxide nanoparticles. Then, the cobalt hydroxide nanoparticles were aggregated to form nanoflakes. Finally, the nanoflakes self-assembled, forming cobalt hydroxide nanoflowers. Adsorption measurement showed that the core-shell composite exhibited excellent adsorption capability of Rhodamine B (RB.

Synthesis, photoelectrochemical properties and solar light-induced photocatalytic activity of bismuth ferrite nanoparticles

Science.gov (United States)

Pattnaik, Sambhu Prasad; Behera, Arjun; Martha, Satyabadi; Acharya, Rashmi; Parida, Kulamani

2018-01-01

Bismuth ferrite (BFO) nanoparticles prepared by solid state reaction route were characterized by various characterization techniques such as XRD, FESEM, HRTEM, UV-Vis DRS, PL etc., and their photocatalytic activities were evaluated by decolorization of aqueous solution of Congo red (CR) under solar light. The photocatalytic activity of BFO was increased by increasing the preparation temperature from 350 to 500 °C and then decreased with rise in temperature. The results of electrochemical measurements such as linear sweep voltammetry (LSV), electrochemical impedence (EIS), and Mott-Schottky analysis of BFO nanoparticles corroborated the findings of their photocatalytic activity. The enhanced photocatalytic response of the sample prepared at 500 °C is attributed to its smallest band gap, minimum crystallite size (30 nm), efficient separation, and lowest possible recombination of photo-generated charge carriers. The effects of amount of nano-BFO, irradiation time, initial CR concentration, and BFO calcination temperature on the decolorization of CR were examined. It was observed that 1 g/L nano-BFO calcined at 500 °C can decolorize up to 77% a 10-ppm CR dye solution under solar irradiation for 60 min. The studies included scavenger tests for identification of reactive species and a possible mechanism of dye decolorization.

Catalytic hydrolysis of ammonia borane via cobalt palladium nanoparticles.

Science.gov (United States)

Sun, Daohua; Mazumder, Vismadeb; Metin, Önder; Sun, Shouheng

2011-08-23

Monodisperse 8 nm CoPd nanoparticles (NPs) with controlled compositions were synthesized by the reduction of cobalt acetylacetonate and palladium bromide in the presence of oleylamine and trioctylphosphine. These NPs were active catalysts for hydrogen generation from the hydrolysis of ammonia borane (AB), and their activities were composition dependent. Among the 8 nm CoPd catalysts tested for the hydrolysis of AB, the Co(35)Pd(65) NPs exhibited the highest catalytic activity and durability. Their hydrolysis completion time and activation energy were 5.5 min and 27.5 kJ mol(-1), respectively, which were comparable to the best Pt-based catalyst reported. The catalytic performance of the CoPd/C could be further enhanced by a preannealing treatment at 300 °C under air for 15 h with the hydrolysis completion time reduced to 3.5 min. This high catalytic performance of Co(35)Pd(65) NP catalyst makes it an exciting alternative in pursuit of practical implementation of AB as a hydrogen storage material for fuel cell applications. © 2011 American Chemical Society

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

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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.

Synthesis and characterisation of doxorubicin-loaded functionalised ...

African Journals Online (AJOL)

The synthesised cobalt ferrite nanoparticles (CFNPs) were functionalised with xanthine gum (XG) and subsequently characterised by Fourier transform-infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and contact angle studies. Vibrating sample magnetometry (VSM) was used for magnetic measurements of ...

Stress-dependent crystal structure of lanthanum strontium cobalt ferrite by in situ synchrotron X-ray diffraction

Science.gov (United States)

Geiger, Philipp T.; Khansur, Neamul H.; Riess, Kevin; Martin, Alexander; Hinterstein, Manuel; Webber, Kyle G.

2018-02-01

Lanthanum strontium cobalt ferrite La1-xSrxCo1-yFeyO3-δ (LSCF) is one of the most studied mixed ionic-electronic conductor materials due to electrical and transport properties, which are attractive for intermediate temperature solid oxide fuel cells (SOFCs), oxygen permeation membranes, and catalysis. The integration of such materials, however, depends on the thermal as well as mechanical behavior. LSCF exhibits nonlinear hysteresis during compressive stress-strain measurements, marked by a remanent strain and coercive stress, i.e., ferroelasticity. However, the origin of ferroelastic behavior has not been investigated under high compressive stress. This study, therefore, investigates the microscopic origin of stress-induced mechanical behavior in polycrystalline (La0.6Sr0.4)0.95Co0.2Fe0.8O3-δ using in situ synchrotron x-ray diffraction. The data presented here reveals that the strain response originates from the intrinsic lattice strain as well as the extrinsic domain switching strain without any apparent change in crystallographic symmetry. A comparison of the calculated microscopic strain contribution with that of a macroscopic measurement indicates a significant change in the relative contributions of intrinsic and extrinsic strain depending on the applied stress state, i.e., under maximum stress and after unloading. Direct evidence of the microscopic origin of stress-strain response outlined in this paper may assist in guiding materials design with the improved mechanical reliability of SOFCs.

Characteristics of Barium Hexaferrite Nanoparticles Prepared by Temperature-Controlled Chemical Coprecipitation

International Nuclear Information System (INIS)

Kwak, Jun Young; Lee, Choong Sub; Kim, Don; Kim, Yeong Il

2012-01-01

Ba-ferrite (BaFe 12 O 19 ) nanoparticles were synthesized by chemical coprecipitation method in an aqueous solution. The particle size and the crystallization temperature of the Ba-ferrite nanoparticles were controlled varying the precipitation temperature. The precipitate that was prepared at 0 .deg. C showed the crystal structure of Ba-ferrite in X-ray diffraction when it was calcined at the temperature above 580 .deg. C, whereas what was prepared at 50 .deg. C showed the crystallinity when it was calcined at the temperature higher than about 700 .deg. C. The particle sizes of the synthesized Ba-ferrite were in a range of about 20-30 nm when it was prepared by being precipitated at 0 .deg. C and calcined at 650 .deg. C. When the precipitation temperature increased, the particle size also increased even at the same calcination temperature. The magnetic properties of the Ba-ferrite nanoparticles were also controlled by the synthetic condition of precipitation and calcination temperature. The coercive force could be appreciably lowered without a loss of saturation magnetization when the Ba-ferrite nanoparticles were prepared by precipitation and calcination both at low temperatures

Radiation induced structural and magnetic transformations in nanoparticle MnxZn(1−x)Fe2O4 ferrites

International Nuclear Information System (INIS)

Naik, P.P.; Tangsali, R.B.; Sonaye, B.; Sugur, S.

2015-01-01

Nanoparticle magnetic materials are suitable for multiple modern high end medical applications like targeted drug delivery, gene therapy, hyperthermia and MR thermometry imaging. Majority of these applications are confined to use of Mn–Zn ferrite nanoparticles. These nanoparticles are normally left in the body after their requisite application. Preparing these nanoparticles is usually a much involved job. However with the development of the simple technique Mn x Zn 1−x Fe 2 O 4 nanoparticles could be prepared with much ease. The nanoparticles of Mn x Zn 1−x Fe 2 O 4 with (x=1.0, 0.7, 0.5, 0.3, 0.0) were prepared and irradiated with gamma radiation of various intensities ranging between 500 R to 10,000 R, after appropriate structural and magnetic characterization. Irradiated samples were investigated for structural and magnetic properties, as well as for structural stability and cation distribution. The irradiated nanoparticles exhibited structural stability with varied cation distribution and magnetic properties, dependent on gamma radiation dose. Surprisingly samples also exhibited quenching of lattice parameter and particle size. The changes introduced in the cation distribution, lattice constant, particle size and magnetic properties were found to be irreversible with time lapse and were of permanent nature exhibiting good stability even after several months. Thus the useful properties of nanoparticles could be enhanced on modifying the cation distribution inside the nanoparticles by application of gamma radiation. - Highlights: • Mn x Zn 1−x Fe 2 O 4 nanoparticles were synthesized using auto combustion method. • The irradiated samples showed a change in cation distribution. • Lattice shrinkage observed due to radiation induced change in cation distribution. • Reduction in particle size was also observed due to gamma exposure. • An enhancement in saturation magnetization was observed in irradiated samples

Morphological impact on the reaction kinetics of size-selected cobalt oxide nanoparticles

International Nuclear Information System (INIS)

Bartling, Stephan; Meiwes-Broer, Karl-Heinz; Barke, Ingo; Pohl, Marga-Martina

2015-01-01

Apart from large surface areas, low activation energies are essential for efficient reactions, particularly in heterogeneous catalysis. Here, we show that not only the size of nanoparticles but also their detailed morphology can crucially affect reaction kinetics, as demonstrated for mass-selected, soft-landed, and oxidized cobalt clusters in a 6 nm to 18 nm size range. The method of reflection high-energy electron diffraction is extended to the quantitative determination of particle activation energies which is applied for repeated oxidation and reduction cycles at the same particles. We find unexpectedly small activation barriers for the reduction reaction of the largest particles studied, despite generally increasing barriers for growing sizes. We attribute these observations to the interplay of reaction-specific material transport with a size-dependent inner particle morphology

Impact of larger rare earth Pr{sup 3+} ions on the physical properties of chemically derived Pr{sub x}CoFe{sub 2−x}O{sub 4} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Pachpinde, A.M.; Langade, M.M. [Department of Chemistry, Jawahar Art Science and Commerce College Andur, Osmanabad, MS (India); Lohar, K.S.; Patange, S.M. [Materials Research Laboratory, Srikrishna Mahavidyalaya Gunjoti, Omerga, Osmanabad 413 613, MS (India); Shirsath, Sagar E., E-mail: shirsathsagar@hotmail.com [Spin Device Technology Center, Department of Information Engineering, Shinshu University, Nagano 380 8553 (Japan)

2014-01-31

Highlights: • Rare earth Pr{sup 3+} substituted CoFe{sub 2}O{sub 4}. • Sol–gel auto combustion synthesis. • XRD and IR spectra reveal the spinel structure. • Magnetization and coercivity increased with Pr{sup 3+} substitution. - Abstract: Rare earth Pr{sup 3+} ions with its larger ionic radii substituted CoFe{sub 2}O{sub 4} nanoparticles with x ranging from 0.0 to 0.1 were synthesized by sol–gel auto-combustion chemical method. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy (IR) and vibrating sample magnetometer (VSM) were employed to characterize the physical properties of these ferrite nanoparticles. XRD pattern reveals the formation of cubic spinel ferrite with the signature of PrFeO{sub 3} phases for x ⩾ 0.05. SEM images show that the synthesized samples are in good homogeneity with uniformly distributed grain. The results of IR spectroscopy analysis indicated that the functional groups of cobalt spinel ferrite were formed during the sol–gel process. The cations distribution between the tetrahedral (A-site) and octahedral sites (B-site) has been estimated by XRD analysis. Room temperature magnetic measurement shows saturation magnetization and coercivity increased from 54.7 to 64.2 emu/g and 644 to 1013 Oe, respectively with the increasing Pr{sup 3+} substitution.

Structural and magnetic properties of nanocrystalline stannic substituted cobalt ferrite

Energy Technology Data Exchange (ETDEWEB)

Abbas, Y.M., E-mail: ymabbas@live.com [Physics Department, Faculty of Science, Suez Canal University, Ismailia (Egypt); Mansour, S.A. [Physics Department, Faculty of Science, Suez Canal University, Ismailia (Egypt); Physics Department, Faculty of Science, King AbdulAziz University, Rabegh (Saudi Arabia); Ibrahim, M.H. [Physics Department, Faculty of Science, Suez Canal University, Ismailia (Egypt); Physics Department, Faculty of Science, King AbdulAziz University (Saudi Arabia); Ali, Shehab. E., E-mail: shehab_ali@science.suez.edu.eg [Physics Department, Faculty of Science, Suez Canal University, Ismailia (Egypt)

2012-09-15

The structural and magnetic properties of the spinel ferrite system Co{sub 1+x}Fe{sub 2-2x}Sn{sub x}O{sub 4} (x=0.0-1.0) have been studied. Samples in the series were prepared by the ceramic technique. The structural and microstructural evolutions of the nanophase have been studied using X-ray powder diffraction and the Rietveld method. The refinement result showed that the type of the cationic distribution over the tetrahedral and octahedral sites in the nanocrystalline lattice is partially an inverse spinel. Far infrared absorption spectra show two significant absorption bands, around 600 cm{sup -1} and 425 cm{sup -1}, which are respectively attributed to tetrahedral (A) and octahedral [B] vibrations of the spinel. Scanning Electron Microscopy (SEM) was used to study surface morphology. SEM images reveal particles in the nanosize range. The transmission electronic microscope (TEM) reveals that the grains are spherical in shape. TEM analysis confirmed the X-ray results. The magnetic properties of the prepared samples were characterized by using a vibrating sample magnetometer. - Highlights: Black-Right-Pointing-Pointer The spinel ferrite system has been formed at 1000 Degree-Sign C by using ceramic techniques. Black-Right-Pointing-Pointer Structural and microstructural evolutions have been studied using XRD and the Rietveld method. Black-Right-Pointing-Pointer The refinement result showed cationic distribution in the lattice is partially an inverse spinel. Black-Right-Pointing-Pointer The transmission electronic microscope analysis confirmed the X-ray results. Black-Right-Pointing-Pointer Magnetic properties of the samples were characterized by using a vibrating sample magnetometer.

Structural and magnetic properties of nanocrystalline stannic substituted cobalt ferrite

International Nuclear Information System (INIS)

Abbas, Y.M.; Mansour, S.A.; Ibrahim, M.H.; Ali, Shehab. E.

2012-01-01

The structural and magnetic properties of the spinel ferrite system Co 1+x Fe 2−2x Sn x O 4 (x=0.0–1.0) have been studied. Samples in the series were prepared by the ceramic technique. The structural and microstructural evolutions of the nanophase have been studied using X-ray powder diffraction and the Rietveld method. The refinement result showed that the type of the cationic distribution over the tetrahedral and octahedral sites in the nanocrystalline lattice is partially an inverse spinel. Far infrared absorption spectra show two significant absorption bands, around 600 cm −1 and 425 cm −1 , which are respectively attributed to tetrahedral (A) and octahedral [B] vibrations of the spinel. Scanning Electron Microscopy (SEM) was used to study surface morphology. SEM images reveal particles in the nanosize range. The transmission electronic microscope (TEM) reveals that the grains are spherical in shape. TEM analysis confirmed the X-ray results. The magnetic properties of the prepared samples were characterized by using a vibrating sample magnetometer. - Highlights: ► The spinel ferrite system has been formed at 1000 °C by using ceramic techniques. ► Structural and microstructural evolutions have been studied using XRD and the Rietveld method. ► The refinement result showed cationic distribution in the lattice is partially an inverse spinel. ► The transmission electronic microscope analysis confirmed the X-ray results. ► Magnetic properties of the samples were characterized by using a vibrating sample magnetometer.

Assessment of Immunotoxicity of Dextran Coated Ferrite Nanoparticles in Albino Mice

Science.gov (United States)

Syama, Santhakumar; Gayathri, Viswanathan; Mohanan, Parayanthala Valappil

2015-01-01

In this study, dextran coated ferrite nanoparticles (DFNPs) of size immunotoxicity, and oxidative stress by in vitro and in vivo methods. Cytotoxicity was performed in vitro using splenocytes with different concentrations of DFNPs. Gene expression of selected cytokines (IL-1, IL-10, and TNF β) secretion by splenocytes was evaluated. Also, 100 mg of DFNPs was injected intraperitoneally to 18 albino mice for immunological stimulations. Six animals each were sacrificed at the end of 7, 14, and 21 days. Spleen was subjected to immunotoxic response and liver was analyzed for antioxidant parameters (lipid peroxidation, reduced glutathione, glutathione peroxidase, superoxide dismutase, and glutathione reductase). The results indicated that DFNPs failed to induce any immunological reactions and no significant alternation in antioxidant defense mechanism. Also, mRNA expression of the cytokines revealed an increase in IL-10 expression and subsequent decreased expression of IL-1 and TNF β. Eventually, DNA sequencing of liver actin gene revealed base alteration in nonconserved regions (10–20 bases) of all the treated groups when compared to control samples. Hence, it can be concluded that the DFNPs were nontoxic at the cellular level and nonimmunotoxic when exposed intraperitoneally to mice. PMID:26576301

Synthesis and characterization of iron cobalt (FECO) nanorods ...

African Journals Online (AJOL)

Synthesis and characterization of iron cobalt (FECO) nanorods prepared by simple ... shaped by increasing annealing temperature from room temperature to 800 ... Keywords: FeCo nanoparticles, sodium borohydrid, CTAB, chemical synthesis ...

Inversion degree and saturation magnetization of different nanocrystalline cobalt ferrites

International Nuclear Information System (INIS)

Concas, G.; Spano, G.; Cannas, C.; Musinu, A.; Peddis, D.; Piccaluga, G.

2009-01-01

The inversion degree of a series of nanocrystalline samples of CoFe 2 O 4 ferrites has been evaluated by a combined study, which exploits the saturation magnetization at 4.2 K and 57 Fe Moessbauer spectroscopy. The samples, prepared by sol-gel autocombustion, have different thermal history and particle size. The differences observed in the saturation magnetization of these samples are explained in terms of different inversion degrees, as confirmed by the analysis of the components in the Moessbauer spectra. It is notable that the inversion degrees of the samples investigated are set among the highest values reported in the literature.

Oxidation behaviour and electrical properties of cobalt/cerium oxide composite coatings for solid oxide fuel cell interconnects

DEFF Research Database (Denmark)

Harthøj, Anders; Holt, Tobias; Møller, Per

2015-01-01

This work evaluates the performance of cobalt/cerium oxide (Co/CeO2) composite coatings and pure Co coatings to be used for solid oxide fuel cell (SOFC) interconnects. The coatings are electroplated on the ferritic stainless steels Crofer 22 APU and Crofer 22H. Coated and uncoated samples...

Bulletin of Materials Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

Synthesis and characterization of M3V2O8 (M = Ca, Sr and Ba) by a ... Spin canting phenomenon in cadmium doped cobalt ferrites, CoCdFe2−O4 ( = 0.0, 0.2, 0.4 ... Biological and electrical properties of biosynthesized silver nanoparticles.

Cobalt Oxide Nanoparticles: Behavior towards Intact and Impaired Human Skin and Keratinocytes Toxicity

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Marcella Mauro

2015-07-01

Full Text Available Skin absorption and toxicity on keratinocytes of cobalt oxide nanoparticles (Co3O4NPs have been investigated. Co3O4NPs are commonly used in industrial products and biomedicine. There is evidence that these nanoparticles can cause membrane damage and genotoxicity in vitro, but no data are available on their skin absorption and cytotoxicity on keratinocytes. Two independent 24 h in vitro experiments were performed using Franz diffusion cells, using intact (experiment 1 and needle-abraded human skin (experiment 2. Co3O4NPs at a concentration of 1000 mg/L in physiological solution were used as donor phase. Cobalt content was evaluated by Inductively Coupled–Mass Spectroscopy. Co permeation through the skin was demonstrated after 24 h only when damaged skin protocol was used (57 ± 38 ng·cm−2, while no significant differences were shown between blank cells (0.92 ± 0.03 ng cm−2 and those with intact skin (1.08 ± 0.20 ng·cm−2. To further investigate Co3O4NPs toxicity, human-derived HaCaT keratinocytes were exposed to Co3O4NPs and cytotoxicity evaluated by MTT, Alamarblue® and propidium iodide (PI uptake assays. The results indicate that a long exposure time (i.e., seven days was necessary to induce a concentration-dependent cell viability reduction (EC50 values: 1.3 × 10−4 M, 95% CL = 0.8–1.9 × 10−4 M, MTT essay; 3.7 × 10−5 M, 95% CI = 2.2–6.1 × 10−5 M, AlamarBlue® assay that seems to be associated to necrotic events (EC50 value: 1.3 × 10−4 M, 95% CL = 0.9–1.9 × 10−4 M, PI assay. This study demonstrated that Co3O4NPs can penetrate only damaged skin and is cytotoxic for HaCat cells after long term exposure.

Cell type-specific response to high intracellular loading of polyacrylic acid-coated magnetic nanoparticles

Science.gov (United States)

Lojk, Jasna; Bregar, Vladimir B; Rajh, Maruša; Miš, Katarina; Kreft, Mateja Erdani; Pirkmajer, Sergej; Veranič, Peter; Pavlin, Mojca

2015-01-01

Magnetic nanoparticles (NPs) are a special type of NP with a ferromagnetic, electron-dense core that enables several applications such as cell tracking, hyperthermia, and magnetic separation, as well as multimodality. So far, superparamagnetic iron oxide NPs (SPIONs) are the only clinically approved type of metal oxide NPs, but cobalt ferrite NPs have properties suitable for biomedical applications as well. In this study, we analyzed the cellular responses to magnetic cobalt ferrite NPs coated with polyacrylic acid (PAA) in three cell types: Chinese Hamster Ovary (CHO), mouse melanoma (B16) cell line, and primary human myoblasts (MYO). We compared the internalization pathway, intracellular trafficking, and intracellular fate of our NPs using fluorescence and transmission electron microscopy (TEM) as well as quantified NP uptake and analyzed uptake dynamics. We determined cell viability after 24 or 96 hours’ exposure to increasing concentrations of NPs, and quantified the generation of reactive oxygen species (ROS) upon 24 and 48 hours’ exposure. Our NPs have been shown to readily enter and accumulate in cells in high quantities using the same two endocytic pathways; mostly by macropinocytosis and partially by clathrin-mediated endocytosis. The cell types differed in their uptake rate, the dynamics of intracellular trafficking, and the uptake capacity, as well as in their response to higher concentrations of internalized NPs. The observed differences in cell responses stress the importance of evaluation of NP–cell interactions on several different cell types for better prediction of possible toxic effects on different cell and tissue types in vivo. PMID:25733835

Preparation and structural characterization of vulcanized natural rubber nanocomposites containing nickel-zinc ferrite nanopowders.

Science.gov (United States)

Bellucci, F S; Salmazo, L O; Budemberg, E R; da Silva, M R; Rodríguez-Pérez, M A; Nobre, M A L; Job, A E

2012-03-01

Single-phase polycrystalline mixed nickel-zinc ferrites belonging to Ni0.5Zn0.5Fe2O4 were prepared on a nanometric scale (mean crystallite size equal to 14.7 nm) by chemical synthesis named the modified poliol method. Ferrite nanopowder was then incorporated into a natural rubber matrix producing nanocomposites. The samples were investigated by means of infrared spectroscopy, X-ray diffraction, scanning electron microscopy and magnetic measurements. The obtained results suggest that the base concentration of nickel-zinc ferrite nanoparticles inside the polymer matrix volume greatly influences the magnetic properties of nanocomposites. A small quantity of nanoparticles, less than 10 phr, in the nanocomposite is sufficient to produce a small alteration in the semi-crystallinity of nanocomposites observed by X-ray diffraction analysis and it produces a flexible magnetic composite material with a saturation magnetization, a coercivity field and an initial magnetic permeability equal to 3.08 emu/g, 99.22 Oe and 9.42 x 10(-5) respectively.

Grain refinement by cold deformation and recrystallization of bainite and acicular ferrite structures of C-Mn steels

International Nuclear Information System (INIS)

Hossein Nedjad, S.; Zahedi Moghaddam, Y.; Mamdouh Vazirabadi, A.; Shirazi, H.; Nili Ahmadabadi, M.

2011-01-01

Research highlights: → Bainite showed weak property improvement after rolling and annealing. → Additions of titanium and titanium oxide stimulated acicular ferrite. → Acicular ferrite obtained by nanoparticles exhibited very high strength. → Rolling and annealing of acicular ferrite gave substantial property improvement. - Abstract: The propensity of bainite and acicular ferrite structures of experimental C-Mn steels for enhanced grain refinement by combining phase transformation and plastic deformation has been investigated. Formation of acicular ferrite structures were stimulated with a small amount of titanium and titanium oxide nanoparticles added into the molten steels of high Mn concentrations. Isothermal transformations into the bainite and acicular ferrite structures were performed for 1.8 ks at 823 K after preliminary austenitization for 1.8 ks at 1523 K. Cold rolling for 50% thickness reduction was conducted on the isothermally transformed structures. Subsequent annealing of the deformed structures was conducted for 3.6 ks at 773, 873 and 973 K. Optical microscopy, scanning electron microscopy and tensile test were used for characterization of the studied steels. Cold rolling and annealing of the transformed structures at 873 K resulted in strengthening at the expense of ductility where an initial stage of recrystallization is realized. Acicular ferrite obtained by the addition of titanium into the molten steel exhibited the remarkable improvement of tensile properties. Discontinuous recrystallization of the deformed structures at 973 K leads to the formation of fine grains wherein acicular structures represented more enhanced grain refinement than bainite.

Sensitive warfarin sensor based on cobalt oxide nanoparticles electrodeposited at multi-walled carbon nanotubes modified glassy carbon electrode (CoxOyNPs/MWCNTs/GCE)

International Nuclear Information System (INIS)

Gholivand, Mohammad Bagher; Solgi, Mohammad

2017-01-01

In this work, cobalt oxide nanoparticles were electrodeposited on multi-walled carbon nanotubes modified glassy carbon electrode (MWCNTs/GCE) to develop a new sensor for warfarin determination. The modified electrodes were characterized by cyclic voltammetry, scanning electron microscopy (SEM) along with energy dispersive x-ray spectroscopy (EDS), and electrochemical impedance spectroscopy (EIS). The presence of cobalt oxide nanoparticles on the electrode surface enhanced the warfarin accumulation and its result was the improvement in the electrochemical response. The effect of various parameters such as pH, scan rate, accumulation potential, accumulation time and pulse amplitude on the sensor response were investigated. Under optimal conditions, the differential pulse adsorptive anodic stripping voltammetric (DPASV) response of the modified electrode was linear in the ranges of 8 nM to 50 μM and 50 μM to 800 μM with correlation coefficients greater than 0.998. The limit of detection of the proposed method was 3.3 nM. The proposed sensor was applied to determine warfarin in urine and plasma samples.

Preferential spin canting in nanosize zinc ferrite

Energy Technology Data Exchange (ETDEWEB)

Pandey, Brajesh, E-mail: bpandey@gmail.com [Department of Applied Science, Symbiosis Institute of Technology, SIU, Lavale, Pune 411112 (India); Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro (Brazil); Litterst, F.J. [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro (Brazil); Institut für Physik der Kondensierten Materie,Technische Universität Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig (Germany); Baggio-Saitovitch, E.M. [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro (Brazil)

2015-07-01

Zinc ferrite nanoparticles powder with average size of 10.0±0.5 nm was synthesized by the citrate precursor route. We studied the structural and magnetic properties using X-ray diffraction, vibrating sample magnetometry and Mössbauer spectroscopy. X-ray diffraction patterns show that the synthesized zinc ferrite possesses good spinel structure. Both Mössbauer and magnetization data indicate superparamagnetic ferrimagnetic particles at room temperature. The magnetic behavior is determined by a considerable degree of cation inversion with Fe{sup III} in tetrahedral A-sites. Mössbauer spectroscopy at low temperature and in high applied magnetic field reveals that A-site spins are aligned antiparallel to the applied field with some possible angular scatter whereas practically all octahedral B-site spins are canted contrasting some earlier reported partial B-site spin canting in nanosize zinc ferrite. Deviations from the antiferromagnetic arrangement of B-site spins are supposed to be caused by magnetic frustration effects. - Highlights: • Spinel structure ZnFe{sub 2}O{sub 4} nanoparticles in the uniform size range of 10.0±0.5 nm have been synthesized using the citrate precursor route. • Canting of the spins of A- and B-sublattice sites has been studied by low temperature and high magnetic field Mössbauer spectroscopy. • A-site spins are aligned antiparallel to the applied field with only small angular scatter. • B-site spins are strongly canted in contrast to earlier quoted only partial canting. • B site spin structure deviates significantly from a collinear antiferromagnetic arrangement.

Synthesis and characterization of nanosized MnZn ferrites via a modified hydrothermal method

Science.gov (United States)

Li, Mingling; Liu, Xiansong; Xu, Taotao; Nie, Yu; Li, Honglin; Zhang, Cong

2017-10-01

Nanosized MnZn ferrite particles, with narrow size distribution, regular morphology and high saturation magnetization have been synthesized via a modified hydrothermal method. This modified hydrothermal method involves a chemical co-precipitation of hydroxides under a vacuum condition using potassium hydroxide as precipitating agent, followed by a separate hydrothermal process. The microstructure and magnetic properties of the synthesized nanoparticles were investigated by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer (VSM). The effects of different synthesis conditions (excess ratio of precipitating agent and hydrothermal reaction time) on the microstructure and magnetic properties of the as-synthesized nanoparticles were discussed. The magnetic measurements indicated that the obtained samples were superparamagnetic in nature at room temperature. Moreover, the MnZn ferrite nanoparticles with excellent magnetic performance could be synthesized at 180 °C for a short reaction time (3 h).

Efficient removal of cobalt from aqueous solution by zinc oxide nanoparticles. Kinetic and thermodynamic studies

Energy Technology Data Exchange (ETDEWEB)

Khezami, L.; Modwi, A. [Al Imam Mohammad Ibn Saud Islamic Univ. (IMSIU), Riyadh (Saudi Arabia). Dept. of Chemistry; Taha, Kamal K. [Al Imam Mohammad Ibn Saud Islamic Univ. (IMSIU), Riyadh (Saudi Arabia). Dept. of Chemistry; Univ. of Bahri, Khartoum (Sudan). College of Applied and Industrial Sciences

2017-08-01

This article deals with the removal of cobalt ions using zinc oxide nanopowder. The nanomaterial was prepared via the sol-gel method under supercritical drying. The nanomaterial was characterised via XRD, SEM, EDX, FTIR, and BET surface area techniques. The kinetics, equilibrium, and thermodynamic studies of the metal ions adsorption on the nanomaterial were conducted in batch mode experiments by varying some parameters such as pH, contact time, initial ion concentrations, nanoparticles dose, and temperature. The data revealed significant dependence of the adsorption process on concentration, and the temperature was found to enhance the adsorption rate indicating an endothermic nature of the adsorption. The adsorption complied well with the pseudo-second-order kinetics model. The adsorption process was found to match the Langmuir adsorption isotherm. The ZnO nanoparticles could successfully remove up to 125 mg.g{sup -1} of Co(II) ions at elevated temperature. The metal ions adsorption could be described as an endothermic, spontaneous physisorption process. A mechanism for the metal ions adsorption was proposed.

Efficient removal of cobalt from aqueous solution by zinc oxide nanoparticles. Kinetic and thermodynamic studies

International Nuclear Information System (INIS)

Khezami, L.; Modwi, A.; Taha, Kamal K.; Univ. of Bahri, Khartoum

2017-01-01

This article deals with the removal of cobalt ions using zinc oxide nanopowder. The nanomaterial was prepared via the sol-gel method under supercritical drying. The nanomaterial was characterised via XRD, SEM, EDX, FTIR, and BET surface area techniques. The kinetics, equilibrium, and thermodynamic studies of the metal ions adsorption on the nanomaterial were conducted in batch mode experiments by varying some parameters such as pH, contact time, initial ion concentrations, nanoparticles dose, and temperature. The data revealed significant dependence of the adsorption process on concentration, and the temperature was found to enhance the adsorption rate indicating an endothermic nature of the adsorption. The adsorption complied well with the pseudo-second-order kinetics model. The adsorption process was found to match the Langmuir adsorption isotherm. The ZnO nanoparticles could successfully remove up to 125 mg.g -1 of Co(II) ions at elevated temperature. The metal ions adsorption could be described as an endothermic, spontaneous physisorption process. A mechanism for the metal ions adsorption was proposed.

Superior magnetic properties of Ni ferrite nanoparticles synthesized by capping agent-free one-step coprecipitation route at different pH values

Science.gov (United States)

Iranmanesh, P.; Tabatabai Yazdi, Sh.; Mehran, M.; Saeednia, S.

2018-03-01

In this work, well-dispersed nanoparticles of NiFe2O4 with diameters less than 10 nm and good crystallinity and excellent magnetic properties were synthesized via a simple one-step capping agent-free coprecipitation route from metal chlorides. The ammonia was used as the precipitating agent and also the solution basicity controller. The effect of pH value during the coprecipitation process was investigated by details through microstructural, optical and magnetic characterizations of the synthesized particles using X-ray diffraction, transmission electron microscopy, Fourier transform infrared and UV-vis spectroscopy, and vibrating sample magnetometer. The results showed that the particle size, departure from the inverse spinel structure, the band gap value and the magnetization of Ni ferrite samples increase with pH value from 9 to 11 indicating the more pronounced surface effects in the smaller nanoparticles.

Design of Cobalt Nanoparticles with Tailored Structural and Morphological Properties via O/W and W/O Microemulsions and Their Deposition onto Silica

Directory of Open Access Journals (Sweden)

Gabriella Di Carlo

2015-03-01

Full Text Available Cobalt nanostructures with different size and morphology, i.e., spherical nanoparticles, nanorods, and particles arranged into elongated structures, were prepared using micelles and microemulsions as confined reaction media. The syntheses were carried out using three types of systems: aqueous surfactant solutions, oil-in water (O/W, and water-in-oil (W/O microemulsions. The influence of the surfactant and the precipitating agent used for synthesis was also investigated. For this purpose, cobalt nanostructures were prepared using different non-ionic surfactants, namely Synperonic® 10/6, Pluronic® P123 and a mixture of SPAN 20–TWEEN 80. Three different precipitating agents were used: sodium borohydride, sodium hydroxide, and oxalic acid. Our findings revealed that by changing the type of reaction media as well as the precipitating agent it is possible to modify the shape and size of the cobalt nanostructures. Moreover, the use of O/W microemulsion generates better results in terms of colloidal stability and uniformity of particle size with respect to W/O microemulsion. The different cobalt nanostructures were supported on commercial and mesoporous silica; transmission electron microscopy (TEM images showed that after deposition the Co nanocrystals remain well dispersed on the silica supports. This behavior suggests their great potential in catalytic applications.

Nickel-zinc ferrite/permalloy (Ni0.5Zn0.5Fe2O4/Ni-Fe soft magnetic nanocomposites fabricated by electro-infiltration

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Xiao Wen

2016-05-01

Full Text Available Magnetically soft NiZn ferrite (Ni0.5Zn0.5Fe2O4 nanoparticles are embedded within a permalloy (Ni-Fe matrix via an electro-infiltration process as thin films intended for use as on-chip inductor cores in the MHz frequency regime. A layer of NiZn ferrite nanoparticles is first deposited, and then permalloy is electroplated through the voids to encapsulate the particles and form three-dimensional ferrite/alloy nanocomposites. The composites are estimated to contain 37% ferrite by volume and exhibit a relative permeability of ∼320, a saturation of ∼1.15 T, and an operational bandwidth of 93 MHz. Compared to a permalloy thin film of similar thickness, the nanocomposite exhibits 39% higher electrical resistivity and 50% higher bandwidth.

Electrical and optical properties of nickel ferrite/polyaniline nanocomposite

Directory of Open Access Journals (Sweden)

M. Khairy

2015-07-01

Full Text Available Polyaniline–NiFe2O4 nanocomposites (PANI–NiFe2O4 with different contents of NiFe2O4 (2.5, 5 and 50 wt% were prepared via in situ chemical oxidation polymerization, while the nanoparticles nickel ferrite were synthesized by sol–gel method. The prepared samples were characterized using some techniques such as Fourier transforms infrared (FTIR, X-ray diffraction (XRD, scanning electron microscopy (SEM and thermogravimetric analysis (TGA. Moreover, the electrical conductivity and optical properties of the nanocomposites were investigated. Pure (PANI and the composites containing 2.5 and 5 wt% NiFe2O4 showed amorphous structures, while the one with 50 wt% NiFe2O4 showed a spinel crystalline structure. The SEM images of the composites showed different aggregations for the different nickel ferrite contents. FTIR spectra revealed to the formation of some interactions between the PANI macromolecule and the NiFe2O4 nanoparticles, while the thermal analyses indicated an increase in the composites stability for samples with higher NiFe2O4 nanoparticles contents. The electrical conductivity of PANI–NiFe2O4 nanocomposite was found to increase with the rise in NiFe2O4 nanoparticle content, probably due to the polaron/bipolaron formation. The optical absorption experiments illustrate direct transition with an energy band gap of Eg = 1.0 for PANI–NiFe2O4 nanocomposite.

Catalytic properties of nickel ferrites for oxidation of glucose, β-nicotiamide adenine dinucleotide (NADH) and methanol

Energy Technology Data Exchange (ETDEWEB)

Galindo, R. [Departamento de Química, Universidad de Guanajuato, Cerro de la Venada s/n, Pueblito de Rocha, C.P. 36040 Guanajuato, Gto (Mexico); Departamento de Química Física Aplicada, Universidad Autónoma de Madrid, Cantoblanco s/n, C.P. 28049 Madrid (Spain); Gutiérrez, S. [Departamento de Química, Universidad de Guanajuato, Cerro de la Venada s/n, Pueblito de Rocha, C.P. 36040 Guanajuato, Gto (Mexico); Menéndez, N. [Departamento de Química Física Aplicada, Universidad Autónoma de Madrid, Cantoblanco s/n, C.P. 28049 Madrid (Spain); Herrasti, P., E-mail: pilar.herrasti@uam.es [Departamento de Química Física Aplicada, Universidad Autónoma de Madrid, Cantoblanco s/n, C.P. 28049 Madrid (Spain)

2014-02-15

Highlights: ► NiFe{sub 2}O{sub 4} nanoparticles obtained by electrochemical method are effective catalyst. ► A partially inverse spinel was obtained with 57% Fe{sup 3+} in tetrahedral position. ► A non-enzymatic electrode using NiFe{sub 2}O{sub 4} nanoparticles has been manufactured. -- Abstract: Nickel ferrite nanoparticles (NiFe{sub 2}O{sub 4}) were synthesized by electrochemical method and used as catalyst for direct oxidation of glucose, NADH and methanol. Characterization of these nanoparticles was carried out by X-ray diffraction, Mössbauer spectroscopy, and colloidal properties such as hydrodynamic radius and Zeta potential. To evaluate the catalytic properties of these nanoparticles against the oxidation process, paste graphite electrodes mixing nickel ferrites and different conductive materials (graphite, carbon nanotubes) and binders agents (mineral oil, 1-octylpyridinium hexafluorophosphate (nOPPF6)) were used. The results prove good catalytic properties of these materials, with an oxidation potential around 0.75, 0.5 and 0.8 V for glucose, NADH, and methanol, respectively.

Electrokinetic properties of PMAA functionalized NiFe2O4 nanoparticles synthesized by thermal plasma route

Science.gov (United States)

Bhosale, Shivaji V.; Mhaske, Pravin; Kanhe, N.; Navale, A. B.; Bhoraskar, S. V.; Mathe, V. L.; Bhatt, S. K.

2014-04-01

The magnetic nickel ferrite (NiFe2O4) nanoparticles with an average size of 30nm were synthesised by Transferred arc DC Thermal Plasma route. The synthesized nickel ferrite nanoparticles were characterized by TEM and FTIR techniques. The synthesized nickel ferrite nanoparticles were further functionalized with PMAA (polymethacrylic acid) by self emulsion polymerization method and subsequently were characterized by FTIR and Zeta Analyzer. The variation of zeta potential with pH was systematically studied for both PMAA functionalized (PNFO) and uncoated nickel ferrite nanoparticles (NFO). The IEP (isoelectric points) for PNFO and NFO was determined from the graph of zeta potential vs pH. It was observed that the IEP for NFO was at 7.20 and for PNFO it was 2.52. The decrease in IEP of PNFO was attributed to the COOH functional group of PMAA.

Green synthesis of cobalt (II, III) oxide nanoparticles using Moringa Oleifera natural extract as high electrochemical electrode for supercapacitors

Science.gov (United States)

Matinise, N.; Mayedwa, N.; Fuku, X. G.; Mongwaketsi, N.; Maaza, M.

2018-05-01

The research work involved the development of a better, inexpensive, reliable, easily and accurate way for the fabrication of Cobalt (II, III) oxide (Co3O4) nanoparticles through a green synthetic method using Moringa Oleifera extract. The electrochemical activity, crystalline structure, morphology, isothermal behaviour and optical properties of Co3O4 nanoparticles were studied using various characterization techniques. The X-ray diffraction (XRD) and Energy Dispersive X-ray Spectroscopy (EDS) analysis confirmed the formation of Co3O4 nanoparticles. The pseudo-capacitor behaviour of spinel Co3O4 nanoparticles on Nickel foam electrode was investigated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) in 3M KOH solution. The CV curve revealed a pairs of redox peaks, indicating the pseudo-capacitive characteristics of the Ni/Co3O4 electrode. EIS results showed a small semicircle and Warburg impedance, indicating that the electrochemical process on the surface electrode is kinetically and diffusion controlled. The charge-discharge results indicating that the specific capacitance Ni/Co3O4 electrode is approximately 1060 F/g at a discharge current density of at 2 A/g.

New approach for direct chemical synthesis of hexagonal Co nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Abel, Frank M., E-mail: fabel@udel.edu [Physics and Astronomy, University of Delaware (United States); Tzitzios, Vasilis [Institute of Nanoscience and Nanotechnology, NCSR, Demokritos (Greece); Hadjipanayis, George C. [Physics and Astronomy, University of Delaware (United States)

2016-02-15

In this paper, we explore the possibility of producing hexagonal Cobalt nanoparticles, with high saturation magnetization by direct chemical synthesis. The nanoparticles were synthesized by reduction of anhydrous cobalt (II) chloride by NaBH{sub 4} in tetraglyme at temperatures in the range of 200–270 °C under a nitrogen–hydrogen atmosphere. The reactions were done at high temperatures to allow for the formation of as-made hexagonal cobalt. The size of the particles was controlled by the addition of different surfactants. The best magnetic properties so far were obtained on spherical hexagonal Co nanoparticles with an average size of 45 nm, a saturation magnetization of 143 emu/g and coercivity of 500 Oe. the saturation magnetization and coercivity were further improved by annealing the Co nanoparticles leading to saturation magnetization of 160 emu/g and coercivity of 540 Oe. - Highlights: • We synthesized hexagonal cobalt nanoparticles by a new wet chemical method. • We considered the effects of different surfactants on particles magnetic properties. • The as-made Co nanoparticles had magnetic properties of 143 emu/g and 500 Oe. • After annealing magnetic properties of 160 emu/g and 540 Oe were obtained.

Effects of synthesis variables on the magnetic properties of CoFe{sub 2}O{sub 4} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Briceno, Sarah, E-mail: sarahbriara@gmail.com [Laboratorio de Fisica de la Materia Condensada, Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas (IVIC), Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of); Braemer-Escamilla, Werner; Silva, Pedro [Laboratorio de Fisica de la Materia Condensada, Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas (IVIC), Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of); Delgado, Gerzon E. [Laboratorio de Cristalografia, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101-A (Venezuela, Bolivarian Republic of); Plaza, Eric [Laboratorio de Microscopia Electronica. Instituto Zuliano de Investigaciones Tecnologicas. Apartado 331. Km. 15. La Canada (Venezuela, Bolivarian Republic of); Palacios, Jordana [Laboratorio de Polimeros, Centro de Quimica, Instituto Venezolano de Investigaciones Cientificas (IVIC), Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of); Canizales, Edgard [Area de Analisis Quimico Inorganico. PDVSA. INTEVEP. Los Teques 1070-A (Venezuela, Bolivarian Republic of)

2012-09-15

Cobalt ferrite nanoparticles (CoFe{sub 2}O{sub 4}) have been synthesized using precipitation in water solution with polyethylene glycol as surfactant. Influence of various synthesis variables included pH, reaction time and annealing temperature on the magnetic properties and particle sizes has also been studied. Structural identification of the samples was carried out using Thermogravimetric and Differential thermal analysis, X-ray diffraction, Fourier transform infrared spectroscopy, Scanning electron microscopy, High resolution transmission electron microscopy. Vibrating sample magnetometer was used for the magnetic investigation of the samples. Magnetic properties of nanoparticles show strong dependence on the particle size. The magnetic properties increase with pH of the precipitating medium and annealing temperature while the coercivity goes through a maximum, peaking at around 25 nm. - Highlights: Black-Right-Pointing-Pointer CoFe{sub 2}O{sub 4} have been synthesized via chemical synthesis route using PEG as surfactant. Black-Right-Pointing-Pointer Influence of various synthesis variables on the magnetic properties has been studied. Black-Right-Pointing-Pointer Magnetic properties of nanoparticles show strong dependence on the particle size. Black-Right-Pointing-Pointer Magnetic properties increase with pH and annealing temperature.

Cobalt oxide nanoparticles as a novel high-efficiency fiber coating for solid phase microextraction of benzene, toluene, ethylbenzene and xylene from aqueous solutions

International Nuclear Information System (INIS)

Gholivand, Mohammad Bagher; Shamsipur, Mojtaba; Shamizadeh, Mohammad; Moradian, Rostam; Astinchap, Bandar

2014-01-01

Highlights: • Co 3 O 4 nanoparticles were introduced as a novel SPME fiber coating. • The fiber was evaluated for the extraction of BTEX in combination with GC–MS. • The fiber showed extraction efficiencies better than a PDMS fiber toward BTEX. • The fiber was successfully applied to the determination of BTEX in real samples. - Abstract: In this work cobalt oxide nanoparticles were introduced for preparation of a novel solid phase microextraction (SPME) fiber coating. Chemical bath deposition (CBD) technique was used in order for synthesis and immobilization of the Co 3 O 4 nanomaterials on a Pt wire for fabrication of SPME fiber. The prepared cobalt oxide coating was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The fiber was evaluated for the extraction of benzene, toluene, ethylbenzene and xylene (BTEX) in combination with GC–MS. A simplex optimization method was used to optimize the factors affecting the extraction efficiency. Under optimized conditions, the proposed fiber showed extraction efficiencies comparable to those of a commercial polydimethylsiloxane (PDMS) fiber toward the BTEX compounds. The repeatability of the fiber and its reproducibility, expressed as relative standard deviation (RSD), were lower than about 11%. No significant change was observed in the extraction efficiency of the new SPME fiber after over 50 extractions. The fiber was successfully applied to the determination of BTEX compounds in real samples. The proposed nanostructure cobalt oxide fiber is a promising alternative to the commercial fibers as it is robust, inexpensive and easily prepared

Cobalt oxide nanoparticles as a novel high-efficiency fiber coating for solid phase microextraction of benzene, toluene, ethylbenzene and xylene from aqueous solutions

Energy Technology Data Exchange (ETDEWEB)

Gholivand, Mohammad Bagher, E-mail: MB.Gholivand@yahoo.com [Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Shamsipur, Mojtaba; Shamizadeh, Mohammad [Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Moradian, Rostam; Astinchap, Bandar [Physics Department, Faculty of Science, Razi University, Kermanshah (Iran, Islamic Republic of); Nano Technology Research Laboratory, Razi University, Kermanshah (Iran, Islamic Republic of)

2014-04-01

Highlights: • Co{sub 3}O{sub 4} nanoparticles were introduced as a novel SPME fiber coating. • The fiber was evaluated for the extraction of BTEX in combination with GC–MS. • The fiber showed extraction efficiencies better than a PDMS fiber toward BTEX. • The fiber was successfully applied to the determination of BTEX in real samples. - Abstract: In this work cobalt oxide nanoparticles were introduced for preparation of a novel solid phase microextraction (SPME) fiber coating. Chemical bath deposition (CBD) technique was used in order for synthesis and immobilization of the Co{sub 3}O{sub 4} nanomaterials on a Pt wire for fabrication of SPME fiber. The prepared cobalt oxide coating was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The fiber was evaluated for the extraction of benzene, toluene, ethylbenzene and xylene (BTEX) in combination with GC–MS. A simplex optimization method was used to optimize the factors affecting the extraction efficiency. Under optimized conditions, the proposed fiber showed extraction efficiencies comparable to those of a commercial polydimethylsiloxane (PDMS) fiber toward the BTEX compounds. The repeatability of the fiber and its reproducibility, expressed as relative standard deviation (RSD), were lower than about 11%. No significant change was observed in the extraction efficiency of the new SPME fiber after over 50 extractions. The fiber was successfully applied to the determination of BTEX compounds in real samples. The proposed nanostructure cobalt oxide fiber is a promising alternative to the commercial fibers as it is robust, inexpensive and easily prepared.

Electrochemical characterization of core@shell CoFe{sub 2}O{sub 4}/Au composite

Energy Technology Data Exchange (ETDEWEB)

Carla, Francesco [' Ugo Schiff' , Universita degli Studi di Firenze, Dipartimento di Chimica (Italy); Campo, Giulio; Sangregorio, Claudio; Caneschi, Andrea; Julian Fernandez, Cesar de; Cabrera, Lourdes I., E-mail: lourisa_cabrera@yahoo.com [Universita degli Studi di Firenze, Laboratorio di Magnetismo Molecolare, INSTM, Dipartimento di Chimica (Italy)

2013-08-15

In this paper, we address the synthesis and characterization of the core@shell composite magneto-plasmonic cobalt ferrite-gold (Co-ferrite/Au) nanosystem. The synthesis Co-ferrite/Au nanocomposite is not obvious, hence it was of interest to generate it in a simple straightforward method. Co-ferrite/Au nanocomposite was generated by synthesizing first by thermal decomposition Co-ferrite nanoparticles (NPs). On a second step, ionic gold (Au{sup 3+}) was reduced at the surface of Co-ferrite NPs by ultrasound, to obtain the metallic Au shell. The characterization of the nanomaterial was achieved by microscopy, spectroscopy, and performing magnetic measurements. However, what is attractive about our work is the use of electrochemical techniques as analytical tools. The key technique was cyclic voltammetry, which provided information about the nature and structure of the nanocomposite, allowing us to confirm the core@shell structure.

The intrinsic antimicrobial activity of citric acid-coated manganese ferrite nanoparticles is enhanced after conjugation with the antifungal peptide Cm-p5

Directory of Open Access Journals (Sweden)

Lopez-Abarrategui C

2016-08-01

studied in biomedicine due to their physicochemical properties. The citric acid-modified manganese ferrite nanoparticles used in this study were characterized by high-resolution transmission electron microscopy, which confirmed the formation of nanocrystals of approximately 5 nm diameter. These nanoparticles were able to inhibit Candida albicans growth in vitro. The minimal inhibitory concentration was 250 µg/mL. However, the nanoparticles were not capable of inhibiting Gram-negative bacteria (Escherichia coli or Gram-positive bacteria (Staphylococcus aureus. Finally, an antifungal peptide (Cm-p5 from the sea animal Cenchritis muricatus (Gastropoda: Littorinidae was conjugated to the modified manganese ferrite nanoparticles. The antifungal activity of the conjugated nanoparticles was higher than their bulk counterparts, showing a minimal inhibitory concentration of 100 µg/mL. This conjugate proved to be nontoxic to a macrophage cell line at concentrations that showed antimicrobial activity. Keywords: nanoparticles, conjugation, antifungal, Cm-p5 peptide

Dopant driven tunability of dielectric relaxation in MxCo(1-x)Fe2O4 (M: Zn2+, Mn2+, Ni2+) nano-ferrites

Science.gov (United States)

Datt, Gopal; Abhyankar, A. C.

2017-07-01

Nano-ferrites with tunable dielectric and magnetic properties are highly desirable in modern electronics industries. This work reports the effect of ferromagnetic (Ni), anti-ferromagnetic (Mn), and non-magnetic (Zn) substitution on cobalt-ferrites' dielectric and magnetic properties. The Rietveld analysis of XRD data and the Raman spectroscopic study reveals that all the samples are crystallized in the Fd-3m space group. The T2g Raman mode was observed to split into branches, which is due to the presence of different cations (with different vibrational frequencies) at crystallographic A and B-sites. The magnetization study shows that the MnCoFe2O4 sample has the highest saturation magnetization of 87 emu/g, which is attributed to the presence of Mn2+ cations at the B-site with a magnetic moment of 5 μB. The dielectric permittivity of these nanoparticles (NPs) obeys the modified Debye model, which is further supported by Cole-Cole plots. The dielectric constant of MnCoFe2O4 ferrite is found to be one order higher than that of the other two ferrites. The increased bond length of the Mn2+-O2- bond along with the enhanced d-d electron transition between Mn 2 +/Co 2 +⇋Fe 3 + cations at the B-site are found to be the main contributing factors for the enhanced dielectric constant of MnCoFe2O4 ferrite. We find evidence of variable-range hopping of localized polarons in these ferrite NPs. The activation energy, hopping range, and density of states N (" separators="|EF ), of these polarons were calculated using Motts' 1/4th law. The estimated activation energies of these polarons at 300 K were found to be 288 meV, 426 meV, and 410 meV, respectively, for the MnCoFe2O4, NiCoFe2O4, and ZnCoFe2O4 ferrite NPs, while the hopping range of these polarons were found to be 27.14 Å, 11.66 Å, and 8.17 Å, respectively. Observation of a low dielectric loss of ˜0.04, in the frequency range of 0.1-1 MHz, in these NPs makes them potential candidates for energy harvesting devices in

Electromagnetic interference shielding and microwave absorption properties of cobalt ferrite CoFe2O4/polyaniline composite

Science.gov (United States)

Ismail, Mukhils M.; Rafeeq, Sewench N.; Sulaiman, Jameel M. A.; Mandal, Avinandan

2018-05-01

Improvement of microwave-absorbing materials (MAMs) is the most important research area in various applications, such as in communication, radiation medical exposure, electronic warfare, air defense, and different civilian applications. Conducting polymer, polyaniline doped with para toluene sulphonic acid (PANI-PTSA) as well as cobalt ferrite (CoFe2O4) is synthesized by sol-gel method and intensely blends in different ratios. The characterization of the composite materials, CoFe2O4/PANI-PTSA (CFP1, CFP2, CFP3 and CFP4), was performed by X-ray diffraction (XRD), atomic force microscopy (AFM) and vibrating sample magnetometry (VSM). The microwave-absorbing properties' reflection loss (dB) and important parameters, such as complex relative permittivity ( ɛ r '- jɛ r ″) and complex relative permeability ( µ r '- jµ r ″) were measured in different microwave frequencies in the X-band (8.2-12.4 GHz) region. The composite material CFP3 showed a wider absorption frequency range and maximum reflection loss of - 28.4 dB (99.8% power absorption) at 8.1 GHz and - 9.6 dB (> 90% power absorption) at 11.2 GHz, and so the composite can be used as a microwave absorber; however, it can be more suitable for application in daily life for making cell phones above 9 GHz. Also the results showed that the thicker composites like CFP3 (4 mm) exhibit obviously better EMI SE as compared with the thinner ones (0.19, 0.19, 0.3 mm); this may be related to the low transmission of the EM wave from the composites.

Wear-resistant and electromagnetic absorbing behaviors of oleic acid post-modified ferrite-filled epoxy resin composite coating

Science.gov (United States)

Wang, Wenjie; Zang, Chongguang; Jiao, Qingjie

2015-03-01

The post-modified Mn-Zn ferrite was prepared by grafting oleic acid on the surface of Mn-Zn ferrite to inhibit magnetic nanoparticle aggregation. Fourier Transform Infrared (FT-IR) spectroscopy was used to characterize the particle surfaces. The friction and electromagnetic absorbing properties of a thin coating fabricated by dispersing ferrite into epoxy resin (EP) were investigated. The roughness of the coating and water contact angle were measured using the VEECO and water contact angle meter. Friction tests were conducted using a stainless-steel bearing ball and a Rockwell diamond tip, respectively. The complex permittivity and complex permeability of the composite coating were studied in the low frequency (10 MHz-1.5 GHz). Surface modified ferrites are found to improve magnetic particles dispersion in EP resulting in significant compatibility between inorganic and organic materials. Results also indicate that modified ferrite/EP coatings have a lower roughness average value and higher water contact angle than original ferrite/EP coatings. The enhanced tribological properties of the modified ferrite/EP coatings can be seen from the increased coefficient value. The composite coatings with modified ferrite are observed to exhibit better reflection loss compared with the coatings with original ferrite.

Eco-friendly microbial route to synthesize cobalt nanoparticles using Bacillus thuringiensis against malaria and dengue vectors.

Science.gov (United States)

Marimuthu, Sampath; Rahuman, Abdul Abdul; Kirthi, Arivarasan Vishnu; Santhoshkumar, Thirunavukkarasu; Jayaseelan, Chidambaram; Rajakumar, Govindasamy

2013-12-01

The developments of resistance and persistence to chemical insecticides and concerns about the non-target effects have prompted the development of eco-friendly mosquito control agents. The aim of this study was to investigate the larvicidal activities of synthesized cobalt nanoparticles (Co NPs) using bio control agent, Bacillus thuringiensis against malaria vector, Anopheles subpictus and dengue vector, Aedes aegypti (Diptera: Culicidae). The synthesized Co NPs were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), Field-emission scanning electron microscopy (FESEM) with energy dispersive X-ray spectroscopy, and Transmission electron microscopy (TEM). XRD analysis showed three distinct diffraction peaks at 27.03°, 31.00°, and 45.58° indexed to the planes 102, 122, and 024, respectively on the face-centered cubic cobalt acetate with an average size of 85.3 nm. FTIR spectra implicated role of the peak at 3,436 cm(-1) for O-H hydroxyl group, 2924 cm(-1) for methylene C-H stretch in the formation of Co NPs. FESEM analysis showed the topological and morphological appearance of NPs which were found to be spherical and oval in shape. TEM analysis showed polydispersed and clustered NPs with an average size of 84.81 nm. The maximum larvicidal mortality was observed in the cobalt acetate solution, B. thuringiensis formulation, and synthesized Co NPs against fourth instar larvae of A. subpictus and A. aegypti with LC50 values of 29.16, 8.12, 3.59 mg/L; 34.61, 6.94, and 2.87 mg/L; r (2) values of 0.986, 0.933, 0.942; 0.962, 0.957, and 0.922, respectively.

The impact of engineered cobalt, iron, nickel and silver nanoparticles on soil bacterial diversity under field conditions

International Nuclear Information System (INIS)

Shah, Vishal; Collins, Daniel; Shah, Shreya; Walker, Virginia K

2014-01-01

Our understanding of how engineered nanoparticles (NPs) migrate through soil and affect microbial communities is scarce. In the current study we examined how metal NPs, including those from the iron triad (iron, cobalt and nickel), moved through pots of soil maintained under winter field conditions for 50 days, when mesophilic bacteria may not be dividing. Based on total metal analysis, cobalt and nickel were localized in the top layer of soil, even after exposure to high precipitation and freeze–thaw cycles. In contrast, a bimodal distribution of silver was observed. Due to high endogenous levels of iron, the migration pattern of these NPs could not be determined. Pyrosequence analysis of the bacterial communities revealed that there was no significant engineered NP-mediated decline in microbial richness. However, analysis of individual genera showed that Sphingomonas and Lysobacter were represented by fewer sequences in horizons containing elevated metal levels whereas there was an increase in the numbers of Flavobacterium and Niastella. Collectively, the results indicate that along with the differential migration behavior of NPs in the soil matrix, their impact on soil bacterial diversity appears to be dependent on environmental parameters. (paper)

The effect of cobalt substitution on magnetic hardening of magnetite

Energy Technology Data Exchange (ETDEWEB)

Mozaffari, M., E-mail: mozafari@sci.ui.ac.ir [Department of Physics, Faculty of Science, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of); Hadadian, Y. [Physics Department, Razi University, Taghebostan, Kermanshah (Iran, Islamic Republic of); Aftabi, A. [Department of Physics, University of Kurdistan, Sanandaj 66177-15175 (Iran, Islamic Republic of); Oveisy Moakhar, M. [Physics Department, Razi University, Taghebostan, Kermanshah (Iran, Islamic Republic of)

2014-03-15

In this work cobalt-substituted magnetite (Co{sub x}Fe{sub 1−x}Fe{sub 2}O{sub 4}, x=0, 0.25, 0.50 and 0.75) nanoparticles were synthesized by coprecipitation method and their structural and magnetic properties were investigated. X-ray diffraction was carried out and the results show that all of the samples have single phase spinel structure. Microstructure of the samples was studied using a field emission scanning electron microscope and the results show that particle sizes of the prepared nanoparticles were uniform and in the 50–55 nm range. Room temperature magnetic properties of the nanoparticles were measured by an alternating gradient force magnetometer and the results revealed that substituting cobalt for iron in magnetite structure, changes the magnetite from a soft magnetic material to a hard one. So that coercivity changes from 0 (a superparamagnetic state) to 337 Oe (a hard magnetic material), which is a remarkable change. Curie temperatures of the samples were determined by recording their susceptibility-temperature (χ–T) curves and the results show that by increasing cobalt content, Curie temperature of the samples also increases. Also χ–T curves of the samples were recorded from above Curie temperature to room temperature (first cooling), while the curves in the second heating and second cooling have the same behaviour as the first cooling curve. The results depict that all samples have different behaviour in the first cooling and in the first heating processes. This shows remarkable changes of the cation distribution in the course of first heating. - Highlights: • It is possible to get Co substituted magnetite nanoparticles by coprecipitation method. • Prepared nanoparticles have different cation distribution in comparison with that of bulk counterparts. • Co substitution increases coercivity of the magnetite.

Ni-Zn Ferrite-graphene Nanohybrids: Synthesis and Characterization of Magnetic and Microwave Absorbing Properties

Directory of Open Access Journals (Sweden)

Thim Ng Yau

2017-01-01

Full Text Available An in-situ deposition technique was used in the synthesis of Ni-Zn ferrite-graphene (NZFG nanohybrids. The XRD patterns revealed the presence of cubic spinel structure of Ni-Zn ferrite (NZF nanoparticles with good crystallinity and small crystallite sizes. The SEM images showed NZF nanoparticles were uniformly deposited on graphene sheets. The effect of different loading amounts of NZF nanoparticles in the nanohybrids was also investigated by tuning the mass ratio of FeCl3 and expanded graphite (EG. The magnetic measurements showed ferromagnetic behaviour with low coercivity. Improvements in saturation magnetization of the nanohybrids can be seen with increasing mass ratio of FeCl3:EG. The microwave absorption properties were determined based on the measured relative complex permittivity and permeability. For the nanohybrids, the minimum reflection loss (RL obtained is -37.57 dB at 7.54 GHz and the absorbing bandwidth in which the RL is less than -10 dB is 7.30 GHz when the NZF content was 79 wt·% at 7 mm thickness. The enhancement in the minimum RL was due to the synergistic effect between NZF nanoparticles and graphene.

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

Structural and surface changes of cobalt modified manganese oxide during activation and ethanol steam reforming reaction

Science.gov (United States)

Gac, Wojciech; Greluk, Magdalena; Słowik, Grzegorz; Turczyniak-Surdacka, Sylwia

2018-05-01

Surface and structural changes of unmodified manganese and cobalt-manganese oxide during activation and ethanol steam reforming reaction conditions (ESR) were studied by means of X-ray diffraction, X-ray photoelectron spectroscopy, temperature-programmed reduction/oxidation (TPR/TPO) and transmission electron microscopy. It was shown that synthesis of cobalt manganese oxide by the redox precipitation method led to the formation of strongly dispersed cobalt ionic species within cryptomelane-based manganese oxide structure. Development of large cube-like MnO nanoparticles with spherical cobalt metallic crystallites decorated by manganese oxide on the high oxidation state and potassium species was observed during reduction. Cobalt manganese catalyst showed high initial activity and selectivity to H2 and CO2 in ethanol stem reforming reaction in the range of 390-480 °C. The drop of ethanol conversion and changes of selectivity with the time-on-stream were observed. An increase of reaction temperature led to intensification of deactivation phenomena. TEM studies evidenced coexistence of Co and CoOx nanoparticles formed under ethanol steam reforming conditions, partially covered by filamentous and encapsulating carbonaceous deposits.

Thin layer chitosan-coated cellulose filter paper as substrate for immobilization of catalytic cobalt nanoparticles.

Science.gov (United States)

Kamal, Tahseen; Khan, Sher Bahadar; Haider, Sajjad; Alghamdi, Yousef Gamaan; Asiri, Abdullah M

2017-11-01

A facile approach utilizing synthesis of cobalt nanoparticles in green polymers of chitosan (CS) coating layer on high surface area cellulose microfibers of filter paper (CFP) is described for the catalytic reduction of nitrophenol and an organic dye using NaBH 4 . Simple steps of CFP coating with 1wt% CS aqueous solution followed by Co 2+ ions adsorption from 0.2M CoCl 2 aqueous solution were carried out to prepare pre-catalytic strips. The Co 2+ loaded pre-catalytic strips of CS-CFP were treated with 0.19M NaBH 4 aqueous solution to convert the ions into nanoparticles. Successful Co nanoparticles formation was assessed by various characterization techniques of FESEM, EDX and XRD analyzes. TGA analyses were carried out on CFP, CS-CFP, and Co-CS-CFP for the determination of the amount of Co particles formed on the CS-FP, and to track their thermal properties. Furthermore, we demonstrated that the Co-CS-CFP showed an excellent catalytic activity and reusability in the reduction reactions a nitroaromatic compound of 2,6-dintirophenol (2,6-DNP) and brilliant cresyl blue (BCB) dye by NaBH 4 . The Co-CS-CFP catalyzed the reduction reactions of 2,6-DNP and BCB by NaBH 4 with psuedo-first order rate constants of 0.0451 and 0.1987min -1 , respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

AC and DC electrical conductivity, dielectric and magnetic properties of Co{sub 0.65}Zn{sub 0.35}Fe{sub 2-x}Mo{sub x}O{sub 4} (x = 0.0, 0.1 and 0.2) ferrites

Energy Technology Data Exchange (ETDEWEB)

Pradhan, A.K.; Saha, S. [Vidyasagar University, Department of Physics and Techno Physics, Midnapore, West Bengal (India); Nath, T.K. [Indian Institute of Technology Kharagpur, Department of Physics, Kharagpur, West Bengal (India)

2017-11-15

Cobalt-Zinc ferrites are an important material for designing multiferroic composite. The Mo (4d-transition metal) doped Cobalt-Zinc ferrites are synthesized using ceramic (solid-state reaction) method. Investigation of detailed ac and dc electrical conductivity, dielectric and magnetic properties of Co{sub 0.65}Zn{sub 0.35}Fe{sub 2-x}Mo{sub x}O{sub 4} (x = 0.0, 0.1 and 0.2) spinel ferrites have been reported here. The recorded XRD pattern confirms the formation of inverse spinel structure of the material. The dielectric dispersion has been studied in detail and the existence of non-Debye type relaxation behavior has been confirmed. The dielectric tangent loss is found to be very small at high frequency. The ac conductivity follows the correlated barrier hopping like model. Also the conduction process can be best explained on the basis of Verwey-de Boer mechanism. Magnetic phase transition of the material is estimated from magnetization vs. temperature plots. (orig.)

Nanoferrites of nickel doped with cobalt: Influence of Co{sup 2+} on the structural and magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Rodrigues, A.P.G. [Federal University of Rio Grande do Norte, Chemical Institute, Natal-RN 59078-970 (Brazil); Gomes, D.K.S., E-mail: dkarinne@yahoo.com.br [Federal University of Rio Grande do Norte, Graduate Program in Materials Science and Engineering, Laboratory of Catalysis and Materials, Natal-RN 59078-970 (Brazil); Coordination of Improvement of Higher Education Personnel, CAPES/PNPD (Brazil); Araújo, J.H., E-mail: humberto@dfte.ufrn.br [Federal University of Rio Grande do Norte, Department of Theoretical and Experimental Physics, Laboratory of Magnetism and Magnetic Materials, Natal-RN 59078-970 (Brazil); Melo, D.M.A., E-mail: daraujomelo@gmail.com [Federal University of Rio Grande do Norte, Chemical Institute, Natal-RN 59078-970 (Brazil); Oliveira, N.A.S. [Federal University of Rio Grande do Norte, Chemical Institute, Natal-RN 59078-970 (Brazil); Braga, R.M., E-mail: renata@cear.ufpb.br [Federal University of Paraíba, DEER-CEAR, João Pessoa–PB 58051-970 (Brazil)

2015-01-15

Nanoferrites of nickel substituted with cobalt of composition Ni{sub 1−x}Co{sub x}Fe{sub 2}O{sub 4} (0≤x≤0.75), were synthesized by combustion reaction assisted in microwaves. The influence of the substitution of Ni{sup 2+} by Co{sup 2+} content and the concentration of Co{sup 2+} in the structural and magnetic properties was investigated. The powders were prepared by combustion according to the concept of chemical propellants and heated in a microwave oven with a power of 7000 kW. The synthesized powders were characterized by absorption spectroscopy in the infrared region (FTIR), X-ray diffraction (XRD) together with Rietveld refinement, surface area (BET) method, scanning electron microscopy (MEV) and magnetic measurements (MAV). The results indicated that it was possible to obtain nickel ferrite doped with cobalt in all compositions and that an increase of cobalt concentration caused an increase in particle size (9.78–21.63 nm), a reduction in surface area, and reduction in magnetic concentrations greater than 50%. - Highlights: • Nanoferrites Ni{sub 1–x}Co{sub x}Fe{sub 2}O{sub 4}(0≤x≤0.75) synthesized by combustion reaction assisted. • The structural and magnetic properties of substitution of Ni{sup 2+} by Co{sup 2+} were investigate. • Combustion reaction takes spinel phase with suitable magnetic properties. • The ferrites presented characteristics of soft and intermediate magnetic materials.

Effect of cobalt doping on crystallinity, stability, magnetic and optical properties of magnetic iron oxide nano-particles

International Nuclear Information System (INIS)

Anjum, Safia; Tufail, Rabia; Rashid, Khalid; Zia, Rehana; Riaz, S.

2017-01-01

Highlights: • The stability of Co x Fe (2-x) O 3 nanoparticles enhances. • Energy losses increases. • Anisotropy of NP is high. - Abstract: This paper is dedicated to investigate the effect of Co 2+ ions in magnetite Fe 3 O 4 nano-particles with stoichiometric formula Co x Fe 3-x O 4 where (x = 0, 0.05, 0.1 and 0.15) prepared by co-precipitation method. The structural, thermal, morphological, magnetic and optical properties of magnetite and Co 2+ doped magnetite nanoparticles have been carried out using X-ray Diffractometer, Fourier Transform Infrared Spectroscopy, Themogravimetric Analysis, Scanning Electron Microscopy, Vibrating Sample Magnetometer (VSM) and UV–Vis Spectrometer (UV–Vis) respectively. Structural analysis verified the formation of single phase inverse spinel cubic structure with decrease in lattice parameters due to increase in cobalt content. FTIR analysis confirms the single phase of Co x Fe 3-x O 4 nanoparticles with the major band at 887 cm −1 , which might be due to the stretching vibrations of metal-oxide bond. The DSC results corroborate the finding of an increase in the maghemite to hematite phase transition temperature with increase in Co 2+ content. The decrease in enthalpy with increase in Co 2+ concentration attributed to the fact that the degree of conversion from maghemite to hematite decrease which shows that the stability increases with increasing Co 2+ content in B-site of Fe 3 O 4 structure. SEM analysis demonstrated the formation of spherical shaped nanoparticles with least agglomeration. The magnetic measurements enlighten that the coercivity and anisotropy of Co x Fe 3-x O 4 nanoparticles are significantly increased. From UV–Vis analysis it is revealed that band gap energy increases with decreasing particle size. This result has a great interest for magnetic fluid hyperthermia application (MPH).

Manufacture of highly loaded silica-supported cobalt Fischer–Tropsch catalysts from a metal organic framework

KAUST Repository

Sun, Xiaohui

2017-11-16

The development of synthetic protocols for the preparation of highly loaded metal nanoparticle-supported catalysts has received a great deal of attention over the last few decades. Independently controlling metal loading, nanoparticle size, distribution, and accessibility has proven challenging because of the clear interdependence between these crucial performance parameters. Here we present a stepwise methodology that, making use of a cobalt-containing metal organic framework as hard template (ZIF-67), allows addressing this long-standing challenge. Condensation of silica in the Co-metal organic framework pore space followed by pyrolysis and subsequent calcination of these composites renders highly loaded cobalt nanocomposites (~ 50 wt.% Co), with cobalt oxide reducibility in the order of 80% and a good particle dispersion, that exhibit high activity, C5 + selectivity and stability in Fischer-Tropsch synthesis.

Impurity content of reduced-activation ferritic steels and a vanadium alloy

International Nuclear Information System (INIS)

Klueh, R.L.; Grossbeck, M.L.; Bloom, E.E.

1997-01-01

Inductively coupled plasma mass spectrometry was used to analyze a reduced-activation ferritic/martensitic steel and a vanadium alloy for low-level impurities that would compromise the reduced-activation characteristics of these materials. The ferritic steel was from the 5-ton IEA heat of modified F82H, and the vanadium alloy was from a 500-kg heat of V-4Cr-4Ti. To compare techniques for analysis of low concentrations of impurities, the vanadium alloy was also examined by glow discharge mass spectrometry. Two other reduced-activation steels and two commercial ferritic steels were also analyzed to determine the difference in the level of the detrimental impurities in the IEA heat and steels for which no extra effort was made to restrict some of the tramp impurities. Silver, cobalt, molybdenum, and niobium proved to be the tramp impurities of most importance. The levels observed in these two materials produced with present technology exceeded the limits for low activation for either shallow land burial or recycling. The chemical analyses provide a benchmark for the improvement in production technology required to achieve reduced activation; they also provide a set of concentrations for calculating decay characteristics for reduced-activation materials. The results indicate the progress that has been made and give an indication of what must still be done before the reduced-activation criteria can be achieved

On the Deactivation of Cobalt-based Fischer-Tropsch Catalysts

NARCIS (Netherlands)

Cats, K.H.

2016-01-01

The Fischer-Tropsch Synthesis (FTS) process is an attractive way to obtain synthetic liquid fuel from alternative energy sources such as natural gas, coal or biomass. However, the deactivation of the catalyst, consisting of cobalt nanoparticles supported on TiO2, currently hampers the industrial

Temperature and composition dependent density of states extracted using overlapping large polaron tunnelling model in Mn{sub x}Co{sub 1−x}Fe{sub 2}O{sub 4} (x=0.25, 0.5, 0.75) nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Jamil, Arifa; Afsar, M.F. [Micro and Nano Devices Group, Department of Metallurgy and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences, PO Nilore, Islamabad 45650 (Pakistan); Sher, F. [Department of Chemistry, SSE, Lahore University of Management Sciences, Lahore 54000 (Pakistan); Rafiq, M.A., E-mail: aftab@cantab.net [Micro and Nano Devices Group, Department of Metallurgy and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences, PO Nilore, Islamabad 45650 (Pakistan)

2017-03-15

We report detailed ac electrical and structural characterization of manganese cobalt ferrite nanoparticles, prepared by coprecipitation technique. X-ray diffraction (XRD) confirmed single-phase cubic spinel structure of the nanoparticles. Tetrahedral (A) and octahedral (B) group complexes were present in the spinel lattice as determined by Fourier Transform Infrared Spectroscopy (FTIR). Scanning Electron Microscope (SEM) images revealed presence of spherical shape nanoparticles having an average diameter ~50–80 nm. Composition, temperature and frequency dependent ac electrical study of prepared nanoparticles interpreted the role of cationic distribution between A and B sites. Overlapping large polaron tunnelling (OLPT) conduction mechanism was observed from 290 to 200 K. Frequency exponent s was fitted theoretically using OLPT model. High values of Density of States (DOS) of the order of 10{sup 22}–10{sup 24} eV{sup −1} cm{sup −3} were extracted from ac conductivity for different compositions. We found that DOS was dependent on distribution of cations in the tunnel-type cavities along the a and b axis.

An electrochemical sensor prepared by sonochemical one-pot synthesis of multi-walled carbon nanotube-supported cobalt nanoparticles for the simultaneous determination of paracetamol and dopamine

International Nuclear Information System (INIS)

Kutluay, Aysegul; Aslanoglu, Mehmet

2014-01-01

Highlights: • A GCE was modified with carbon nanotubes and cobalt nanoparticles. • The composite material was obtained using an ultrasonic chemical deposition method. • The CoNPs/MWCNT/GCE was applied for the simultaneous determination of PAR and DA. • The presence of AA and UA did not affect the responses of PAR and DA. • Lower detection limits were obtained using the CoNPs/MWCNT/GCE. - Abstract: Multi-walled carbon nanotubes (MWCNTs) functionalized by cobalt nanoparticles were obtained using a single step chemical deposition method in an ultrasonic bath. The composite material was characterized using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The electroactivity of the cobalt-functionalized MWCNTs was assessed in respect to the electrooxidation of paracetamol (PAR) and dopamine (DA). It was found that the carbon nanotube supported cobalt nanoparticles have significantly higher catalytic properties. The proposed electrode has been applied for the simultaneous determination of PAR and DA. The modified electrode could resolve the overlapped voltammetric waves of PAR and DA into two well-defined voltammetric peaks with peak to peak separation of about 203 mV. On the other hand, the presence of potential drug interfering compounds AA and UA did not affect the voltammetric responses of PAR and DA. The current of oxidation peaks showed a linear dependent on the concentrations of PAR and DA in the range of 5.2 × 10 −9 –4.5 × 10 −7 M (R 2 = 0.9987) and 5.0 × 10 −8 –3.0 × 10 −6 M (R 2 = 0.9999), respectively. The detection limits of 1.0 × 10 −9 M and 1.5 × 10 −8 M were obtained for PAR and DA, respectively. The proposed electrode showed good stability (peak current change: 4.9% with and RSD of 2.6% for PAR; 5.5% with and RSD of 3.0% for DA over 3 weeks), reproducibility (RSD 2.3% for PAR and RSD 1.5% for DA), repeatability (RSD 2.25% for PAR and RSD 2.50% for DA) and high recovery (99.7% with an RSD of 1

An electrochemical sensor prepared by sonochemical one-pot synthesis of multi-walled carbon nanotube-supported cobalt nanoparticles for the simultaneous determination of paracetamol and dopamine

Energy Technology Data Exchange (ETDEWEB)

Kutluay, Aysegul; Aslanoglu, Mehmet, E-mail: maslanoglu@harran.edu.tr

2014-08-11

Highlights: • A GCE was modified with carbon nanotubes and cobalt nanoparticles. • The composite material was obtained using an ultrasonic chemical deposition method. • The CoNPs/MWCNT/GCE was applied for the simultaneous determination of PAR and DA. • The presence of AA and UA did not affect the responses of PAR and DA. • Lower detection limits were obtained using the CoNPs/MWCNT/GCE. - Abstract: Multi-walled carbon nanotubes (MWCNTs) functionalized by cobalt nanoparticles were obtained using a single step chemical deposition method in an ultrasonic bath. The composite material was characterized using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The electroactivity of the cobalt-functionalized MWCNTs was assessed in respect to the electrooxidation of paracetamol (PAR) and dopamine (DA). It was found that the carbon nanotube supported cobalt nanoparticles have significantly higher catalytic properties. The proposed electrode has been applied for the simultaneous determination of PAR and DA. The modified electrode could resolve the overlapped voltammetric waves of PAR and DA into two well-defined voltammetric peaks with peak to peak separation of about 203 mV. On the other hand, the presence of potential drug interfering compounds AA and UA did not affect the voltammetric responses of PAR and DA. The current of oxidation peaks showed a linear dependent on the concentrations of PAR and DA in the range of 5.2 × 10{sup −9}–4.5 × 10{sup −7} M (R{sup 2} = 0.9987) and 5.0 × 10{sup −8}–3.0 × 10{sup −6} M (R{sup 2} = 0.9999), respectively. The detection limits of 1.0 × 10{sup −9} M and 1.5 × 10{sup −8} M were obtained for PAR and DA, respectively. The proposed electrode showed good stability (peak current change: 4.9% with and RSD of 2.6% for PAR; 5.5% with and RSD of 3.0% for DA over 3 weeks), reproducibility (RSD 2.3% for PAR and RSD 1.5% for DA), repeatability (RSD 2.25% for PAR and RSD 2.50% for DA) and

Structural and magnetic properties of cadmium substituted manganese ferrites prepared by hydrothermal route

Energy Technology Data Exchange (ETDEWEB)

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); Zaki, Z.I. [Faculty of Science, Taif University, P.O. Box: 888, Al-Haweiah, Taif (Saudi Arabia); Advanced Materials Division, Central Metallurgical R and D Institute (CMRDI), P.O. Box: 87 Helwan, Cairo (Egypt); 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)

2013-03-15

Cd-substituted manganese ferrite Mn{sub 1-x}Cd{sub x}Fe{sub 2}O{sub 4} powders with x having values 0.0, 0.1, 0.3 and 0.5 have been synthesized by hydrothermal route at 180 Degree-Sign C in presence of NaOH as mineralizer. The obtained ferrite samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM). The XRD analysis showed that pure single phases of cubic ferrites were obtained with x upto 0.3. However, sample with x{>=}0.5 showed hexagonal phase of cadmium hydroxide (Cd(OH){sub 2}) besides the ferrite phase. The increase in Cd-substitution upto x=0.3 leads to an increase in the lattice parameter as well as the average crystallite size of the prepared ferrites. The average crystallite size increased by increasing the Cd-content and was in the range of 39-57 nm. According to VSM results, the saturation magnetization increased with Cd ion substitution. - Highlights: Black-Right-Pointing-Pointer Hydrothermal synthesized of mono dispersed Cd-substituted MnFe{sub 2}O{sub 4} nanoparticles. Black-Right-Pointing-Pointer The change in Ms with increasing Cd-substitution was investigated Black-Right-Pointing-Pointer Pure single phases of cubic ferrites were obtained with x up to 0.3 Black-Right-Pointing-Pointer Sample with x{>=}0.5 showed hexagonal phase of Cd(OH){sub 2} beside the ferrite.

Self-assembled organic-inorganic magnetic hybrid adsorbent ferrite based on cyclodextrin nanoparticles.

Science.gov (United States)

Denadai, Angelo M L; De Sousa, Frederico B; Passos, Joel J; Guatimosim, Fernando C; Barbosa, Kirla D; Burgos, Ana E; de Oliveira, Fernando Castro; da Silva, Jeann C; Neves, Bernardo R A; Mohallem, Nelcy D S; Sinisterra, Rubén D

2012-01-01

Organic-inorganic magnetic hybrid materials (MHMs) combine a nonmagnetic and a magnetic component by means of electrostatic interactions or covalent bonds, and notable features can be achieved. Herein, we describe an application of a self-assembled material based on ferrite associated with β-cyclodextrin (Fe-Ni/Zn/βCD) at the nanoscale level. This MHM and pure ferrite (Fe-Ni/Zn) were used as an adsorbent system for Cr(3+) and Cr(2)O(7) (2-) ions in aqueous solutions. Prior to the adsorption studies, both ferrites were characterized in order to determine the particle size distribution, morphology and available binding sites on the surface of the materials. Microscopy analysis demonstrated that both ferrites present two different size domains, at the micro- and nanoscale level, with the latter being able to self-assemble into larger particles. Fe-Ni/Zn/βCD presented smaller particles and a more homogeneous particle size distribution. Higher porosity for this MHM compared to Fe-Ni/Zn was observed by Brunauer-Emmett-Teller isotherms and positron-annihilation-lifetime spectroscopy. Based on the pKa values, potentiometric titrations demonstrated the presence of βCD in the inorganic matrix, indicating that the lamellar structures verified by transmission electronic microscopy can be associated with βCD assembled structures. Colloidal stability was inferred as a function of time at different pH values, indicating the sedimentation rate as a function of pH. Zeta potential measurements identified an amphoteric behavior for the Fe-Ni/Zn/βCD, suggesting its better capability to remove ions (cations and anions) from aqueous solutions compared to that of Fe-Ni/Zn.

Self-assembled organic–inorganic magnetic hybrid adsorbent ferrite based on cyclodextrin nanoparticles

Directory of Open Access Journals (Sweden)

Ângelo M. L. Denadai

2012-11-01

Full Text Available Organic–inorganic magnetic hybrid materials (MHMs combine a nonmagnetic and a magnetic component by means of electrostatic interactions or covalent bonds, and notable features can be achieved. Herein, we describe an application of a self-assembled material based on ferrite associated with β-cyclodextrin (Fe-Ni/Zn/βCD at the nanoscale level. This MHM and pure ferrite (Fe-Ni/Zn were used as an adsorbent system for Cr3+ and Cr2O72− ions in aqueous solutions. Prior to the adsorption studies, both ferrites were characterized in order to determine the particle size distribution, morphology and available binding sites on the surface of the materials. Microscopy analysis demonstrated that both ferrites present two different size domains, at the micro- and nanoscale level, with the latter being able to self-assemble into larger particles. Fe-Ni/Zn/βCD presented smaller particles and a more homogeneous particle size distribution. Higher porosity for this MHM compared to Fe-Ni/Zn was observed by Brunauer–Emmett–Teller isotherms and positron-annihilation-lifetime spectroscopy. Based on the pKa values, potentiometric titrations demonstrated the presence of βCD in the inorganic matrix, indicating that the lamellar structures verified by transmission electronic microscopy can be associated with βCD assembled structures. Colloidal stability was inferred as a function of time at different pH values, indicating the sedimentation rate as a function of pH. Zeta potential measurements identified an amphoteric behavior for the Fe-Ni/Zn/βCD, suggesting its better capability to remove ions (cations and anions from aqueous solutions compared to that of Fe-Ni/Zn.

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

Energy Technology Data Exchange (ETDEWEB)

Sam, Shiju, E-mail: shiju@ipr.res.in [Institute for Plasma Research, Gandhinagar, Gujarat 382 428 (India); Das, C.R.; Ramasubbu, V.; Albert, S.K.; Bhaduri, A.K.; Jayakumar, T. [Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Rajendra Kumar, E. [Institute for Plasma Research, Gandhinagar, Gujarat 382 428 (India)

2014-12-15

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.

Synthesis, characterization and gas sensitivity investigation of Ni0.5Zn0.5Fe2O4 nanoparticles

Science.gov (United States)

Ebrahimi, Hamid Reza; Parish, Mohammad; Amiri, Gholam Reza; Bahraminejad, Behzad; Fatahian, Soheil

2016-09-01

Nickel zinc ferrite nanoparticles with diameters less than 20 nm were synthesized by co-precipitation method. The synthesized nanoparticles were annealed at 500 °C. Two types of samples (powder and disk) were prepared. The disk sample was prepared by pressing the powder sample. Magnetic and structural properties of the products were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and alternating gradient-force magnetometer (AGFM). The X-ray analysis shows that the formation of the synthesized nickel zinc ferrite is spinell. The average crystalline size for nickel zinc ferrite powder was found around 19 nm (calculated by Debye-Scherer formula).The formation, size and the uniformity of the samples were determined by TEM. It was found that the size of nanoparticles should be around 18 nm from the SEM image. AGFM diagrams shows that the magnetization of the powder sample at the 9 kOe is 21.5 emu/g that of disk sample is 33 emu/g. Therefore, the magnetization was increased by pressing the nickel zinc ferrite nanoparticles. Sensor sensitivity of this disk ferrite is investigated in an isolated box. For this purpose, the samples are injected to this box and six gases (ethanol, methanol, chloroform, acetonitrile, acetone and methane) are exposed to the ferrite by a mechanical gate. The acetonitrile had the best sensitivity performance.

Magnetic heating by silica-coated Co–Zn ferrite particles

Czech Academy of Sciences Publication Activity Database

Veverka, Miroslav; Závěta, K.; Kaman, Ondřej; Veverka, Pavel; Knížek, Karel; Pollert, Emil; Burian, M.; Kašpar, P.

2014-01-01

Roč. 47, č. 6 (2014), "065503-1"-"065503-11" ISSN 0022-3727 R&D Projects: GA ČR GAP204/10/0035; GA ČR(CZ) GAP108/11/0807 Institutional support: RVO:68378271 Keywords : cobalt–zinc ferrite * magnetic nanoparticles * coprecipitation * silica coating * hysteresis loops * calorimetric measurements * hyperthermia Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.721, year: 2014 http://stacks.iop.org/0022-3727/47/065503

Controlling of morphology and electrocatalytic properties of cobalt oxide nanostructures prepared by potentiodynamic deposition method

Energy Technology Data Exchange (ETDEWEB)

Hallaj, Rahman [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Akhtari, Keivan [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Research Center for Nanotechnology, University of Kurdistan, P.O.Box 416, Sanandaj (Iran, Islamic Republic of); Salimi, Abdollah, E-mail: absalimi@uok.ac.ir [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Research Center for Nanotechnology, University of Kurdistan, P.O.Box 416, Sanandaj (Iran, Islamic Republic of); Soltanian, Saied [Department of Physics, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of)

2013-07-01

Electrodeposited cobalt oxide nanostructures were prepared by Repetitive Triangular Potential Scans (RTPS) as a simple, remarkably fast and scalable potentiodynamic method. Electrochemical deposition of cobalt oxide nanostructures onto GC electrode was performed from aqueous Co(NO{sub 3}){sub 2}, (pH 6) solution using cyclic voltammetry method. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to characterize the morphology of fabricated nanostructures. The evaluation of electrochemical properties of deposited films was performed using cyclic voltametry (CV) and impedance spectroscopy (IS) techniques. The analysis of the experimental data clearly showed that the variations of potential scanning ranges during deposition process have drastic effects on the geometry, chemical structure and particle size of cobalt oxide nanoparticles. In addition, the electrochemical and electrocatalytic properties of prepared nanostructures can be controlled through applying different potential windows in electrodeposition process. The imaging and voltammetric studies suggested to the existence of at least three different shapes of cobalt-oxide nanostructures in various potential windows applied for electrodeposition. With enlarging the applied potential window, the spherical-like cobalt oxide nanoparticles with particles sizes about 30–50 nm changed to the grain-like structures (30 nm × 80 nm) and then to the worm-like cobalt oxide nanostructures with 30 nm diameter and 200–400 nm in length. Furthermore, the roughness of the prepared nanostructures increased with increasing positive potential window. The GC electrodes modified with cobalt oxide nanostructures shows excellent electrocatalytic activity toward H{sub 2}O{sub 2} and As (III) oxidation. The electrocatalytic activity of cobalt oxide nanostructures prepared at more positive potential window toward hydrogen peroxide oxidation was increased, while for As(III) oxidation the electrocatalytic