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Sample records for ferritic nanocrystalline material

  1. Synthesis and characterization of nanocrystalline zinc ferrite

    DEFF Research Database (Denmark)

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

    1999-01-01

    Nanocrystalline zinc ferrite powders with a partially inverted spinel structure were synthesized by high-energy ball milling in a closed container at ambient temperature from a mixture of alpha-Fe2O3 and ZnO crystalline powders in equimolar ratio. From low-temperature and in-field Mossbauer...

  2. Nanocrystalline ceramic materials

    Science.gov (United States)

    Siegel, Richard W.; Nieman, G. William; Weertman, Julia R.

    1994-01-01

    A method for preparing a treated nanocrystalline metallic material. The method of preparation includes providing a starting nanocrystalline metallic material with a grain size less than about 35 nm, compacting the starting nanocrystalline metallic material in an inert atmosphere and annealing the compacted metallic material at a temperature less than about one-half the melting point of the metallic material.

  3. Magnetic behavior of nanocrystalline nickel ferrite

    International Nuclear Information System (INIS)

    Nathani, H.; Gubbala, S.; Misra, R.D.K.

    2005-01-01

    In the previous papers [R.D.K. Misra, A. Kale, R.S. Srivatsava, O. Senkov, Mater. Sci. Technol. 19 (2003) 826; R.D.K. Misra, A. Kale, B. Hooi, J.Th. DeHosson, Mater. Sci. Technol. 19 (2003) 1617; A. Kale, S. Gubbala, R.D.K. Misra, J. Magn. Magn. Mater. 277 (2004) 350; S. Gubbala, H. Nathani, K. Koizol, R.D.K. Misra, Phys. B 348 (2004) 317; R.D.K. Misra, S. Gubbala, A. Kale, W.F. Egelhoff, Mater. Sci. Eng. B. 111 (2004) 164], we reported the synthesis, structural characterization and magnetic behavior of nanocrystalline ferrites of inverse and mixed spinel structure made by reverse micelle technique that enabled a narrow particle size distribution to be obtained. In the present paper, the reverse micelle approach has been extended to synthesize nanocrystalline ferrites with varying surface roughness of 8-18 A (the surface roughness was measured by atomic force microscopy) and the magnetic behavior studied by SQUID magnetometer. Two different kinds of measurement were performed: (a) zero-field cooling (ZFC) and field cooling (FC) magnetization versus temperature measurements and (b) magnetization as a function of applied field. The analysis of magnetic measurement suggests significant influence of surface roughness of particles on the magnetic behavior. While the superparamagnetic behavior is retained by the nanocrystalline ferrites of different surface roughness at 300 K, the hysteresis loop at 2 K becomes non-squared and the coercivity increases with increase in surface roughness. This behavior is discussed in terms of broken bonds and degree of surface spin disorder

  4. Nanocrystalline spinel ferrites by solid state reaction route

    Indian Academy of Sciences (India)

    Wintec

    Nanocrystalline spinel ferrites by solid state reaction route. T K KUNDU* and S MISHRA. Department of Physics, Visva-Bharati, Santiniketan 731 235, India. Abstract. Nanostructured NiFe2O4, MnFe2O4 and (NiZn)Fe2O4 were synthesized by aliovalent ion doping using conventional solid-state reaction route. With the ...

  5. 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.

  6. 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.

  7. Ferrite materials for memory applications

    CERN Document Server

    Saravanan, R

    2017-01-01

    The book discusses the synthesis and characterization of various ferrite materials used for memory applications. The distinct feature of the book is the construction of charge density of ferrites by deploying the maximum entropy method (MEM). This charge density gives the distribution of charges in the ferrite unit cell, which is analyzed for charge related properties.

  8. 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.

  9. Surface effects on the magnetic behavior of nanocrystalline nickel ferrites and nickel ferrite-polymer nanocomposites

    International Nuclear Information System (INIS)

    Nathani, H.; Misra, R.D.K.

    2004-01-01

    The magnetization studies on nanocrystalline nickel ferrite as powder particles, and as diluted dispersion (10 wt.%) in polymer matrix (polymer nanocomposites) are presented. The two polymer-based nanocomposites were prepared via ball-milling and in situ polymerization, respectively. The magnetization measurements provide strong evidence of surface effects to magnetization, which explains the non-saturation of magnetization at high fields. The differences in the magnetization behavior of nickel ferrite as powder particles and in the ball-milled nanocomposite and the nanocomposite prepared via in situ polymerization are attributed to the different extent of interparticle interactions between the particles and the preparation route. The magnetization versus applied field behavior of the three ferrite systems show a similar jump in the initial part of the magnetization curve in all the cases which implies the existence of a core-shell like morphology of the particles over a large temperature range and its dominance over the interparticle interaction effects between the particles

  10. Nanocrystalline zinc ferrite films studied by magneto-optical spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lišková-Jakubisová, E., E-mail: liskova@karlov.mff.cuni.cz; Višňovský, Š. [Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, Prague (Czech Republic); Široký, P.; Hrabovský, D.; Pištora, J. [Nanotechnology Center, VŠB-Technical University of Ostrava, 17. listopadu 15, 708 33 Ostrava-Poruba (Czech Republic); Sahoo, Subasa C. [Department of Physics, Central University of Kerala, Kasaragod, Kerala 671314 (India); Prasad, Shiva [Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Venkataramani, N. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Bohra, Murtaza [Okinawa Institute of Science and Technology Graduate University (OIST), Okinawa (Japan); Krishnan, R. [Groupe d' Etude de la Matière Condensée (GEMaC), CNRS-UVSQ, 45 Avenue des Etats-Unis, 78935 Versailles (France)

    2015-05-07

    Ferrimagnetic Zn-ferrite (ZnFe{sub 2}O{sub 4}) films can be grown with the ferromagnetic resonance linewidth of 40 Oe at 9.5 GHz without going through a high temperature processing. This presents interest for applications. The work deals with laser ablated ZnFe{sub 2}O{sub 4} films deposited at O{sub 2} pressure of 0.16 mbar onto fused quartz substrates. The films about 120 nm thick are nanocrystalline and their spontaneous magnetization, 4πM{sub s}, depends on the nanograin size, which is controlled by the substrate temperature (T{sub s}). At T{sub s} ≈ 350 °C, where the grain distribution peaks around ∼20–30 nm, the room temperature 4πM{sub s} reaches a maximum of ∼2.3 kG. The films were studied by magnetooptical polar Kerr effect (MOKE) spectroscopy at photon energies between 1 and 5 eV. The complementary characteristics were provided by spectral ellipsometry (SE). Both the SE and MOKE spectra confirmed ferrimagnetic ordering. The structural details correspond to those observed in MgFe{sub 2}O{sub 4} and Li{sub 0.5}Fe{sub 2.5}O{sub 4} spinels. SE experiments confirm the insulator behavior. The films display MOKE amplitudes somewhat reduced with respect to those in Li{sub 0.5}Fe{sub 2.5}O{sub 4} and MgFe{sub 2}O{sub 4} due to a lower degree of spinel inversion and nanocrystalline structure. The results indicate that the films are free of oxygen vacancies and Fe{sup 3+}-Fe{sup 2+} exchange.

  11. 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.

  12. 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.

  13. 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.

  14. Structure and thermal stability of nanocrystalline materials

    Indian Academy of Sciences (India)

    In addition, study of the thermal stability of nanocrystalline materials against significant grain growth is both scientific and technological interest. A sharp increase in grain size (to micron levels) during consolidation of nanocrystalline powders to obtain fully dense materials may consequently result in the loss of some unique ...

  15. Some aspects of nanocrystalline nickel and zinc ferrites processed using microemulsion technique

    NARCIS (Netherlands)

    Misra, RDK; Kale, A; Kooi, BJ; De Hosson, JTM

    2003-01-01

    Nanocrystalline nickel and zinc ferrites synthesised using a microemulsion technique were characterised by high resolution transmission electron microscopy and vibrating sample magnetometry. A narrow and uniform distribution of crystals of size range 5-8 nm, distinguished by a clear lack of

  16. 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

  17. Microwave Measurements of Ferrite Polymer Composite Materials

    Directory of Open Access Journals (Sweden)

    Rastislav Dosoudil

    2004-01-01

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

  18. Magnetic properties of bioactive glass-ceramics containing nanocrystalline zinc ferrite

    International Nuclear Information System (INIS)

    Singh, Rajendra Kumar; Srinivasan, A.

    2011-01-01

    Glass-ceramics with finely dispersed zinc ferrite (ZnFe 2 O 4 ) nanocrystallites were obtained by heat treatment of x(ZnO,Fe 2 O 3 )(65-x)SiO 2 20(CaO,P 2 O 5 )15Na 2 O (6≤x≤21 mole%) glasses. X-ray diffraction patterns of the glass-ceramic samples revealed the presence of calcium sodium phosphate [NaCaPO 4 ] and zinc ferrite [ZnFe 2 O 4 ] as major crystalline phases. Zinc ferrite present in nanocrystalline form contributes to the magnetic properties of the glass-ceramic samples. Magnetic hysteresis cycles of the glass-ceramic samples were obtained with applied magnetic field sweeps of ±20 kOe and ±500 Oe, in order to evaluate the potential of these glass-ceramics for hyperthermia treatment of cancer. The evolution of magnetic properties in these samples, viz., from a partially paramagnetic to fully ferrimagnetic nature has been explored using magnetometry and X-ray diffraction studies. - Research highlights: → The glass-ceramics contain bone mineral and magnetic phases. → Calcium sodium phosphate and zinc ferrite nanocrystallites have been identified in all the sample. → With an increase in ZnO and Fe2O3 content, magnetic property of samples evolved from partially paramagnetic to fully ferrimagnetic nature. → Large magnetic hysteresis loops have been obtained for samples with high ZnO+Fe2O3 content.

  19. Magneto acoustical emission in nanocrystalline Mn–Zn ferrites

    International Nuclear Information System (INIS)

    Praveena, K.; Murthty, S.R.

    2013-01-01

    Graphical abstract: Mn 0.4 Zn 0.6 Fe 2 O 4 powders were prepared by microwave hydrothermal method. The powders were characterized by X-ray diffraction, transmission electron microscope. The powders were sintered at different temperatures 400, 500, 600, 700, 800 and 900 °C/30 min using microwave sintering method. The grain size was estimated by scanning electron microscope. The room temperature dielectric and magnetic properties were studied in the frequency range (100 kHz–1.8 GHz). The magnetization properties were measured upto 1.5 T. The acoustic emission has been measured along the hysteresis loops from 80 K to Curie temperature. It is found that the magneto-acoustic emission (MAE) activity along hysteresis loop is proportional to the hysteresis losses during the same loop. This law has been verified on series of polycrystalline ferrites and found that the law is valid whatever the composition, the grain size and temperature. It is also found that the domain wall creation/or annihilation processes are the origin of the MAE. - Highlights: • The AE been measured along the hysteresis loops from 80 K to Curie temperature. • The MAE activity along hysteresis loop is proportional to P h during the same loop. • It is found that the domain wall creation/or annihilation processes are the origin of the MAE. - Abstract: Mn 0.4 Zn 0.6 Fe 2 O 4 powders were prepared by microwave hydrothermal method. The powders were characterized by X-ray diffraction, transmission electron microscope. The powders were sintered at different temperatures 400, 500, 600, 700, 800 and 900 °C/30 min using microwave sintering method. The grain size was estimated by scanning electron microscope. The room temperature dielectric and magnetic properties were studied in the frequency range (100 kHz–1.8 GHz). The magnetization properties were measured upto 1.5 T. The acoustic emission has been measured along the hysteresis loops from 80 K to Curie temperature. It is found that the magneto

  20. Structural, electrical and dielectric properties of nanocrystalline Mg-Zn ferrites

    International Nuclear Information System (INIS)

    Anis-ur-Rehman, M.; Malik, M.A.; Nasir, S.; Mubeen, M.; Khan, K.; Maqsood, A.

    2011-01-01

    The nanocrystalline Mg-Zn ferrites having general formula Mg/sub 1-x/Zn/sub x/Fe/sub 2/O/sub 4/ (x=0, 0.1, 0.2, 0.3, 0.4, 0. 5) were prepared by WOWS sol-gel route. All prepared samples were sintered at 700 deg. C for 2 h. X-ray powder diffraction (XRD) technique was used to investigate structural properties of the samples. The crystal structure was found to be spinel. The crystallite size, lattice parameters and porosity of samples were calculated by XRD data analysis as function of zinc concentration. The crystallite size for each sample was calculated using the Scherrer formula considering the most intense (3 1 1) peak and the range obtained was 34-68 nm. The dielectric constant, dielectric loss tangent and AC electrical conductivity of nanocrystalline Mg-Zn ferrites are investigated as a function of frequency. The dielectric constant, dielectric loss tangent increased with increase of Zn concentration. All the electrical properties are explained in accordance with Maxwell Wagner model and K/sub oops/ phenomenological theory. (author)

  1. 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.

  2. Synthesis and Characterization of Nano-Crystalline Cu and Pb0.5-Cu0.5- ferrites by Mechanochemical Method and Their Electrical and Gas Sensing Properties

    Directory of Open Access Journals (Sweden)

    V. B. GAIKWAD

    2011-11-01

    Full Text Available In the present communication, we have reported the synthesis of nanocrystalline ferrites of the type CuFe2O4 and Pb0.5Cu0.5Fe2O4 by mechanochemical alloying at 960 0C. The samples prepared were characterized by X-ray diffraction (XRD, VSM, FT-IR, UV-DRS, and SEM. The average particle size was determined by XRD pattern using Scherrer equation and it is 7.295 nm, 4.484 nm for CuFe2O4, and Pb0.5Cu0.5Fe2O4. The surface morphology of the samples is characterized by scanning electron microscopy (SEM. Magnetic studies were carried out using vibrating sample magnetometer (VSM and shows very high coercive field for the mixed ferrite. UV-DRS studies were performed to investigate the band gap of synthesized nanocrystalline material. Electrical properties show semiconducting nature of synthesized ferrites. The thick films of the material were prepared by screen printing method. The gas sensing properties were studied towards reducing gases like CO, NH3 and H2S and it was revealed that CuFe2O4 is the most sensitive and selective to H2S gas at relatively lower operating temperature 200 0C. Furthermore Pb0.5Cu0.5Fe2O4 also shows the response to H2S at operating temperature 300 0C.

  3. Influence of rare earth (Nd{sup +3}) doping on structural and magnetic properties of nanocrystalline manganese-zinc ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Naik, Pranav P., E-mail: drppn1987@gmail.com [Department of Physics, Goa University, Taleigao Plateau, Goa, 403206 (India); Tangsali, R.B. [Department of Physics, Goa University, Taleigao Plateau, Goa, 403206 (India); Meena, S.S.; Yusuf, S.M. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai, 400085 (India)

    2017-04-15

    Ultrafine nanopowders of Mn{sub 0.6}Zn{sub 0.4}Fe{sub 2-x}Nd{sub x}O{sub 4} (x = 0, 0.04, 0.06, 0.08, and 0.1) were prepared using combustion method. The influence of Nd{sup +3} doping on structural parameters, morphological characteristics and magnetic properties were investigated. Formation of pure spinel phase was confirmed using X-ray powder diffraction (XRPD). Nd{sup +3} doping in Mn-Zn ferrite samples have shown remarkable influence on all the properties that were under investigation. An increase in lattice constant commensurate with increasing Nd{sup +3} concentrations was observed in the samples. The crystallite size calculated from XRPD data and grain size observed from Transmission Electron Microscope showed a proportionate decrement with increment in rare earth doping. An increase in mass density, X-ray density, particle strain and decrease in porosity were the other effects noticed on the samples as a result of Nd{sup +3} doping. The corresponding tetrahedral, octahedral bond lengths and bond angles estimated from XRPD data have also shown substantial influence of the Nd{sup +3} doping. Magnetic parameters namely saturation magnetization (M{sub S}) and net magnetic moment η{sub B}, estimated using vibrating sample magnetometer (VSM) were found to depend on the Nd{sup +3} doping. Mössbauer spectroscopy was employed to study the magnetic environment of Mössbauer active ions and detection of superparamagnetic behavior in nanocrystalline rare earth ferrite material. The isomer shift values obtained from Mössbauer spectra indicate the presence of Fe{sup +3} ions at tetrahedral site (A-site) and octahedral site (B-site), respectively. - Highlights: • Synthesis of Nd doped Mn-Zn ferrite nanoparticles using combustion method. • Successful doping of Nd{sup +3} at octahedral site in ferrite structure. • Existence of Fe{sup +3} oxidation state at both A-Site and B-site. • Enhanced saturation magnetization due to altered cation distribution by Nd doping

  4. 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.

  5. 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

  6. Amorphous and nanocrystalline materials preparation, properties, and applications

    CERN Document Server

    Inoue, A

    2001-01-01

    Amorphous and nanocrystalline materials are a class of their own. Their properties are quite different to those of the corresponding crystalline materials. This book gives systematic insight into their physical properties, structure, behaviour, and design for special advanced applications.

  7. Structure and magnetic properties of highly textured nanocrystalline Mn–Zn ferrite thin film

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, Jaison, E-mail: jaisonjosephp@gmail.com [Department of Physics, Goverment College, Khandola, Goa 403107 India (India); Tangsali, R.B. [Department of Physics, Goa University, Taleigao Plateau, Goa 403206 India (India); Pillai, V.P. Mahadevan [Department of Optoelectronics, University of Kerala,Thiruvananthapuram, Kerala 695581 India (India); Choudhary, R.J.; Phase, D.M.; Ganeshan, V. [UGC-DAE-CSR Indore, Madhya Pradesh 452017 India. (India)

    2015-01-01

    Nanoparticles of Mn{sub 0.2}Zn{sub 0.8}Fe{sub 2}O{sub 4} were chemically synthesized by co-precipitating the metal ions in aqueous solutions in a suitable alkaline medium. The identified XRD peaks confirm single phase spinal formation. The nanoparticle size authentication is carried out from XRD data using Debye Scherrer equation. Thin film fabricated from this nanomaterial by pulse laser deposition technique on quartz substrate was characterized using XRD and Raman spectroscopic techniques. XRD results revealed the formation of high degree of texture in the film. AFM analysis confirms nanogranular morphology and preferred directional growth. A high deposition pressure and the use of a laser plume confined to a small area for transportation of the target species created certain level of porosity in the deposited thin film. Magnetic property measurement of this highly textured nanocrystalline Mn–Zn ferrite thin film revealed enhancement in properties, which are explained on the basis of texture and surface features originated from film growth mechanism.

  8. Electrochemistry of Inorganic Nanocrystalline Electrode Materials for Lithium Batteries

    Directory of Open Access Journals (Sweden)

    C. W. Kwon

    2003-01-01

    much different from that of traditional crystalline ones because of their significant ‘surface effects’. In connection with that, the nanocrystalline cathode materials are reported to have an enhanced electrochemical activity when the first significative electrochemical step is insertion of Li ions (discharge process. The “electrochemical grafting” concept will be given as a plausible explanation. As illustrative examples, electrochemical behaviors of nanocrystalline manganese oxydes are presented.

  9. 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.

  10. Nanocrystalline spinel ferrite (MFe2O4, M = Ni, Co, Mn, Mg, Zn) powders prepared by a simple aloe vera plant-extracted solution hydrothermal route

    International Nuclear Information System (INIS)

    Phumying, Santi; Labuayai, Sarawuth; Swatsitang, Ekaphan; Amornkitbamrung, Vittaya; Maensiri, Santi

    2013-01-01

    Graphical abstract: This figure shows the specific magnetization curves of the as-prepared MFe 2 O 4 (M = Ni, Co, Mn, Mg, Zn) powders obtained from room temperature VSM measurement. These curves are typical for a soft magnetic material and indicate hysteresis ferromagnetism in the field ranges of ±500 Oe, ±1000 Oe, and ±2000 Oe for the CoFe 2 O 4 , MgFe 2 O 4 and MnFe 2 O 4 respectively, whereas the samples of NiFe 2 O 4 and ZnFe 2 O 4 show a superparamagnetic behavior. Highlights: ► Nanocrystalline MFe 2 O 4 powders were synthesized by a novel hydrothermal method. ► Metal acetylacetonates and aloe vera plant-extracted solution are used. ► This biosynthetic route is very simple and provides high-yield oxide nanomaterials. ► XRD and TEM results indicate that the prepared samples have only spinel structure. ► The maximum M s of 68.9 emu/g at 10 kOe were observed for the samples of MnFe 2 O 4 . - Abstract: Nanocrystalline spinel ferrite MFe 2 O 4 (M = Ni, Co, Mn, Mg, Zn) powders were synthesized by a novel hydrothermal method using Fe(acac) 3 , M(acac) 3 (M = Ni, Co, Mn, Mg, Zn) and aloe vera plant extracted solution. The X-ray diffraction and selected-area electron diffraction results indicate that the synthesized nanocrystalline have only spinel structure without the presence of other phase impurities. The crystal structure and morphology of the spinel ferrite powders, as revealed by TEM, show that the NiFe 2 O 4 and CoFe 2 O 4 samples contain nanoparticles, whereas the MnFe 2 O 4 and MgFe 2 O 4 samples consist of many nanoplatelets and nanoparticles. Interestingly, the ZnFe 2 O 4 sample contains plate-like structure of networked nanocrystalline particles. Room temperature magnetization results show a ferromagnetic behavior of the CoFe 2 O 4 , MnFe 2 O 4 and MgFe 2 O 4 samples, whereas the samples of NiFe 2 O 4 and ZnFe 2 O 4 exhibit a superparamagnetic behavior

  11. Structural, magnetic and electrical characterization of Mg–Ni nano-crystalline ferrites prepared through egg-white precursor

    Energy Technology Data Exchange (ETDEWEB)

    Gabal, M.A., E-mail: mgabalabdonada@yahoo.com [Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); Al Angari, Y.M. [Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); Zaki, H.M. [Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); Physics Department, Faculty of Science, Zagazig University, Zagazig (Egypt)

    2014-08-01

    Soft Ni–Mg nano-crystalline ferrites with the general formula Ni{sub 1−x}Mg{sub x}Fe{sub 2}O{sub 4} (0≤x≤1) were synthesized through egg-white method. The precursor decomposition was followed by thermal analysis techniques. The obtained ferrites were characterized by X-ray diffraction, Fourier transform infrared and transmission electron microscopy measurements. X-ray diffraction showed the cubic spinel structure with crystallite size variation within the range 20–45 nm. The different structural data obtained were discussed in the view of ionic radii of the entire ions and their distribution within the lattice. The appropriate suggested cation distribution was then confirmed through Fourier transform infrared as well as electrical and magnetic properties measurements. Transmission electron microscopy exhibited a nano-crystal aggregation phenomenon. The observed size of the spherical particles agrees well with that obtained by X-ray diffraction. Hysteresis loop measurements revealed dilution in the obtained magnetic parameters by Mg-substitution due to the preferential occupancy of Mg{sup 2+} ions by the octahedral sites. Ac-electrical conductivity as a function of temperature and frequency exhibited a semi-conducting behavior with conductivity decreases by increasing Mg-content. The change in the slope of the curve indicates the changing in the conduction mechanism from electron hopping to polaron mechanism by increasing temperature. The obtained structural, electrical and magnetic properties were explained based on the cation distribution among tetrahedral and octahedral sites. - Highlights: • Ni–Mg nano-crystalline ferrites were synthesized through egg-white method. • An appropriate cation distribution was suggested. • Conductivity revealed a change in conduction mechanism by increasing temperature. • The effect of Mg-substitution on different properties was studied.

  12. RF electromagnetic wave absorbing properties of ferrite polymer composite materials

    International Nuclear Information System (INIS)

    Dosoudil, Rastislav; Usakova, Marianna; Franek, Jaroslav; Slama, Jozef; Olah, Vladimir

    2006-01-01

    The frequency dispersion of complex initial (relative) permeability (μ * =μ ' -jμ ' ') and the electromagnetic wave absorbing properties of composite materials based on NiZn sintered ferrite and a polyvinylchloride (PVC) polymer matrix have been studied in frequency range from 1MHz to 1GHz. The complex permeability of the composites was found to increase as the ferrite content increased, and was characterized by frequency dispersion localized above 50MHz. The variation of return loss (RL) of single-layer RF absorbers using the prepared composite materials has been investigated as a function of frequency, ferrite content and the thickness of the absorbers

  13. Oxidation rate in ferritic superheater materials

    International Nuclear Information System (INIS)

    Falk, I.

    1992-05-01

    On the steam side of superheater tubes, compact oxide layers are formed which have a tendency to crack and flake off (exfoliate). Oxide particles then travel with the steam and can give rise to erosion damage in valves and on turbine blades. In an evaluation of conditions in superheater tubes from Swedish power boilers, it was found that the exfoliation frequency for one material quality (SS 2218) was greater than for other qualities. Against this background, a literature study has been carried out in order to determine which mechanisms govern the build-up of oxide and the exfoliation phenomenon. The study reveals that the oxide morphology is similar on all ferritic steels with Cr contents up to 5%. and that the oxide properties can therefore be expected to be similar. The reason why the exfoliation frequency is greater for tubes of SS 2218 is probably that the tubes have been exposed to higher temperatures. SS 2218 (2.25 Cr) is normally used in a higher temperature range which is accompanied by improved strength data as compared with SS 2216 (1 Cr). The principal cause of the exfoliation is said to be stresses which arise in the oxide during the cooling-down process associated with shutdowns. The stresses give rise to longitudinal cracks in the oxide, and are formed as a result of differences in thermal expansion between the oxide and the tube material. In addition, accounts are presented of oxidation constants and growth velocities, and thickness and running time. These data constitute a valuable basis for practical estimates of the operating temperature in routine checks and investigations into damage in superheater tubes. (au)

  14. 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.

  15. 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

  16. Advances in ferrite microwave materials and devices

    International Nuclear Information System (INIS)

    Schloemann, Ernst

    2000-01-01

    The application of ferrites in non-reciprocal components is discussed, with the emphasis on broadband isolators and circulators. The performance of such devices may be characterized by the ratio f max /f min of the frequencies that define the edges of the frequency band, within which satisfactory performance has been achieved. For the best currently available devices this ratio is approx. 3 : 1, but larger values appear feasible according to a detailed analysis of the 'low-field, low-frequency loss' that limits the performance

  17. Electron holography of Fe-based nanocrystalline magnetic materials (invited)

    International Nuclear Information System (INIS)

    Shindo, Daisuke; Park, Young-Gil; Gao, Youhui; Park, Hyun Soon

    2004-01-01

    Magnetic domain structures of nanocrystalline magnetic materials were extensively investigated by electron holography with a change in temperature or magnetic field applied. In both soft and hard magnetic materials, the distribution of lines of magnetic flux clarified in situ by electron holography was found to correspond well to their magnetic properties. An attempt to produce a strong magnetic field using a sharp needle made of a permanent magnet, whose movement is controlled by piezo drives has been presented. This article demonstrates that the attempt is promising to investigate the magnetization process of hard magnetic materials by electron holography

  18. Effect of Cu-Cr co-substitution on magnetic properties of nanocrystalline magnesium ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Muhammad Javed, E-mail: mjiqauchem@yahoo.com [Surface and Solid State Chemistry Laboratory, Department of Chemistry, Quaid-I-Azam University, Islamabad 45320 (Pakistan); Ahmad, Zahoor [Surface and Solid State Chemistry Laboratory, Department of Chemistry, Quaid-I-Azam University, Islamabad 45320 (Pakistan); Melikhov, Yevgen [Wolfson Centre for Magnetics, School of Engineering, Cardiff University, Cardiff CF24 3AA (United Kingdom); Nlebedim, Ikenna Cajetan [Ames Laboratory of US Department of Energy, Ames, IA 50011 (United States)

    2012-03-15

    This study deals with the temperature and composition dependence of magnetization and magnetic anisotropy of Cu{sup 2+}-Cr{sup 3+} co-substituted magnesium ferrite, Mg{sub 1-x}Cu{sub x}Cr{sub x}Fe{sub 2-x}O{sub 4} (x=0.0-0.5). The synthesized materials are characterized using thermo gravimetric analysis, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray fluorescence, Moessbauer spectrometer, superconducting quantum interference device magnetometer and vibrating sample magnetometer. The M-H loops measured up to 50 kOe at 300, 200 and 100 K, revealed narrow hysteresis curves with a coercive field and saturation magnetization varying for different compositions. The high field regimes of these loops are modeled using the Law of Approach to saturation to extract anisotropy information and saturation magnetization. Both the saturation magnetization and the anisotropy constant are observed to increase with the decrease in temperature while decrease with the Cu-Cr co-substituents for all the samples. Explanation of the observed behavior is proposed in terms of the preference of the co-substituent ions of Cu{sup 2+} and Cr{sup 3+} and their predominant choice to substitute into the octahedral sites of the cubic spinel lattice. - Highlights: Black-Right-Pointing-Pointer Mg{sub 1-x}Cu{sub x}Cr{sub x}Fe{sub 2-x}O{sub 4} was synthesized by novel PEG assisted microemulsion method. Black-Right-Pointing-Pointer Present paper dealt with magnetic properties of Mg{sub 1-x}Cu{sub x}Cr{sub x}Fe{sub 2-x}O{sub 4}. Black-Right-Pointing-Pointer XRD patterns revealed tetragonal distorted cubic structure of Mg{sub 1-x}Cu{sub x}Cr{sub x}Fe{sub 2-x}O{sub 4}. Black-Right-Pointing-Pointer Mossbauer spectroscopy confirmed that Cu-Cr occupy octahedral sites. Black-Right-Pointing-Pointer High field regime of M-H loops was modeled using Law of Approach to saturation.

  19. The effect of solution pH on the electrochemical performance of nanocrystalline metal ferrites MFe2O4 (M=Cu, Zn, and Ni) thin films

    Science.gov (United States)

    Elsayed, E. M.; Rashad, M. M.; Khalil, H. F. Y.; Ibrahim, I. A.; Hussein, M. R.; El-Sabbah, M. M. B.

    2016-04-01

    Nanocrystalline metal ferrite MFe2O4 (M=Cu, Zn, and Ni) thin films have been synthesized via electrodeposition-anodization process. Electrodeposited (M)Fe2 alloys were obtained from aqueous sulfate bath. The formed alloys were electrochemically oxidized (anodized) in aqueous (1 M KOH) solution, at room temperature, to the corresponding hydroxides. The parameters controlling the current efficiency of the electrodeposition of (M)Fe2 alloys such as the bath composition and the current density were studied and optimized. The anodized (M)Fe2 alloy films were annealed in air at 400 °C for 2 h. The results revealed the formation of three ferrite thin films were formed. The crystallite sizes of the produced films were in the range between 45 and 60 nm. The microstructure of the formed film was ferrite type dependent. The corrosion behavior of ferrite thin films in different pH solutions was investigated using open circuit potential (OCP) and potentiodynamic polarization measurements. The open circuit potential indicates that the initial potential E im of ZnFe2O4 thin films remained constant for a short time, then sharply increased in the less negative direction in acidic and alkaline medium compared with Ni and Cu ferrite films. The values of the corrosion current density I corr were higher for the ZnFe2O4 films at pH values of 1 and 12 compared with that of NiFe2O4 and CuFe2O4 which were higher only at pH value 1. The corrosion rate was very low for the three ferrite films when immersion in the neutral medium. The surface morphology recommended that Ni and Cu ferrite films were safely used in neutral and alkaline medium, whereas Zn ferrite film was only used in neutral atmospheres.

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

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoud, Mohamed, E-mail: mamdouh-2000-2000@yahoo.com [Assiut University, Department of Physics (Egypt); Hassan, Azza Mohamed [Asuite University, Physics Department, Faculty of Sciences (Egypt); Ahmed, Mamdouh Abdel aal [Al Azhar University, Physics Department, Faculty of Science (Egypt); Zhu, Kaixin; Ganeshraja, Ayyakannu Sundaram; Wang, Junhu, E-mail: Wangjh@dicp.ac.cn [Chinese Academy Sciences, Mössbauer Effect Data Center & Laboratory of Catalysts and New Materials for Aerospace, Dalian Institute of Chemical Physics (China)

    2016-12-15

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

  1. Effect of Dy3+ substitution on structural and magnetic properties of nanocrystalline Ni-Cu-Zn ferrites

    Science.gov (United States)

    Kabbur, S. M.; Ghodake, U. R.; Nadargi, D. Y.; Kambale, Rahul C.; Suryavanshi, S. S.

    2018-04-01

    Nanocrystalline Ni0.25Cu0.30Zn0.45DyxFe2-xO4 (x = 0.0, 0.025, 0.05, 0.075, 0.1 and 0.125 mol.) ferrimagnetic oxides have been synthesized by sol-gel autocombustion route. X-ray diffraction study reveals the formation of spinel cubic structure with an expansion of the unit cell by Dy addition. Bertaut method was employed to propose the site occupancy i.e. cation distribution for elements at A-tetrahedral and B-octahedral sites of spinel lattice. The intrinsic vibrational absorption bands i.e. υ1 (712-719 cm-1) and υ2 (496-506 cm-1) are observed for tetrahedral and octahedral sites respectively. The microstructural aspect confirms the formation of an average grain size (∼7-99 nm) with presence of expected elements. Magnetization studies reveal that the magnetic moments are no longer linear but exhibit canting effect due to spin frustration. The frequency dispersion spectrum of initial permeability has been explained based on grain size, saturation magnetization and anisotropy constant. Thermal hysteresis curve (initial permeability versus temperature) indicates magnetic disordering to paramagnetic state at Néel temperature (TN). High values of TN show that the present ferrite samples are cation-ordered with d-electrons contributing towards the magnetic interaction at the sublattice.

  2. Material physical properties of 11Cr-ferritic/martensitic steel (PNC-FMS) wrapper tube materials

    International Nuclear Information System (INIS)

    Yano, Yasuhide; Kaito, Takeji; Ohtsuka, Satoshi; Tanno, Takashi; Uwaba, Tomoyuki; Koyama, Shinichi

    2012-09-01

    It is necessary to develop core materials for fast reactors in order to achieve high-burnup. Ferritic steels are expected to be good candidate core materials to achieve this objective because of their excellent void swelling resistance. Therefore, oxide dispersion strengthened (ODS) ferritic steel and 11Cr-ferritic/martensitic steel (PNC-FMS) have been respectively developed for cladding and wrapper tube materials in Japan Atomic Energy Agency. In this study, various physical properties of PNC-FMS wrapper materials were measured and equations and future standard measurement technique of physical properties for the design and evaluation were conducted. (author)

  3. Bismuth ferrite as low-loss switchable material for plasmonic waveguide modulator

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Zhukovsky, Sergei; Lavrinenko, Andrei

    2014-01-01

    We propose new designs of plasmonic modulators, which can beused for dynamic signal switching in photonic integrated circuits. We studyperformance of a plasmonic waveguide modulator with bismuth ferrite as atunable material. The bismuth ferrite core is sandwiched between metalplates (metal...

  4. 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.

  5. Evaluation of structural, morphological and magnetic properties of CuZnNi (Cu_xZn_0_._5_−_xNi_0_._5Fe_2O_4) nanocrystalline ferrites for core, switching and MLCI’s applications

    International Nuclear Information System (INIS)

    Akhtar, Majid Niaz; Khan, Muhammad Azhar; Ahmad, Mukhtar; Nazir, M.S.; Imran, M.; Ali, A.; Sattar, A.; Murtaza, G.

    2017-01-01

    The influence of Cu substitution on the structural and morphological characteristics of Ni–Zn nanocrystalline ferrites have been discussed in this work. The detailed and systematic magnetic characterizations were also done for Cu substituted Ni–Zn nanoferrites. The nanocrystalline ferrites of Cu substituted Cu_xZn_0_._5_−_xNi_0_._5Fe_2O_4 ferrites (x=0, 0.1, 0.2, 0.3, 0.4 and 0.5) were synthesized using sol gel self-combustion hybrid method. X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscope (TEM) and Vibrating sample magnetometer (VSM) were used to investigate the properties of Cu substituted nanocrystalline ferrites. Single phase structure of Cu substituted in Ni–Zn nanocrystalline ferrites were investigated for all the samples. Crystallite size, lattice constant and volume of the cell were found to increase by increasing Cu contents in spinel structure. The better morphology with well-organized nanocrystals of Cu–Zn–Ni ferrites at x=0 and 0.5 were observed from both FESEM and TEM analysis. The average grain size was 35–46 nm for all prepared nanocrystalline samples. Magnetic properties such as coercivity, saturation, remanence, magnetic squareness, magneto crystalline anisotropy constant (K) and Bohr magneton were measured from the recorded M–H loops. The magnetic saturation and remanence were increased by the incorporation of Cu contents. However, coercivity follow the Stoner-Wolforth model except for x=0.3 which may be due to the site occupancy and replacement of Cu contents from octahedral site. The squareness ratio confirmed the super paramgnetic behaviour of the Cu substituted in Ni–Zn nanocrystalline ferrites. Furthermore, Cu substituted Ni–Zn nanocrystalline ferrites may be suitable for many industrial and domestic applications such as components of transformers, core, switching, and MLCI’s due to variety of the soft magnetic characteristics. - Highlights: • Cu substituted

  6. Interface effects on effective elastic moduli of nanocrystalline materials

    International Nuclear Information System (INIS)

    Wang Gangfeng; Feng Xiqiao; Yu Shouwen; Nan Cewen

    2003-01-01

    Interfaces often play a significant role in many physical properties and phenomena of nanocrystalline materials (NcMs). In the present paper, the interface effects on the effective elastic property of NcMs are investigated. First, an atomic potential method is suggested for estimating the effective elastic modulus of an interface phase. Then, the Mori-Tanaka effective field method is employed to determine the overall effective elastic moduli of a nanocrystalline material, which is regarded as a binary composite consisting of a crystal or inclusion phase with regular lattice connected by an amorphous-like interface or matrix phase. Finally, the stiffening effects of strain gradients are examined on the effective elastic property by using the strain gradient theory to analyze a representative unit cell. Our analysis shows two physical mechanisms of interfaces that influence the effective stiffness and other mechanical properties of materials. One is the softening effect due to the distorted atomic structures and the increased atomic spacings in interface regions, and another is the baffling effect due to the existence of boundary layers between the interface phase and the crystalline phase

  7. Nanocrystalline materials: recent advances in crystallographic characterization techniques

    Directory of Open Access Journals (Sweden)

    Emilie Ringe

    2014-11-01

    Full Text Available Most properties of nanocrystalline materials are shape-dependent, providing their exquisite tunability in optical, mechanical, electronic and catalytic properties. An example of the former is localized surface plasmon resonance (LSPR, the coherent oscillation of conduction electrons in metals that can be excited by the electric field of light; this resonance frequency is highly dependent on both the size and shape of a nanocrystal. An example of the latter is the marked difference in catalytic activity observed for different Pd nanoparticles. Such examples highlight the importance of particle shape in nanocrystalline materials and their practical applications. However, one may ask `how are nanoshapes created?', `how does the shape relate to the atomic packing and crystallography of the material?', `how can we control and characterize the external shape and crystal structure of such small nanocrystals?'. This feature article aims to give the reader an overview of important techniques, concepts and recent advances related to these questions. Nucleation, growth and how seed crystallography influences the final synthesis product are discussed, followed by shape prediction models based on seed crystallography and thermodynamic or kinetic parameters. The crystallographic implications of epitaxy and orientation in multilayered, core-shell nanoparticles are overviewed, and, finally, the development and implications of novel, spatially resolved analysis tools are discussed.

  8. A variational multiscale constitutive model for nanocrystalline materials

    KAUST Repository

    Gurses, Ercan

    2011-03-01

    This paper presents a variational multi-scale constitutive model in the finite deformation regime capable of capturing the mechanical behavior of nanocrystalline (nc) fcc metals. The nc-material is modeled as a two-phase material consisting of a grain interior phase and a grain boundary effected zone (GBAZ). A rate-independent isotropic porous plasticity model is employed to describe the GBAZ, whereas a crystal-plasticity model which accounts for the transition from partial dislocation to full dislocation mediated plasticity is employed for the grain interior. The constitutive models of both phases are formulated in a small strain framework and extended to finite deformation by use of logarithmic and exponential mappings. Assuming the rule of mixtures, the overall behavior of a given grain is obtained via volume averaging. The scale transition from a single grain to a polycrystal is achieved by Taylor-type homogenization where a log-normal grain size distribution is assumed. It is shown that the proposed model is able to capture the inverse HallPetch effect, i.e., loss of strength with grain size refinement. Finally, the predictive capability of the model is validated against experimental results on nanocrystalline copper and nickel. © 2010 Elsevier Ltd. All rights reserved.

  9. Microwave left-handed composite material made of slim ferrite rods and metallic wires

    International Nuclear Information System (INIS)

    Fang, Xu; Yang, Bai; Li-Jie, Qiao; Hong-Jie, Zhao; Ji, Zhou

    2009-01-01

    This paper reports on experimental study of the microwave properties of a composite material consisting of ferrite and copper wires. It finds that the slim ferrite rods can modify the magnetic field distribution through their anisotropy, so that the ferrite's negative influence on the copper wires' plasma will be reduced. Left-handed properties are observed even in the specimen with close stuck ferrite rods and copper wires. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  10. Comparison of ferrite materials for pulse applications

    International Nuclear Information System (INIS)

    Dinkel, J.A.; Jensen, C.C.

    1993-06-01

    Materials are the limiting factor in many pulse power projects. The magnetic materials available from several manufacturers were experimentally compared for their usefulness in high speed magnetic field applications. This particular application is a high speed kicker magnet for manipulation of a charged particle beam

  11. Nanocrystalline functional materials and nanocomposites synthesis through aerosol routes

    Directory of Open Access Journals (Sweden)

    Milošević Olivera B.

    2003-01-01

    Full Text Available This paper represents the results of the design of functional nanocrystalline powders and nanocomposites using chemical reactions in aerosols. The process involves ultrasonic aerosol formation (mist generators with the resonant frequencies of 800 kHz, 1.7 and 2.5 MHz from precursor salt solutions and control over the aerosol decomposition in a high-temperature tubular flow reactor. During decomposition, the aerosol droplets undergo evaporation/drying, precipitation and thermolysis in a single-step process. Consequently, spherical, solid, agglomerate-free submicronic particles are obtained. The particle morphology, revealed as a composite structure consisting of primary crystallites smaller than 20 nm was analysed by several methods (XRD, DSC/DTA, SEM, TEM and discussed in terms of precursor chemistry and process parameters. Following the initial attempts, a more detailed aspect of nanocrystalline particle synthesis was demonstrated for the case of nanocomposites based on ZnO-MeO (MeO=Bi Cr+, suitable for electronic applications, as well as an yttrium-aluminum base complex system, suitable for phosphorus applications. The results imply that parts of the material structure responsible for different functional behaviour appear through in situ aerosol synthesis by processes of intraparticle agglomeration, reaction and sintering in the last synthesis stage.

  12. New atom probe approaches to studying segregation in nanocrystalline materials

    International Nuclear Information System (INIS)

    Samudrala, S.K.; Felfer, P.J.; Araullo-Peters, V.J.; Cao, Y.; Liao, X.Z.; Cairney, J.M.

    2013-01-01

    Atom probe is a technique that is highly suited to the study of nanocrystalline materials. It can provide accurate atomic-scale information about the composition of grain boundaries in three dimensions. In this paper we have analysed the microstructure of a nanocrystalline super-duplex stainless steel prepared by high pressure torsion (HPT). Not all of the grain boundaries in this alloy display obvious segregation, making visualisation of the microstructure challenging. In addition, the grain boundaries present in the atom probe data acquired from this alloy have complex shapes that are curved at the scale of the dataset and the interfacial excess varies considerably over the boundaries, making the accurate characterisation of the distribution of solute challenging using existing analysis techniques. In this paper we present two new data treatment methods that allow the visualisation of boundaries with little or no segregation, the delineation of boundaries for further analysis and the quantitative analysis of Gibbsian interfacial excess at boundaries, including the capability of excess mapping. - Highlights: ► New data treatment methods allow delineation of grain boundaries, even without segregation. ► Proxigrams calculated from the surfaces accurately show the extent of segregation. ► Tessellation of the data volume can be used to map the Gibbsian interfacial excess

  13. New atom probe approaches to studying segregation in nanocrystalline materials

    Energy Technology Data Exchange (ETDEWEB)

    Samudrala, S.K.; Felfer, P.J.; Araullo-Peters, V.J. [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia); The Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); Cao, Y.; Liao, X.Z. [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia); Cairney, J.M., E-mail: julie.cairney@sydney.edu.au [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia); The Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia)

    2013-09-15

    Atom probe is a technique that is highly suited to the study of nanocrystalline materials. It can provide accurate atomic-scale information about the composition of grain boundaries in three dimensions. In this paper we have analysed the microstructure of a nanocrystalline super-duplex stainless steel prepared by high pressure torsion (HPT). Not all of the grain boundaries in this alloy display obvious segregation, making visualisation of the microstructure challenging. In addition, the grain boundaries present in the atom probe data acquired from this alloy have complex shapes that are curved at the scale of the dataset and the interfacial excess varies considerably over the boundaries, making the accurate characterisation of the distribution of solute challenging using existing analysis techniques. In this paper we present two new data treatment methods that allow the visualisation of boundaries with little or no segregation, the delineation of boundaries for further analysis and the quantitative analysis of Gibbsian interfacial excess at boundaries, including the capability of excess mapping. - Highlights: ► New data treatment methods allow delineation of grain boundaries, even without segregation. ► Proxigrams calculated from the surfaces accurately show the extent of segregation. ► Tessellation of the data volume can be used to map the Gibbsian interfacial excess.

  14. New atom probe approaches to studying segregation in nanocrystalline materials.

    Science.gov (United States)

    Samudrala, S K; Felfer, P J; Araullo-Peters, V J; Cao, Y; Liao, X Z; Cairney, J M

    2013-09-01

    Atom probe is a technique that is highly suited to the study of nanocrystalline materials. It can provide accurate atomic-scale information about the composition of grain boundaries in three dimensions. In this paper we have analysed the microstructure of a nanocrystalline super-duplex stainless steel prepared by high pressure torsion (HPT). Not all of the grain boundaries in this alloy display obvious segregation, making visualisation of the microstructure challenging. In addition, the grain boundaries present in the atom probe data acquired from this alloy have complex shapes that are curved at the scale of the dataset and the interfacial excess varies considerably over the boundaries, making the accurate characterisation of the distribution of solute challenging using existing analysis techniques. In this paper we present two new data treatment methods that allow the visualisation of boundaries with little or no segregation, the delineation of boundaries for further analysis and the quantitative analysis of Gibbsian interfacial excess at boundaries, including the capability of excess mapping. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. MnZn-ferrites: Targeted Material Design for New Emerging Application Products

    OpenAIRE

    Zaspalis V. T.; Tsakaloudi V.; Kogias G.

    2014-01-01

    In this article the main characteristics for emerging MnZn-ferrite applications are described on the basis of the new demands they possess on the ferrite material development. A number of recently developed MnZn-ferrite materials is presented together with the main scientific principles lying behind their development. These include: (i) high saturation flux density MnZn-ferrites (i.e. Bsat=550 mT at 10 kHz, 1200 A/m, 100°C), (ii) low power losses MnZn-ferrites (i.e. Pv~210 mW cm-3 at 100 kHz,...

  16. Novel synthesis of Ni-ferrite (NiFe2O4) electrode material for supercapacitor applications

    International Nuclear Information System (INIS)

    Venkatachalam, V.; Jayavel, R.

    2015-01-01

    Novel nanocrystalline NiFe 2 O 4 has been synthesized through combustion route using citric acid as a fuel. Phase of the synthesized material was analyzed using powder X-ray diffraction. The XRD study revealed the formation of spinel phase cubic NiFe 2 O 4 with high crystallinity. The average crystallite size of NiFe 2 O 4 nanomaterial was calculated from scherrer equation. The electrochemical properties were realized by cyclic voltammetry, chronopotentiometry and electrochemical impedance spectroscopy. The electrode material shows a maximum specific capacitance of 454 F/g with pseudocapacitive behavior. High capacitance retention of electrode material over 1000 continuous charging-discharging cycles suggests its excellent electrochemical stability. The results revealed that the nickel ferrite electrode is a potential candidate for energy storage applications in supercapacitor

  17. Nanocrystalline spinel ferrite (MFe{sub 2}O{sub 4}, M = Ni, Co, Mn, Mg, Zn) powders prepared by a simple aloe vera plant-extracted solution hydrothermal route

    Energy Technology Data Exchange (ETDEWEB)

    Phumying, Santi; Labuayai, Sarawuth; Swatsitang, Ekaphan; Amornkitbamrung, Vittaya [Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Integrated Nanotechnology Research Center (INRC), Khon Kaen University, Khon Kaen 40002 (Thailand); Maensiri, Santi, E-mail: santimaensiri@gmail.com [School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand)

    2013-06-01

    Graphical abstract: This figure shows the specific magnetization curves of the as-prepared MFe{sub 2}O{sub 4} (M = Ni, Co, Mn, Mg, Zn) powders obtained from room temperature VSM measurement. These curves are typical for a soft magnetic material and indicate hysteresis ferromagnetism in the field ranges of ±500 Oe, ±1000 Oe, and ±2000 Oe for the CoFe{sub 2}O{sub 4}, MgFe{sub 2}O{sub 4} and MnFe{sub 2}O{sub 4} respectively, whereas the samples of NiFe{sub 2}O{sub 4} and ZnFe{sub 2}O{sub 4} show a superparamagnetic behavior. Highlights: ► Nanocrystalline MFe{sub 2}O{sub 4} powders were synthesized by a novel hydrothermal method. ► Metal acetylacetonates and aloe vera plant-extracted solution are used. ► This biosynthetic route is very simple and provides high-yield oxide nanomaterials. ► XRD and TEM results indicate that the prepared samples have only spinel structure. ► The maximum M{sub s} of 68.9 emu/g at 10 kOe were observed for the samples of MnFe{sub 2}O{sub 4}. - Abstract: Nanocrystalline spinel ferrite MFe{sub 2}O{sub 4} (M = Ni, Co, Mn, Mg, Zn) powders were synthesized by a novel hydrothermal method using Fe(acac){sub 3}, M(acac){sub 3} (M = Ni, Co, Mn, Mg, Zn) and aloe vera plant extracted solution. The X-ray diffraction and selected-area electron diffraction results indicate that the synthesized nanocrystalline have only spinel structure without the presence of other phase impurities. The crystal structure and morphology of the spinel ferrite powders, as revealed by TEM, show that the NiFe{sub 2}O{sub 4} and CoFe{sub 2}O{sub 4} samples contain nanoparticles, whereas the MnFe{sub 2}O{sub 4} and MgFe{sub 2}O{sub 4} samples consist of many nanoplatelets and nanoparticles. Interestingly, the ZnFe{sub 2}O{sub 4} sample contains plate-like structure of networked nanocrystalline particles. Room temperature magnetization results show a ferromagnetic behavior of the CoFe{sub 2}O{sub 4}, MnFe{sub 2}O{sub 4} and MgFe{sub 2}O{sub 4} samples, whereas the

  18. Modeling of ferrite-based materials for shielding enclosures

    International Nuclear Information System (INIS)

    Koledintseva, Marina; Drewniak, James; Zhang Yaojiang; Lenn, James; Thoms, Melanie

    2009-01-01

    An analytical model for a magneto-dielectric composite material is presented based on the Maxwell Garnett rule for a dielectric mixture, and on Bruggeman's effective medium theory for permeability of a ferrite powder embedded in a dielectric. In order to simultaneously treat frequency-dispersive permittivity and permeability of a composite in a full-wave FDTD code, a new algorithm based on discretized auxiliary differential equations has been implemented. In this paper, numerical examples of modeling structures containing different magneto-dielectric mixtures are presented

  19. 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...

  20. Level Set-Based Topology Optimization for the Design of an Electromagnetic Cloak With Ferrite Material

    DEFF Research Database (Denmark)

    Otomori, Masaki; Yamada, Takayuki; Andkjær, Jacob Anders

    2013-01-01

    . A level set-based topology optimization method incorporating a fictitious interface energy is used to find optimized configurations of the ferrite material. The numerical results demonstrate that the optimization successfully found an appropriate ferrite configuration that functions as an electromagnetic......This paper presents a structural optimization method for the design of an electromagnetic cloak made of ferrite material. Ferrite materials exhibit a frequency-dependent degree of permeability, due to a magnetic resonance phenomenon that can be altered by changing the magnitude of an externally...

  1. Postirradiation thermocyclic loading of ferritic-martensitic structural materials

    Science.gov (United States)

    Belyaeva, L.; Orychtchenko, A.; Petersen, C.; Rybin, V.

    Thermonuclear fusion reactors of the Tokamak-type will be unique power engineering plants to operate in thermocyclic mode only. Ferritic-martensitic stainless steels are prime candidate structural materials for test blankets of the ITER fusion reactor. Beyond the radiation damage, thermomechanical cyclic loading is considered as the most detrimental lifetime limiting phenomenon for the above structure. With a Russian and a German facility for thermal fatigue testing of neutron irradiated materials a cooperation has been undertaken. Ampule devices to irradiate specimens for postirradiation thermal fatigue tests have been developed by the Russian partner. The irradiation of these ampule devices loaded with specimens of ferritic-martensitic steels, like the European MANET-II, the Russian 05K12N2M and the Japanese Low Activation Material F82H-mod, in a WWR-M-type reactor just started. A description of the irradiation facility, the qualification of the ampule device and the modification of the German thermal fatigue facility will be presented.

  2. Round table discussion: Present and future applications of nanocrystalline magnetic materials

    International Nuclear Information System (INIS)

    Herzer, G.; Vazquez, M.; Knobel, M.; Zhukov, A.; Reininger, T.; Davies, H.A.; Groessinger, R.; Sanchez Ll, J.L.

    2005-01-01

    Examples of existing or potential applications of nanocrystalline magnetic materials, ranging from soft to hard magnetic alloys, are presented and discussed by experts in the respective fields of research and technology

  3. Path E alloys: ferritic material development for magnetic fusion energy applications

    International Nuclear Information System (INIS)

    Holmes, J.J.

    1980-09-01

    The application of ferritic materials in irradiation environments has received greatly expanded attention in the last few years, both internationally and in the United States. Ferritic materials are found to be resistant to irradiation damage and have in many cases superior properties to those of AISI 316. It has been shown that for magnetic fusion energy applications the low thermal expansion behavior of the ferritic alloy class will result in lower thermal stresses during reactor operation, leading to significantly longer ETF operating lifetimes. The Magnetic Fusion Energy Program therefore now includes a ferritic alloy option for alloy selection and this option has been designated Path E

  4. Nanophotonic Modulator with Bismuth Ferrite as Low-loss Switchable Material

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Zhukovsky, Sergei; Lavrinenko, Andrei

    2015-01-01

    We propose a nanophotonic waveguide modulator with bismuth ferrite as a tunable material. Due to near-zero losses in bismuth ferrite, modulation with up to 20 dB/μm extinction ratio and 12 μm propagation length is achieved.......We propose a nanophotonic waveguide modulator with bismuth ferrite as a tunable material. Due to near-zero losses in bismuth ferrite, modulation with up to 20 dB/μm extinction ratio and 12 μm propagation length is achieved....

  5. The use of ferritic materials in light water reactor power plants

    International Nuclear Information System (INIS)

    Marston, T.V.

    1984-01-01

    This paper reviews the use of ferritic materials in LWR power plant components. The two principal types of LWR systems, the boiling water reactor (BWR) and the pressurized water reactor (PWR) are described. The evolution of the construction materials, including plates and forgings, is presented. The fabrication process for both reactors constructed with plates and forgings are described in detail. Typical mechanical properties of the reactor vessel materials are presented. Finally, one critical issue radiation embrittlement dealing with ferritic materials is discussed. This has been one of the major issues regarding the use of ferritic material in the construction of LWR pressure vessels

  6. Removal of radioactive materials from waste solutions via magnetic ferrites

    International Nuclear Information System (INIS)

    Boyd, T.E.; Kochen, R.L.; Price, M.Y.

    1982-01-01

    Ferrite waste treatment was found to be effective in removing actinides from simulated Rocky Flats process waste solutions. With a one-stage ferrite treatment, plutonium concentrations were consistently reduced from 10 -4 g/l to less than 10 -8 g/l, and americium concentrations were lowered from 10 -7 g/l to below 10 -10 g/l. In addition, siginficantly less solid was produced as compared with the flocculant precipitation technique now employed at Rocky Flats. Aging of ferrite solids and elevated beryllium and phosphate concentrations were identified as interferences in the ferrite treatment of process waste, but neither appeeared serious enough to prevent implementation in plant operations

  7. Basic fracture toughness requirements for ferritic materials of nuclear class pressure retaining equipment in NPP

    International Nuclear Information System (INIS)

    Ning Dong; Yao Weida

    2005-01-01

    In this paper, theory basis on cold brittleness and anti-brittle fracture design of ferritic materials are introduced summarily and fracture toughness requirements for ferritic materials in ASME code for nuclear safety class pressure retaining equipment in NPP are summarized and evaluated. The results show that notch impact toughness requirements for materials relate to nuclear safety class of materials so as to ensure that brittle fracture of retaining pressure boundary in NPP can not occur. (authors)

  8. Materials Synthesis Of Barium Hexa ferrite Used Local Natural Resources

    International Nuclear Information System (INIS)

    Ridwan; Sulungbudi, Grace Tj.; Mujamilah

    2003-01-01

    The magnetic materials of barium hexa ferrites, Ba O.6Fe 2 O 3 successfully synthesized by powder metallurgy method used local natural resources from materials waste of steel fabrication (HSM, CRM), waste of polymer fabrication (LK) as well as iron sands (PBA). These waste as well as iron sands were the main resources of iron oxide, Fe 2 O 3 . The barium oxide used in this experiments are from BaCO 3 product of Merck, and BaCO 4 which is commercially available in the market as barite. Phase identification by x-ray diffraction technique show the synthesized magnetic materials are agreed with the available commercial product, (SUMI). The energy product maximum (BH) max measured by vibrating sample magnetometer (VSM) for the samples used HSM-, CRM- and BaCO 3 as basic materials are 1.141 MGOe and 1.136 MGOe while SUMI is 1.142 MGOe. However for the samples made from LK-, PBA- used of BaCO 3 or CRM- with barite, the energy product maximum (BH) max are relatively lower than commercial product

  9. 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.

  10. High Pressure X-Ray Diffraction Studies on Nanocrystalline Materials

    Science.gov (United States)

    Palosz, B.; Stelmakh, S.; Grzanka, E.; Gierlotka, S.; Pielaszek, R.; Bismayer, U.; Werner, S.; Palosz, W.

    2003-01-01

    Application of in situ high pressure powder diffraction technique for examination of specific structural properties of nanocrystals based on the experimental data of SiC nanocrystalline powders of 2 to 30 nrn diameter in diameter is presented. Limitations and capabilities of the experimental techniques themselves and methods of diffraction data elaboration applied to nanocrystals with very small dimensions (nanoparticles of different grain size.

  11. Nanocrystalline Al-based alloys - lightweight materials with attractive mechanical properties

    International Nuclear Information System (INIS)

    Latuch, J; Cieslak, G; Dimitrov, H; Krasnowski, M; Kulik, T

    2009-01-01

    In this study, several ways of bulk nanocrystalline Al-based alloys' production by high-pressure compaction of powders were explored. The effect of chemical composition and compaction parameters on the structure, quality and mechanical properties of the bulk samples was studied. Bulk nanocrystalline Al-Mm-Ni-(Fe,Co) alloys were prepared by ball-milling of amorphous ribbons followed by consolidation. The maximum microhardness (540 HV0.1) was achieved for the samples compacted at 275 deg. C under 7.7 GPa (which resulted in an amorphous bulk) and nanocrystallised at 235 deg. C for 20 min. Another group of the produced materials were bulk nanocrystalline Al-Si-(Ni,Fe)-Mm alloys obtained by ball-milling of nanocrystalline ribbons and consolidation. The hardness of these samples achieved the value five times higher (350HV) than that of commercial 4xxx series Al alloys. Nanocrystalline Al-based alloys were also prepared by mechanical alloying followed by hot-pressing. In this group of materials, there were Al-Fe alloys containing 50-85 at.% of Al and ternary or quaternary Al-Fe-(Ti, Si, Ni, Mg, B) alloys. Microhardness of these alloys was in the range of 613 - 1235 HV0.2, depending on the composition.

  12. The Formation of Lithiated Ti-Doped {alpha}-Fe{sub 2}O{sub 3} Nanocrystalline Particles by Mechanical Milling of Ti-Doped Lithium Spinel Ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Widatallah, H. M., E-mail: hisham@ictp.trieste.it [Khartoum University, Department of Physics (Sudan); Gismelseed, A. M.; Bouziane, K. [Sultan Qaboos University, Department of Physics (Oman); Berry, F. J. [Open University, Department of Chemistry (United Kingdom); Al Rawas, A. D.; Al-Omari, I. A.; Yousif, A. A.; Elzain, M. E. [Sultan Qaboos University, Department of Physics (Oman)

    2004-12-15

    The milling of spinel-related Ti-doped Li{sub 0.5}Fe{sub 2.5}O{sub 4} for different times is studied with XRD, Moessbauer spectroscopy and magnetic measurements. Milling converts the material to Li-Ti-doped {alpha}-Fe{sub 2}O{sub 3} nanocrystalline particles via an intermediate {gamma}-LiFeO{sub 2}-related phase. The role played by the dopant Ti-ion in the process is emphasized.

  13. The Formation of Lithiated Ti-Doped α-Fe2O3 Nanocrystalline Particles by Mechanical Milling of Ti-Doped Lithium Spinel Ferrite

    International Nuclear Information System (INIS)

    Widatallah, H. M.; Gismelseed, A. M.; Bouziane, K.; Berry, F. J.; Al Rawas, A. D.; Al-Omari, I. A.; Yousif, A. A.; Elzain, M. E.

    2004-01-01

    The milling of spinel-related Ti-doped Li 0.5 Fe 2.5 O 4 for different times is studied with XRD, Moessbauer spectroscopy and magnetic measurements. Milling converts the material to Li-Ti-doped α-Fe 2 O 3 nanocrystalline particles via an intermediate γ-LiFeO 2 -related phase. The role played by the dopant Ti-ion in the process is emphasized.

  14. New technique for enhancing helium production in ferritic materials

    International Nuclear Information System (INIS)

    Greenwood, L.R.; Graczyk, D.G.; Kneff, D.W.

    1987-10-01

    Analyses of iron samples irradiated up to 10 27 n/m 2 in HFIR found more helium than was expected from fast neutron reactions at high neutron fluences. The helium excess increases systematically with neutron exposure, suggesting a transmutation-driven process. The extra helium may be produced in two different ways, either by fast neutron reactions on the transmuted isotopes of iron or by a thermal neutron reaction with the radioactive isotope 55 Fe. Radiometric and mass spectrometric measurements of the iron isotopes composing the irradiated samples have been used to determine limits on the cross sections for each process. Either of these processes can be used to enhance helium production in ferritic materials during irradiations in mixed-spectrum reactors by isotopically enriching the samples. Further work is needed to clarify the reaction mechanisms and helium production cross sections. Our measurements determined the thermal neutron total absorption cross section of 55 Fe to be 13.2 +- 2.1 barns. 16 refs., 3 figs., 3 tabs

  15. Emission of partial dislocations from triple junctions of grain boundaries in nanocrystalline materials

    International Nuclear Information System (INIS)

    Gutkin, M Yu; Ovid'ko, I A; Skiba, N V

    2005-01-01

    A theoretical model is suggested that describes emission of partial Shockley dislocations from triple junctions of grain boundaries (GBs) in deformed nanocrystalline materials. In the framework of the model, triple junctions accumulate dislocations due to GB sliding along adjacent GBs. The dislocation accumulation at triple junctions causes partial Shockley dislocations to be emitted from the dislocated triple junctions and thus accommodates GB sliding. Ranges of parameters (applied stress, grain size, etc) are calculated in which the emission events are energetically favourable in nanocrystalline Al, Cu and Ni. The model accounts for the corresponding experimental data reported in the literature

  16. Powder-based synthesis of nanocrystalline material components for structural application. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Ilyuschenko, A.F.; Ivashko, V.S.; Okovity, V.A. [Powder Metallurgy Research Inst., Minsk (Belarus)] [and others

    1998-12-01

    Hydroxiapate spray coatings and substrates for implant production as well as multilayered metal ceramic coatings from nanocrystalline materials are a subject of the investigation. The work aims at the improvement of quality of said objects. This study has investigated the processes of hydroxiapatite powder production. Sizes, shapes and relief of initial HA powder surface are analyzed using SEM and TEM. Modes of HA plasma spraying on a substrate from titanium and associated compositions of traditional and nanocrystalline structure are optimized. The quality of the sprayed samples are studied using X-ray phase analysis and metallographic analysis. The results of investigations of bioceramic coating spraying on titanium are theoretically generalized, taking into account obtained experimental data. The results of investigations of ion-beam technology are presented for spraying multilayered coatings consisting of alternating metal-ceramic layers of nanocrystalline structure.

  17. Influence of pH Adjustment Parameter for Sol-Gel Modification on Structural, Microstructure, and Magnetic Properties of Nanocrystalline Strontium Ferrite.

    Science.gov (United States)

    Azis, Raba'ah Syahidah; Sulaiman, Sakinah; Ibrahim, Idza Riati; Zakaria, Azmi; Hassan, Jumiah; Muda, Nor Nadhirah Che; Nazlan, Rodziah; Saiden, Norlaily M; Fen, Yap Wing; Mustaffa, Muhammad Syazwan; Matori, Khamirul Amin

    2018-05-23

    Synthesis of nanocrystalline strontium ferrite (SrFe 12 O 19 ) via sol-gel is sensitive to its modification parameters. Therefore, in this study, an attempt of regulating the pH as a sol-gel modification parameter during preparation of SrFe 12 O 19 nanoparticles sintered at a low sintering temperature of 900 °C has been presented. The relationship of varying pH (pH 0 to 8) on structural, microstructures, and magnetic behaviors of SrFe 12 O 19 nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning microscope (FESEM), and vibrating sample magnetometer (VSM). Varying the pH of precursor exhibited a strong effect on the sintered density, crystal structure and magnetic properties of the SrFe 12 O 19 nanoparticles. As the pH is 0, the SrFe 12 O 19 produced relatively largest density, saturation magnetization, M s , and coercivity, H c , at a low sintering temperature of 900 °C. The grain size of SrFe 12 O 19 is obtained in the range of 73.6 to 133.3 nm. The porosity of the sample affected the density and the magnetic properties of the SrFe 12 O 19 ferrite. It is suggested that the low-temperature sintered SrFe 12 O 19 at pH 0 displayed M s of 44.19 emu/g and H c of 6403.6 Oe, possessing a significant potential for applying in low-temperature co-fired ceramic permanent magnet.

  18. Evaluation of structural, morphological and magnetic properties of CuZnNi (Cu{sub x}Zn{sub 0.5−x}Ni{sub 0.5}Fe{sub 2}O{sub 4}) nanocrystalline ferrites for core, switching and MLCI’s applications

    Energy Technology Data Exchange (ETDEWEB)

    Akhtar, Majid Niaz, E-mail: majidniazakhtar@ciitlahore.edu.pk [Department of Physics, COMSATS Institute of Information Technology, Lahore, 54000 Pakistan (Pakistan); Khan, Muhammad Azhar [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur, 63100 Pakistan (Pakistan); Ahmad, Mukhtar [Department of Physics, COMSATS Institute of Information Technology, Lahore, 54000 Pakistan (Pakistan); Nazir, M.S. [Department of Chemical Engineering, COMSATS Institute of Information Technology, Lahore, 54000 Pakistan (Pakistan); Imran, M.; Ali, A.; Sattar, A. [Department of Physics, COMSATS Institute of Information Technology, Lahore, 54000 Pakistan (Pakistan); Murtaza, G. [Centre for Advanced Studies in Physics, G.C. University, Lahore (Pakistan)

    2017-01-01

    The influence of Cu substitution on the structural and morphological characteristics of Ni–Zn nanocrystalline ferrites have been discussed in this work. The detailed and systematic magnetic characterizations were also done for Cu substituted Ni–Zn nanoferrites. The nanocrystalline ferrites of Cu substituted Cu{sub x}Zn{sub 0.5−x}Ni{sub 0.5}Fe{sub 2}O{sub 4} ferrites (x=0, 0.1, 0.2, 0.3, 0.4 and 0.5) were synthesized using sol gel self-combustion hybrid method. X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscope (TEM) and Vibrating sample magnetometer (VSM) were used to investigate the properties of Cu substituted nanocrystalline ferrites. Single phase structure of Cu substituted in Ni–Zn nanocrystalline ferrites were investigated for all the samples. Crystallite size, lattice constant and volume of the cell were found to increase by increasing Cu contents in spinel structure. The better morphology with well-organized nanocrystals of Cu–Zn–Ni ferrites at x=0 and 0.5 were observed from both FESEM and TEM analysis. The average grain size was 35–46 nm for all prepared nanocrystalline samples. Magnetic properties such as coercivity, saturation, remanence, magnetic squareness, magneto crystalline anisotropy constant (K) and Bohr magneton were measured from the recorded M–H loops. The magnetic saturation and remanence were increased by the incorporation of Cu contents. However, coercivity follow the Stoner-Wolforth model except for x=0.3 which may be due to the site occupancy and replacement of Cu contents from octahedral site. The squareness ratio confirmed the super paramgnetic behaviour of the Cu substituted in Ni–Zn nanocrystalline ferrites. Furthermore, Cu substituted Ni–Zn nanocrystalline ferrites may be suitable for many industrial and domestic applications such as components of transformers, core, switching, and MLCI’s due to variety of the soft magnetic characteristics. - Highlights

  19. Material physical properties of 12 chromium ferritic steel

    International Nuclear Information System (INIS)

    Ando, Masanori; Wakai, Takashi; Aoto, Kazumi

    2003-09-01

    High chromium ferritic steel is an attractive candidate for structural material of the next Fast Breeder Reactor, since both of thermal properties and high temperature strength of the steel are superior to those of conventional austenitic stainless steels. In this study, physical properties of 12Cr steels are measured and compared to those obtained in the previous studies to discuss about stochastic dispersions. The effect of measurement technique on Young's modulus and the influence of the specimen size on coefficient of thermal expansion are also investigated. The following conclusions are obtained. (1) Young's modulus of 12Cr steels obtained in this study tends to larger than those obtained in the previous studies especially in high temperature. Such a discrepancy is resulted from the difference in measurement technique. It was clarified that Young's modulus obtained by free vibration method is more adequate those obtained by the cantilever characteristic vibration method. Therefore, the authors recommend using the values obtained by free vibration method as Young's modulus of 12Cr steels. (2) Both instant and mean coefficient of thermal expansion of 12Cr steels obtained in this study is in a good agreement with those obtained in the previous studies. However, the obviously different values are obtained from the measurement by large size specimens. Such a discrepancy is resulted from heterogeneous during heating process of the specimens. Therefore, the authors recommend using the values obtained by φ4 x 20 mm specimens as instant and mean coefficient of thermal expansion of 12Cr steels. (3) Specific heat of 12Cr steels obtained in this study agree with those obtained in the previous studies with a few exceptions. (4)Thermal conductivity of 12Cr steels obtained in this study agree with those obtained in the previous studies. (5) It was confirmed that instant and mean coefficient of thermal expansion, density, specific heat and thermal conductivity of 12Cr steels

  20. Comparison of material property specifications of ferritic steels in fast-breeder reactor technology

    International Nuclear Information System (INIS)

    Delporte, E.; Vanderborck, Y.

    1988-01-01

    The component fabrications for the fast breeder reactors request the use of ferritic steels specially appropriated for the construction of the equipments sustaining pressure and high temperature. The Activity Group nr 3 Materials of the FRCC has decided to make a study to compare the different norms related to the properties of somme ferritic steels used in the different European fast breeder projects. In particular, this study should allow in the different countries of the Community, to identify the designation of a specific steel and to compare its properties. Deviations between the different norms of a same material are mentioned to facilitate European standardization of this type of material

  1. Development and Application of High-Cr Ferritic Stainless Steels as Building Exterior Materials

    International Nuclear Information System (INIS)

    Kim, Yeong H.; Lee, Yong H.; Lee, Yong D.

    2008-01-01

    Stainless Steels have been widely used as a building exterior materials in Asian countries for the last decade. It is required for the materials in this field to have an aesthetic appearance,a relatively high strength, and an excellent corrosion resistance. Other metallic materials such as copper, aluminum, and carbon steels have been also used as the exterior materials. Considering the cost of maintenance, stainless steel, having the outstanding corrosion resistance, is replacing other materials in the several parts in the building exteriors. Ferritic stainless steel has been applied as the roofing materials because its thermal expansion is much smaller than that of austenitic stainless steel. Therefore, it is suitable for the large-scale construction such as airport terminal, convention center, and football stadium. To improve the corrosion resistance of the ferritic stainless steels, the modification of alloy composition has been studied to develop new grade materials and the progress in the surface technology has been introduced. Corrosion properties, of these materials were evaluated in the laboratory and in the field for longer than two years. High-Cr ferritic stainless steel showed excellent corrosion resistance to the atmospheric environments. In the region close to the sea, the corrosion resistance of high-Cr ferritic stainless steel was much superior to that of other materials, which may prove this steel to be the appropriate materials for the construction around seashore. In some of the large constructions around seashore in South Korea, high-Cr ferritic stainless steels have been used as the building exterior materials for six years

  2. Development and Application of High-Cr Ferritic Stainless Steels as Building Exterior Materials

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yeong H.; Lee, Yong H.; Lee, Yong D. [POSCO Technical Reseaarch Lab., Pohang (Korea, Republic of)

    2008-12-15

    Stainless Steels have been widely used as a building exterior materials in Asian countries for the last decade. It is required for the materials in this field to have an aesthetic appearance,a relatively high strength, and an excellent corrosion resistance. Other metallic materials such as copper, aluminum, and carbon steels have been also used as the exterior materials. Considering the cost of maintenance, stainless steel, having the outstanding corrosion resistance, is replacing other materials in the several parts in the building exteriors. Ferritic stainless steel has been applied as the roofing materials because its thermal expansion is much smaller than that of austenitic stainless steel. Therefore, it is suitable for the large-scale construction such as airport terminal, convention center, and football stadium. To improve the corrosion resistance of the ferritic stainless steels, the modification of alloy composition has been studied to develop new grade materials and the progress in the surface technology has been introduced. Corrosion properties, of these materials were evaluated in the laboratory and in the field for longer than two years. High-Cr ferritic stainless steel showed excellent corrosion resistance to the atmospheric environments. In the region close to the sea, the corrosion resistance of high-Cr ferritic stainless steel was much superior to that of other materials, which may prove this steel to be the appropriate materials for the construction around seashore. In some of the large constructions around seashore in South Korea, high-Cr ferritic stainless steels have been used as the building exterior materials for six years.

  3. Nanocrystalline material in toroidal cores for current transformer: analytical study and computational simulations

    Directory of Open Access Journals (Sweden)

    Benedito Antonio Luciano

    2005-12-01

    Full Text Available Based on electrical and magnetic properties, such as saturation magnetization, initial permeability, and coercivity, in this work are presented some considerations about the possibilities of applications of nanocrystalline alloys in toroidal cores for current transformers. It is discussed how the magnetic characteristics of the core material affect the performance of the current transformer. From the magnetic characterization and the computational simulations, using the finite element method (FEM, it has been verified that, at the typical CT operation value of flux density, the nanocrystalline alloys properties reinforce the hypothesis that the use of these materials in measurement CT cores can reduce the ratio and phase errors and can also improve its accuracy class.

  4. Preparation of nanocrystalline iron-carbon materials as fillers for polymers

    International Nuclear Information System (INIS)

    Narkiewicz, U; Pelech, I; Roslaniec, Z; Kwiatkowska, M; Arabczyk, W

    2007-01-01

    This paper presents a method of preparing nanocrystalline iron-carbon materials which can be applied as fillers for polymers. Nanocrystalline iron samples were carburized either under ethylene/hydrogen mixture or under pure ethylene. Three kinds of samples were prepared: cementite/carbon (Fe 3 C/C), iron/cementite (Fe/Fe 3 C) and iron/carbon (Fe/C) ones. After carburization the samples were characterized using XRD and SEM methods. The obtained samples of iron-carbon nanoparticles were applied as fillers to polymer nanocomposites prepared in a polycondensation reaction (in situ) in a poly(ether-ester) matrix. The nanofillers were dispersed in monomers (diols) using a sonificator and a high-speed rotary stirrer. The obtained nanocomposites were characterized as regards their structure (SEM method) and mechanical behaviour

  5. Grain boundaries of nanocrystalline materials - their widths, compositions, and internal structures

    International Nuclear Information System (INIS)

    Fultz, B.; Frase, H.N.

    2000-01-01

    Nanocrystalline materials contain many atoms at and near grain boundaries. Sufficient numbers of Moessbauer probe atoms can be situated in grain boundary environments to make a clear contribution to the measured Moessbauer spectrum. Three types of measurements on nanocrystalline materials are reported here, all using Moessbauer spectrometry in conjunction with X-ray diffractometry, transmission electron microscopy, or small angle neutron scattering. By measuring the fraction of atoms contributing to the grain boundary component in a Moessbauer spectrum, and by knowing the grain size of the material, it is possible to deduce the average width of grain boundaries in metallic alloys. It is found that these widths are approximately 0.5 nm for fcc alloys and slightly larger than 1.0 nm for bcc alloys.Chemical segregation to grain boundaries can be measured by Moessbauer spectrometry, especially in conjunction with small angle neutron scattering. Such measurements on Fe-Cu and Fe 3 Si-Nb were used to study how nanocrystalline materials could be stabilized against grain growth by the segregation of Cu and Nb to grain boundaries. The segregation of Cu to grain boundaries did not stabilize the Fe-Cu alloys against grain growth, since the grain boundaries were found to widen and accept more Cu atoms during annealing. The Nb additions to Fe 3 Si did suppress grain growth, perhaps because of the low mobility of Nb atoms, but also perhaps because Nb atoms altered the chemical ordering in the alloy.The internal structure of grain boundaries in nanocrystalline materials prepared by high-energy ball milling is found to be unstable against internal relaxations at low temperatures. The Moessbauer spectra of the nanocrystalline samples showed changes in the hyperfine fields attributable to movements of grain boundary atoms. In conjunction with SANS measurements, the changes in grain boundary structure induced by cryogenic exposure and annealing at low temperature were found to be

  6. Magnetically controlled multifrequency invisibility cloak with a single shell of ferrite material

    Science.gov (United States)

    Wang, Xiaohua; Liu, Youwen

    2015-02-01

    A magnetically controlled multifrequency invisibility cloak with a single shell of the isotropic and homogeneous ferrite material has been investigated based on the scattering cancellation method from the Mie scattering theory. The analytical and simulated results have demonstrated that such this shell can drastically reduce the total scattering cross-section of this cloaking system at multiple frequencies. These multiple cloaking frequencies of this shell can be externally controlled since the magnetic permeability of ferrites is well tuned by the applied magnetic field. This may provide a potential way to design a tunable multifrequency invisibility cloak with considerable flexibility.

  7. Contributions from research on irradiated ferritic/martensitic steels to materials science and engineering

    Science.gov (United States)

    Gelles, D. S.

    1990-05-01

    Ferritic and martensitic steels are finding increased application for structural components in several reactor systems. Low-alloy steels have long been used for pressure vessels in light water fission reactors. Martensitic stainless steels are finding increasing usage in liquid metal fast breeder reactors and are being considered for fusion reactor applications when such systems become commercially viable. Recent efforts have evaluated the applicability of oxide dispersion-strengthened ferritic steels. Experiments on the effect of irradiation on these steels provide several examples where contributions are being made to materials science and engineering. Examples are given demonstrating improvements in basic understanding, small specimen test procedure development, and alloy development.

  8. Optimization principles for preparation methods and properties of fine ferrite materials

    Science.gov (United States)

    Borisova, N. M.; Golubenko, Z. V.; Kuz'micheva, T. G.; Ol'khovik, L. P.; Shabatin, V. P.

    1992-08-01

    The paper is devoted to the problems of development of fine materials based on Ba-ferrite for vertical magnetic recording in particular. Taking an analogue — BaFe 12-2 xCo xTe xO 19 — we have optimized the melt co-precipitation method and shown a new opportunity to provide chemical homogeneity of microcrystallites by means of cryotechnology. Magnetic characteristics of the magnetic tape experimental sample for digital video recording are presented. A series of principles of consistent control of ferrite powder properties are formulated and illustrated with specific developments.

  9. Martensitic/ferritic steels as container materials for liquid mercury target of ESS

    International Nuclear Information System (INIS)

    Dai, Y.

    1996-01-01

    In the previous report, the suitability of steels as the ESS liquid mercury target container material was discussed on the basis of the existing database on conventional austenitic and martensitic/ferritic steels, especially on their representatives, solution annealed 316 stainless steel (SA 316) and Sandvik HT-9 martensitic steel (HT-9). Compared to solution annealed austenitic stainless steels, martensitic/ferritic steels have superior properties in terms of strength, thermal conductivity, thermal expansion, mercury corrosion resistance, void swelling and irradiation creep resistance. The main limitation for conventional martensitic/ferritic steels (CMFS) is embrittlement after low temperature (≤380 degrees C) irradiation. The ductile-brittle transition temperature (DBTT) can increase as much as 250 to 300 degrees C and the upper-shelf energy (USE), at the same time, reduce more than 50%. This makes the application temperature range of CMFS is likely between 300 degrees C to 500 degrees C. For the present target design concept, the temperature at the container will be likely controlled in a temperature range between 180 degrees C to 330 degrees C. Hence, CMFS seem to be difficult to apply. However, solution annealed austenitic stainless steels are also difficult to apply as the maximum stress level at the container will be higher than the design stress. The solution to the problem is very likely to use advanced low-activation martensitic/ferritic steels (LAMS) developed by the fusion materials community though the present database on the materials is still very limited

  10. Deformation of nanocrystalline materials by molecular-dynamics simulation: relationship to experiments?

    International Nuclear Information System (INIS)

    Wolf, D.; Yamakov, V.; Phillpot, S.R.; Mukherjee, A.; Gleiter, H.

    2005-01-01

    We review the results of recent molecular-dynamics simulations of the structure and deformation behavior of nanocrystalline materials, i.e., polycrystalline materials with a grain size of typically less than about 100 nm. These simulations have now become large enough and sophisticated enough that they are beginning to cover the entire range of grain sizes over which the experimentally suggested transition from a dislocation-based deformation mechanism to one involving GB processes takes place. Their atomic-level resolution provides novel insights into the intricate interplay between the dislocation and GB processes responsible for this crossover. These simulations also reveal how and why this crossover in the dominant mechanism leads to a transition in the mechanical behavior. However, in spite of these early successes, these simulations are inherently limited to rather idealized model microstructures and extremely high deformation rates. We therefore address the critical question as to the degree to which they begin to capture the experimentally observed, albeit controversial, deformation behavior of real nanocrystalline materials. (Supplementary material to this article, in the form of color graphs of some of the figures and several deformation-simulation movies, can be viewed at http://phillpot.mse.ufl.edu/review.html.)

  11. Formation of nanocrystalline surface layers in various metallic materials by near surface severe plastic deformation

    Directory of Open Access Journals (Sweden)

    Masahide Sato, Nobuhiro Tsuji, Yoritoshi Minamino and Yuichiro Koizumi

    2004-01-01

    Full Text Available The surface of the various kinds of metallic materials sheets were severely deformed by wire-brushing at ambient temperature to achieve nanocrystalline surface layer. The surface layers of the metallic materials developed by the near surface severe plastic deformation (NS-SPD were characterized by means of TEM. Nearly equiaxed nanocrystals with grain sizes ranging from 30 to 200 nm were observed in the near surface regions of all the severely scratched metallic materials, which are Ti-added ultra-low carbon interstitial free steel, austenitic stainless steel (SUS304, 99.99 wt.%Al, commercial purity aluminum (A1050 and A1100, Al–Mg alloy (A5083, Al-4 wt.%Cu alloy, OFHC-Cu (C1020, Cu–Zn alloy (C2600 and Pb-1.5%Sn alloy. In case of the 1050-H24 aluminum, the depth of the surface nanocrystalline layer was about 15 μm. It was clarified that wire-brushing is an effective way of NS-SPD, and surface nanocrystallization can be easily achieved in most of metallic materials.

  12. Outgassing characteristics of F82H ferritic steel as a low activation material for fusion reactor

    International Nuclear Information System (INIS)

    Odaka, Kenji; Satou, Osamu; Ootsuka, Michio; Abe, Tetsuya; Hara, Shigemitsu; Takatsu, Hideyuki; Enoeda, Mikio.

    1997-01-01

    Outgassing characteristics of F82H ferritic steel as a low activation material for the blanket of fusion device were investigated. A test chamber was constructed by welding F82H ferritic steel plates. The inner surface of the chamber was buffed and electropolished. The test chamber was degassed by the prebaking at temperature of 350degC for 20 h in vacuum. Then outgassing rates of the test chamber were measured by the throughput method as a function of pumping time for the cases that the test chamber was baked and not baked. The typical outgassing rate after baking at 250degC for 24 h was 3 x 10 -9 Pa·ms -1 and it seems that this value is sufficiently small to produce pressures at least as low as 10 -9 Pa in the vacuum chamber made of F82H ferritic steel. In the pump-down of the test chamber without baking after exposure to air, the outgassing rate decreases with pumping time and reached 1 x 10 -7 Pa·ms -1 at t = 10 5 s. The activation energy of hydrogen in bulk diffusion in the F82H ferritic steel was measured and found to be 7 kcal/mol. (author)

  13. A phenomenological variational multiscale constitutive model for intergranular failure in nanocrystalline materials

    KAUST Repository

    Siddiq, A.; El Sayed, Tamer S.

    2013-01-01

    We present a variational multiscale constitutive model that accounts for intergranular failure in nanocrystalline fcc metals due to void growth and coalescence in the grain boundary region. Following previous work by the authors, a nanocrystalline

  14. A phenomenological variational multiscale constitutive model for intergranular failure in nanocrystalline materials

    KAUST Repository

    Siddiq, A.

    2013-09-01

    We present a variational multiscale constitutive model that accounts for intergranular failure in nanocrystalline fcc metals due to void growth and coalescence in the grain boundary region. Following previous work by the authors, a nanocrystalline material is modeled as a two-phase material consisting of a grain interior phase and a grain boundary affected zone (GBAZ). A crystal plasticity model that accounts for the transition from partial dislocation to full dislocation mediated plasticity is used for the grain interior. Isotropic porous plasticity model with further extension to account for failure due to the void coalescence was used for the GBAZ. The extended model contains all the deformation phases, i.e. elastic deformation, plastic deformation including deviatoric and volumetric plasticity (void growth) followed by damage initiation and evolution due to void coalescence. Parametric studies have been performed to assess the model\\'s dependence on the different input parameters. The model is then validated against uniaxial loading experiments for different materials. Lastly we show the model\\'s ability to predict the damage and fracture of a dog-bone shaped specimen as observed experimentally. © 2013 Elsevier B.V.

  15. Neutron scattering study of the magnetism in a nanocrystalline/amorphous material

    Energy Technology Data Exchange (ETDEWEB)

    Rosov, N. [National Inst. of Standards and Technology, Gaithersburg, MD (United States). Reactor Radiation Div.; Lynn, J.W. [National Inst. of Standards and Technology, Gaithersburg, MD (United States). Reactor Radiation Div.]|[Univ. of Maryland, College Park, MD (United States). Dept. of Physics; Fish, G.E. [Allied Signal Inc., Morristown, NJ (United States)

    1995-12-31

    Recently developed nanocrystalline magnetic systems are of considerable interest fundamentally as well as technologically. One such material is Fe{sub 73.5}B{sub 9}Si{sub 13.5}Cu{sub 1}Nb{sub 3}, which can be produced by heat treating the amorphous precursor. This forms a noncrystalline phase with typical dimension of 350 {angstrom} as determined by neutron diffraction. Small angle neutron scattering (SANS) has been employed to investigate the properties of the nanocrystallized material over the temperature range from 10 K to 725 K, a regime where no significant structural changes are expected to occur. In zero field and low temperature (10 K) the authors obtained an isotropic scattering pattern. The application of a relatively modest field to sweep out the domains changed the scattering to a butterfly wings pattern typical of patterns dominated by magnetic elastic intensity. Up to 450 K this pattern changed only modestly, while for substantially higher temperatures the ratio of inelastic to elastic scattering increased rapidly as the magnetic phase transition of the intergranular component ({approx_equal} 575 K) was approached. Triple axis inelastic measurements showed that the majority of the magnetic inelastic scattering was from the nanocrystalline phase.

  16. Neutron scattering study of the magnetism in a nanocrystalline/amorphous material

    International Nuclear Information System (INIS)

    Rosov, N.

    1995-01-01

    Recently developed nanocrystalline magnetic systems are of considerable interest fundamentally as well as technologically. One such material is Fe 73.5 B 9 Si 13.5 Cu 1 Nb 3 , which can be produced by heat treating the amorphous precursor. This forms a noncrystalline phase with typical dimension of 350 angstrom as determined by neutron diffraction. Small angle neutron scattering (SANS) has been employed to investigate the properties of the nanocrystallized material over the temperature range from 10 K to 725 K, a regime where no significant structural changes are expected to occur. In zero field and low temperature (10 K) the authors obtained an isotropic scattering pattern. The application of a relatively modest field to sweep out the domains changed the scattering to a butterfly wings pattern typical of patterns dominated by magnetic elastic intensity. Up to 450 K this pattern changed only modestly, while for substantially higher temperatures the ratio of inelastic to elastic scattering increased rapidly as the magnetic phase transition of the intergranular component (≅ 575 K) was approached. Triple axis inelastic measurements showed that the majority of the magnetic inelastic scattering was from the nanocrystalline phase

  17. The utilization of mechanochemistry in the extractive metallurgy and at the nanocrystalline materials preparation

    Directory of Open Access Journals (Sweden)

    Boldižárová Eva

    2002-03-01

    Full Text Available The possibility of the application of mechanochemistry in the extractive metallurgy and the nanocrystalline materials preparation is studied. The aim of the experiments is the chloride leaching of a complex sulphidic CuPbZn concentrate (Hodruša-Hámre, the modification of properties of CaCO3 (Yauli, Peru for zinc sorption from model solutions and the mechanochemical reduction of copper sulphide by elemental iron.The chloride leaching of mechanically activated complex sulphidic CuPbZn concentrate is a selective process. While the recoveries of copper, lead and zinc are 65-85 %, the recoveries of silver and gold are less than 7 % and 2 %, respectively.The positive influence of CaCO3 mechanical activation for zinc sorption from ZnSO4 solution was observed. While only 58 % of zinc sorption was determined after 30 minutes for a non-activated sample, 98 % of zinc sorption was determined after 3 minutes sorption for the sample mechanically activated for 15 minutes.By the mechanochemical reduction of copper sulphide with iron, nanocrystalline copper and iron sulphide are formed. This reaction is an example of the new “solid state technology“, where chemical processes in the gaseous and liquid states are excluded.The results can serve as a contribution to the optimization of copper, lead and zinc extraction from complex sulphidic concentrates, the increase of non-ferrous metals sorption efficiency on mineral sorbents as well as to the nanocrystalline copper preparation.The application of mechanical activation has grown in the laboratory research. The Institute of Geotechnics of SAS has also achieved significant theoretical results in study of mechanical activation of sulphides and their reactivity in the different solid-phase reactions with the effect on industrial applications. The Institute has developed the technology of mechanochemical leaching (process MELT which was successfully tested in a pilot plant unit.

  18. A quantitative understanding on effects of finest nanograins on nanovoid growth in nanocrystalline materials

    International Nuclear Information System (INIS)

    He, Tongyang; Zhou, Jianqiu; Liu, Hongxi

    2015-01-01

    For evaluating the effects of finest nanograins, whose grain size ranging from 2 to 4 nm, on nanovoid growth in nanocrystalline (NC) materials, we proposed a new theoretical model composed of finest nanograins evenly located at the triple junctions of conventional NC materials (grain size ranging from 10 to 100 nm). In the framework of the model, the mechanism of nanovoid growth is the dislocation emission. The blocking effect of finest nanograin on the motion of dislocations emitted from the nanovoid surface was taken into consideration. The critical condition required for dislocations emitted from the nanovoid surface and the influences of the finest nanograin on the nanovoid growth were calculated separately. The quantitatively analyzed results showed that finest nanograins could significantly suppress the growth of nanovoids compared with the triple junctions without finest nanograins. Therefore, the fracture toughness of the NC materials could be enhanced by finest nanograins

  19. Influences of triple junctions on stress-assisted grain boundary motion in nanocrystalline materials

    International Nuclear Information System (INIS)

    Aramfard, Mohammad; Deng, Chuang

    2014-01-01

    Stress-assisted grain boundary motion is among the most studied modes of microstructural evolution in crystalline materials. In this study, molecular dynamics simulations were used to systematically investigate the influences of triple junctions on the stress-assisted motion of symmetric tilt grain boundaries in Cu by considering a honeycomb nanocrystalline model. It was found that the grain boundary motion in nanocrystalline models was highly sensitive to the loading mode, and a strong coupling effect which was prevalent in bicrystal models was only observed when simple shear was applied. In addition, the coupling factor extracted from the honeycomb model was found to be larger and more sensitive to temperature change than that from bicrystal models for the same type of grain boundary under the same loading conditions. Furthermore, the triple junctions seemed to exhibit unusual asymmetric pinning effects to the migrating grain boundary and the constraints by the triple junctions and neighboring grains led to remarkable non-linear grain boundary motion in directions both parallel and normal to the applied shear, which was in stark contrast to that observed in bicrystal models. In addition, dislocation nucleation and propagation, which were absent in the bicrystal model, were found to play an important role on shear-induced grain boundary motion when triple junctions were present. In the end, a generalized model for shear-assisted grain boundary motion was proposed based on the findings from this research. (paper)

  20. Synthesis and properties of nickel-doped nanocrystalline barium hexaferrite ceramic materials

    Science.gov (United States)

    Waqar, Moaz; Rafiq, Muhammad Asif; Mirza, Talha Ahmed; Khalid, Fazal Ahmad; Khaliq, Abdul; Anwar, Muhammad Sabieh; Saleem, Murtaza

    2018-04-01

    M-type barium hexaferrite ceramics have emerged as important materials both for technological and commercial applications. However, limited work has been reported regarding the investigation of nanocrystalline Ni-doped barium hexaferrites. In this study, nanocrystalline barium hexaferrite ceramics with the composition BaFe12- x Ni x O19 (where x = 0, 0.3 and 0.5) were synthesized by sol-gel method and characterized using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, vibrating sample magnetometer and precision impedance analyzer. All the synthesized samples had single magnetoplumbite phase having space group P63/mmc showing the successful substitution of Ni in BaFe12O19 without the formation of any impurity phase. Average grain size of undoped samples was around 120 nm which increased slightly with the addition of Ni. Saturation magnetization ( M s) and remnant magnetization ( M r) increased with the addition of Ni, however, coercivity ( H c) decreased with the increase in Ni from x = 0 to x = 0.5. Real and imaginary parts of permittivity decreased with the increasing frequency and increased with Ni content. Dielectric loss and conductivity showed slight variation with the increase in Ni concentration.

  1. Nanocrystalline silicon as the light emitting material of a field emission display device

    International Nuclear Information System (INIS)

    Biaggi-Labiosa, A; Sola, F; Resto, O; Fonseca, L F; Gonzalez-BerrIos, A; Jesus, J De; Morell, G

    2008-01-01

    A nanocrystalline Si-based paste was successfully tested as the light emitting material in a field emission display test device that employed a film of carbon nanofibers as the electron source. Stable emission in the 550-850 nm range was obtained at 16 V μm -1 . This relatively low field required for intense cathodoluminescence (CL) from the PSi paste may lead to longer term reliability of both the electron emitting and the light emitting materials, and to lower power consumption. Here we describe the synthesis, characterization, and analyses of the light emitting nanostructured Si paste and the electron emitting C nanofibers used for building the device, including x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. The corresponding spectra and field emission curves are also shown and discussed

  2. Characterizing deformed ultrafine-grained and nanocrystalline materials using transmission Kikuchi diffraction in a scanning electron microscope

    International Nuclear Information System (INIS)

    Trimby, Patrick W.; Cao, Yang; Chen, Zibin; Han, Shuang; Hemker, Kevin J.; Lian, Jianshe; Liao, Xiaozhou; Rottmann, Paul; Samudrala, Saritha; Sun, Jingli; Wang, Jing Tao; Wheeler, John; Cairney, Julie M.

    2014-01-01

    Graphical abstract: -- Abstract: The recent development of transmission Kikuchi diffraction (TKD) in a scanning electron microscope enables fast, automated orientation mapping of electron transparent samples using standard electron backscatter diffraction (EBSD) hardware. TKD in a scanning electron microscope has significantly better spatial resolution than conventional EBSD, enabling routine characterization of nanocrystalline materials and allowing effective measurement of samples that have undergone severe plastic deformation. Combining TKD with energy dispersive X-ray spectroscopy (EDS) provides complementary chemical information, while a standard forescatter detector system below the EBSD detector can be used to generate dark field and oriented dark field images. Here we illustrate the application of this exciting new approach to a range of deformed, ultrafine grained and nanocrystalline samples, including duplex stainless steel, nanocrystalline copper and highly deformed titanium and nickel–cobalt. The results show that TKD combined with EDS is a highly effective and widely accessible tool for measuring key microstructural parameters at resolutions that are inaccessible using conventional EBSD

  3. Creep deformation of high Cr-Mo ferritic/martensitic steels by material softening

    International Nuclear Information System (INIS)

    Kim, Sung Ho; Song, B. J.; Ryu, Woo Seog

    2005-01-01

    High Cr (9-12%Cr) ferritic/martensitic steels represent a valuable alternative to austenitic stainless steel for high temperature applications up to 600 .deg. C both in power and petrochemical plant, as well as good resistance to oxidation and corrosion. Material softening is the main physical phenomenon observed in the crept material. Thermally-induced change (such as particle coarsening or matrix solute depletion) and strain-induced change (such as dynamic subgrain growth) of microstructure degraded the alloy strength. These microstructural changes during a creep test cause the material softening, so the strength of the materials decreased. Many researches have been performed for the microstructural changes during a creep test, but the strength of crept materials has not been measured. In the present work, we measured the yield and tensile strength of crept materials using Indentationtyped Tensile Test System (AIS 2000). Material softening was quantitatively evaluated with a creep test condition, such as temperature and applied stress

  4. Thermal decomposition of barium ferrate(VI): Mechanism and formation of FeIV intermediate and nanocrystalline Fe2O3 and ferrite

    International Nuclear Information System (INIS)

    Machala, Libor; Sharma, Virender K.; Kuzmann, Ernö; Homonnay, Zoltán; Filip, Jan; Kralchevska, Radina P.

    2016-01-01

    Simple high-valent iron-oxo species, ferrate(VI) (Fe VI O 4 2− , Fe(VI)) has applications in energy storage, organic synthesis, and water purification. Of the various salts of Fe(VI), barium ferrate(VI) (BaFeO 4 ) has also a great potential as a battery material. This paper presents the thermal decomposition of BaFeO 4 in static air and nitrogen atmosphere, monitored by combination of thermal analysis, Mössbauer spectroscopy, X-ray powder diffraction, and electron-microscopic techniques. The formation of Fe IV species in the form of BaFeO 3 was found to be the primary decomposition product of BaFeO 4 at temperature around 190 °C under both studied atmospheres. BaFeO 3 was unstable in air reacting with CO 2 to form barium carbonate and speromagnetic amorphous iron(III) oxide nanoparticles (<5 nm). Above 600 °C, a solid state reaction between BaCO 3 and Fe 2 O 3 occurred, leading to the formation of barium ferrite nanoparticles, BaFe 2 O 4 (20–100 nm). - Highlights: • We explained the mechanism of thermal decomposition of barium ferrate(VI). • We confirmed the formation of Fe(IV) intermediate phase during the decomposition. • The mechanism of the decomposition is influenced by a presence of carbon dioxide.

  5. Ferrites and ceramic composites

    CERN Document Server

    Jotania, Rajshree B

    2013-01-01

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

  6. Sinus Floor Elevation and Augmentation Using Synthetic Nanocrystalline and Nanoporous Hydroxyapatite Bone Substitute Materials: Preliminary Histologic Results.

    Science.gov (United States)

    Belouka, Sofia-Maria; Strietzel, Frank Peter

    To compare the tissue composition of augmented sites after using two different synthetic bone substitute materials, nanocrystalline and nanoporous hydroxyapatite (HA), for sinus floor elevation and augmentation. Forty-four patients received 88 titanium screw implants (Camlog Promote plus) of 4.3-mm diameter and 11- or 13-mm length, placed simultaneously during sinus floor elevation and augmentation. Nanocrystalline (Ostim) or nanoporous (NanoBone) HA were used exclusively. Bone substitute materials and implant lengths were allocated by randomization. Bone biopsy specimens were obtained from the former area of the lateral access window at implant exposure during healing abutment placement after 6 months. Biopsy specimens were prepared and examined histologically and histomorphometrically. All implants were osseointegrated at the time of exposure. Clinically and histologically, no signs of inflammation in the augmented sites were present. The histomorphometric analysis of 44 biopsy specimens revealed 31.8% ± 11.6% newly formed bone for sites augmented with nanocrystalline HA and 34.6% ± 9.2% for nanoporous HA (P = .467). The proportion of remaining bone substitute material was 28.4% ± 18.6% and 30% ± 13%, respectively (P = .453). The proportion of soft tissue within the biopsy specimens was 39.9% ± 11.1% and 35.4% ± 6.8%, respectively (P = .064). No significant differences were found between the area fractions of bone, bone substitute material, and soft tissue concerning the bone substitute material utilized. Within the present study, both synthetic bone substitute materials, nanocrystalline and nanoporous HA, were found to support bone formation in sinus floor elevation and augmentation procedures by osteoconductivity. They were not completely resorbed after 6 months. The amounts of newly formed bone, soft tissue, and bone substitute material remnants were found to be similar, indicating that both materials are likewise suitable for sinus floor elevation and

  7. The effects of the finest grains on the mechanical behaviours of nanocrystalline materials

    International Nuclear Information System (INIS)

    Hu Lingling; Huo Ruxiao; Zhou Jianqiu; Wang Ying; Zhang Shu

    2012-01-01

    This article proposes a new constitutive model to account for effects of the finest grains, with sizes ranging from 2 to 4 nm, on the mechanical behaviours of nanocrystalline (NC) materials. In this model, the normal nanograins (ranging from 20 to 100 nm) were treated as though they were composed of a grain interior (GI) and a grain boundary (GB) affected zone (GBAZ). The finest grains were considered to be part of the GBAZ, denoted as super triple junctions (STJs). For the initial plastic deformation stage of the NC materials, a phenomenological constitutive equation was suggested to predict the deformation behaviours of the GBAZ. The formation of GB dislocation (GBD) pileups provides dramatic strain hardening in deformed NC materials and thereby enhances their ductility. Then, the constitutive equations to describe the plastic deformation of the GI and the GBAZ lattice region were established. In this stage, the GBAZ are already saturated with GBD pileups, and GI deformation is the dominant mechanism. Finally, the mechanical model for the NC materials with the finest grains was built using the self-consistent method, and an overall moderate “work hardening,” sustained over a long range of plastic strain, was predicted. The effects of TJs/STJs on the deformation mechanism were quantitatively analysed. The analysis demonstrated that the existence of the finest grains will simultaneously lead to good strength and good ductility.

  8. Thermal decomposition of barium ferrate(VI): Mechanism and formation of Fe{sup IV} intermediate and nanocrystalline Fe{sub 2}O{sub 3} and ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Machala, Libor, E-mail: libor.machala@upol.cz [Regional Centre of Advanced Technologies and Materials, Department of Experimental Physics, Faculty of Science, Palacký University, Olomouc (Czech Republic); Sharma, Virender K. [Department of Environmental and Occupational Health, School of Public Health, Texas A& M University, 1266 TAMU, College Station, TX 77843 (United States); Kuzmann, Ernö; Homonnay, Zoltán [Institute of Chemistry, Eötvös Loránd University, Budapest (Hungary); Filip, Jan; Kralchevska, Radina P. [Regional Centre of Advanced Technologies and Materials, Department of Experimental Physics, Faculty of Science, Palacký University, Olomouc (Czech Republic)

    2016-05-25

    Simple high-valent iron-oxo species, ferrate(VI) (Fe{sup VI}O{sub 4}{sup 2−}, Fe(VI)) has applications in energy storage, organic synthesis, and water purification. Of the various salts of Fe(VI), barium ferrate(VI) (BaFeO{sub 4}) has also a great potential as a battery material. This paper presents the thermal decomposition of BaFeO{sub 4} in static air and nitrogen atmosphere, monitored by combination of thermal analysis, Mössbauer spectroscopy, X-ray powder diffraction, and electron-microscopic techniques. The formation of Fe{sup IV} species in the form of BaFeO{sub 3} was found to be the primary decomposition product of BaFeO{sub 4} at temperature around 190 °C under both studied atmospheres. BaFeO{sub 3} was unstable in air reacting with CO{sub 2} to form barium carbonate and speromagnetic amorphous iron(III) oxide nanoparticles (<5 nm). Above 600 °C, a solid state reaction between BaCO{sub 3} and Fe{sub 2}O{sub 3} occurred, leading to the formation of barium ferrite nanoparticles, BaFe{sub 2}O{sub 4} (20–100 nm). - Highlights: • We explained the mechanism of thermal decomposition of barium ferrate(VI). • We confirmed the formation of Fe(IV) intermediate phase during the decomposition. • The mechanism of the decomposition is influenced by a presence of carbon dioxide.

  9. The heat storage material based on paraffin-modified multilayer carbon nanotubes with Nickel-zinc ferrite

    Science.gov (United States)

    Shchegolkov, A.; Shchegolkov, A.; Dyachkova, T.; Semenov, A.

    2018-02-01

    The paper presents an investigation of magnetically controlled heat-storage material based on paraffin, modified with multilayer carbon nanotubes with nickel-zinc ferrite. The technology of obtaining nanomodified material capable of interacting with magnetic field is presented. The study of the heat-exchange processes of charge/discharge with the help of magnetic field are carried out.

  10. Lithium potential variations for metastable materials: case study of nanocrystalline and amorphous LiFePO4.

    Science.gov (United States)

    Zhu, Changbao; Mu, Xiaoke; Popovic, Jelena; Weichert, Katja; van Aken, Peter A; Yu, Yan; Maier, Joachim

    2014-09-10

    Much attention has been paid to metastable materials in the lithium battery field, especially to nanocrystalline and amorphous materials. Nonetheless, fundamental issues such as lithium potential variations have not been pertinently addressed. Using LiFePO4 as a model system, we inspect such lithium potential variations for various lithium storage modes and evaluate them thermodynamically. The conclusions of this work are essential for an adequate understanding of the behavior of electrode materials and even helpful in the search for new energy materials.

  11. Structure and properties of nanocrystalline soft magnetic composite materials with silicon polymer matrix

    International Nuclear Information System (INIS)

    Dobrzanski, L.A.; Nowosielski, R.; Konieczny, J.; PrzybyI, A.; WysIocki, J.

    2005-01-01

    The paper concerns investigation of nanocrystalline composites technology preparation. The composites in the form of rings with rectangular transverse section, and with polymer matrix and nanocrystalline metallic powders fulfillment were made, for obtaining good ferromagnetic properties. The nanocrystalline ferromagnetic powders were manufactured by high-energy ball milling of metallic glasses strips in an as-quenched state. Generally for investigation, Co matrix alloys with the silicon polymer were used. Magnetic properties in the form of hysteresis loop by rings method were measured. Generally composite cores showed lower soft ferromagnetic properties than winded cores of nanocrystalline strips, but composite cores showed interesting mechanical properties. Furthermore, the structure of strips and powders on properties of composites were investigated

  12. Problems of increasing of thermostability of highly permeable Ni-Zn ferrites and relative materials for telecommunications

    Energy Technology Data Exchange (ETDEWEB)

    Gonchar, A. E-mail: letyuk@mail.ru; Andreev, V.; Letyuk, L.; Shishkanov, A.; Maiorov, V

    2003-01-01

    The work considers ways of increasing of thermostability of ferrites of the basic systems NiO-ZnO-Fe{sub 2}O{sub 3} and MgO-ZnO-Fe{sub 2}O{sub 3} and relative materials for telecommunication. Sufficient results in increasing of the thermostability were achieved by doping Cu ions and controlling rejection of Fe{sub 2}O{sub 3} content from equimolar composition. These results allow to increase the Curie temperature to 130-140 deg. C for Ni-Zn ferrites with initial permeability 2000.

  13. Nanocrystalline hydroxyapatite doped with selenium oxyanions: A new material for potential biomedical applications

    International Nuclear Information System (INIS)

    Kolmas, Joanna; Oledzka, Ewa; Sobczak, Marcin; Nałęcz-Jawecki, Grzegorz

    2014-01-01

    Selenium-substituted hydroxyapatites containing selenate SeO 4 2− or selenite SeO 3 2− ions were synthesized using a wet precipitation method. The selenium content was determined by atomic absorbance spectrometry. The raw, unsintered powders were also characterized using powder X-ray diffraction, middle-range FT-IR spectroscopy and transmission electron microscopy with energy-dispersive X-ray spectroscopic microanalysis. The synthesized apatites were found to be pure and nanocrystalline with a crystal size similar to that in bone mineral. The incorporation of selenium oxyanions into the crystal lattice was confirmed. The toxicity of hydroxyapatites containing selenite or selenate ions was evaluated with a protozoan assay and bacterial luminescence test. - Highlights: • We synthesized and analyzed hydroxyapatites doped with selenium oxyanions. • We used various analytical methods, i.e. XRD, TEM, AAS and FT-IR. • We confirmed incorporation of SeO 3 2− and SeO 4 2− into the crystal lattice. • The toxicity of the materials was studied

  14. Nanocrystalline hydroxyapatite doped with selenium oxyanions: A new material for potential biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Kolmas, Joanna, E-mail: joanna.kolmas@wum.edu.pl [Medical University of Warsaw, Faculty of Pharmacy, Department of Inorganic and Analytical Chemistry, ul. Banacha 1, 02-097 Warsaw (Poland); Oledzka, Ewa; Sobczak, Marcin [Medical University of Warsaw, Faculty of Pharmacy, Department of Inorganic and Analytical Chemistry, ul. Banacha 1, 02-097 Warsaw (Poland); Nałęcz-Jawecki, Grzegorz [Medical University of Warsaw, Faculty of Pharmacy, Department of Environmental Health Sciences, ul. Banacha 1, 02-097 Warsaw (Poland)

    2014-06-01

    Selenium-substituted hydroxyapatites containing selenate SeO{sub 4}{sup 2−} or selenite SeO{sub 3}{sup 2−} ions were synthesized using a wet precipitation method. The selenium content was determined by atomic absorbance spectrometry. The raw, unsintered powders were also characterized using powder X-ray diffraction, middle-range FT-IR spectroscopy and transmission electron microscopy with energy-dispersive X-ray spectroscopic microanalysis. The synthesized apatites were found to be pure and nanocrystalline with a crystal size similar to that in bone mineral. The incorporation of selenium oxyanions into the crystal lattice was confirmed. The toxicity of hydroxyapatites containing selenite or selenate ions was evaluated with a protozoan assay and bacterial luminescence test. - Highlights: • We synthesized and analyzed hydroxyapatites doped with selenium oxyanions. • We used various analytical methods, i.e. XRD, TEM, AAS and FT-IR. • We confirmed incorporation of SeO{sub 3}{sup 2−} and SeO{sub 4}{sup 2−} into the crystal lattice. • The toxicity of the materials was studied.

  15. Synthesis of CuO nanocrystalline and their application as electrode materials for capacitors

    International Nuclear Information System (INIS)

    Zhang Hongxia; Zhang Milin

    2008-01-01

    Cauliflower-like, nanobelt-shaped and feather-like CuO nanocrystallines were synthesized by the chemical deposition method. The microstructure and morphology of CuO were characterized by X-ray diffraction (XRD), energy-dispersive spectrum (EDS) and field emission scanning electron microscopy (FESEM). Results showed that the morphology of CuO was affected by property of alkali added into system. The probable mechanisms of the formation of CuO with different morphologies were discussed. The electrochemical properties of CuO as electrode material were enhanced by the improving of morphology. Cauliflower-like CuO exhibited a higher specific capacitance (116.9 F g -1 ) than nanobelt-shaped and feather-like CuO, and also showed good reversibility. Specific capacitance of cauliflower-like CuO (115.3 F g -1 ) was 343.5% higher than CuO bought (26 F g -1 ) at 5 mA cm -2

  16. Synthesis of CuO nanocrystalline and their application as electrode materials for capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Hongxia [Department of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)], E-mail: zhanghongxia.412@163.com; Zhang Milin [Department of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)], E-mail: zhangmilin@hrbeu.edu.cn

    2008-04-15

    Cauliflower-like, nanobelt-shaped and feather-like CuO nanocrystallines were synthesized by the chemical deposition method. The microstructure and morphology of CuO were characterized by X-ray diffraction (XRD), energy-dispersive spectrum (EDS) and field emission scanning electron microscopy (FESEM). Results showed that the morphology of CuO was affected by property of alkali added into system. The probable mechanisms of the formation of CuO with different morphologies were discussed. The electrochemical properties of CuO as electrode material were enhanced by the improving of morphology. Cauliflower-like CuO exhibited a higher specific capacitance (116.9 F g{sup -1}) than nanobelt-shaped and feather-like CuO, and also showed good reversibility. Specific capacitance of cauliflower-like CuO (115.3 F g{sup -1}) was 343.5% higher than CuO bought (26 F g{sup -1}) at 5 mA cm{sup -2}.

  17. High-performance zig-zag and meander inductors embedded in ferrite material

    International Nuclear Information System (INIS)

    Stojanovic, Goran; Damnjanovic, Mirjana; Desnica, Vladan; Zivanov, Ljiljana; Raghavendra, Ramesh; Bellew, Pat; Mcloughlin, Neil

    2006-01-01

    This paper describes the design, modeling, simulation and fabrication of zig-zag and meander inductors embedded in low- or high-permeability soft ferrite material. These microinductors have been developed with ceramic coprocessing technology. We compare the electrical properties of zig-zag and meander inductors structures installed as surface-mount devices. The equivalent model of the new structures is presented, suitable for design, circuit simulations and for prediction of the performance of proposed inductors. The relatively high impedance values allow these microinductors to be used in high-frequency suppressors. The components were tested in the frequency range of 1 MHz-3 GHz using an Agilent 4287A RF LCR meter. The measurements confirm the validity of the analytical model

  18. 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+.

  19. Adhesive bonding and brazing of nanocrystalline diamond foil onto different substrate materials

    Science.gov (United States)

    Lodes, Matthias A.; Sailer, Stefan; Rosiwal, Stefan M.; Singer, Robert F.

    2013-10-01

    Diamond coatings are used in heavily stressed industrial applications to reduce friction and wear. Hot-filament chemical vapour deposition (HFCVD) is the favourable coating method, as it allows a coating of large surface areas with high homogeneity. Due to the high temperatures occurring in this CVD-process, the selection of substrate materials is limited. With the desire to coat light materials, steels and polymers a new approach has been developed. First, by using temperature-stable templates in the HFCVD and stripping off the diamond layer afterwards, a flexible, up to 150 μm thick and free standing nanocrystalline diamond foil (NCDF) can be produced. Afterwards, these NCDF can be applied on technical components through bonding and brazing, allowing any material as substrate. This two-step process offers the possibility to join a diamond layer on any desired surface. With a modified scratch test and Rockwell indentation testing the adhesion strength of NCDF on aluminium and steel is analysed. The results show that sufficient adhesion strength is reached both on steel and aluminium. The thermal stress in the substrates is very low and if failure occurs, cracks grow undercritically. Adhesion strength is even higher for the brazed samples, but here crack growth is critical, delaminating the diamond layer to some extent. In comparison to a sample directly coated with diamond, using a high-temperature CVD interlayer, the brazed as well as the adhesively bonded samples show very good performance, proving their competitiveness. A high support of the bonding layer could be identified as crucial, though in some cases a lower stiffness of the latter might be acceptable considering the possibility to completely avoid thermal stresses which occur during joining at higher temperatures.

  20. Some initial considerations on the suitability of Ferritic/ martensitic stainless steels as first wall and blanket materials in fusion reactors

    International Nuclear Information System (INIS)

    Butterworth, G.J.

    1982-01-01

    The constitution of stainless iron alloys and the characteristic properties of alloys in the main ferritic, martensitic and austenitic groups are discussed. A comparison of published data on the mechanical, thermal and irradiation properties of typical austenitic and martensitic/ferritic steels shows that alloys in the latter groups have certain advantages for fusion applications. The ferromagnetism exhibited by martensitic and ferritic alloys has, however, been identified as a potentially serious obstacle to their utilisation in magnetic confinement devices. The paper describes measurements performed in other laboratories on the magnetic properties of two representative martensitic alloys 12Cr-1Mo and 9Cr-2Mo. These observations show that a modest bias magnetic field of magnitude 1 - 2 tesla induces a state of magnetic saturation in these materials. They would thus behave as essentially paramagnetic materials having a relative permeability close to unity when saturated by the toroidal field of a tokamak reactor. The results of computations by the General Atomic research group to assess the implications of such magnetic behaviour on reactor design and operation are presented. The results so far indicate that the ferromagnetism of martensitic/ferritic steels would not represent a major obstacle to their utilisation as first wall or blanket materials. (author)

  1. Gap Analysis of Material Properties Data for Ferritic/Martensitic HT-9 Steel

    International Nuclear Information System (INIS)

    Brown, Neil R.; Serrano De Caro, Magdalena; Rodriguez, Edward A.

    2012-01-01

    The US Department of Energy (DOE), Office of Nuclear Energy (NE), is supporting the development of an ASME Code Case for adoption of 12Cr-1Mo-VW ferritic/martensitic (F/M) steel, commonly known as HT-9, primarily for use in elevated temperature design of liquid-metal fast reactors (LMFR) and components. In 2011, Los Alamos National Laboratory (LANL) nuclear engineering staff began assisting in the development of a small modular reactor (SMR) design concept, previously known as the Hyperion Module, now called the Gen4 Module. LANL staff immediately proposed HT-9 for the reactor vessel and components, as well as fuel clad and ducting, due to its superior thermal qualities. Although the ASME material Code Case, for adoption of HT-9 as an approved elevated temperature material for LMFR service, is the ultimate goal of this project, there are several key deliverables that must first be successfully accomplished. The most important key deliverable is the research, accumulation, and documentation of specific material parameters; physical, mechanical, and environmental, which becomes the basis for an ASME Code Case. Time-independent tensile and ductility data and time-dependent creep and creep-rupture behavior are some of the material properties required for a successful ASME Code case. Although this report provides a cursory review of the available data, a much more comprehensive study of open-source data would be necessary. This report serves three purposes: (a) provides a list of already existing material data information that could ultimately be made available to the ASME Code, (b) determines the HT-9 material properties data missing from available sources that would be required and (c) estimates the necessary material testing required to close the gap. Ultimately, the gap analysis demonstrates that certain material properties testing will be required to fulfill the necessary information package for an ASME Code Case.

  2. High burnup performance of an advanced oxide fuel assembly in FFTF [Fast Flux Test Facility] with ferritic/martensitic materials

    International Nuclear Information System (INIS)

    Bridges, A.E.; Saito, G.H.; Lovell, A.J.; Makenas, B.J.

    1986-05-01

    An advanced oxide fuel assembly with ferritic/martensitic materials has successfully completed its sixth cycle of irradiation in the FFTF, reaching a peak pellet burnup greater than 100 MWd/KgM and a peak fast fluence greater than 15 x 10 22 n/cm 2 . The cladding, wire-wrap, and duct material for the ACO-1 test assembly is the ferritic/martensitic alloy, HT9, which was chosen for use in long-lifetime fuel assemblies because of its good nominal temperature creep strength and low swelling rate. Valuable experience on the performance of HT9 materials has been gained from this test, advancing our quest for long-lifetime fuel. Pertinent data, obtained from the ACO-1 test assembly, will support the irradiation of the Core Demonstration Experiment in FFTF

  3. Measurement of the magnetic material properties for ferrite-loaded cavities

    Directory of Open Access Journals (Sweden)

    Klaus Klopfer

    2015-01-01

    Full Text Available Measurements of the magnetic characteristics of the Ferroxcube 8C12m ferrite material in the parameter range where the GSI heavy-ion synchrotron SIS 18 cavity resonator is operated are presented. At first, the permeability is determined as a function of frequency and bias magnetic field strength for low radio-frequency power levels. For this purpose, both reflection and transmission measurements are carried out in a test setup with two toroids. The values for the real and imaginary part obtained from the data analysis of both approaches are fully in agreement with each other, albeit the range of application of the latter setup is limited to moderate frequencies due to parasitic resonances. An empirical analytical expression is formulated which approximates the complex permeability reasonably well in the whole investigated bias and frequency range. Moreover, the B-H curve is recorded for a reduced bias current range of the cavity. The gained material characteristics are well suited for numerical eigenmode simulations for the GSI SIS 18 cavity.

  4. Synthesis of nanocrystalline nickel-zinc ferrite (Ni0.8Zn0.2Fe2O4) thin films by chemical bath deposition method

    International Nuclear Information System (INIS)

    Pawar, D.K.; Pawar, S.M.; Patil, P.S.; Kolekar, S.S.

    2011-01-01

    Graphical abstract: Display Omitted Research highlights: → We have successfully synthesized nickel-zinc ferrite (Ni 0.8 Zn 0.2 Fe 2 O 4 ) thin films on stainless steel substrates using a low temperature chemical bath deposition method. → The surface morphological study showed the compact flakes like morphology. → The as-deposited thin films are hydrophilic (10 o o ) whereas the annealed thin films are super hydrophilic (θ o ) in nature. → Ni 0.8 Zn 0.2 Fe 2 O 4 thin films could be used in supercapacitor. - Abstract: The nickel-zinc ferrite (Ni 0.8 Zn 0.2 Fe 2 O 4 ) thin films have been successfully deposited on stainless steel substrates using a chemical bath deposition method from alkaline bath. The films were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), static water contact angle and cyclic voltammetry measurements. The X-ray diffraction pattern shows that deposited Ni 0.8 Zn 0.2 Fe 2 O 4 thin films were oriented along (3 1 1) plane. The FTIR spectra showed strong absorption peaks around 600 cm -1 which are typical for cubic spinel crystal structure. SEM study revealed compact flakes like morphology having thickness ∼1.8 μm after air annealing. The annealed films were super hydrophilic in nature having a static water contact angle (θ) of 5 o .The electrochemical supercapacitor study of Ni 0.8 Zn 0.2 Fe 2 O 4 thin films has been carried out in 6 M KOH electrolyte. The values of interfacial and specific capacitances obtained were 0.0285 F cm -2 and 19 F g -1 , respectively.

  5. Development of a low-cost double rotor axial flux motor with soft magnetic composite and ferrite permanent magnet materials

    Science.gov (United States)

    Liu, Chengcheng; Zhu, Jianguo; Wang, Youhua; Guo, Youguang; Lei, Gang; Liu, Xiaojing

    2015-05-01

    This paper proposes a low-cost double rotor axial flux motor (DRAFM) with low cost soft magnetic composite (SMC) core and ferrite permanent magnets (PMs). The topology and operating principle of DRAFM and design considerations for best use of magnetic materials are presented. A 905 W 4800 rpm DRAFM is designed for replacing the high cost NdFeB permanent magnet synchronous motor (PMSM) in a refrigerator compressor. By using the finite element method, the electromagnetic parameters and performance of the DRAFM operated under the field oriented control scheme are calculated. Through the analysis, it is shown that that the SMC and ferrite PM materials can be good candidates for low-cost electric motor applications.

  6. Creep behaviour and microstructure of the ferritic material No. 1-6770 under irradiation

    International Nuclear Information System (INIS)

    Herschbach, K.; Ehrlich, K.; Materna, E.

    Creep behaviour under irradiation of the ferritic steel-DIN-1-6770 is quite different of austenitic steel behaviour, in particular temperature sensitivity is important and response to stress is non linear. The microstructure stays unchanged

  7. Composites of amorphous and nanocrystalline Zr–Cu–Al–Nb bulk materials synthesized by spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Drescher, P., E-mail: philipp.drescher@uni-rostock.de [Fluidic Technology and Microfluidics, Faculty of Mechanical Engineering and Marine Technology, University of Rostock, 18059 Rostock (Germany); Witte, K. [Physics of New Materials, Institute of Physics, University of Rostock, 18051 Rostock (Germany); Yang, B. [Polymer Physics, Institute of Physics, University of Rostock, 18051 Rostock (Germany); Steuer, R.; Kessler, O. [Chair of Materials Science, Faculty of Mechanical Engineering and Marine Technology, University of Rostock, 18059 Rostock (Germany); Burkel, E. [Physics of New Materials, Institute of Physics, University of Rostock, 18051 Rostock (Germany); Schick, C. [Polymer Physics, Institute of Physics, University of Rostock, 18051 Rostock (Germany); Seitz, H. [Fluidic Technology and Microfluidics, Faculty of Mechanical Engineering and Marine Technology, University of Rostock, 18059 Rostock (Germany)

    2016-05-15

    The fabrication of Zr{sub 70}Cu{sub 24}Al{sub 4}Nb{sub 2} bulk metallic glass composite samples by spark plasma sintering (SPS) process has been successfully realized. The unique characteristics of bulk metallic glasses could lead to the possibility of future applications as new structural and functional materials. The densification of an amorphous Zr{sub 70}Cu{sub 24}Al{sub 4}Nb{sub 2} powder was realized in a systematic study changing the sintering temperature in the SPS process leading to stable composites characteristic of amorphous and nanocrystalline structures. X-ray diffractometry (XRD) and differential scanning calorimetry (DSC) analysis, transmission electron microscopy (TEM) as well as hardness tests were applied to determine the structural and mechanical properties of the sintered materials. A stable amorphous bulk metallic glass based on Zr{sub 70}Cu{sub 24}Al{sub 4}Nb{sub 2} with a low fraction of crystallites could be fabricated applying a nominal sintering temperature of 400 °C. Higher sintering temperatures lead to composites with high fractions of nanocrystalline material with porosities below 0.5%.

  8. European experiences of the proposed ASTM test method for crack arrest toughness of ferritic materials

    International Nuclear Information System (INIS)

    Jutla, T.; Lidbury, D.P.G.; Ziebs, J.; Zimmermann, C.

    1986-01-01

    The proposed ASTM test method for measuring the crack arrest toughness of ferritic materials using wedge-loaded, side-grooved, compact specimens was applied to three steels: A514 bridge steel, A588 bridge steel, and A533B pressure vessel steel. Five sets of results from different laboratories are discussed here. Notches were prepared by spark erosion, although root radii varied from ∝0.1-1.5 mm. Although fast fractures were successfully initiated, arrest did not occur in a significant number of cases. The results showed no obvious dependence of crack arrest toughness, K a , (determined by a static analysis) on crack initiation toughness, K 0 . It was found that K a decreases markedly with increasing crack jump distance. A limited amount of further work on smaller specimens of the A533B steel showed that lower K a values tended to be recorded. It is concluded that a number of points relating to the proposed test method and notch preparation are worthy of further consideration. It is pointed out that the proposed validity criteria may screen out lower bound data. Nevertheless, for present practical purposes, K a values may be regarded as useful in providing an estimate of arrest toughness - although not necessarily a conservative estimate. (orig./HP)

  9. Study the effect of Gd{sup 3+} incorporation into nanocrystalline (Ni–Ti) substituted Mn–Zn ferrites on its structure and functional properties

    Energy Technology Data Exchange (ETDEWEB)

    Rady, K.E., E-mail: k_rady_2001@yahoo.com [Engineering Basic Sciences Department, Faculty of Engineering, Menoufia University, Shebin El-El, Kom (Egypt); Shams, M.S. [Department of Physics and Engineering Mathematics, Faculty of Electronic Engineering, Menoufia University, Menouf (Egypt)

    2017-03-15

    Ferrite samples with general chemical formula Mn{sub 0.9}Zn{sub 0.1}Ni{sub 0.05}Ti{sub 0.05}Gd{sub t}Fe{sub 1.9−t}O{sub 4}; (0.0≤ t≤0.05; step 0.01) were prepared using solid state reaction technique and the effect of Gd{sup 3+} ions incorporation on its physical properties has been studied. From the obtained results, XRD analysis reveals that the samples have a cubic spinel single phase structure for 0.0≤ t≤0.02; while for t≥0.03 a small peak of secondary phase (Gd{sub 3}Fe{sub 5}O{sub 12}) appears and becomes more noticeable with increasing Gd content. The lattice parameter (a) of the prepared samples was found to be initially increases and then decreases with increasing Gd content which may be attributed to the difference in the ionic radii of the cations involved and the solubility limit of Gd{sup 3+} ions. The crystallite size of the samples was estimated using Scherrer's equation and ranged from 96 nm to 107 nm. A vibrating sample magnetometer (VSM) was used at room temperature in order to study the effect of Gd content on the magnetic hysteresis parameters of the prepared ferrites such as saturation magnetization and coercivity. DC molar magnetic susceptibility (χ{sub M}) for the prepared samples was measured using Faraday's method as a function of temperature and the Curie temperature was calculated from the magnetic susceptibility measurements. Also the DC resistivity of the samples was measured at room temperature. The obtained results show that, the substitution by Gd{sup 3+} ions improves the electrical properties of the samples by increasing it DC electrical resistivity by 118% and consequently decreases it eddy current loss while the saturation magnetization slightly decreased by 14% only. The sample of t=0.01 shows a high dc magnetic susceptibility, high saturation magnetization (43.1 emu/g), high electric resistivity 12×10{sup 3} Ω.m and high Curie temperature (496 K), which is useful in some technological applications such

  10. M-type barium hexa ferrite magnetic material for anti radar materials at s band frequency

    International Nuclear Information System (INIS)

    Priyono; Azwar Manaf

    2010-01-01

    In this paper, preparation and characteristic evaluation of microwave absorber materials of BaFe_1_2_-_2_x Mn_x Ti _xO_1_9 (x = 0,0 - 1,5) compositions are discussed. The absorber material was obtained by a co-substitution of Mn and Ti to Fe in a Barium Hexaferrite (BaO.6Fe_2O_3 ) basic compound through a mechanical alloying process. In this respect, a co-substitution of Mn and Ti ions for Fe was applied to Fe_2O_3 component at a temperature ~ 1,300 °C. The substituted alloy component was further alloyed mechanically with BaCO_3 to form M-Type hexaferrite after the solid state reaction. Identification of X-ray diffraction peaks for the mechanically alloyed materials indicates confidently that a single phase BaFe_1_2_-_x_-_yMn_x Ti_yO_1_9 material was formed. Materials characterization is covering the average grain sizes and absorption of microwaves in the frequency range 1-6 GHz. Absorption with a relatively high coefficient at frequencies ~ 2,000 MHz and ~ 3,500 MHz within the available frequency range was obtained. It is shown that the co-substitution of Mn and Ti ion able to widen the absorption frequency especially in the frequencies of about 3,500 MHz. (author)

  11. Ferritic Alloys as Accident Tolerant Fuel Cladding Material for Light Water Reactors

    International Nuclear Information System (INIS)

    Rebak, Raul B.

    2014-01-01

    provide hermetic seal. The replacement of a zirconium alloy using a ferritic material containing chromium and aluminum appears to be the most near term implementation for accident tolerant nuclear fuels.

  12. Ferritic Alloys as Accident Tolerant Fuel Cladding Material for Light Water Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Rebak, Raul B. [General Electric Global Research, Schnectady, NY (United States)

    2014-09-30

    provide hermetic seal. The replacement of a zirconium alloy using a ferritic material containing chromium and aluminum appears to be the most near term implementation for accident tolerant nuclear fuels.

  13. XXIst Century Ferrites

    International Nuclear Information System (INIS)

    Mazaleyrat, F; Zehani, K; Pasko, A; Loyau, V; LoBue, M

    2012-01-01

    Ferrites have always been a subject of great interest from point of view of magnetic application, since the fist compass to present date. In contrast, the scientific interest for iron based magnetic oxides decreased after Oersted discovery as they where replaced by coil as magnetizing sources. Neel discovery of ferrimagnetism boosted again interest and leads to strong developments during two decades before being of less interest. Recently, the evolution of power electronics toward higher frequency, the down sizing of ceramics microstructure to nanometer scale, the increasing price of rare-earth elements and the development of magnetocaloric materials put light again on ferrites. A review on three ferrite families is given herein: harder nanostructured Ba 2+ Fe 12 O 19 magnet processed by spark plasma sintering, magnetocaloric effect associated to the spin transition reorientation of W-ferrite and low temperature spark plasma sintered Ni-Zn-Cu ferrites for high frequency power applications.

  14. MEMS based fabrication of high-frequency integrated inductors on Ni–Cu–Zn ferrite substrates

    Energy Technology Data Exchange (ETDEWEB)

    Anthony, Ricky, E-mail: ricky.anthony@tyndall.ie; Wang, Ningning, E-mail: ning.wang@tyndall.ie; Casey, Declan P.; Ó Mathúna, Cian; Rohan, James F.

    2016-05-15

    A surface micro-machining process is described to realize planar inductors on ferrite (Ni{sub 0.49}Zn{sub 0.33}Cu{sub 0.18} Fe{sub 2}O{sub 4}) for high-frequency applications (<30 MHz). The highly resistive nature (~10{sup 8} Ω m) of the Ni–Cu–Zn substrate allows direct conductor patterning by electroplating of Cu windings through a photoresist mold on a sputtered seed layer and eliminates the need for a dielectric layer to isolate the windings from the bottom magnetic core. Measured inductances~367 nH (DC resistance~1.16 Ω and Q-value>14 at 30 MHz) and ~244 nH (DC resistance~0.86 Ω and Q-value~18 at 30 MHz) at 1 MHz for elongated racetrack (10.75 nH/mm{sup 2}) and racetrack inductors (12.5 nH/mm{sup 2}), respectively show good agreement with simulated finite element method analysis. This device can be integrated with power management ICs PMICs for cost-effective, high-performance realization of power-supply in package (PSiP) or on-chip (PSoC). This simple process lays the foundation for fabricating closed core ferrite nano-crystalline core micro-inductors. - Graphical abstract: Material Characterization of Ni–Cu–Zn ferrite substrate and process developed for on-ferrite integrated micro-inductor fabrication. - Highlights: • High-frequency microinductors have been fabricated on Ni-Cu-Zn substrates. • High-resistive ferrite substrates assist direct conductor patterning on the surface. • Uniform inductances ~365 nH over 30 MHz frequency have been achieved. • High Q-values (>18 at 30 MHz) attained are applicable for high-frequency DC–DC conversion applications. • The described process lays the foundation for fabricating closed core ferrite nano-crystalline core.

  15. Magnetic materials based on manganese–zinc ferrite with surface organized polyaniline coating

    Czech Academy of Sciences Publication Activity Database

    Kazantseva, N. E.; Bespyatykh, Y.; Sapurina, I.; Stejskal, Jaroslav; Vilčáková, J.; Sáha, P.

    2006-01-01

    Roč. 301, č. 1 (2006), s. 155-165 ISSN 0304-8853 R&D Projects: GA AV ČR IAA4050313 Keywords : ferrite * coated particles * conducting polymer Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.212, year: 2006

  16. Iron-rich (Fe1-x-yNixCoy)88Zr7B4Cu1 nanocrystalline magnetic materials for high temperature applications with minimal magnetostriction

    Science.gov (United States)

    Martone, Anthony; Dong, Bowen; Lan, Song; Willard, Matthew A.

    2018-05-01

    As inductor technology advances, greater efficiency and smaller components demand new core materials. With recent developments of nanocrystalline magnetic materials, soft magnetic properties of these cores can be greatly improved. FeCo-based nanocrystalline magnetic alloys have resulted in good soft magnetic properties and high Curie temperatures; however, magnetoelastic anisotropies persist as a main source of losses. This investigation focuses on the design of a new Fe-based (Fe,Ni,Co)88Zr7B4Cu1 alloy with reduced magnetostriction and potential for operation at elevated temperatures. The alloys have been processed by arc melting, melt spinning, and annealing in a protective atmosphere to produce nanocrystalline ribbons. These ribbons have been analyzed for structure, hysteresis, and magnetostriction using X-Ray diffraction, vibrating sample magnetometry (VSM), and a home-built magnetostriction system, respectively. In addition, Curie temperatures of the amorphous phase were analyzed to determine the best performing, high-temperature material. Our best result was found for a Fe77Ni8.25Co2.75Zr7B4Cu1 alloy with a 12 nm average crystallite size (determined from Scherrer broadening) and a 2.873 Å lattice parameter determined from the Nelson-Riley function. This nanocrystalline alloy possesses a coercivity of 10 A/m, magnetostrictive coefficient of 4.8 ppm, and amorphous phase Curie temperature of 218°C.

  17. Synthesis of Nanocrystalline SnO2 Modified TiO2:a Material for Carbon Monoxide Gas Sensor

    Directory of Open Access Journals (Sweden)

    A. B. BODADE

    2008-11-01

    Full Text Available Nanocrystalline SnO2 doped TiO2 having average crystallite size of 45-50 nm were synthesized by the sol-gel method and studied for gas sensing behavior to reducing gases like CO, liquefied petroleum gas (LPG, NH3 and H2. The material characterization was done by using X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FT-IR and scanning electron microscope (SEM. The sensitivity measurements were carried out as a function of different operating temperature in SnO2 doped TiO2. The 15 wt.% SnO2 doped TiO2 based CO sensor shows better sensitivity at an operating temperature 240°C Incorporation of 0.5 wt% Pd improved the sensitivity, selectivity, response time and reduced the operating temperature from 240°C to 200°C for CO sensor.

  18. Main properties of nanocrystalline hydroxyapatite as a bone graft material in treatment of periodontal defects. A review of literature

    International Nuclear Information System (INIS)

    Bayani, Mojtaba; Torabi, Sepehr; Shahnaz, Aysan; Pourali, Mohammad

    2017-01-01

    This study aims to provide a literature review on nanocrystalline hydroxyapatite (n-HA). n-HA constitutes the principle inorganic part of hard tissues. Therefore, preparation of commercial synthetic analogues, the so-called ‘biomimetic’, has gained a lot of attention since it can precisely mimic the physicochemical features of biological apatite compounds. Due to its improved osseointegrative properties, n-HA may represent a promising class of bone graft materials. n-HA binds to the bone and by stimulation of osteoblast activity and enhancing local growth factors it improves bone healing. Periodontitis is an inflammatory condition in response to microbial plaque that leads to periodontal tissue destruction and osseous defects in alveolar bone. A review of the extant literature reveals that n-HA has certain advantages in periodontal tissue regeneration including minimal patient morbidity, better biocompatibility, and lack of toxicity

  19. Synthesis and properties of Pr-substituted MgZn ferrites for core materials and high frequency applications

    Energy Technology Data Exchange (ETDEWEB)

    Mukhtar, Muhammad Waqas; Irfan, Muhammad [Department of Physics, Federal Urdu University of Arts, Science and Technology, Islamabad 44000 (Pakistan); Ahmad, Ishtiaq; Ali, Ihsan [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Akhtar, Majid Niaz [Department of Physics, COMSATS Institute of Information Technology, Lahore (Pakistan); Khan, Muhammad Azhar [Department of Physics, Islamia University, Bahawalpur (Pakistan); Abbas, Ghazanfar [Department of Physics, COMSATS Institute of Information Technology, Islamabad 44000 (Pakistan); Rana, M.U. [Center of Excellence in Solid State Physics, University of the Punjab, Lahore (Pakistan); Ali, Akbar [Department of Basic Sciences, Riphah International University, Islamabad-44000 (Pakistan); Ahmad, Mukhtar, E-mail: ahmadmr25@yahoo.com [Department of Physics, COMSATS Institute of Information Technology, Islamabad 44000 (Pakistan)

    2015-05-01

    A series of single phase spinel ferrites having chemical formula Mg{sub 0.5}Zn{sub 0.5}Pr{sub x}Fe{sub 2−x}O{sub 4} (x=0.00, 0.05, 0.10, 0.15, 0.20, 0.25) were prepared using the sol–gel technique after sintering at 700 °C. The thermal decomposition behavior of an as prepared powder was investigated by means of DTA/TGA analyses. The sintered powders were then characterized by Fourier transform infrared spectroscope, X-ray diffraction, scanning electron microscope, energy dispersive X-ray spectroscope and vibrating sample magnetometer. X-ray diffraction patterns confirm the single phase spinel structure of prepared ferrites without the presence of any impurity phase. The value of lattice parameter (a) increases with the increase of Pr contents (x) into the spinel lattice. The grain size estimated from electron microscope images is in the range of 2.75–5.4 µm which confirms the spinel crystalline nature of the investigated samples. The saturation magnetization (M{sub s}) decreases whereas coercivity (H{sub c}) increases with the increase of Pr contents (x). The measured parameters suggest that these materials are favorable for high frequency applications and as core materials. - Highlights: • Pr-substituted spinel ferrites synthesized by autocombustion route have been investigated. • The average grain size was in the range of 2.75–5.4 µm estimated by SEM technique. • The (M{sub s}) decreases whereas (H{sub c}) increases with the increase of Pr contents (x). • These parameters are favorable for high frequency applications and as core materials.

  20. Synthesis and properties of Pr-substituted MgZn ferrites for core materials and high frequency applications

    International Nuclear Information System (INIS)

    Mukhtar, Muhammad Waqas; Irfan, Muhammad; Ahmad, Ishtiaq; Ali, Ihsan; Akhtar, Majid Niaz; Khan, Muhammad Azhar; Abbas, Ghazanfar; Rana, M.U.; Ali, Akbar; Ahmad, Mukhtar

    2015-01-01

    A series of single phase spinel ferrites having chemical formula Mg 0.5 Zn 0.5 Pr x Fe 2−x O 4 (x=0.00, 0.05, 0.10, 0.15, 0.20, 0.25) were prepared using the sol–gel technique after sintering at 700 °C. The thermal decomposition behavior of an as prepared powder was investigated by means of DTA/TGA analyses. The sintered powders were then characterized by Fourier transform infrared spectroscope, X-ray diffraction, scanning electron microscope, energy dispersive X-ray spectroscope and vibrating sample magnetometer. X-ray diffraction patterns confirm the single phase spinel structure of prepared ferrites without the presence of any impurity phase. The value of lattice parameter (a) increases with the increase of Pr contents (x) into the spinel lattice. The grain size estimated from electron microscope images is in the range of 2.75–5.4 µm which confirms the spinel crystalline nature of the investigated samples. The saturation magnetization (M s ) decreases whereas coercivity (H c ) increases with the increase of Pr contents (x). The measured parameters suggest that these materials are favorable for high frequency applications and as core materials. - Highlights: • Pr-substituted spinel ferrites synthesized by autocombustion route have been investigated. • The average grain size was in the range of 2.75–5.4 µm estimated by SEM technique. • The (M s ) decreases whereas (H c ) increases with the increase of Pr contents (x). • These parameters are favorable for high frequency applications and as core materials

  1. Nanocrystalline hydroxyapatite doped with selenium oxyanions: a new material for potential biomedical applications.

    Science.gov (United States)

    Kolmas, Joanna; Oledzka, Ewa; Sobczak, Marcin; Nałęcz-Jawecki, Grzegorz

    2014-06-01

    Selenium-substituted hydroxyapatites containing selenate SeO4(2-) or selenite SeO3(2-) ions were synthesized using a wet precipitation method. The selenium content was determined by atomic absorbance spectrometry. The raw, unsintered powders were also characterized using powder X-ray diffraction, middle-range FT-IR spectroscopy and transmission electron microscopy with energy-dispersive X-ray spectroscopic microanalysis. The synthesized apatites were found to be pure and nanocrystalline with a crystal size similar to that in bone mineral. The incorporation of selenium oxyanions into the crystal lattice was confirmed. The toxicity of hydroxyapatites containing selenite or selenate ions was evaluated with a protozoan assay and bacterial luminescence test. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Relationship of microstructure properties to oxygen impurities in nanocrystalline silicon photovoltaic materials

    Science.gov (United States)

    Xu, H.; Wen, C.; Liu, H.; Li, Z. P.; Shen, W. Z.

    2013-03-01

    We have fully investigated the correlation of microstructure properties and oxygen impurities in hydrogenated nanocrystalline silicon photovoltaic films. The achievement has been realized through a series of different hydrogen dilution ratio treatment by plasma enhanced chemical vapor deposition system. Raman scattering, x-ray diffraction, and ultraviolet-visible transmission techniques have been employed to characterize the physical structural characterization and to elucidate the structure evolution. The bonding configuration of the oxygen impurities was investigated by x-ray photoelectron spectroscopy and the Si-O stretching mode of infrared-transmission, indicating that the films were well oxidized in SiO2 form. Based on the consistence between the proposed structure factor and the oxygen content, we have demonstrated that there are two dominant disordered structure regions closely related to the post-oxidation contamination: plate-like configuration and clustered microvoids.

  3. Effect of composition and cold work on the ferrite transformation in feroplug materials

    International Nuclear Information System (INIS)

    Lai, J.K.L.; Wong, K.W.; Shek, C.H.; Duggan, B.J.

    1993-01-01

    Feroplug is a newly developed temperature indicator suitable for use in the remaining life assessment of high temperature components in power generating plants. The device has been patented in the US on March 17, 1992 under patent number 5,096,304, by the British Technology Group. The Feroplug uses the phase transformation characteristics of duplex stainless steels for temperature measurement. Duplex stainless steels contain ferrite and austenite. Upon exposure to elevated temperatures, the ferrite transforms into austenite, carbides and intermetallic phases. The transformation can be easily monitored by magnetic measurements using a device called the Feritscope. A number of specially designed duplex stainless steels have been produced and the effects of silicon, carbon, and prior cold work on the phase transformation in these alloys. The ferrite transformation was found to be accelerated by prior cold work and by the addition of silicon. The effect of carbon was complicated. Increase in carbon content resulted in a slight increase in the rate of transformation at the early stage, but at the later stage of the transformation the effect of higher carbon content was to reduce the rate of transformation

  4. Amorphous and nanocrystalline titanium nitride and carbonitride materials obtained by solution phase ammonolysis of Ti(NMe2)4

    International Nuclear Information System (INIS)

    Jackson, Andrew W.; Shebanova, Olga; Hector, Andrew L.; McMillan, Paul F.

    2006-01-01

    Solution phase reactions between tetrakisdimethylamidotitanium (Ti(NMe 2 ) 4 ) and ammonia yield precipitates with composition TiC 0.5 N 1.1 H 2.3 . Thermogravimetric analysis (TGA) indicates that decomposition of these precursor materials proceeds in two steps to yield rocksalt-structured TiN or Ti(C,N), depending upon the gas atmosphere. Heating to above 700 deg. C in NH 3 yields nearly stoichiometric TiN. However, heating in N 2 atmosphere leads to isostructural carbonitrides, approximately TiC 0.2 N 0.8 in composition. The particle sizes of these materials range between 4-12 nm. Heating to a temperature that corresponds to the intermediate plateau in the TGA curve (450 deg. C) results in a black powder that is X-ray amorphous and is electrically conducting. The bulk chemical composition of this material is found to be TiC 0.22 N 1.01 H 0.07 , or Ti 3 (C 0.17 N 0.78 H 0.05 ) 3.96 , close to Ti 3 (C,N) 4 . Previous workers have suggested that the intermediate compound was an amorphous form of Ti 3 N 4 . TEM investigation of the material indicates the presence of nanocrystalline regions x (C,N) y crystalline phases

  5. Structural and transport properties of nanocrystalline MnFe/sub 2/O/sub 4/ synthesized by co-precipitation method

    International Nuclear Information System (INIS)

    Akhtar, M.J.; Younas, M.

    2012-01-01

    The nanocrystalline ferrites with spinel structures have been the focus of scientific investigation and received continuous interest in recent decades. The structural and electrical properties of these materials have become an important area of research and are attracting considerable interest due to broad range of applications. Spinel ferrites have been shown to exhibit interesting dielectric properties in the nanocrystalline form in comparison to the corresponding bulk materials. Structural and electrical properties of nanocrystalline MnFe/sub 2/O/sub 4/ were investigated. X-ray diffraction and X-ray absorption fine structure spectroscopy results showed that nanocrystalline MnFe/sub 2/O/sub 4/ had cubic symmetry with 80% inversion. shows the X-ray absorption near edge structure (XANES) spectra of MnFe/sub 2/O/sub 4/ and Zn/sub 1-x/Ni/sub x/Fe/sub 2/O/sub 4/, used as model compounds. The electrical transport properties were investigated by employing impedance spectroscopy. It was observed that the dielectric constant decreased with the increase in frequency. The effects of frequency on dielectric properties were more prominent in the low frequency region, where dielectric constant increased as temperature was increased. (Orig./A.B.)

  6. The effect of patient age on bone formation using a fully synthetic nanocrystalline bone augmentation material in maxillary sinus grafting.

    Science.gov (United States)

    Wolf, Michael; Wurm, Alexander; Heinemann, Friedhelm; Gerber, Thomas; Reichert, Christoph; Jäger, Andreas; Götz, Werner

    2014-01-01

    Maxillary sinus floor augmentation is a treatment that has been proposed for patients in whom the alveolar bone height is insufficient. This procedure is commonly used in patients aged 40 to 70 years and older. However, little information exists whether the factor of age might influence the outcome of augmentation procedures. The aim of this study was to investigate whether the patient's age has an effect on bone formation and incorporation in maxillary sinus floor augmentation procedures. A fully synthetic nanocrystalline bone augmentation material (NanoBone, Artoss) was used for sinus floor augmentation in patients with a subantral vertical bone height of at least 3 mm and maximum of 7 mm. After 7 months healing time, biopsy specimens were taken and were divided into two groups according to the patient's age. Exclusion criteria were poor general health (eg, severe renal/and or liver disease), history of a radiotherapy in the head region, chemotherapy at the time of surgical procedure, noncompensated diabetes mellitus, symptoms of a maxillary sinus disease, active periodontal or systemic diseases, smoking, and poor oral hygiene. Histologic analyses with hematoxylin-eosin stain were performed. Multinucleated osteoclast-like cells were identified by histochemical staining (tartrate-resistant acid phosphatase [TRAP]). Quantitative and age-dependent assessment of bone formation, residual bone grafting material, and soft tissue formation following sinus augmentation was performed using histomorphometric analysis and the Bonferroni adjustment of the Student t test. Twenty biopsy specimens from 17 patients were taken and divided into two groups according to age (group 1: 41 to 52 years; group 2: 66 to 71 years) containing 10 specimens each, which were analyzed in triplicate resulting in a total of 30 specimens per group. A regeneration process with varying amounts of newly formed bone surrounded by marrow-like tissue was present in all augmented regions. No signs of

  7. Crystallization of -type hexagonal ferrites from mechanically

    Indian Academy of Sciences (India)

    Crystallization of -type hexagonal ferrites from mechanically activated mixtures of barium carbonate and goethite ... Abstract. -type hexagonal ferrite precursor was prepared by a soft mechanochemical ... Bulletin of Materials Science | News.

  8. Atomistic simulations of diffusional creep in a nanocrystalline body-centered cubic material

    International Nuclear Information System (INIS)

    Millett, Paul C.; Desai, Tapan; Yamakov, Vesselin; Wolf, Dieter

    2008-01-01

    Molecular dynamics (MD) simulations are used to study diffusion-accommodated creep deformation in nanocrystalline molybdenum, a body-centered cubic metal. In our simulations, the microstructures are subjected to constant-stress loading at levels below the dislocation nucleation threshold and at high temperatures (i.e., T > 0.75T melt ), thereby ensuring that the overall deformation is indeed attributable to atomic self-diffusion. The initial microstructures were designed to consist of hexagonally shaped columnar grains bounded by high-energy asymmetric tilt grain boundaries (GBs). Remarkably the creep rates, which exhibit a double-exponential dependence on temperature and a double power-law dependence on grain size, indicate that both GB diffusion in the form of Coble creep and lattice diffusion in the form of Nabarro-Herring creep contribute to the overall deformation. For the first time in an MD simulation, we observe the formation and emission of vacancies from high-angle GBs into the grain interiors, thus enabling bulk diffusion

  9. Nanocrystalline solids

    International Nuclear Information System (INIS)

    Gleiter, H.

    1991-01-01

    Nanocrystalline solids are polycrystals, the crystal size of which is a few (typically 1 to 10) nanometres so that 50% or more of the solid consists of incoherent interfaces between crystals of different orientations. Solids consisting primarily of internal interfaces represent a separate class of atomic structures because the atomic arrangement formed in the core of an interface is known to be an arrangement of minimum energy in the potential field of the two adjacent crystal lattices with different crystallographic orientations on either side of the boundary core. These boundary conditions result in atomic structures in the interfacial cores which cannot be formed elsewhere (e.g. in glasses or perfect crystals). Nanocrystalline solids are of interest for the following four reasons: (1) Nanocrystalline solids exhibit an atomic structure which differs from that of the two known solid states: the crystalline (with long-range order) and the glassy (with short-range order). (2) The properties of nanocrystalline solids differ (in some cases by several orders of magnitude) from those of glasses and/or crystals with the same chemical composition, which suggests that they may be utilized technologically in the future. (3) Nanocrystalline solids seem to permit the alloying of conventionally immiscible components. (4) If small (1 to 10 nm diameter) solid droplets with a glassy structure are consolidated (instead of small crystals), a new type of glass, called nanoglass, is obtained. Such glasses seem to differ structurally from conventional glasses. (orig.)

  10. Significance of size dependent and material structure coupling on the characteristics and performance of nanocrystalline micro/nano gyroscopes

    Science.gov (United States)

    Larkin, K.; Ghommem, M.; Abdelkefi, A.

    2018-05-01

    Capacitive-based sensing microelectromechanical (MEMS) and nanoelectromechanical (NEMS) gyroscopes have significant advantages over conventional gyroscopes, such as low power consumption, batch fabrication, and possible integration with electronic circuits. However, inadequacies in the modeling of these inertial sensors have presented issues of reliability and functionality of micro-/nano-scale gyroscopes. In this work, a micromechanical model is developed to represent the unique microstructure of nanocrystalline materials and simulate the response of micro-/nano-gyroscope comprising an electrostatically-actuated cantilever beam with a tip mass at the free end. Couple stress and surface elasticity theories are integrated into the classical Euler-Bernoulli beam model in order to derive a size-dependent model. This model is then used to investigate the influence of size-dependent effects on the static pull-in instability, the natural frequencies and the performance output of gyroscopes as the scale decreases from micro-to nano-scale. The simulation results show significant changes in the static pull-in voltage and the natural frequency as the scale of the system is decreased. However, the differential frequency between the two vibration modes of the gyroscope is observed to drastically decrease as the size of the gyroscope is reduced. As such, the frequency-based operation mode may not be an efficient strategy for nano-gyroscopes. The results show that a strong coupling between the surface elasticity and material structure takes place when smaller grain sizes and higher void percentages are considered.

  11. Evaluation of the material in creep-exposed critical 12Cr-1Mo-V ferritic steel components of the pressure section of power plant steam boilers

    International Nuclear Information System (INIS)

    Dobrzanski, J.

    2002-01-01

    Metallographic examinations were carried out on ferritic 12Cr-1Mo-V steel with tempered martensite structure after 68,000 - 145,000 hr service in creep conditions. Structural evolution related to the form of martensite, carbide precipitation and internal damage due to long-term action of thermally activated processes was discussed. A generalised scheme of structural evolution and progress of the internal damage was developed in correlation with the life exhaustion ratio. Principles of the classification for ferritic 12Cr-1Mo-V steel after long-term-service were proposed together with the method for evolution of the state of the material for the industrial practice. (author)

  12. Stress effects in cylindrical tubes of austenitic and ferritic/martensitic steels with oxide scales. Materials selection for a HPLWR

    International Nuclear Information System (INIS)

    Steiner, H.

    2002-11-01

    In the frame of the studies for a high performance concept of a light water reactor (LWR) different materials for the cladding are investigated, among them are austenitic and ferritic/martensitic (f/m) steels of different Cr content. Due to the envisaged very extended life times of the fuel elements in the reactor, corrosion problems may arise. Thus, cracking and/or spalling effects in oxide scales on metallic components may play an important role in the corrosion process as they lead, in general, to a drastic enhancement in the oxidation rates. Analytical models for different fundamental stress problems in the compound oxide scale/metallic substrate have been developed and implemented in the computer code OXSPA. These models concern the growth stresses in the cylindrical tubes, the stresses due to temperature changes and radial temperature gradients and the stresses due to inside and outside pressures. (orig.)

  13. Percolation-induced plasmonic state and double negative electromagnetic properties of Ni-Zn Ferrite/Cu granular composite materials

    Science.gov (United States)

    Massango, Herieta; Kono, Koji; Tsutaoka, Takanori; Kasagi, Teruhiro; Yamamoto, Shinichiro; Hatakeyama, Kenichi

    2018-05-01

    Complex permeability and permittivity spectra of Ni-Zn Ferrite/Cu hybrid granular composite materials have been studied in the RF to microwave frequency range. The electrical conductivity σ shows insulating properties in the volume fraction of Cu particles below φ = 0.14. A large jump in conductivity was observed between φ = 0.14 and 0.24 indicating that the Cu particles make metallic conduction between this interval. Hence, the percolation threshold φC, was estimated to be 0.14. A percolation-induced low frequency plasmonic state with negative permittivity spectrum was observed from φ = 0.14-0.24. Meanwhile the negative permeability was observed at φ = 0.16, 0.19 and 0.24. Hence the DNG characteristic was realized in these Cu volume content in the frequency range from 105 MHz to 2 GHz.

  14. Strength and structure of nanocrystalline titanium

    International Nuclear Information System (INIS)

    Noskova, N.I.; Pereturina, I.A.; Elkina, O.A.; Stolyarov, V.V.

    2004-01-01

    Investigation results on strength and plasticity of nanocrystalline titanium VT-1 are presented. Specific features of plastic deformation on tension of this material specimens in an electron microscope column are studied in situ. It is shown that nanocrystalline titanium strength and plasticity at room temperature are dependent on the structure and nanograin size. It is revealed that deformation processes in nanocrystalline titanium are characterized by activation of deformation rotational modes and microtwinning [ru

  15. Material properties of oxide dispersion strengthened (ODS) ferritic steels for core materials of FBR. Tensile properties of sodium exposed and nickel diffused materials

    International Nuclear Information System (INIS)

    Kato, Shoichi; Yoshida, Eiichi

    2002-12-01

    An oxide dispersion strengthened (ODS) ferritic steel is candidate for a long-life core materials of future FBR, because of good swelling resistance and high creep strength. In this study, tensile tests were carried out the long-term extrapolation of sodium environmental effects on the mechanical properties of ODS steels. The tested heats of materials are M93, M11 and F95. The specimens were pre-exposed to sodium for 1,000 and 3,000 hours under non-stress conditions. The pre-exposure to sodium was conducted using a sodium test loop constituted by austenitic steels. For the conditions of sodium exposure test, the sodium temperature was 650 and 700degC, the oxygen concentration in sodium was about 1 ppm and sodium flow rate on the surface of specimen was less than 1x10 -4 m/seconds (nearly static). Further the specimen with the nickel diffused was prepared, which is simulate to nickel diffusing through sodium from the surface of structural stainless steels. The main results obtained were as follows; (1) The tensile strength and the fracture elongation after sodium exposure (maximum 3,000 hours) were same as that of as-received materials. If was considered that the sodium environmental effect is negligible under the condition of this study. (2) Tensile properties of nickel diffused specimens were slightly lower than that of the as-received specimens, but it remains equal to that of thermal aging specimens. (3) The change in microstructure such as a degraded layer was observed on the surface of nickel diffused specimen. In the region of the degraded layer, phase transformations from the α-phase to the γ-phase were recognized. But, the microscopic oxide particles were observed same as that of α-phase base metal. (author)

  16. Nanocrystalline LiMn2O4 thin film cathode material prepared by polymer spray pyrolysis method for Li-ion battery

    International Nuclear Information System (INIS)

    Karthick, S.N.; Richard Prabhu Gnanakan, S.; Subramania, A.; Kim, Hee-Je

    2010-01-01

    Nanocrystalline cubic spinel lithium manganese oxide thin film was prepared by a polymer spray pyrolysis method using lithium acetate and manganese acetate precursor solution and polyethylene glycol-4000 as a polymeric binder. The substrate temperature was selected from the thermogravimetric analysis by finding the complete crystallization temperature of LiMn 2 O 4 precursor sample. The deposited LiMn 2 O 4 thin films were annealed at 450, 500 and 600 o C for 30 min. The thin film annealed at 600 o C was found to be the sufficient temperature to form high phase pure nanocrystalline LiMn 2 O 4 thin film. The formation of cubic spinel thin film was confirmed by X-ray diffraction study. Scanning electron microscopy and atomic force microscopy analysis revealed that the thin film annealed at 600 o C was found to be nanocrystalline in nature and the surface of the films were uniform without any crack. The electrochemical charge/discharge studies of the prepared LiMn 2 O 4 film was found to be better compared to the conventional spray pyrolysed thin film material.

  17. High Performance Nano-Crystalline Oxide Fuel Cell Materials. Defects, Structures, Interfaces, Transport, and Electrochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Barnett, Scott [Northwestern Univ., Evanston, IL (United States); Poeppelmeier, Ken [Northwestern Univ., Evanston, IL (United States); Mason, Tom [Northwestern Univ., Evanston, IL (United States); Marks, Lawrence [Northwestern Univ., Evanston, IL (United States); Voorhees, Peter [Northwestern Univ., Evanston, IL (United States)

    2016-09-07

    This project addresses fundamental materials challenges in solid oxide electrochemical cells, devices that have a broad range of important energy applications. Although nano-scale mixed ionically and electronically conducting (MIEC) materials provide an important opportunity to improve performance and reduce device operating temperature, durability issues threaten to limit their utility and have remained largely unexplored. Our work has focused on both (1) understanding the fundamental processes related to oxygen transport and surface-vapor reactions in nano-scale MIEC materials, and (2) determining and understanding the key factors that control their long-term stability. Furthermore, materials stability has been explored under the “extreme” conditions encountered in many solid oxide cell applications, i.e, very high or very low effective oxygen pressures, and high current density.

  18. Magnetic ageing study of high and medium permeability nanocrystalline FeSiCuNbB alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lekdim, Atef, E-mail: atef.lekdim@univ-lyon1.fr; Morel, Laurent; Raulet, Marie-Ange

    2017-04-15

    increasing the energy efficiency is one of the most important issues in modern power electronic systems. In aircraft applications, the energy efficiency must be associated with a maximum reduction of mass and volume, so a high components compactness. A consequence from this compactness is the increase of operating temperature. Thus, the magnetic materials used in these applications, have to work at high temperature. It raises the question of the thermal ageing problem. The reliability of these components operating at this condition becomes a real problem which deserves serious interest. Our work takes part in this context by studying the magnetic material thermal ageing. The nanocrystalline materials are getting more and more used in power electronic applications. Main advantages of nanocrystalline materials compared to ferrite are: high saturation flux density of almost 1.25 T and low dynamic losses for low and medium frequencies. The nanocrystalline Fe{sub 73.5}Cu{sub 1}Nb{sub 3}Si{sub 15.5}B{sub 7} alloys have been chosen in our aging study. This study is based on monitoring the magnetic characteristics for several continuous thermal ageing (100, 150, 200 and 240 °C). An important experimental work of magnetic characterization is being done following a specific monitoring protocol. Elsewhere, X-Ray Diffraction and magnetostriction measurements were carried out to support the study of the anisotropy energies evolution with ageing. This latter is discussed in this paper to explain and give hypothesis about the ageing phenomena. - Highlights: • The magnetic ageing of the nanocrystalline materials is related to their annealing. • The degradations with ageing are not related to a change of the grain size diameter. • The amount of anisotropies introduced with ageing depends just on ageing conditions.

  19. Material properties of oxide dispersion strengthened (ODS) ferritic steels for core materials of FBR. Mechanical strength properties of sodium exposed and Nickel diffused materials. Interim report

    International Nuclear Information System (INIS)

    Kato, Shoichi; Yoshida, Eiichi

    2004-02-01

    An oxide dispersion strengthened (ODS) ferritic steel have excellent resistance to swelling and superior creep strength, they are expected to be used as a long-life cladding material in future advanced fast reactor. In this study, sodium environmental effects on the ODS steel developed by JNC were clarified through tensile test after sodium exposure for maximum 10,000hrs and creep-rupture test in sodium at elevated temperature. The exposure to sodium was conducted using a sodium test loop constituted by austenitic steels. For the conditions of sodium exposure test, the sodium temperatures were 923 K and 973 K, the oxygen concentration in sodium was below 2ppm and sodium flow rate on the surface of specimen was less than 1x10 -4 m/s. Further the specimen with the nickel diffused was prepared, which is simulate to nickel diffusing through sodium from the surface of structural stainless steels. The main results obtained were as follows; (1) The results showed excellent sodium-resistance up to a high temperature of about 973 K in stagnant sodium conditions, and its considered that the effects of sodium environment of tensile properties were negligible. In case of stagnant sodium condition, creep-rupture strength in sodium was equal to the in argon gas, and no sodium environmental effect was observed. The same is true for the creep-rupture ductility. (2) The tensile properties of nickel diffused test specimens at high temperatures simulating microstructure change were equal to that of the thermal aging process specimens. These tensile tests suggest that sodium environmental effects can be ignored. However, the effect of nickel diffusion on creep strength are not clear at present and experimental investigation are being conducted. (3) The coefficient of nickel diffusion in the ODS steel can be estimated based on the results of nickel concentration measurement. This value is larger than that of the diffusion coefficient for typical α-Fe steel at temperature below 973 K

  20. Arsenic removal by magnetic nanocrystalline barium hexaferrite

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Hasmukh A.; Byun, Jeehye; Yavuz, Cafer T., E-mail: yavuz@kaist.ac.kr [Graduate School of EEWS, Korea Advanced Institute of Science and Technology (KAIST) (Korea, Republic of)

    2012-07-15

    Nanoscale magnetite (Fe{sub 3}O{sub 4}) (<15 nm) is known to remove arsenic efficiently but is very difficult to separate or require high magnetic fields to separate out from the waste water after treatment. Anisotropic hexagonal ferrite (BaFe{sub 12}O{sub 19}, BHF) is a well-known permanent magnet (i.e., fridge magnets) and attractive due to its low cost in making large quantities. BHF offers a viable alternative to magnetite nanocrystals for arsenic removal since it features surfaces similar to iron oxides but with much enhanced magnetism. Herein, we employ BHF nanocrystalline materials for the first time in arsenic removal from wastewater. Our results show better (75 %) arsenic removal than magnetite of the similar sizes. The BHF nanoparticles, 6.06 {+-} 0.52 nm synthesized by thermolysis method at 320 Degree-Sign C do not show hexagonal phase, however, subsequent annealing at 750 Degree-Sign C produced pure hexagonal BHF in >200 nm assemblies. By using BHF, we demonstrate that nanoparticle removal is more efficient and fixed bed type cartridge applications are more possible.

  1. Physics and measurements of magnetic materials

    CERN Document Server

    Sgobba, S

    2010-01-01

    Magnetic materials, both hard and soft, are used extensively in several components of particle accelerators. Magnetically soft iron-nickel alloys are used as shields for the vacuum chambers of accelerator injection and extraction septa; Fe-based material is widely employed for cores of accelerator and experiment magnets; soft spinel ferrites are used in collimators to damp trapped modes; innovative materials such as amorphous or nanocrystalline core materials are envisaged in transformers for high-frequency polyphase resonant convertors for application to the International Linear Collider (ILC). In the field of fusion, for induction cores of the linac of heavy-ion inertial fusion energy accelerators, based on induction accelerators requiring some 107 kg of magnetic materials, nanocrystalline materials would show the best performance in terms of core losses for magnetization rates as high as 105 T/s to 107 T/s. After a review of the magnetic properties of materials and the different types of magnetic behaviour...

  2. Role of chlorine in the nanocrystalline silicon film formation by rf plasma-enhanced chemical vapor deposition of chlorinated materials

    International Nuclear Information System (INIS)

    Shirai, Hajime

    2004-01-01

    We demonstrate the disorder-induced low-temperature crystallization in the nanocrystalline silicon film growth by rf plasma-enhanced chemical vapor deposition of H 2 -diluted SiH 2 Cl 2 and SiCl 4 . The combination of the chemical reactivity of SiCld (d: dangling bond) and SiHCl complexes and the release of the disorder-induced stress near the growing surface tightly correlate with the phase transitionity of SiCld and SiHCl complexes near the growing surface with the aid of atomic hydrogen, which induce higher degree of disorder in the a-Si network. These features are most prominent in the SiCl 4 compared with those of SiH 2 Cl 2 and SiH 4 , which preferentially enhance the nanocrystalline Si formation

  3. Induced magnetic anisotropy in Si-free nanocrystalline soft magnetic materials: A transmission x-ray diffraction study

    International Nuclear Information System (INIS)

    Parsons, R.; Suzuki, K.; Yanai, T.; Kishimoto, H.; Kato, A.; Ohnuma, M.

    2015-01-01

    In order to better understand the origin of field-induced anisotropy (K u ) in Si-free nanocrystalline soft magnetic alloys, the lattice spacing of the bcc-Fe phase in nanocrystalline Fe 94−x Nb 6 B x (x = 10, 12, 14) alloys annealed under an applied magnetic field has been investigated by X-ray diffraction in transmission geometry (t-XRD) with the diffraction vector parallel and perpendicular to the field direction. The saturation magnetostriction (λ s ) of nanocrystalline Fe 94−x Nb 6 B x was found to increase linearly with the volume fraction of the residual amorphous phase and is well described by taking into account the volume-weighted average of two local λ s values for the bcc-Fe nanocrystallites (−5 ± 2 ppm) and the residual amorphous matrix (+8 ± 2 ppm). The lattice distortion required to produce the measured K u values (∼100 J/m 3 ) was estimated via the inverse magnetostrictive effect using the measured λ s values and was compared to the lattice spacing estimations made by t-XRD. The lattice strain required to produce K u under the magnetoelastic model was not observed by the t-XRD experiments and so the findings of this study suggest that the origin of magnetic field induced K u cannot be explained through the magnetoelastic effect

  4. Visible-light photochemical activity of heterostructured core-shell materials composed of selected ternary titanates and ferrites coated by tiO2.

    Science.gov (United States)

    Li, Li; Liu, Xuan; Zhang, Yiling; Nuhfer, Noel T; Barmak, Katayun; Salvador, Paul A; Rohrer, Gregory S

    2013-06-12

    Heterostructured photocatalysts comprised of microcrystalline (mc-) cores and nanostructured (ns-) shells were prepared by the sol-gel method. The ability of titania-coated ATiO3 (A = Fe, Pb) and AFeO3 (A = Bi, La, Y) catalysts to degrade methylene blue in visible light (λ > 420 nm) was compared. The catalysts with the titanate cores had enhanced photocatalytic activities for methylene blue degradation compared to their components alone, whereas the catalysts with ferrite cores did not. The temperature at which the ns-titania shell is crystallized influences the photocatalytic dye degradation. mc-FeTiO3/ns-TiO2 annealed at 500 °C shows the highest reaction rate. Fe-doped TiO2, which absorbs visible light, did not show enhanced photocatalytic activity for methylene blue degradation. This result indicates that iron contamination is not a decisive factor in the reduced reactivity of the titania coated ferrite catalysts. The higher reactivity of materials with the titanate cores suggests that photogenerated charge carriers are more easily transported across the titanate-titanate interface than the ferrite-titanate interface and this provides guidance for materials selection in composite catalyst design.

  5. 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)

  6. Tunable ferrites as environmentally friendly materials for energy-efficient processes

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez-Serrano, Inmaculada; Arillo, Maria Angeles; Lopez, Maria Luisa; Veiga, Maria Luisa; Pico, Carlos [Departamento de Quimica Inorganica, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid (Spain)

    2011-11-23

    Novel materials and methods of synthesis in the field of energy conversion and economy are reported. The main goal is to prepare and characterize Li{sub (4-x)}Mn{sub (5-2x)}Fe{sub 3x}O{sub 12} compounds. These compounds crystallize in a spinel-type structure, AB{sub 2}O{sub 4}, in which the cationic location in the A and B sublattices drives the potential application of these materials in two current prominent research fields: magnetic refrigeration and lithium batteries. This solid solution is revealed as a tunable system that nicely permits a specific response to be highlighted, depending on the composition and particle size: the magnetocaloric effect or active electrochemical behavior. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Material science and manufacturing of heat-resistant reduced-activation ferritic-martensitic steels for fusion

    International Nuclear Information System (INIS)

    Ioltukhovskiy, A.G.; Blokhin, A.I.; Budylkin, N.I.; Chernov, V.M.; Leont'eva-Smirnova, M.V.; Mironova, E.G.; Medvedeva, E.A.; Solonin, M.I.; Porollo, S.I.; Zavyalsky, L.P.

    2000-01-01

    A number of issues regarding the development and use of 10-12% Cr reduced-activation ferritic-martensitic steels (RAFMS) for fusion are considered. These include: (1) problems of manufacturing and modifying their composition and metallurgical condition; (2) the influence on properties of their composition, purity, δ-ferrite concentration and cooling rates in the final stages of manufacturing; and (3) the effects of neutron irradiation at 320-650 deg. C up to 108 dpa on their mechanical properties. In addition, neutron activation and nuclear accumulation of elements in RAFMS with different initial concentrations of alloying and impurity elements for typical fusion reactor (DEMO) irradiation regimes have been calculated

  8. Induced magnetic anisotropy in Si-free nanocrystalline soft magnetic materials: A transmission x-ray diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Parsons, R., E-mail: rparsons01@gmail.com; Suzuki, K. [Department of Materials Science and Engineering, Monash University, Clayton, Victoria 3800 (Australia); Yanai, T. [Graduate School of Engineering, Nagasaki University, Nagasaki 852-8521 (Japan); Kishimoto, H.; Kato, A. [Toyota Motor Corporation, Mishuku, Susono, Shizuoka 410-1193 (Japan); Ohnuma, M. [Faculty and Graduate School of Engineering, Hokkaido University, Sapporo 060-8628 (Japan)

    2015-05-07

    In order to better understand the origin of field-induced anisotropy (K{sub u}) in Si-free nanocrystalline soft magnetic alloys, the lattice spacing of the bcc-Fe phase in nanocrystalline Fe{sub 94−x}Nb{sub 6}B{sub x} (x = 10, 12, 14) alloys annealed under an applied magnetic field has been investigated by X-ray diffraction in transmission geometry (t-XRD) with the diffraction vector parallel and perpendicular to the field direction. The saturation magnetostriction (λ{sub s}) of nanocrystalline Fe{sub 94−x}Nb{sub 6}B{sub x} was found to increase linearly with the volume fraction of the residual amorphous phase and is well described by taking into account the volume-weighted average of two local λ{sub s} values for the bcc-Fe nanocrystallites (−5 ± 2 ppm) and the residual amorphous matrix (+8 ± 2 ppm). The lattice distortion required to produce the measured K{sub u} values (∼100 J/m{sup 3}) was estimated via the inverse magnetostrictive effect using the measured λ{sub s} values and was compared to the lattice spacing estimations made by t-XRD. The lattice strain required to produce K{sub u} under the magnetoelastic model was not observed by the t-XRD experiments and so the findings of this study suggest that the origin of magnetic field induced K{sub u} cannot be explained through the magnetoelastic effect.

  9. Synchrotron X-ray diffraction studies of phase transitions and mechanical properties of nanocrystalline materials at high pressure

    International Nuclear Information System (INIS)

    Prilliman, Gerald Stephen

    2003-01-01

    The behavior of nanocrystals under extreme pressure was investigated using synchrotron x-ray diffraction. A major part of this investigation was the testing of a prototype synchrotron endstation on a bend magnet beamline at the Advanced Light Source for high pressure work using a diamond anvil cell. The experiments conducted and documented here helped to determine issues of efficiency and accuracy that had to be resolved before the construction of a dedicated ''super-bend'' beamline and endstation. The major conclusions were the need for a cryo-cooled monochromator and a fully remote-controllable pressurization system which would decrease the time to change pressure and greatly reduce the error created by the re-placement of the diamond anvil cell after each pressure change. Two very different types of nanocrystal systems were studied, colloidal iron oxide (Fe 2 O 3 ) and thin film TiN/BN. Iron oxide nanocrystals were found to have a transition from the γ to the α structure at a pressure strongly dependent on the size of the nanocrystals, ranging from 26 GPa for 7.2 nm nanocrystals to 37 GPa for 3.6 nm nanocrystals. All nanocrystals were found to remain in the α structure even after release of pressure. The transition pressure was also found, for a constant size (5.7 nm) to be strongly dependent on the degree of aggregation of the nanocrystals, increasing from 30 GPa for completely dissolved nanocrystals to 45 GPa for strongly aggregated nanocrystals. Furthermore, the x-ray diffraction pattern of the pressure induced α phase demonstrated a decrease in intensity for certain select peaks. Together, these observations were used to make a complete picture of the phase transition in nanocrystalline systems. The size dependence of the transition was interpreted as resulting from the extremely high surface energy of the α phase which would increase the thermodynamic offset and thereby increase the kinetic barrier to transition that must be overridden with pressure

  10. Synchrotron X-ray diffraction studies of phase transitions and mechanical properties of nanocrystalline materials at high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Prilliman, Stephen Gerald [Univ. of California, Berkeley, CA (United States)

    2003-01-01

    The behavior of nanocrystals under extreme pressure was investigated using synchrotron x-ray diffraction. A major part of this investigation was the testing of a prototype synchrotron endstation on a bend magnet beamline at the Advanced Light Source for high pressure work using a diamond anvil cell. The experiments conducted and documented here helped to determine issues of efficiency and accuracy that had to be resolved before the construction of a dedicated ''super-bend'' beamline and endstation. The major conclusions were the need for a cryo-cooled monochromator and a fully remote-controllable pressurization system which would decrease the time to change pressure and greatly reduce the error created by the re-placement of the diamond anvil cell after each pressure change. Two very different types of nanocrystal systems were studied, colloidal iron oxide (Fe2O3) and thin film TiN/BN. Iron oxide nanocrystals were found to have a transition from the γ to the α structure at a pressure strongly dependent on the size of the nanocrystals, ranging from 26 GPa for 7.2 nm nanocrystals to 37 GPa for 3.6 nm nanocrystals. All nanocrystals were found to remain in the α structure even after release of pressure. The transition pressure was also found, for a constant size (5.7 nm) to be strongly dependent on the degree of aggregation of the nanocrystals, increasing from 30 GPa for completely dissolved nanocrystals to 45 GPa for strongly aggregated nanocrystals. Furthermore, the x-ray diffraction pattern of the pressure induced α phase demonstrated a decrease in intensity for certain select peaks. Together, these observations were used to make a complete picture of the phase transition in nanocrystalline systems. The size dependence of the transition was interpreted as resulting from the extremely high surface energy of the α phase which would increase the thermodynamic offset and thereby increase the kinetic barrier to transition

  11. Nanocrystal conversion chemistry: A unified and materials-general strategy for the template-based synthesis of nanocrystalline solids

    International Nuclear Information System (INIS)

    Vasquez, Yolanda; Henkes, Amanda E.; Chris Bauer, J.; Schaak, Raymond E.

    2008-01-01

    The concept of nanocrystal conversion chemistry, which involves the use of pre-formed nanoparticles as templates for chemical transformation into derivative solids, has emerged as a powerful approach for designing the synthesis of complex nanocrystalline solids. The general strategy exploits established synthetic capabilities in simple nanocrystal systems and uses these nanocrystals as templates that help to define the composition, crystal structure, and morphology of product nanocrystals. This article highlights key examples of 'conversion chemistry' approaches to the synthesis of nanocrystalline solids using a variety of techniques, including galvanic replacement, diffusion, oxidation, and ion exchange. The discussion is organized according to classes of solids, highlighting the diverse target systems that are accessible using similar chemical concepts: metals, oxides, chalcogenides, phosphides, alloys, intermetallic compounds, sulfides, and nitrides. - Graphical abstract: Nanocrystal conversion chemistry uses pre-formed nanoparticles as templates for chemical transformation into derivative solids, helping to define the composition, crystal structure, and morphology of product nanocrystals that have more complex features than their precursor templates. This article highlights the application of this concept to diverse classes of solids, including metals, oxides, chalcogenides, phosphides, alloys, intermetallics, sulfides, and nitrides

  12. 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.

  13. Quantitative analysis of microstructure deformation in creep fenomena of ferritic SA-213 T22 and austenitic SA-213 TP304H material

    Science.gov (United States)

    Mulyana, Cukup; Taufik, Ahmad; Gunawan, Agus Yodi; Siregar, Rustam Efendi

    2013-09-01

    The failure of critical component of fossil fired power plant that operated in creep range (high stress, high temperature and in the long term) depends on its microstructure characteristics. Ferritic low carbon steel (2.25Cr-1Mo) and Austenitic stainless alloy (18Cr-8Ni) are used as a boiler tube in the secondary superheater outlet header to deliver steam before entering the turbin. The tube failure is occurred in a form of rupture, resulting trip that disrupts the continuity of the electrical generation. The research in quantification of the microstructure deformation has been done in predicting the remaining life of the tube through interrupted accelerated creep test. For Austenitic Stainless Alloy (18Cr-8Ni), creep test was done in 550°C with the stress 424.5 MPa and for Ferritic Low Carbon Steel (2.25Cr-1Mo) in 570°C with the stress 189 MPa. The interrupted accelerated creep test was done by stopping the observation in condition 60%, 70%, 80% and 90% of remaining life, the creep test fracture was done before. Then the micro hardness test, photo micro, SEM and EDS were obtained from those samples. Refer to ASTM E122, microstructure parameters were calculated. The results indicated that there are a consistency of decreasing their grain diameters, increasing their grain size numbers, micro hardness, and the length of crack or void number per unit area with the decreasing of remaining life. While morphology of grain (stated in parameter α=LV/LH) relatively constant for austenitic. However, for ferritic the change of morphology revealed significantly. Fracture mode propagation of ferritic material is growth with voids transgranular and intergranular crack, and for austenitic material the fracture growth with intergranular creep fracture void and wedge crack. In this research, it was proposed a formulation of mathematical model for creep behavior corresponding their curve fitting resulted for the primary, secondary and tertiary in accelerated creep test. In

  14. Bilirubin adsorption on nanocrystalline titania films

    International Nuclear Information System (INIS)

    Yang Zhengpeng; Si Shihui; Fung Yingsing

    2007-01-01

    Bilirubin produced from hemoglobin metabolism and normally conjugated with albumin is a kind of lipophilic endotoxin, and can cause various diseases when its concentration is high. Bilirubin adsorption on the nanocrystalline TiO 2 films was investigated using quartz crystal microbalance, UV-vis and IR techniques, and factors affecting its adsorption such as pH, bilirubin concentration, solution ionic strength, temperature and thickness of TiO 2 films were discussed. The amount of adsorption and parameters for the adsorption kinetics were estimated from the frequency measurements of quartz crystal microbalance. A fresh surface of the nanocrystalline TiO 2 films could be photochemically regenerated because holes and hydroxyl radicals were generated by irradiating the nanocrystalline TiO 2 films with UV light, which could oxidize and decompose organic materials, and the nanocrystalline TiO 2 films can be easily regenerated when it is used as adsorbent for the removal of bilirubin

  15. Synthesis of nanocrystalline nickel-zinc ferrite (Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4}) thin films by chemical bath deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Pawar, D.K. [Department of Chemistry, Shivaji University, Kolhapur 416 004 (M.S.) (India); Pawar, S.M. [Department of Materials Science and Engineering, Chonnam National University, 500 757 (Korea, Republic of); Patil, P.S. [Department of Physics, Shivaji University, Kolhapur 416 004 (M.S.) (India); Kolekar, S.S., E-mail: kolekarss2003@yahoo.co.in [Department of Chemistry, Shivaji University, Kolhapur 416 004 (M.S.) (India)

    2011-02-24

    Graphical abstract: Display Omitted Research highlights: > We have successfully synthesized nickel-zinc ferrite (Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4}) thin films on stainless steel substrates using a low temperature chemical bath deposition method. > The surface morphological study showed the compact flakes like morphology. > The as-deposited thin films are hydrophilic (10{sup o} < {theta} < 90{sup o}) whereas the annealed thin films are super hydrophilic ({theta} < 10{sup o}) in nature. > Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4} thin films could be used in supercapacitor. - Abstract: The nickel-zinc ferrite (Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4}) thin films have been successfully deposited on stainless steel substrates using a chemical bath deposition method from alkaline bath. The films were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), static water contact angle and cyclic voltammetry measurements. The X-ray diffraction pattern shows that deposited Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4} thin films were oriented along (3 1 1) plane. The FTIR spectra showed strong absorption peaks around 600 cm{sup -1} which are typical for cubic spinel crystal structure. SEM study revealed compact flakes like morphology having thickness {approx}1.8 {mu}m after air annealing. The annealed films were super hydrophilic in nature having a static water contact angle ({theta}) of 5{sup o}.The electrochemical supercapacitor study of Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4} thin films has been carried out in 6 M KOH electrolyte. The values of interfacial and specific capacitances obtained were 0.0285 F cm{sup -2} and 19 F g{sup -1}, respectively.

  16. 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.

  17. In-situ tensile test of high strength nanocrystalline bainitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Haddad, Mike, E-mail: mike.haddad@uni-ulm.de [Institute of Micro and Nanomaterials, University of Ulm, Ulm (Germany); Ivanisenko, Yulia; Courtois-Manara, Eglantine [Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe (Germany); Fecht, Hans-Jörg [Institute of Micro and Nanomaterials, University of Ulm, Ulm (Germany)

    2015-01-03

    Because of its great importance in modern engineering and technology applications, steel continues to be highly relevant in the modern research field of nanocrystalline materials. Innovative processing methods and procedures are required for the production of such materials, which possess superior properties compared to their conventional counter parts. In this research, the original microstructure of a commercial C45 steel (Fe, 0.42–0.5 wt% C, 0.5–0.8 wt% Mn) was modified from ferritic–pearlitic to bainitic. Warm high pressure torsion for 5 rotations at 6 GPa and 350 °C was used to process the bainitic sample leading to an ultrafine/nano-scale grain size. A unique nano-crystalline microstructure consisting of equiaxed and elongated ferrite grains with a mean size smaller than 150 nm appeared in images taken by Transmission Electron Microscopy. Results of in-situ tensile testing in a scanning electron microscope showed very high tensile strength, on the order of 2100 MPa with a total elongation of 4.5% in comparison with 800 MPa and around 16% in the original state. Fracture occurred abruptly, without any sign of necking, and was typically caused by the stress concentration at a surface flaw. Also, stress concentrations near all surface defects were observed on the sample, visualized by the formation of shear bands. The fracture surface was covered with dimples, indicating ductile fracture. These properties are fully comparable with high strength, high alloyed steels.

  18. Characterization of nanostructure ferrite material on gallium nitride on SiC substrate for millimeter wave integrated circuit

    Directory of Open Access Journals (Sweden)

    Brian O’Keefe

    2017-05-01

    Full Text Available In this paper, for the first time, the characterization of spin-casted thick Barium nano-hexaferrite film on GaN-on-SiC substrate over a broad frequency range of 30-110 GHz is presented. Real and imaginary parts of both permittivity and permeability of the ferrite/polymer film are computed from transmittance data obtained by using a free space quasi-optical millimeter wave spectrometer. The spin-casted composite film shows strong resonance in the Q band, and mixing the powder with polymer slightly shifts the resonance frequency lower compared to pure powder. The high temperature compatibility of GaN substrate enables us to run burn-out tests at temperatures up to 900°C. Significant shortening phenomenon of resonance linewidth after heat treatment was found. Linewidth is reduced from 2.8 kOe to 1.7 kOe. Experiment results show that the aforementioned film is a good candidate in applications of non-reciprocal ferrite devices like isolators, phase shifters, and circulators.

  19. Manganese ferrite prepared using reverse micelle process: Structural and magnetic properties characterization

    Energy Technology Data Exchange (ETDEWEB)

    Hashim, Mohd, E-mail: md.hashim09@gmail.com [Department of Physics, Aligarh Muslim University, Aligarh 202002 (India); Shirsath, Sagar E. [Spin Device Technology Centre, Department of Engineering, Shinshu University, Nagano 380-8553 (Japan); Meena, S.S. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Mane, M.L. [Department of Physics, S.G.R.G. Shinde Mahavidyalaya, Paranda 413502, MS (India); Kumar, Shalendra [School of Materials Science and Engineering, Changwon National University, Changwon, Gyeongnam 641-773 (Korea, Republic of); Bhatt, Pramod [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Kumar, Ravi [Centre for Material Science Engineering, National Institute of Technology, Hamirpur, HP (India); Prasad, N.K.; Alla, S.K. [Deptartment of Metallurgical Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Shah, Jyoti; Kotnala, R.K. [National Physical Laboratory (CSIR), Dr. K.S. Krishnan Road, New Delhi 110012 (India); Mohammed, K.A. [Department of Mathematics & Physics Sciences, College of Arts and Sciences, University of Nizwa, Nizwa (Oman); Şentürk, Erdoğan [Department of Physics, Sakarya University, Esentepe, 54187 Sakarya (Turkey); Alimuddin [Department of Physics, Aligarh Muslim University, Aligarh 202002 (India)

    2015-09-05

    Highlights: • Preparation of Mn{sup 3+} substituted MnFe{sub 2}O{sub 4} ferrite by Reverse microemulsion process. • Characterization by XRD, SEM, VSM, Mössbauer spectroscopy and dielectric measurements techniques. • Magnetic properties of MnFe{sub 2}O{sub 4} enhanced after Mn{sup 3+} substitution. • The dielectric constant and ac conductivity increased with Mn{sup 3+} substitution. - Abstract: Reverse microemulsion process was employed to prepare of nanocrystalline Mn{sup 3+} substituted MnFe{sub 2−x}Mn{sub x}O{sub 4} ferrites. The structural, magnetic and dielectric properties were studied for different concentrations of Mn{sup 3+}. The structural and microstructural properties were analyzed using X-ray diffraction technique (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy techniques. The phase identification of the materials was studied by Rietveld refined XRD patterns which reveals single phase with cubic symmetry for the samples. The lattice parameters were ranged in between 8.369 and 8.379 Å and do not show any significant change with the substitution of Mn{sup 3+}. The average particles size was found to be around 11 ± 3 nm. Magnetization results obtained from the vibrating sample magnetometer (VSM) confirm that the substitution of Mn{sup 3+} in MnFe{sub 2}O{sub 4} ferrite caused an increase in the saturation magnetization and coercivity. The dependence of Mössbauer parameters on Mn{sup 3+} substitution has been analyzed. Magnetic behavior of the samples were also studied at field cooled (FC) and zero field cooled (ZFC) mode. The dependence of Mössbauer parameters on Mn{sup 3+} substitution was also analyzed. All the magnetic characterization shows that Mn{sup 3+} substitution enhance the magnetic behavior of MnFe{sub 2}O{sub 4} ferrite nanoparticles.

  20. Grain size and nanoscale effects on the nonlinear pull-in instability and vibrations of electrostatic actuators made of nanocrystalline material

    Science.gov (United States)

    Gholami, R.; Ansari, R.

    2018-01-01

    Presented herein is the study of grain size, grain surface energy and small scale effects on the nonlinear pull-in instability and free vibration of electrostatic nanoscale actuators made of nanocrystalline silicon (Nc-Si). A Mori-Tanaka micromechanical model is utilized to calculate the effective material properties of Nc-Si considering material structure inhomogeneity, grain size and grain surface energy. The small-scale effect is also taken into account using Mindlin’s strain gradient theory. Governing equations are derived in the discretized weak form using the variational differential quadrature method based on the third-order shear defamation beam theory in conjunction with the von Kármán hypothesis. The electrostatic actuation is modeled considering the fringing field effects based upon the parallel plate approximation. Moreover, the Casimir force effect is considered. The pseudo arc-length continuation technique is used to obtain the applied voltage-deflection curve of Nc-Si actuators. Then, a time-dependent small disturbance around the deflected configuration is assumed to solve the free vibration problem. By performing a numerical study, the influences of various factors such as length scale parameter, volume fraction of the inclusion phase, density ratio, average inclusion radius and Casimir force on the pull-in instability and free vibration of Nc-Si actuators are investigated.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-11-05

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

  2. Polymethyl methacrylate (PMMA)-bismuth ferrite (BFO) nanocomposite: low loss and high dielectric constant materials with perceptible magnetic properties.

    Science.gov (United States)

    Tamboli, Mohaseen S; Palei, Prakash K; Patil, Santosh S; Kulkarni, Milind V; Maldar, Noormahmad N; Kale, Bharat B

    2014-09-21

    Herein, poly(methyl methacrylate)-bismuth ferrite (PMMA-BFO) nanocomposites were successfully prepared by an in situ polymerization method for the first time. Initially, the as prepared bismuth ferrite (BFO) nanoparticles were dispersed in the monomer, (methyl methacrylate) by sonication. Benzoyl peroxide was used to initiate the polymerization reaction in ethyl acetate medium. The nanocomposite films were subjected to X-ray diffraction analysis (XRD), (1)H NMR, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA), infrared spectroscopy (IR), dielectric and magnetic characterizations. The dielectric measurement of the nanocomposites was investigated at a frequency range of 10 Hz to 1 MHz. It was found that the nanocomposites not only showed a significantly increased value of the dielectric constant with an increase in the loading percentage of BFO as compared to pure PMMA, but also exhibited low dielectric loss values over a wide range of frequencies. The values of the dielectric constant and dielectric loss of the PMMA-BFO5 (5% BFO loading) sample at 1 kHz frequency was found be ~14 and 0.037. The variation of the ferromagnetic response of the nanocomposite was consistent with the varying volume percentage of the nanoparticles. The remnant magnetization (Mr) and saturation magnetization (Ms) values of the composites were found to be enhanced by increasing the loading percentage of BFO. The value of Ms for PMMA-BFO5 was found to be ~6 emu g(-1). The prima facie observations suggest that the nanocomposite is a potential candidate for application in high dielectric constant capacitors. Significantly, based on its magnetic properties the composite will also be useful for use in hard disk components.

  3. Synthesis of Nanocrystalline CaWO4 as Low-Temperature Co-fired Ceramic Material: Processing, Structural and Physical Properties

    Science.gov (United States)

    Vidya, S.; Solomon, Sam; Thomas, J. K.

    2013-01-01

    Nanocrystalline scheelite CaWO4, a promising material for low-temperature co-fired ceramic (LTCC) applications, has been successfully synthesized through a single-step autoignition combustion route. Structural analysis of the sample was performed by powder x-ray diffraction (XRD), Fourier-transform infrared spectroscopy, and Raman spectroscopy. The XRD analysis revealed that the as-prepared sample was single phase with scheelite tetragonal structure. The basic optical properties and optical constants of the CaWO4 nanopowder were studied using ultraviolet (UV)-visible absorption spectroscopy, which showed that the material was a wide-bandgap semiconductor with bandgap of 4.7 eV at room temperature. The sample showed poor transmittance in the ultraviolet region but maximum transmission in the visible/near-infrared regions. The photoluminescence spectra recorded at different temperatures showed intense emission in the green region. The particle size estimated from transmission electron microscopy was 23 nm. The feasibility of CaWO4 for LTCC applications was studied from its sintering behavior. The sample was sintered at a relatively low temperature of 810°C to high density, without using any sintering aid. The surface morphology of the sintered sample was analyzed by scanning electron microscopy. The dielectric constant and loss factor of the sample measured at 5 MHz were found to be 10.50 and 1.56 × 10-3 at room temperature. The temperature coefficient of the dielectric constant was -88.71 ppm/°C. The experimental results obtained in this work demonstrate the potential of nano-CaWO4 as a low-temperature co-fired ceramic as well as an excellent luminescent material.

  4. Novel analytical model for the determination of grain size distributions in nanocrystalline materials with low lattice microstrains by X-ray diffractometry

    International Nuclear Information System (INIS)

    Sanchez-Bajo, F.; Ortiz, A.L.; Cumbrera, F.L.

    2006-01-01

    We have developed a novel, analytical model for the determination of grain size distributions in nanocrystalline (nc) materials with low internal stresses by X-ray diffractometry (XRD). The model assumes explicitly that the XRD peaks are pseudo-Voigtian and that the grain size distributions are lognormal, both of which are assumptions amply supported by the experimental evidence. It was found analytically that the grain size dispersion depends on the shape of the XRD peaks only, whereas the grain size median depends on both the shape and width of the XRD peaks. In addition, the theoretical predictions resulting from the model were validated using standard XRD peaks obtained by computer simulation from first principles. Particular emphasis is given to the discussion of the validity limits of the model, and to the analysis of the influence of the characteristics of the grain size distributions on the nature of the XRD peaks. We then show how to calculate the average and apparent grain sizes from the grain size distribution determined with the model, and how this compares with the Scherrer method. Implications for the characterization of (undistorted and distorted) nc-materials are indicated, and a case study of an nc-powder of cubic ZrO 2 is presented. The application of the model itself is simple, involving only the fit of a pseudo-Voigt function to a single XRD peak followed by the use of two equations. This suggests that the model may have an important role to play in the characterization of nc-materials

  5. Novel analytical model for the determination of grain size distributions in nanocrystalline materials with low lattice microstrains by X-ray diffractometry

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Bajo, F. [Departamento de Electronica e Ingenieria Electromecanica, Escuela de Ingenierias Industriales, Universidad de Extremadura, Avda. de Elvas S/N, Badajoz 06071 (Spain); Ortiz, A.L. [Departamento de Electronica e Ingenieria Electromecanica, Escuela de Ingenierias Industriales, Universidad de Extremadura, Avda. de Elvas S/N, Badajoz 06071 (Spain)]. E-mail: alortiz@unex.es; Cumbrera, F.L. [Departamento de Fisica, Facultad de Ciencias, Universidad de Extremadura, Badajoz 06071 (Spain)

    2006-01-15

    We have developed a novel, analytical model for the determination of grain size distributions in nanocrystalline (nc) materials with low internal stresses by X-ray diffractometry (XRD). The model assumes explicitly that the XRD peaks are pseudo-Voigtian and that the grain size distributions are lognormal, both of which are assumptions amply supported by the experimental evidence. It was found analytically that the grain size dispersion depends on the shape of the XRD peaks only, whereas the grain size median depends on both the shape and width of the XRD peaks. In addition, the theoretical predictions resulting from the model were validated using standard XRD peaks obtained by computer simulation from first principles. Particular emphasis is given to the discussion of the validity limits of the model, and to the analysis of the influence of the characteristics of the grain size distributions on the nature of the XRD peaks. We then show how to calculate the average and apparent grain sizes from the grain size distribution determined with the model, and how this compares with the Scherrer method. Implications for the characterization of (undistorted and distorted) nc-materials are indicated, and a case study of an nc-powder of cubic ZrO{sub 2} is presented. The application of the model itself is simple, involving only the fit of a pseudo-Voigt function to a single XRD peak followed by the use of two equations. This suggests that the model may have an important role to play in the characterization of nc-materials.

  6. Solid state consolidation nanocrystalline copper-tungsten using cold spray

    Energy Technology Data Exchange (ETDEWEB)

    Hall, Aaron Christopher [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sarobol, Pylin [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Argibay, Nicolas [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Clark, Blythe [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Diantonio, Christopher [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    It is well known that nanostructured metals can exhibit significantly improved properties compared to metals with conventional grain size. Unfortunately, nanocrystalline metals typically are not thermodynamically stable and exhibit rapid grain growth at moderate temperatures. This severely limits their processing and use, making them impractical for most engineering applications. Recent work has shown that a number of thermodynamically stable nanocrystalline metal alloys exist. These alloys have been prepared as powders using severe plastic deformation (e.g. ball milling) processes. Consolidation of these powders without compromise of their nanocrystalline microstructure is a critical step to enabling their use as engineering materials. We demonstrate solid-state consolidation of ball milled copper-tantalum nanocrystalline metal powder using cold spray. Unfortunately, the nanocrystalline copper-tantalum powder that was consolidated did not contain the thermodynamically stable copper-tantalum nanostructure. Nevertheless, this does this demonstrates a pathway to preparation of bulk thermodynamically stable nanocrystalline copper-tantalum. Furthermore, it demonstrates a pathway to additive manufacturing (3D printing) of nanocrystalline copper-tantalum. Additive manufacturing of thermodynamically stable nanocrystalline metals is attractive because it enables maximum flexibility and efficiency in the use of these unique materials.

  7. Thermally Stable Nanocrystalline Steel

    Science.gov (United States)

    Hulme-Smith, Christopher Neil; Ooi, Shgh Woei; Bhadeshia, Harshad K. D. H.

    2017-10-01

    Two novel nanocrystalline steels were designed to withstand elevated temperatures without catastrophic microstructural changes. In the most successful alloy, a large quantity of nickel was added to stabilize austenite and allow a reduction in the carbon content. A 50 kg cast of the novel alloy was produced and used to verify the formation of nanocrystalline bainite. Synchrotron X-ray diffractometry using in situ heating showed that austenite was able to survive more than 1 hour at 773 K (500 °C) and subsequent cooling to ambient temperature. This is the first reported nanocrystalline steel with high-temperature capability.

  8. Plasma discharge in ferritic first wall vacuum vessel of the Hitachi Tokamak HT-2

    International Nuclear Information System (INIS)

    Abe, Mitsushi; Nakayama, Takeshi; Asano, Katsuhiko; Otsuka, Michio

    1997-01-01

    A tokamak discharge with ferritic material first wall was tried successfully. The Hitachi Tokamak HT-2 had a stainless steel SUS304 vacuum vessel and modified to have a ferritic plate first wall for experiments to investigate the possibility of ferritic material usage in magnetic fusion devices. The achieved vacuum pressure and times used for discharge cleaning was roughly identical with the stainless steel first wall or the original HT-2. We concluded that ferritic material vacuum vessel is possible for tokamaks. (author)

  9. NATO Advanced Research Workshop on Properties and Applications of Nanocrystalline Alloys from Amorphous Precursors

    CERN Document Server

    Idzikowski, Bogdan; Miglierini, Marcel

    2005-01-01

    Metallic (magnetic and non-magnetic) nanocrystalline materials have been known for over ten years but only recent developments in the research into those complex alloys and their metastable amorphous precursors have created a need to summarize the most important accomplishments in the field. This book is a collection of articles on various aspects of metallic nanocrystalline materials, and an attempt to address this above need. The main focus of the papers is put on the new issues that emerge in the studies of nanocrystalline materials, and, in particular, on (i) new compositions of the alloys, (ii) properties of conventional nanocrystalline materials, (iii) modeling and simulations, (iv) preparation methods, (v) experimental techniques of measurements, and (vi) different modern applications. Interesting phenomena of the physics of nanocrystalline materials are a consequence of the effects induced by the nanocrystalline structure. They include interface physics, the influence of the grain boundaries, the aver...

  10. Oxide dispersion-strengthened ferritic alloys

    International Nuclear Information System (INIS)

    Asbroeck, P. van.

    1976-10-01

    The publication gives the available data on the DTO2 dispersion-strengthened ferritic alloy developed at C.E.N./S.C.K. Mol, Belgium. DTO2 is a Fe-Cr-Mo ferritic alloy, strengthened by addition of titanium oxide and of titanium leading to the formation of Chi phase. It was developed for use as canning material for fast breeder reactors. (author)

  11. Direct Coating of Nanocrystalline Diamond on Steel

    Science.gov (United States)

    Tsugawa, Kazuo; Kawaki, Shyunsuke; Ishihara, Masatou; Hasegawa, Masataka

    2012-09-01

    Nanocrystalline diamond films have been successfully deposited on stainless steel substrates without any substrate pretreatments to promote diamond nucleation, including the formation of interlayers. A low-temperature growth technique, 400 °C or lower, in microwave plasma chemical vapor deposition using a surface-wave plasma has cleared up problems in diamond growth on ferrous materials, such as the surface graphitization, long incubation time, substrate softening, and poor adhesion. The deposited nanocrystalline diamond films on stainless steel exhibit good adhesion and tribological properties, such as a high wear resistance, a low friction coefficient, and a low aggression strength, at room temperature in air without lubrication.

  12. Vibrational thermodynamics of Fe90Zr7B3 nanocrystalline alloy from nuclear inelastic scattering

    DEFF Research Database (Denmark)

    Stankov, S.; Miglierini, M.; Chumakov, A. I.

    2010-01-01

    Recently we determined the iron-partial density of vibrational states (DOS) of nanocrystalline Fe(90)Zr(7)B(3) (Nanoperm), synthesized by crystallization of an amorphous precursor, for various stages of nanocrystallization separating the DOS of the nanograins from that of the interfaces [S. Stank......, vibrational entropy, and lattice specific heat as the material transforms from amorphous, through nanocrystalline, to fully crystallized state. The reported results shed new light on the previously observed anomalies in the vibrational thermodynamics of nanocrystalline materials....

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

    Energy Technology Data Exchange (ETDEWEB)

    Pavithradevi, S. [Assistant Professor, Department of Physics, Park College of Engineering and Technology, Coimbatore (India); Suriyanarayanan, N., E-mail: madurasuri2210@yahoo.com [Prof & Head, Department of Physics, Government College of Technology, Coimbatore (India); Boobalan, T. [Lecturer, Department of Physics, PSG Polytechnic College, Coimbatore (India)

    2017-03-15

    Nanocrystalline copper ferrite CuFe{sub 2}O{sub 4} is synthesized by co-precipitation method in ethylene glycol as chelating agent, using sodium Hydroxide as precipitator at pH 8. The as synthesized CuFe{sub 2}O{sub 4} is annealed at temperatures of 350 °C, 700 °C, and 1050 °C for 2 h respectively. The thermal analysis of the synthesized sample is done by TG technique. It is shown that at 260 °C ethylene glycol has evaporated completely and after 715 °C, spinel ferrite is formed with a cubic structure. The calculated lattice parameters are in agreement with the reported values. FTIR spectra of CuFe{sub 2}O{sub 4} nano particles are as synthesized and annealed at 1050 °C and recorded between 400 cm{sup −1} and 4000 cm{sup −1}. It shows that when the temperature increases ethylene glycol gradually evaporates. Finally, nano crystalline single phase spinel ferrite is obtained. X-ray diffraction (XRD) and electron diffraction (EDS) studies show that the sample is indexed as the face centered cubic spinel structure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that the particles are flaky and spherical with the crystallite size in the range of 25–34 nm. From the dielectric studies, the dielectric constant decreases as the frequency increases. Low value of dielectric loss at higher frequencies suggests that the material is suitable for high frequency applications. AC conductivity increases with frequency. The magnetic properties of the samples are measured using a vibrating sample magnetometer (VSM) at room temperature, which shows that the sample exhibited a typical super paramagnetic behavior at low temperature. The saturation magnetization, remanant magnetism, and coercivity increases with applied field. - Highlights: • Complete removal of hematite phase along with ethylene glycol at 1050 °C. • Large decrease in particle sizes noticed along with ethylene glycol. • Ethylene glycol improves purity of the

  14. Synthesis of nano-crystalline NiFe2O4 powders in subcritical and supercritical ethanol

    Czech Academy of Sciences Publication Activity Database

    Ćosović, A.; Žák, Tomáš; Glisić, S.; Sokić, M.; Lazarević, S.; Ćosović, V.; Orlović, A.

    2016-01-01

    Roč. 113, JUL (2016), s. 96-105 ISSN 0896-8446 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : supercritical * subcritical * nano-crystalline powders * nickel ferrite * metal oxide * magnetic properties Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.991, year: 2016

  15. Reduced Antivation Ferritic/Martensitic Steel Eurofer 97 as Possible Structural Material for Fusion Devices. Metallurgical Characterization on As-Received Condition and after Simulated Services Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, P.; Lancha, A. M.; Lapena, J.; Serrano, M.; Hernandez-Mayoral, M.

    2004-07-01

    Metallurgical Characterization of the reduced activation ferritic/martensitic steel Eurofer'97, on as-received condition and after thermal ageing treatment in the temperature range from 400 degree centigree to 600 degree centigree for periods up to 10.000 h, was carried out. The microstructure of the steel remained stable (tempered martensite with M{sub 2}3 C{sub 6} and MX precipitates) after the thermal ageing treatments studied in this work. In general, this stability was also observed in the mechanical properties. The Eurofer'97 steel exhibited similar values of hardness, ultimate tensile stress, 0,2% proof stress, USE and T{sub 0}3 regardless of the investigated material condition. However, ageing at 600 degree centigree for 10.000 ha caused a slight increase in the DBTT, of approximately 23. In terms of creep properties, the steel shows in general adequate creep rupture strength levels for short rupture times. However, the results obtained up to now for long time creep rupture tests at 500 degree centigree suggests a change in the deformation mechanisms. (Author) 62 refs.

  16. Reduced Activation Ferritic/Martensitic Steel Eurofer 97 as Possible Structural Material for Fusion Devices. Metallurgical Characterization on As-Received Condition and after Simulated Services Conditions

    International Nuclear Information System (INIS)

    Fernandez, P.; Lancha, A. M.; Lapena, J.; Serrano, M.; Hernandez-Mayoral, M.

    2004-01-01

    Metallurgical Characterization of the reduced activation ferritic/martensitic steel Eurofer'97, on as-received condition and after thermal ageing treatment in the temperature range from 400 degree centigree to 600 degree centigree for periods up to 10.000 h, was carried out. The microstructure of the steel remained stable (tempered martensite with M 2 3 C 6 and MX precipitates) after the thermal ageing treatments studied in this work. In general, this stability was also observed in the mechanical properties. The Eurofer'97 steel exhibited similar values of hardness, ultimate tensile stress, 0,2% proof stress, USE and T 0 3 regardless of the investigated material condition. However, ageing at 600 degree centigree for 10.000 ha caused a slight increase in the DBTT, of approximately 23 . In terms of creep properties, the steel shows in general adequate creep rupture strength levels for short rupture times. However, the results obtained up to now for long time creep rupture tests at 500 degree centigree suggests a change in the deformation mechanisms. (Author) 62 refs

  17. Properties of Ferrite Garnet (Bi, Lu, Y3(Fe, Ga5O12 Thin Film Materials Prepared by RF Magnetron Sputtering

    Directory of Open Access Journals (Sweden)

    Mohammad Nur-E-Alam

    2018-05-01

    Full Text Available This work is devoted to physical vapor deposition synthesis, and characterisation of bismuth and lutetium-substituted ferrite-garnet thin-film materials for magneto-optic (MO applications. The properties of garnet thin films sputtered using a target of nominal composition type Bi0.9Lu1.85Y0.25Fe4.0Ga1O12 are studied. By measuring the optical transmission spectra at room temperature, the optical constants and the accurate film thicknesses can be evaluated using Swanepoel’s envelope method. The refractive index data are found to be matching very closely to these derived from Cauchy’s dispersion formula for the entire spectral range between 300 and 2500 nm. The optical absorption coefficient and the extinction coefficient data are studied for both the as-deposited and annealed garnet thin-film samples. A new approach is applied to accurately derive the optical constants data simultaneously with the physical layer thickness, using a combination approach employing custom-built spectrum-fitting software in conjunction with Swanepoel’s envelope method. MO properties, such as specific Faraday rotation, MO figure of merit and MO swing factor are also investigated for several annealed garnet-phase films.

  18. Study of the influence of thermal treatment on the magnetic properties of lithium ferrite prepared by wet ball-milling using nitrates as raw material

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, S. Soreto, E-mail: silvia.soreto@ua.pt; Graça, M.P.F., E-mail: mpfg@ua.pt; Costa, L.C., E-mail: kady@ua.pt; Valente, M.A., E-mail: mav@ua.pt

    2014-08-01

    Graphical abstract: - Highlights: • The saturation magnetization increases with heat-treatment temperature until 1200 °C. • 1200 °C sample presents, at 5 K, a magnetic moment of 73 emu/g and 66 emu/g at 300 K. • Heat-treatment promotes the formation of lithium ferrate and hematite, decreasing the magnetic moment. - Abstract: Lithium ferrite (LiFe{sub 5}O{sub 8}) is an attractive material for several potential technological applications. Critical to such attractiveness are its physical properties, such as high Curie temperature, square hysteresis loop and high magnetization. Knowing that the properties of these crystals depend on the preparation method and raw materials, in this work LiFe{sub 5}O{sub 8} crystallites were obtained by controlled heat-treatments, between 200 and 1400 °C, of homogeneous Li{sub 2}O-Fe{sub 2}O{sub 3} powders prepared by wet ball-milling method and using lithium and iron nitrates as raw materials. LiFe{sub 5}O{sub 8} crystal phase was formed through heat-treatments at temperatures above 500 °C. At higher temperatures the formation of lithium ferrate and hematite is promoted, leading to a decrease in the magnetic moment. Heat-treated the sample at 1200 °C results in the highest levels of magnetic saturation, presenting a magnetic moment of 73 emu/g at 5 K and 66 emu/g at 300 K, respectively.

  19. 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

  20. Contribution to the structural study of austeno-ferritic steels. Morphological and analytical definition of the ferritic phase

    International Nuclear Information System (INIS)

    Bathily, Alassane.

    1977-07-01

    Conditions of fast and selective austenite dissolution were defined by means of current-voltage curves using AISI 316-type materials (welding beads). The ferritic phase was isolated and identified with X-rays. The percentages of ferrite were compared gravimetrically with those obtained by traditional methods. The ferrite isolated was chemically analysed by atomic absorption, the only doubtful value being carbon. It is shown by this method that a morphological study of the solidification of the ferritic lattice is possible, even for percentages around 1% [fr

  1. Recent advances in processing and applications of microwave ferrites

    International Nuclear Information System (INIS)

    Harris, Vincent G.; Geiler, Anton; Chen Yajie; Yoon, Soack Dae; Wu Mingzhong; Yang, Aria; Chen Zhaohui; He Peng; Parimi, Patanjali V.; Zuo Xu; Patton, Carl E.; Abe, Manasori; Acher, Olivier

    2009-01-01

    Next generation magnetic microwave devices will be planar, smaller, weigh less, and perform well beyond the present state-of-the-art. For this to become a reality advances in ferrite materials must first be realized. These advances include self-bias magnetization, tunability of the magnetic anisotropy, low microwave loss, and volumetric and weight reduction. To achieve these goals one must turn to novel materials processing methods. Here, we review recent advances in the processing of microwave ferrites. Attention is paid to the processing of ferrite films by pulsed laser deposition, liquid phase epitaxy, spin spray ferrite plating, screen printing, and compaction of quasi-single crystals. Conventional and novel applications of ferrite materials, including microwave non-reciprocal passive devices, microwave signal processing, negative index metamaterial-based electronics, and electromagnetic interference suppression are discussed.

  2. Calcium ferrite formation from the thermolysis of calcium tris (maleato)

    Indian Academy of Sciences (India)

    microwave and satellite communication, bubble devices, audio-video, digital recording and as permanent magnets. (Viswanathan and Murthy 1990), ferrites have opened a new vista in the field of chemical physics of materials. Keeping in view these technological applications, ferrites have been regarded as an important ...

  3. Accumulation and recovery of defects in ion-irradiated nanocrystalline gold

    Energy Technology Data Exchange (ETDEWEB)

    Chimi, Y. E-mail: chimi@popsvr.tokai.jaeri.go.jp; Iwase, A.; Ishikawa, N.; Kobiyama, M.; Inami, T.; Okuda, S

    2001-09-01

    Effects of 60 MeV {sup 12}C ion irradiation on nanocrystalline gold (nano-Au) are studied. The experimental results show that the irradiation-produced defects in nano-Au are thermally unstable because of the existence of a large volume fraction of grain boundaries. This suggests a possibility of the use of nanocrystalline materials as irradiation-resistant materials.

  4. Investigations of the boundary conditions of acicular ferrite formation in fast-quenched welded materials. Final report; Untersuchungen der Randbedingungen fuer die Bildung von 'acicular ferrite' in Schweissguetern bei schneller Abkuehlung. Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Dilthey, U.; Biesenbach, M.

    2000-06-19

    The authors investigated the boundary conditions in which a fine-grained ferritic needle structure with sufficient low-temperature toughness is obtained in conditions of extreme heating and cooling. Alloy compositions and welding boundary conditions were investigated for laser welding, electron beam welding in a vacuum and electron beam welding at atmospheric pressure. [German] Im Rahmen dieser Arbeit soll untersucht werden, welche Randbedingungen erfuellt sein muessen, damit sich unter extremen Aufheiz- und Abkuehlbedingungen, wie sie bei den Strahlschweissverfahren vorliegen, ein feinkoerniges nadelferritisches Gefuege mit ausreichend hoher Tieftemperaturzaehigkeit bildet. Diesbezueglich ist fuer die Strahlschweissverfahren Laserstrahlschweissen, Elektronenstrahlschweissen im Vakuum und Elektronenstrahlschweissen unter Atmosphaerendruck zu ermitteln, welche Legierungszusammensetzungen diese Voraussetzungen erfuellen und wie sie unter realen Schweissbedingungen verwirklicht werden koennen. (orig.)

  5. Effects of sintering temperature on structural and electrical transport properties of zinc ferrites prepared by sol-gel route

    International Nuclear Information System (INIS)

    Anis-ur-Rehman, M.; Malik, M.A.; Ahmad, I.; Nasir, S.; Mubeen, M.; Abdullah, A.

    2011-01-01

    The effects of sintering temperature on the structural and electrical transport properties of nanocrystalline zinc ferrites are reported. The zinc ferrites were prepared by WOWS sol-gel synthesis route. The prepared sample was sintered at temperatures 500 deg. C, 700 deg. C and 900 deg. C respectively for 2 h. X-ray Diffraction (XRD) technique was used to describe the structural properties. The crystallite size, lattice parameters and porosity of samples were measured from the analysis of XRD data. The average crystallite size for each sample was measured using the Scherrer formula by considering the most intense (3 1 1) peak. The dielectric constant (e), dielectric loss tangent (tan theta ) and AC electrical conductivity of nanocrystalline Zn ferrites are investigated as a function of frequency and sintering temperature. All the electrical properties are explained in accordance with MaxwellWagner model and Koops phenomenological theory. (author)

  6. Tailoring and patterning the grain size of nanocrystalline alloys

    International Nuclear Information System (INIS)

    Detor, Andrew J.; Schuh, Christopher A.

    2007-01-01

    Nanocrystalline alloys that exhibit grain boundary segregation can access thermodynamically stable or metastable states with the average grain size dictated by the alloying addition. Here we consider nanocrystalline Ni-W alloys and demonstrate that the W content controls the grain size over a very broad range: ∼2-140 nm as compared with ∼2-20 nm in previous work on strongly segregating systems. This trend is attributed to a relatively weak tendency for W segregation to the grain boundaries. Based upon this observation, we introduce a new synthesis technique allowing for precise composition control during the electrodeposition of Ni-W alloys, which, in turn, leads to precise control of the nanocrystalline grain size. This technique offers new possibilities for understanding the structure-property relationships of nanocrystalline solids, such as the breakdown of Hall-Petch strength scaling, and also opens the door to a new class of customizable materials incorporating patterned nanostructures

  7. Developments in nanocrystalline magnetic alloys for industry; Alliages magnetiques nanocristallins industriels. Etat de l'art et evolution

    Energy Technology Data Exchange (ETDEWEB)

    Waeckerle, T.; Cremer, P. [Imphy Ugine Precision, 92 - Paris la Defense (France); Gautard, D. [Mecagis, 45 - Amilly (France)

    2003-10-01

    The French industrial production of nanocrystalline precursor ribbon (Imphy Ugine Precision - IUP) and nanocrystalline wound cores (Mecagis) is now mature, promoting then one of the first worldwide provider in this market. Recent progress in ribbon elaboration will provide large increase of industrial efficiency, leading the cost of a nanocrystalline solution to be closed to the cost of a ferrite solution. The precise study and control of magnetoelastic energy allowed the production scattering to be reduced, the alloy to be weakly dependant on external stresses (production, packaging, thermal dilatation), further promoting the performances. Whatever the alloy is very brittle in the nanocrystalline state, some improvements are using or are going around this intrinsic behaviour, and are now developed: powder core for low dissipative filtering, cut core for storage and strong power transformation, wound cores from ribbon nano-crystallized with high stresses during annealing, for the storage and current metering. (authors)

  8. Size dependence of elastic mechanical properties of nanocrystalline aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Wenwu; Dávila, Lilian P., E-mail: ldavila@ucmerced.edu

    2017-04-24

    The effect of grain size on the elastic mechanical properties of nanocrystalline pure metal Al is quantified by molecular dynamics simulation method. In this work, the largest nanocrystalline Al sample has a mean grain size of 29.6 nm and contains over 100 millions atoms in the modeling system. The simulation results show that the elastic properties including elastic modulus and ultimate tensile strength of nanocrystalline Al are relatively insensitive to the variation of mean grain size above 13 nm yet they become distinctly grain size dependent below 13 nm. Moreover, at a grain size <13 nm, the elastic modulus decreases monotonically with decreasing grain size while the ultimate tensile strength of nanocrystalline Al initially decreases with the decrease of the grain size down to 9 nm and then increases with further reduction of grain size. The increase of ultimate tensile strength below 9 nm is believed to be a result of an extended elasticity in the ultrafine grain size nanocrystalline Al. This study can facilitate the prediction of varied mechanical properties for similar nanocrystalline materials and even guide testing and fabrication schemes of such materials.

  9. Bulletin of Materials Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Three methods including sol–gel, rf sputtering and pulsed laser deposition (PLD) have been used for the fabrication of high coercivity Co-ferrite thin films with a nanocrystalline structure. The PLD method is demonstrated to be a possible tool to achieve Co-ferrite films with high coercivity and small grain size at low ...

  10. Bulletin of Materials Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    The self-propagating low-temperature combustion method was used to produce nanocrystalline particles of zinc ferrite. The products were characterized for chemical and phase composition, morphology and magnetic properties. The results obtained showed the formation of single-phase zinc ferrite nanoparticles with an ...

  11. Nanocrystalline LiMn2O4 derived by HMTA-assisted solution combustion synthesis as a lithium-intercalating cathode material

    International Nuclear Information System (INIS)

    Fey, G.T.-K.; Cho, Y.-D.; Kumar, T. Prem

    2006-01-01

    Nanocrystalline LiMn 2 O 4 was synthesized by a self-sustaining solution combustion method with hexamethylenetetramine as a fuel. Ammonium nitrate was used as an additional oxidant-and-porogen. Thermal analytical studies showed the formation of LiMn 2 O 4 by a single-step decomposition process between 300 and 380 deg. C. The products were highly crystalline with an average crystallite size of ∼30 nm. Charge-discharge studies showed that the optimal heat treatment protocol was a 10 h calcination at 700 deg. C. A product obtained under these conditions from a precursor containing a 1:1 molar ratio of [LiNO 3 + Mn(NO 3 ) 2 ] and NH 4 NO 3 sustained 202 cycles between 3.0 and 4.3 V at a charge-discharge rate of 0.1 C before reaching an 80% charge retention cut-off value. Nanocrystalline particles provide small diffusion pathways that lead to an improvement in the lithium-ion intercalation kinetics and minimize surface distortions during cycling. These factors are believed to confer excellent electrochemical properties to the product

  12. 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

  13. Ferritic steels for French LMFBR steam generators

    International Nuclear Information System (INIS)

    Aubert, M.; Mathieu, B.; Petrequin, P.

    1983-06-01

    Austenitic stainless steels have been widely used in many components of the French LMFBR. Up to now, ferritic steels have not been considered for these components, mainly due to their relatively low creep properties. Some ferritic steels are usable when the maximum temperatures in service do not exceed about 530 0 C. It is the case of the steam generators of the Phenix plant, where the exchange tubes of the evaporator are made of 2,25% Cr-1% Mo steel, stabilized or not by addition of niobium. These ferritic alloys have worked successfully since the first steam production in October 1973. For the SuperPhenix power plant, an ''all austenitic stainless alloy'' apparatus has been chosen. However, for the future, ferritic alloys offer potential for use as alternative materials in the evaporators: low alloys steels type 2,25% Cr-1% Mo (exchange tubes, tube-sheets, shells), or at higher chromium content type 9% Cr-2% Mo NbV (exchange tubes) or 12M Cr-1% Mo-V (tube-sheets). Most of these steels have already an industrial background, and are widely used in similar applications. The various potential applications of these steels are reviewed with regards to the French LMFBR steam generators, indicating that some points need an effort of clarification, for instance the properties of the heterogeneous ferritic/austenitic weldments

  14. Ferritic/martensitic steels: Promises and problems

    International Nuclear Information System (INIS)

    Klueh, R.L.; Ehrlich, K.; Abe, F.

    1992-01-01

    Ferritic/martensitic steels are candidate structural materials for fusion reactors because of their higher swelling resistance, higher thermal conductivity, lower thermal expansion, and better liquid-metal compatibility than austenitic steels. Irradiation effects will ultimately determine the applicability of these steels, and the effects of irradiation on microstructure and swelling, and on the tensile, fatigue, and impact properties of the ferritic/martensitic steels are discussed. Most irradiation studies have been carried out in fast reactors, where little transmutation helium forms. Helium has been shown to enhance swelling and affect tensile and fracture behavior, making helium a critical issue, since high helium concentrations will be generated in conjunction with displacement damage in a fusion reactor. These issues are reviewed to evaluate the status of ferritic/martensitic steels and to assess the research required to insure that such steels are viable candidates for fusion applications

  15. Synthesis and Characterization of Cobalt Ferrite Nanoparticles ...

    African Journals Online (AJOL)

    prepared material. It was observed that surface modification such as with silica coating on the cobalt ferrite will have significant effect on the structural and magnetic properties. It is also observed that, silica coated nanoparticles could be used in biomedical applications (Hong et al., 2013). In this work we have chosen sol-gel ...

  16. Modeling of austenite to ferrite transformation

    Indian Academy of Sciences (India)

    395–398. c Indian Academy of Sciences. Modeling of austenite to ferrite transformation. MOHSEN KAZEMINEZHAD. ∗. Department of Materials Science and Engineering, Sharif University of Technology, Azadi Avenue, Tehran, Iran. MS received 17 January 2011; revised 9 July 2011. Abstract. In this research, an algorithm ...

  17. Behavior of ferritic steels irradiated by fast neutrons

    International Nuclear Information System (INIS)

    Erler, Jean; Maillard, Arlette; Brun, Gilbert; Lehmann, Jeanne; Dupouy, J.-M.

    1979-01-01

    Ferritic steels were irradiated in Rapsodie and Phenix at varying doses. The swelling and irradiation creep characteristics are reported below as are the mechanical characteristics of these materials [fr

  18. The behaviour of ferritic steels under fast neutron irradiation

    International Nuclear Information System (INIS)

    Erler, J.; Maillard, A.; Brun, G.; Lehmann, J.; Dupouy, J.M.

    1979-07-01

    Ferritic steels have been irradiated in Rapsodie and Phenix to doses up to 150 dpa F. The swelling and irradiation creep characteristics and the mechanical properties of these materials are reported. (author)

  19. A Novel Composite Material Designed from FeSi Powder and Mn0.8Zn0.2Fe2O4 Ferrite

    Czech Academy of Sciences Publication Activity Database

    Strečková, M.; Bureš, R.; Fáberová, M.; Kurek, P.; Roupcová, Pavla; Hadraba, Hynek; Girman, V.; Strečka, J.

    2015-01-01

    Roč. 2015, č. 1 (2015), Art. n. 924859 ISSN 1687-8434 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068; GA ČR(CZ) GAP108/11/1350 Institutional support: RVO:68081723 Keywords : soft-magnetic composite s * Mn-Zn ferrites * nanoparticles * coprecipitation * combustion * batteries Subject RIV: JG - Metallurgy Impact factor: 1.010, year: 2015

  20. Uniform nanocrystalline AB{sub 5}-type hydrogen storage alloy: Preparation and properties as negative materials of Ni/MH battery

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Dongsheng; Li, Weishan; Hu, Shejun [Department of Chemistry, South China Normal University, 510631 (China); Xiao, Fangming; Tang, Renheng [Guangzhou Institute for Nonferrous Metal Research, 510651 (China)

    2006-05-15

    AB{sub 5}-type nanocrystalline hydrogen storage alloy was prepared by a twin-roll process. X-ray diffraction (XRD), scanning electron microscope (SEM), pressure-composition isotherms (PCT), and charge-discharge cycling were used to characterize its performances. The alloy has a hexagonal CaCu{sub 5}-type structure and a uniform crystallite size of about 40nm. It shows good high-rate discharge ability (HRD). The initial discharge capacity of the alloy is high up to 312mAh/g, and its capacity loss is low, only about 20% after 400 cycles under 640mA/g. At the discharge current density of 2000mA/g, the high-rate discharge ability (HRD) is 90% and the discharge capacity 211mAh/g after 400 cycles, 85% of the initial capacity. (author)

  1. Development of Bulk Nanocrystalline Cemented Tungsten Carbide for Industrial Applicaitons

    Energy Technology Data Exchange (ETDEWEB)

    Z. Zak Fang, H. Y. Sohn

    2009-03-10

    This report contains detailed information of the research program entitled "Development of Bulk Nanocrystalline Cemented Tungsten Carbide Materials for Industrial Applications". The report include the processes that were developed for producing nanosized WC/Co composite powders, and an ultrahigh pressure rapid hot consolidation process for sintering of nanosized powders. The mechanical properties of consolidated materials using the nanosized powders are also reported.

  2. Initial Ferritic Wall Mode studies on HBT-EP

    Science.gov (United States)

    Hughes, Paul; Bialek, J.; Boozer, A.; Mauel, M. E.; Levesque, J. P.; Navratil, G. A.

    2013-10-01

    Low-activation ferritic steels are leading material candidates for use in next-generation fusion development experiments such as a prospective US component test facility and DEMO. Understanding the interaction of plasmas with a ferromagnetic wall will provide crucial physics for these experiments. Although the ferritic wall mode (FWM) was seen in a linear machine, the FWM was not observed in JFT-2M, probably due to eddy current stabilization. Using its high-resolution magnetic diagnostics and positionable walls, HBT-EP has begun exploring the dynamics and stability of plasma interacting with high-permeability ferritic materials tiled to reduce eddy currents. We summarize a simple model for plasma-wall interaction in the presence of ferromagnetic material, describe the design of a recently-installed set of ferritic shell segments, and report initial results. Supported by U.S. DOE Grant DE-FG02-86ER53222.

  3. Characterization of amorphous and nanocrystalline carbon films

    International Nuclear Information System (INIS)

    Chu, Paul K.; Li Liuhe

    2006-01-01

    Amorphous and nanocrystalline carbon films possess special chemical and physical properties such as high chemical inertness, diamond-like properties, and favorable tribological proprieties. The materials usually consist of graphite and diamond microstructures and thus possess properties that lie between the two. Amorphous and nanocrystalline carbon films can exist in different kinds of matrices and are usually doped with a large amount of hydrogen. Thus, carbon films can be classified as polymer-like, diamond-like, or graphite-like based on the main binding framework. In order to characterize the structure, either direct bonding characterization methods or the indirect bonding characterization methods are employed. Examples of techniques utilized to identify the chemical bonds and microstructure of amorphous and nanocrystalline carbon films include optical characterization methods such as Raman spectroscopy, Ultra-violet (UV) Raman spectroscopy, and infrared spectroscopy, electron spectroscopic and microscopic methods such as scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy, transmission electron microscopy, and electron energy loss spectroscopy, surface morphology characterization techniques such as scanning probe microscopy (SPM) as well as other characterization methods such as X-ray reflectivity and nuclear magnetic resonance. In this review, the structures of various types of amorphous carbon films and common characterization techniques are described

  4. Synthesis and Characterization of Oxide Dispersion Strengthened Ferritic Steel via a Sol-Gel Route

    International Nuclear Information System (INIS)

    Sun Qinxing; Zhang Tao; Wang Xianping; Fang Qianfeng; Hu Jing; Liu Changsong

    2012-01-01

    Nanocrystalline oxide dispersion strengthened (ODS) ferritic steel powders with nominal composition of Fe-14Cr-3W-0.3Ti-0.4Y 2 O 3 are synthesized using sol-gel method and hydrogen reduction. At low reduction temperature the impurity phase of CrO is detected. At higher reduction temperature the impurity phase is Cr 2 O 3 which eventually disappears with increasing reduction time. A pure ODS ferritic steel phase is obtained after reducing the sol-gel resultant products at 1200°C for 3 h. The HRTEM and EDS mapping indicate that the Y 2 O 3 particles with a size of about 15 nm are homogenously dispersed in the alloy matrix. The bulk ODS ferritic steel samples prepared from such powders exhibit good mechanical performance with an ultimate tensile stress of 960 MPa.

  5. EXAFS and XRD studies of nanocrystalline cerium oxide: the effect of preparation method on the microstructure

    International Nuclear Information System (INIS)

    Savin, S.L.P.; Chadwick, A.V.; Smith, M.E.; O'Dell, L.A.

    2007-01-01

    There is considerable interest in nanocrystalline materials due to their unusual properties, such as enhanced ionic conductivity in the case of nanocrystalline ionic solids. This has potential commercial applications, particularly for oxide ion conductors. However, a detailed knowledge of the microstructure is important in fully understanding the novel properties exhibited by nanocrystalline materials. The final microstructure of a material is dependent on the preparation method used, for example, sol-gel and ball-milling methods are commonly used in the preparation of nanocrystalline oxides. Additionally, there is a problem in maintaining the materials in nanocrystalline form when they are subjected to elevated temperatures. We have been exploring strategies to restrict the growth of nanocrystalline oxides and have found that adding a small amount of an inert material, e.g. SiO 2 or Al 2 O 3 , is particularly effective. We will report XRD and EXAFS studies of nanocrystalline ceria prepared by sol-gel, sol-gel pinned and ball-milling methods and the effect of preparation method on the final microstructure. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. High strength ferritic alloy

    International Nuclear Information System (INIS)

    1977-01-01

    A high strength ferritic steel is specified in which the major alloying elements are chromium and molybdenum, with smaller quantities of niobium, vanadium, silicon, manganese and carbon. The maximum swelling is specified for various irradiation conditions. Rupture strength is also specified. (U.K.)

  7. Silicon carbide modified carbon materials. Formation of nanocrystalline SiC from thermochemical processes in the system coal tar pitch/poly(carbosilane)

    Energy Technology Data Exchange (ETDEWEB)

    Czosnek, C.; Janik, J.F.; Olejniczak, Z. [Stanislaw Staszic University of Mining & Meterology, AGH, Krakow (Poland)

    2002-12-01

    Poly(carbosilane) or PCS, (-CH{sub 2}-SiH(CH{sub 3})-){sub n}, is used as a Si-bearing precursor in combination with a coal tar pitch to study thermally induced transformations toward SiC-modified carbon composites. Following mixing of the components in the molten pitch at 160{sup o}C, the mixture is heated under argon atmosphere at 500{sup o}C yielding a solid carbonizate that is further subjected to separate pyrolysis experiments at 1300{sup o}C or 1650{sup o}C. At temperatures up to 500{sup o}C, the PCS reacts with suitable pitch components as well as undergoing decomposition reactions. At higher temperatures, clusters of prevailingly nanocrystalline beta-SiC are confirmed after the 1650{sup o}C pyrolysis step with indications that the formation of the compound starts at 1300{sup o}C. Si-29 MAS NMR, XRD, FT-IR, XPS, and elemental analysis are used to characterize each pyrolysis step, especially, from the viewpoint of transformation of silicon species to silicon carbide in the carbon matrix evolved from the pitch.

  8. Structural elucidation of nanocrystalline biomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Maltsev, S.

    2008-10-23

    Bone diseases, such as osteoporosis and osteoarthritis, are the second most prevalent health problem worldwide. In Germany approximately 5 millions people are affected by arthritis. Investigating biomineralization processes and bone molecular structure is of key importance for developing new drugs for preventing and healing bone diseases. Nuclear magnetic resonance (NMR) was the primary technique used due to its advantages in characterising poorly ordered and disordered materials. Compared to all the diffraction techniques that widely applied in structural investigations, the usefulness of NMR is independent of long range molecular order. This makes NMR an outstanding technique for studies of complex/amorphous materials. Conventional NMR experiments (single pulse, spin-echo, cross polarization (CP), etc.) as well as their modifications and high-end techniques (2D HETCOR, REDOR, etc.) were used in this work. Combining the contributions from different techniques enhances the information content of the investigations and can increase the precision of the overall conclusions. Also XRD, TEM and FTIR were applied to different extent in order to get a general idea of nanocrystalline hydroxyapatite crystallite structure. Results: - A new approach named 'Solid-state NMR spectroscopy using the lost I spin magnetization in polarization transfer experiments' has been developed for measuring the transferred I spin magnetization from abundant nuclei, which is normally lost when detecting the S spin magnetization. - A detailed investigation of nanocrystalline hydroxyapatite core was made to prove that proton environment of the phosphates units and phosphorus environment of hydroxyl units are the same as in highly crystalline hydroxyapatite sample. - Using XRD it was found that the surface of the hydroxyapatite nanocrystals is not completely disordered, as it was suggested before, but resembles the hydroxyapatite structure with HPO{sub 4}{sup 2-} (and some CO{sub 3}{sup

  9. Structural elucidation of nanocrystalline biomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Maltsev, S

    2008-10-23

    Bone diseases, such as osteoporosis and osteoarthritis, are the second most prevalent health problem worldwide. In Germany approximately 5 millions people are affected by arthritis. Investigating biomineralization processes and bone molecular structure is of key importance for developing new drugs for preventing and healing bone diseases. Nuclear magnetic resonance (NMR) was the primary technique used due to its advantages in characterising poorly ordered and disordered materials. Compared to all the diffraction techniques that widely applied in structural investigations, the usefulness of NMR is independent of long range molecular order. This makes NMR an outstanding technique for studies of complex/amorphous materials. Conventional NMR experiments (single pulse, spin-echo, cross polarization (CP), etc.) as well as their modifications and high-end techniques (2D HETCOR, REDOR, etc.) were used in this work. Combining the contributions from different techniques enhances the information content of the investigations and can increase the precision of the overall conclusions. Also XRD, TEM and FTIR were applied to different extent in order to get a general idea of nanocrystalline hydroxyapatite crystallite structure. Results: - A new approach named 'Solid-state NMR spectroscopy using the lost I spin magnetization in polarization transfer experiments' has been developed for measuring the transferred I spin magnetization from abundant nuclei, which is normally lost when detecting the S spin magnetization. - A detailed investigation of nanocrystalline hydroxyapatite core was made to prove that proton environment of the phosphates units and phosphorus environment of hydroxyl units are the same as in highly crystalline hydroxyapatite sample. - Using XRD it was found that the surface of the hydroxyapatite nanocrystals is not completely disordered, as it was suggested before, but resembles the hydroxyapatite structure with HPO{sub 4}{sup 2-} (and some CO{sub 3}{sup 2

  10. Chromium Enrichment on P11 Ferritic Steel by Pack Cementation

    OpenAIRE

    Fauzi F. A.; Kurniawan T.; Salwani M. S.; Bin Y. S.; Harun W. S. W.

    2016-01-01

    The future thermal power plant is expected to operate at higher temperature to improve its efficiency and to reduce greenhouse gas emission. This target requires better corrosion properties of ferritic steels, which commonly used as materials for superheater and reheater of boiler tubes. In this work, chromium enrichment on the surface of ferritic steel is studied. The deposited chromium is expected to become a reservoir for the formation of chromia protective layer. Chromium was deposited on...

  11. Synthesis of nanocrystalline fluorinated hydroxyapatite

    Indian Academy of Sciences (India)

    Fluorinated hydroxyapatite; nanocrystalline; microwave synthesis; dissolution. ... HA by the presence of other ions such as carbonate, magnesium, fluoride, etc. ... Fourier transform infrared spectroscopy (FT–IR) and laser Raman spectroscopy.

  12. Topological characterization of nanocrystalline cellulose reinforced Poly (lactic acid) and Poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) bionanocomposites

    Science.gov (United States)

    Bhat, A. H.; Dasan, Y. K.; Khan, Ihsan Ullah; Ahmad, Faiz; Ayoub, Muhammad

    2016-11-01

    This study was conducted to evaluate the morphological and barrier properties of nanocrystalline cellulose reinforced Poly (lactic acid) and Poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) bionanocomposites. Nanocrystalline cellulose was isolated from waste oil palm empty fruit bunch fiber using Sulphuric acid hydrolysis. Chemical modifications of nanocrystalline cellulose was performed to allow good compatibilization between fiber and the polymer matrices and also to improve dispersion of fillers. Bionanocomposite materials were produced from these nanocrystalline cellulose reinforced Poly (lactic acid) and Poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) using solvent casting and evaporation techniques. The properties of extracted nanocrystalline cellulose were examined using FT-IR spectroscopy, X-ray diffractometer, TEM and AFM. Besides that, the properties of bionanocomposites were examined through FESEM and oxygen permeability properties analysis. Better barrier and morphological properties were obtained for nanocrystalline cellulose reinforced bionanocomposites than for neat polymer blend.

  13. Specific heat of nano-ferrites modified composites

    Directory of Open Access Journals (Sweden)

    Muntenita Cristian

    2017-01-01

    Full Text Available The specific heat of nano-ferrites modified composites was studied using differential scanning calorimeter (DSC method in the temperature range of 30 to 150°C. Initially, nano-ferrites were introduced in epoxy systems in order to improve the electromagnetic properties of formed materials. Together with the changes in electromagnetic properties some modifications occur regarding thermal and mechanical properties. The materials were formed by placing 5g or 10g of ferrite into 250g polymer matrix leading to a very low weight ratio of modifying agent. At so low ratios the effect of ferrite presence should be insignificant according to mixing rule. Anyway there is possible to appear some chelation reaction with effects on thermal properties of materials. Three types of epoxy resins had been used as matrix and barium ferrite and strontium ferrite as modifying agents. The thermal analysis was developed on two heatingcooling cycles and the specific heat was evaluated for each segment of the cycle analysis.

  14. Inter- and intra-agglomerate fracture in nanocrystalline nickel.

    Science.gov (United States)

    Shan, Zhiwei; Knapp, J A; Follstaedt, D M; Stach, E A; Wiezorek, J M K; Mao, S X

    2008-03-14

    In situ tensile straining transmission electron microscopy tests have been carried out on nanocrystalline Ni. Grain agglomerates (GAs) were found to form very frequently and rapidly ahead of an advancing crack with sizes much larger than the initial average grain size. High-resolution electron microscopy indicated that the GAs most probably consist of nanograins separated by low-angle grain boundaries. Furthermore, both inter- and intra-GA fractures were observed. The observations suggest that these newly formed GAs may play an important role in the formation of the dimpled fracture surfaces of nanocrystalline materials.

  15. High-pressure structural behaviour of nanocrystalline Ge

    International Nuclear Information System (INIS)

    Wang, H; Liu, J F; He, Y; Wang, Y; Chen, W; Jiang, J Z; Olsen, J Staun; Gerward, L

    2007-01-01

    The equation of state and the pressure of the I-II transition have been studied for nanocrystalline Ge using synchrotron x-ray diffraction. The bulk modulus and the transition pressure increase with decreasing particle size for both Ge-I and Ge-II, but the percentage volume collapse at the transition remains constant. Simplified models for the high-pressure structural behaviour are presented, based on the assumption that a large fraction of the atoms reside in grain boundary regions of the nanocrystalline material. The interface structure plays a significant role in affecting the transition pressure and the bulk modulus

  16. Creep behavior of a nanocrystalline Fe-B-Si alloy

    International Nuclear Information System (INIS)

    Xiao, M.; Kong, Q.P.

    1997-01-01

    The research of nanocrystalline materials has attracted much attention in the world. In recent years, there have been several studies on their creep behavior. Among these, the authors have studied the tensile creep of a nanocrystalline Ni-P alloy (28 nm) at temperatures around 0.5 Tm (Tm is the melting point). The samples were prepared by the method of crystallization of amorphous ribbon. Based on the data of stress exponent and activation energy, they suggested that the creep was controlled by boundary diffusion; while the creep of the same alloy with a larger grain size (257 nm) was controlled by a different mechanism. In the present paper, the authors extend the research to the creep of a nanocrystalline Fe-B-Si alloy. The samples are also prepared by crystallization of amorphous ribbon. The samples such prepared have an advantage that the interfaces are naturally formed without artificial compaction and porosity

  17. Correlation of thermodynamics and grain growth kinetics in nanocrystalline metals

    International Nuclear Information System (INIS)

    Song Xiaoyan; Zhang Jiuxing; Li Lingmei; Yang Keyong; Liu Guoquan

    2006-01-01

    We investigated the correlation of thermodynamics and grain growth kinetics of nanocrystalline metals both theoretically and experimentally. A model was developed to describe the thermodynamic properties of nanograin boundaries, which could give reliable predictions in the destabilization characteristics of nanograin structures and the slowing down of grain growth kinetics at a constant temperature. Both the temperature-varying and isothermal nanograin growth behaviors in pure nanocrystalline Co were studied to verify the thermodynamic predictions. The experimental results showing that discontinuous nanograin growth takes place at a certain temperature and grain growth rate decreases monotonically with time confirm our thermodynamics-based description of nanograin growth characteristics. Therefore, we propose a thermodynamic viewpoint to explain the deviation of grain growth kinetics in nanocrystalline metals from those of polycrystalline materials

  18. Nanocrystalline Aluminum Truss Cores for Lightweight Sandwich Structures

    Science.gov (United States)

    Schaedler, Tobias A.; Chan, Lisa J.; Clough, Eric C.; Stilke, Morgan A.; Hundley, Jacob M.; Masur, Lawrence J.

    2017-12-01

    Substitution of conventional honeycomb composite sandwich structures with lighter alternatives has the potential to reduce the mass of future vehicles. Here we demonstrate nanocrystalline aluminum-manganese truss cores that achieve 2-4 times higher strength than aluminum alloy 5056 honeycombs of the same density. The scalable fabrication approach starts with additive manufacturing of polymer templates, followed by electrodeposition of nanocrystalline Al-Mn alloy, removal of the polymer, and facesheet integration. This facilitates curved and net-shaped sandwich structures, as well as co-curing of the facesheets, which eliminates the need for extra adhesive. The nanocrystalline Al-Mn alloy thin-film material exhibits high strength and ductility and can be converted into a three-dimensional hollow truss structure with this approach. Ultra-lightweight sandwich structures are of interest for a range of applications in aerospace, such as fairings, wings, and flaps, as well as for the automotive and sports industries.

  19. MHD Effects of a Ferritic Wall on Tokamak Plasmas

    Science.gov (United States)

    Hughes, Paul E.

    It has been recognized for some time that the very high fluence of fast (14.1MeV) neutrons produced by deuterium-tritium fusion will represent a major materials challenge for the development of next-generation fusion energy projects such as a fusion component test facility and demonstration fusion power reactor. The best-understood and most promising solutions presently available are a family of low-activation steels originally developed for use in fission reactors, but the ferromagnetic properties of these steels represent a danger to plasma confinement through enhancement of magnetohydrodynamic instabilities and increased susceptibility to error fields. At present, experimental research into the effects of ferromagnetic materials on MHD stability in toroidal geometry has been confined to demonstrating that it is still possible to operate an advanced tokamak in the presence of ferromagnetic components. In order to better quantify the effects of ferromagnetic materials on tokamak plasma stability, a new ferritic wall has been installated in the High Beta Tokamak---Extended Pulse (HBT-EP) device. The development, assembly, installation, and testing of this wall as a modular upgrade is described, and the effect of the wall on machine performance is characterized. Comparative studies of plasma dynamics with the ferritic wall close-fitting against similar plasmas with the ferritic wall retracted demonstrate substantial effects on plasma stability. Resonant magnetic perturbations (RMPs) are applied, demonstrating a 50% increase in n = 1 plasma response amplitude when the ferritic wall is near the plasma. Susceptibility of plasmas to disruption events increases by a factor of 2 or more with the ferritic wall inserted, as disruptions are observed earlier with greater frequency. Growth rates of external kink instabilities are observed to be twice as large in the presence of a close-fitting ferritic wall. Initial studies are made of the influence of mode rotation frequency

  20. Preparation and mechanical properties of ultra-high-strength nanocrystalline metals

    Czech Academy of Sciences Publication Activity Database

    Marek, I.; Vojtěch, D.; Michalcová, A.; Kubatík, Tomáš František

    2015-01-01

    Roč. 15, č. 4 (2015), s. 596-600 ISSN 1213-2489 Institutional support: RVO:61389021 Keywords : Mechanical properties * Nanocrystalline materials * Selective leaching * Silver * Spark plasma sintering Subject RIV: JG - Metallurgy

  1. Fast response time alcohol gas sensor using nanocrystalline F

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 36; Issue 4. Fast response time alcohol gas sensor using nanocrystalline F-doped SnO2 films derived via sol–gel method. Sarbani Basu Yeong-Her Wang C Ghanshyam Pawan Kapur. Volume 36 Issue 4 August 2013 pp 521-533 ...

  2. Induced anisotropy effect in nanocrystalline cores for GFCBs

    Energy Technology Data Exchange (ETDEWEB)

    Waeckerle, T. E-mail: thierry.waeckerle@imphy.usinor.com; Verin, Ph.; Cremer, P.; Gautard, D

    2000-06-02

    Nanocrystalline materials are very efficient for GFCB cores with flat hysteresis loop, especially if permeability may be raised in keeping low the remanent induction. This can be achieved with peculiar field annealing . A thermodynamic model is proposed to explain the experimental evidence.

  3. Oxygen reduction on nanocrystalline ruthenia-local structure effects

    DEFF Research Database (Denmark)

    Abbott, Daniel F.; Mukerjee, Sanjeev; Petrykin, Valery

    2015-01-01

    Nanocrystalline ruthenium dioxide and doped ruthenia of the composition Ru1-xMxO2 (M = Co, Ni, Zn) with 0 ≤ x ≤ 0.2 were prepared by the spray-freezing freeze-drying technique. The oxygen reduction activity and selectivity of the prepared materials were evaluated in alkaline media using the RRDE ...

  4. Structural, magnetic and spectral properties of Gd and Dy co-doped dielectrically modified Co-Ni (Ni{sub 0.4}Co{sub 0.6}Fe{sub 2}O{sub 4}) ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Ditta, Allah [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Khan, Muhammad Azhar, E-mail: azhar.khan@iub.edu.pk [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Junaid, Muhammad, E-mail: junaid.malik95@yahoo.com [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Khalil, R.M. Arif [Department of Physics, Sahiwal Sub-Campus Bahauddin Zakariya University, Sahiwal (Pakistan); Warsi, Muhammad Farooq [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan)

    2017-02-15

    Gadolinium (Gd) and Dysprosium (Dy) co-doped Ni-Co (Ni{sub 0.4}Co{sub 0.6}Fe{sub 2}O{sub 4}) ferrites were prepared by micro-emulsion route. X-ray diffraction (XRD) analysis indicated the development of cubic spinel structure. The lattice parameter and X-ray density were found to increase from 8.24 to 8.31 Å and 5.57 to 5.91 (gm/cm{sup 3}) respectively as the Gd-Dy contents increased in nickel-cobalt ferrites. The crystallite size calculated from the Scherrer's formula exhibited the formation of nanocrystalline ferrites (13–26 nm). Two foremost absorption bands observed in FTIR spectra within 400 cm{sup −1} (υ{sub 2}) to 600 cm{sup −1} (υ{sub 1}) which correspond to stretching vibrations of tetrahedral and octahedral complexes respectively. The dielectric constant (ε) and dielectric loss (tanδ) were decreased by the optimization of frequency and abrupt decrease in the low frequency region and higher values in the high frequency region were observed. The dielectric dispersion was due to rapid decrease of dielectric constant in the low frequency region. This variation of dielectric dispersion was explicated in the light of space charge polarization model of Maxwell-Wagner. The dielectric loss occurs in these ferrites due to electron hopping and defects in the dipoles. The electron hopping was possible at low frequency range but at higher frequency the dielectric loss was decreased with the decrease of electron hopping. Magnetic properties were observed by measuring M-H loops. Due to low dielectric loss and dielectric constant these materials were appropriate in the fabrication of switching and memory storage devices.

  5. Microwave firing of MnZn-ferrites

    International Nuclear Information System (INIS)

    Tsakaloudi, V.; Papazoglou, E.; Zaspalis, V.T.

    2004-01-01

    Microwave firing is evaluated in comparison to conventional firing for MnZn-ferrites. For otherwise identical conditions, microwave firing results to higher densities and coarser microstructures. Initial magnetic permeability values (25 kHz, 25 deg. C, <0.1 mT) after conventional firing are approximately 5000, but the corresponding values after microwave firing are approximately 6000. Unlike the conventional firing process, the final density after microwave firing is increased by increasing the prefiring temperature. As appears from the results of this study, microwave firing could be in principle a promising MnZn-ferrite firing technology for materials to be used in high magnetic permeability applications. No advantages of microwave firing are evident for materials intended to be used in high field power applications

  6. The influence of the heat treatment on delta ferrite transformation in austenitic stainless steel welds

    Directory of Open Access Journals (Sweden)

    B. Mateša

    2012-04-01

    Full Text Available Shielded metal arc (SMAW welded specimens using austenitic consumable materials with different amount of delta-ferrite are annealed in range 650-750 °C through 2-10 hours. Factorial plan 33 with influenced factors regression analyze of measured delta-ferrite values is used. The transformation i.e. decomposition of delta ferrite during annealing was analyzed regarding on weld cracking resistance using metallographic examination and WRC-1992 diagram.

  7. Low activation ferritic alloys

    Science.gov (United States)

    Gelles, David S.; Ghoniem, Nasr M.; Powell, Roger W.

    1986-01-01

    Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

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

    International Nuclear Information System (INIS)

    Amiri, S.; Shokrollahi, H.

    2013-01-01

    The nanotechnology industry is rapidly growing and promises that the substantial changes that will have significant economic and scientific impacts be applicable to a wide range of areas, such as aerospace engineering, nano-electronics, environmental remediation and medical healthcare. In this area, cobalt ferrite nanoparticles have been regarded as one of the competitive candidates because of their suitable physical, chemical and magnetic properties like the high anisotropy constant, high coercivity and high Curie temperature, moderate saturation magnetization and ease of synthesis. This paper introduces the magnetic properties, synthesis methods and some medical applications, including the hyperthermia, magnetic resonance imaging (MRI), magnetic separation and drug delivery of cobalt ferrite nanoparticles. Highlights: ► Cobalt ferrite nanoparticles are one of the most important materials for nanomedicine. ► They have high coercivity and moderate saturation magnetization. ► Cobalt ferrite nanoparticles are synthesized easily. ► They are a good candidate for hyperthermia and magnetic resonance imaging.

  9. Titanium oxide dispersion-strengthened ferritic alloys

    International Nuclear Information System (INIS)

    Hendrix, W.; Vandermeulen, W.

    1980-04-01

    The available data on the DT02 and DT3911 ferritic dispersion strengthened alloys, developed at SCK/CEN, Mol, Belgium, are presented. Both alloys consist of Fe - 13% Cr - 1.5% Mo to which 2% TiO 2 and about 3.5% Ti are added (wt.%). Their main use is for the fabrication of fast breeder reactor cladding tubes but their application as turbine blade material is also envisaged for cases where high damping is important. (auth.)

  10. Analyse des structures planaires multicouches à ferrite par la ...

    African Journals Online (AJOL)

    Finite element analysis of multi-layer planar structures with Ferrite. Electromagnetic Analysis of microwave integrated circuits is an attractive subject do to the recent development and use of new materials such as magnetic anisotropic materials (hexaferrite, ...). These materials are used in many microwave components ...

  11. Structural investigation of chemically synthesized ferrite magnetic nanomaterials

    Science.gov (United States)

    Uyanga, E.; Sangaa, D.; Hirazawa, H.; Tsogbadrakh, N.; Jargalan, N.; Bobrikov, I. A.; Balagurov, A. M.

    2018-05-01

    In recent times, interest in ferrite magnetic nanomaterials has considerably grown, mainly due to their highly promising medical and biological applications. Spinel ferrite powder samples, with high heat generation abilities in AC magnetic fields, were studied for their application to the hyperthermia treatment of cancer tumors. These properties of ferrites strongly depend on their chemical composition, ion distribution between crystallographic positions, magnetic structure and method of preparation. In this study, crystal and magnetic structures of several magnetic spinels were investigated by neutron diffraction. The explanation of the mechanism triggering the heat generation ability in the magnetic materials, and the electronic and magnetic states of ferrite-spinel type structures, were theoretically defined by a first-principles method. Ferrites with the composition of CuxMg1-xFe2O4 have been investigated as a heat generating magnetic nanomaterial. Atomic fraction of copper in ferrite was varied between 0 and 100% (that is, x between 0 and 1.0 with 0.2 steps), with the copper dope limit corresponding to appear a tetragonal phase.

  12. DARHT-II Injector Transients and the Ferrite Damper

    Energy Technology Data Exchange (ETDEWEB)

    Waldron, Will; Reginato, Lou; Chow, Ken; Houck, Tim; Henestroza, Enrique; Yu, Simon; Kang, Michael; Briggs, Richard

    2006-08-04

    This report summarizes the transient response of the DARHT-II Injector and the design of the ferrite damper. Initial commissioning of the injector revealed a rise time excited 7.8 MHz oscillation on the diode voltage and stalk current leading to a 7.8 MHz modulation of the beam current, position, and energy. Commissioning also revealed that the use of the crowbar to decrease the voltage fall time excited a spectrum of radio frequency modes which caused concern that there might be significant transient RF electric field stresses imposed on the high voltage column insulators. Based on the experience of damping the induction cell RF modes with ferrite, the concept of a ferrite damper was developed to address the crowbar-excited oscillations as well as the rise-time-excited 7.8 MHz oscillations. After the Project decided to discontinue the use of the crowbar, further development of the concept focused exclusively on damping the oscillations excited by the rise time. The design was completed and the ferrite damper was installed in the DARHT-II Injector in February 2006. The organization of this report is as follows. The suite of injector diagnostics are described in Section 2. The data and modeling of the injector transients excited on the rise-time and also by the crowbar are discussed in Section 3; the objective is a concise summary of the present state of understanding. The design of the ferrite damper, and the small scale circuit simulations used to evaluate the ferrite material options and select the key design parameters like the cross sectional area and the optimum gap width, are presented in Section 4. The details of the mechanical design and the installation of the ferrite damper are covered in Section 5. A brief summary of the performance of the ferrite damper following its installation in the injector is presented in Section 6.

  13. Application Potential of Nanocrystalline Ribbons Still Pending

    Science.gov (United States)

    Butvin, Pavol; Butvinová, Beata; Švec, Peter; Sitek, Jozef

    2010-09-01

    Nanocrystalline soft-magnetic ribbons promised a wide-spread practical use when introduced at the beginning of nineties. After 20 years of extensive research there are still unclear material problems which are thought to be the principal reason why these materials show but marginal use. Poorly controllable magnetic anisotropy due to spontaneous intrinsic macroscopic stress that comes from an inevitable heterogeneity of the ribbon materials is pointed to in this work. Certain stress-based mechanisms are shown to induce the unintended anisotropy in the already familiar Finemets as well as in the newer Hitperms. Hysteresis loops, domain structure and power loss is used to reveal the anisotropy consequences and particular connected but still unanswered questions are pinpointed.

  14. Thermal stability of grain boundaries in nanocrystalline Zn studied by positron lifetime spectroscopy

    International Nuclear Information System (INIS)

    Zhou Kai; Li Hui; Pang Jinbiao; Wang Zhu

    2012-01-01

    Nanocrystalline Zn prepared by compacting nanoparticles with mean grain size about 55 nm at 15 MPa has been studied by positron lifetime spectroscopy. For the bulk Zn sample, the vacancy defect is annealed out at about 350 °C, but for the nanocrystalline Zn sample, the vacancy cluster in grain boundaries is quite difficult to be annealed out even at very high temperature (410 °C). In the grain boundaries of nanocrystalline Zn, the small free volume defect (not larger than divacancy) is dominant according to the high relative intensity for the short positron lifetime (τ 1 ). The oxide (ZnO) inside the grain boundaries has been found having an effect to hinder the decrease of average positron lifetime (τ av ), which probably indicates that the oxide stabilizes the microstructure of the grain boundaries. This stabilization is very important for the nanocrystalline materials using as radiation resistant materials.

  15. Influence of fuel ratios on auto combustion synthesis of barium ferrite ...

    Indian Academy of Sciences (India)

    Unknown

    Influence of fuel ratios on auto combustion synthesis of barium ferrite nano particles. D BAHADUR*, S RAJAKUMAR and ANKIT KUMAR. Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology,. Mumbai 400 076 e-mail: dhirenb@iitb.ac.in. Abstract. Single-domain barium ferrite nano ...

  16. A new application and experimental validation of moulding technology for ferrite magnet assisted synchronous reluctance machine

    DEFF Research Database (Denmark)

    Wu, Qian; Lu, Kaiyuan; Rasmussen, Peter Omand

    2016-01-01

    This paper introduces a new application of moulding technology to the installation of ferrite magnet material into the rotor flux barriers of Ferrite Magnet Assisted Synchronous Reluctance Machine (FASynRM). The feasibility of this application with respect to manufacturing process and motor...

  17. Low temperature synthesis of nanosized Mn1–xZnxFe2O4 ferrites ...

    Indian Academy of Sciences (India)

    Administrator

    spectrum analysis were carried out to confirm the spinel phase formation as well as to ascertain the cation distri- bution in the ferrite ... structured materials technology opening up in the last few ... recent years, the design and synthesis of nano-magnetic particles ..... complex system like the ferrites where many cations are.

  18. 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.

  19. Ferromagnetism appears in nitrogen implanted nanocrystalline diamond films

    Czech Academy of Sciences Publication Activity Database

    Remeš, Zdeněk; Sun, S. J.; Varga, M.; Chou, H.; Hsu, H.S.; Kromka, A.; Horák, Pavel

    2015-01-01

    Roč. 394, Nov (2015), s. 477-480 ISSN 0304-8853 R&D Projects: GA ČR(CZ) GBP108/12/G108; GA MŠk(CZ) LD14011 EU Projects: European Commission(XE) COST Action MP1202 HINT Institutional support: RVO:68378271 ; RVO:61389005 Keywords : diamond * nonmetallic ferromagnetic materials * fine-particle systems * nanocrystalline materials Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.357, year: 2015

  20. Nanocrystalline sp{sup 2} and sp{sup 3} carbons: CVD synthesis and applications

    Energy Technology Data Exchange (ETDEWEB)

    Terranova, M. L. [Università degli Studi di Roma “Tor Vergata,” via Della Ricerca Scientifica, Dipartimento di Scienze e Tecnologie Chimiche—MinimaLab (Italy); Rossi, M. [Università degli Studi di Roma “Sapienza,” via A. Scarpa, Dipartimento di Scienze di Base e Applicate per l’Ingegneria and Centro di Ricerca per le Nanotecnologie Applicate all’Ingegneria (CNIS) (Italy); Tamburri, E., E-mail: emanuela.tamburri@uniroma2.it [Università degli Studi di Roma “Tor Vergata,” via Della Ricerca Scientifica, Dipartimento di Scienze e Tecnologie Chimiche—MinimaLab (Italy)

    2016-11-15

    The design and production of innovative materials based on nanocrystalline sp{sup 2}- and sp{sup 3}-coordinated carbons is presently a focus of the scientific community. We present a review of the nanostructures obtained in our labs using a series of synthetic routes, which make use of chemical vapor deposition (CVD) techniques for the selective production of non-planar graphitic nanostructures, nanocrystalline diamonds, and hybrid two-phase nanostructures.

  1. Self-composite comprised of nanocrystalline diamond and a non-diamond component useful for thermoelectric applications

    Science.gov (United States)

    Gruen, Dieter M [Downers Grove, IL

    2009-08-11

    One provides nanocrystalline diamond material that comprises a plurality of substantially ordered diamond crystallites that are sized no larger than about 10 nanometers. One then disposes a non-diamond component within the nanocrystalline diamond material. By one approach this non-diamond component comprises an electrical conductor that is formed at the grain boundaries that separate the diamond crystallites from one another. The resultant nanowire is then able to exhibit a desired increase with respect to its ability to conduct electricity while also preserving the thermal conductivity behavior of the nanocrystalline diamond material.

  2. Microhardness studies of nanocrystalline lead molybdate

    International Nuclear Information System (INIS)

    Anandakumar, V.M.; Abdul Khadar, M.

    2009-01-01

    Nanocrystalline lead molybdate (PbMoO 4 ) of four different grain sizes were synthesized through chemical precipitation technique and the grain sizes and crystal structure are determined using the broadening of X-ray diffraction patterns and transmission electron microscopy. The microhardness of nanocrystalline lead molybdate (PbMoO 4 ) with different grain sizes were measured using a Vicker's microhardness tester for various applied loads ranging from 0.049 to 1.96 N. The microhardness values showed significant indentation size effect at low indentation loads. The proportional specimen resistance model put forward by Li and Bradt and energy balance model put forward by Gong and Li were used to analyze the behaviour of measured microhardness values under different indentation loads. The microhardness data obtained for samples of different grain sizes showed grain size dependent strengthening obeying normal Hall-Petch relation. The dependence of compacting pressure and annealing temperature on microhardness of the nanostructured sample with grain size of ∼18 nm were also studied. The samples showed significant increase in microhardness values as the compacting pressure and annealing time were increased. The variation of microhardness of the material with pressure of pelletization and annealing time are discussed in the light of change of pore size distribution of the samples.

  3. Grain growth studies on nanocrystalline Ni powder

    International Nuclear Information System (INIS)

    Rane, G.K.; Welzel, U.; Mittemeijer, E.J.

    2012-01-01

    The microstructure of nanocrystalline Ni powder produced by ball-milling and its thermal stability were investigated by applying different methods of X-ray diffraction line-profile analysis: single-line analysis, whole powder-pattern modelling and the (modified) Warren–Averbach method were employed. The kinetics of grain growth were investigated by both ex-situ and in-situ X-ray diffraction measurements. With increasing milling time, the grain-size reduction is accompanied by a considerable narrowing of the size distribution and an increase in the microstrain. Upon annealing, initial, rapid grain growth occurs, accompanied by the (almost complete) annihilation of microstrain. For longer annealing times, the grain-growth kinetics depend on the initial microstructure: a smaller microstrain with a broad grain-size distribution leads to linear grain growth, followed by parabolic grain growth, whereas a larger microstrain with a narrow grain-size distribution leads to incessant linear grain growth. These effects have been shown to be incompatible with grain-boundary curvature driven growth. The observed kinetics are ascribed to the role of excess free volume at the grain boundaries of nanocrystalline material and the prevalence of an “abnormal grain-growth” mechanism.

  4. Critical currents and fields of disordered nanocrystalline superconductors

    International Nuclear Information System (INIS)

    Yavary, H.; Shahzamanian, M.A.; Rabbani, H.

    2007-01-01

    Full text: There is an enormous effort directed at increasing the upper critical field of the superconducting materials because this upper critical field provides a fundamental limit to the maximum field a magnet system can produce. High-energy particle accelerators and medical resonance imaging body scanners are limited by the for NbTi (10 T). Gigahertz class nuclear-magnetic-resonance and high field laboratory magnets are limited by for Nb 3 Sn (23 T) [1]. However, the values of critical current density are too low for industrial use, possibly because of degraded or nonsuperconducting phases, such as MoS 2 or Mo 2 S 3 , at the grain boundaries or because the pinning site density is not high enough. It has long been known that decreasing the grain size of low-temperature superconducting (LTS) materials, such as Nb 3 Sn, increases the density of flux pinning sites and hence. Nanocrystalline materials are characterized by ultrafine grains and a high density of grain boundaries [2]. Hence nanocrystalline materials can exhibit unusual physical, chemical, and mechanical properties with respect to conventional polycrystalline materials. The purpose of this paper is to investigate the structure of currents and fields in disordered nanocrystalline superconducting materials by the use of quasiclassical many body techniques. The Keldish Greens functions are used to calculate the current density of the system. Since the disorder and microstructure of these nanocrystalline materials are on a sufficiently short length scale as to increase both the density of pinning site and the upper critical field. (authors)

  5. Structural characterization of nanocrystalline cadmium sulphide powder prepared by solvent evaporation technique

    Science.gov (United States)

    Pandya, Samir; Tandel, Digisha; Chodavadiya, Nisarg

    2018-05-01

    CdS is one of the most important compounds in the II-VI group of semiconductor. There are numerous applications of CdS in the form of nanoparticles and nanocrystalline. Semiconductors nanoparticles (also known as quantum dots), belong to state of matter in the transition region between molecules and solids, have attracted a great deal of attention because of their unique electrical and optical properties, compared to bulk materials. In the field of optoelectronic, nanocrystalline form utilizes mostly in the field of catalysis and fluid technology. Considering these observations, presented work had been carried out, i.e. based on the nanocrystalline material preparation. In the present work CdS nano-crystalline powder was synthesized by a simple and cost effective chemical technique to grow cadmium sulphide (CdS) nanoparticles at 200 °C with different concentrations of cadmium. The synthesis parameters were optimized. The synthesized powder was structurally characterized by X-ray diffraction and particle size analyzer. In the XRD analysis, Micro-structural parameters such as lattice strain, dislocation density and crystallite size were analysed. The broadened diffraction peaks indicated nanocrystalline particles of the film material. In addition to that the size of the prepared particles was analyzed by particle size analyzer. The results show the average size of CdS particles ranging from 80 to 100 nm. The overall conclusion of the work can be very useful in the synthesis of nanocrystalline CdS powder.

  6. Hot pressing of nanocrystalline tantalum using high frequency induction heating and pulse plasma sintering

    Science.gov (United States)

    Jakubowicz, J.; Adamek, G.; Sopata, M.; Koper, J. K.; Siwak, P.

    2017-12-01

    The paper presents the results of nanocrystalline powder tantalum consolidation using hot pressing. The authors used two different heating techniques during hot pressing: high-frequency induction heating (HFIH) and pulse plasma sintering (PPS). A comparison of the structure, microstructure, mechanical properties and corrosion resistance of the bulk nanocrystalline tantalum obtained in both techniques was performed. The nanocrystalline powder was made to start from the microcrystalline one using the high-energy ball milling process. The nanocrystalline powder was hot-pressed at 1000 °C, whereas, for comparison, the microcrystalline powder was hot pressed up to 1500 °C for proper consolidation. The authors found that during hot pressing, the powder partially reacts with the graphite die covered by boron nitride, which facilitated punches and powder displacement in the die during densification. Tantalum carbide and boride in the nanocrystalline material was found, which can improve the mechanical properties. The hardness of the HFIH and PPS nanocrystalline tantalum was as high as 625 and 615 HV, respectively. The microstructure was more uniform in the PPS nanomaterial. The corrosion resistance in both cases deteriorated, in comparison to the microcrystalline material, while the PPS material corrosion resistance was slightly better than that of the HFIH one.

  7. Research Update: Phonon engineering of nanocrystalline silicon thermoelectrics

    Directory of Open Access Journals (Sweden)

    Junichiro Shiomi

    2016-10-01

    Full Text Available Nanocrystalline silicon thermoelectrics can be a solution to improve the cost-effectiveness of thermoelectric technology from both material and integration viewpoints. While their figure-of-merit is still developing, recent advances in theoretical/numerical calculations, property measurements, and structural synthesis/fabrication have opened up possibilities to develop the materials based on fundamental physics of phonon transport. Here, this is demonstrated by reviewing a series of works on nanocrystalline silicon materials using calculations of multiscale phonon transport, measurements of interfacial heat conduction, and synthesis from nanoparticles. Integration of these approaches allows us to engineer phonon transport to improve the thermoelectric performance by introducing local silicon-oxide structures.

  8. Limitation of biocompatibility of hydrated nanocrystalline hydroxyapatite

    Science.gov (United States)

    Minaychev, V. V.; Teleshev, A. T.; Gorshenev, V. N.; Yakovleva, M. A.; Fomichev, V. A.; Pankratov, A. S.; Menshikh, K. A.; Fadeev, R. S.; Fadeeva, I. S.; Senotov, A. S.; Kobyakova, M. I.; Yurasova, Yu B.; Akatov, V. S.

    2018-04-01

    Nanostructured hydroxyapatite (HA) in the form of hydrated paste is considered to be a promising material for a minor-invasive surgical curing of bone tissue injure. However questions about adhesion of cells on this material and its biocompatibility still remain. In this study biocompatibility of paste-formed nanosized HA (nano-HA) by in vitro methods is investigated. Nano-HA (particles sized about 20 nm) was synthesized under conditions of mechano-acoustic activation of an aqueous reaction mixture of ammonium hydrophosphate and calcium nitrate. It was ascertained that nanocrystalline paste was not cytotoxic although limitation of adhesion, spreading and growth of the cells on its surface was revealed. The results obtained point on the need of modification of hydrated nano-HA in the aims of increasing its biocompatibility and osteoplastic potential.

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

    Science.gov (United States)

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

    2015-11-09

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

  10. Large zinc cation occupancy of octahedral sites in mechanically activated zinc ferrite powders

    International Nuclear Information System (INIS)

    Oliver, S. A.; Harris, V. G.; Hamdeh, H. H.; Ho, J. C.

    2000-01-01

    The cation site occupancy of a mechanically activated nanocrystalline zinc ferrite powder was determined as (Zn 0.55 2+ Fe 0.18 3+ ) tet [Zr 0.45 2+ Fe 1.82 3+ ] oct O 4 through analysis of extended x-ray absorption fine structure measurements, showing a large redistribution of cations between sites compared to normal zinc ferrite samples. The overpopulation of cations in the octahedral sites was attributed to the ascendance in importance of the ionic radii over the crystal energy and bonding coordination in determining which interstitial sites are occupied in this structurally disordered powder. Slight changes are observed in the local atomic environment about the zinc cations, but not the iron cations, with respect to the spinel structure. The presence of Fe 3+ on both sites is consistent with the measured room temperature magnetic properties. (c) 2000 American Institute of Physics

  11. Nanocrystalline SiC and Ti3SiC2 Alloys for Reactor Materials: Annual Report

    Energy Technology Data Exchange (ETDEWEB)

    Henager, Charles H. [pnnl; Alvine, Kyle J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Roosendaal, Timothy J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Shin, Yongsoon [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Nguyen, Ba Nghiep; Borlaug, Brennan A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jiang, Weilin [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Arreguin, Shelly A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-01-15

    A new dual-phase nanocomposite of Ti₃SiC₂/SiC is being synthesized using preceramic polymers, ceramic powders, and carbon nanotubes (CNTs) designed to be suitable for advanced nuclear reactors and perhaps as fuel cladding. The material is being designed to have superior fracture toughness compared to SiC, adequate thermal conductivity, and higher density than SiC/SiC composites. This annual report summarizes the progress towards this goal and reports progress in understanding certain aspects of the material behavior but some shortcomings in achieving full density or in achieving adequate incorporation of CNTs. The measured thermal conductivity is adequate and falls into an expected range based on SiC and Ti₃SiC₂. Part of this study makes an initial assessment for Ti₃SiC₂ as a barrier to fission product transport. Ion implantation was used to introduce fission product surrogates (Ag and Cs) and a noble metal (Au) in Ti₃SiC₂, SiC, and a synthesized at PNNL. The experimental results indicate that the implanted Ag in SiC is immobile up to the highest temperature (1273 K) applied in this study; in contrast, significant out-diffusion of both Ag and Au in MAX phase Ti₃SiC₂ occurs during ion implantation at 873 K. Cs in Ti₃SiC₂ is found to diffuse during post-irradiation annealing at 973 K, and noticeable Cs release from the sample is observed. This study may suggest caution in using Ti₃SiC₂ as a fuel cladding material for advanced nuclear reactors operating at very high temperatures. Progress is reported in thermal conductivity modeling of SiC-based materials that is relevant to this research, as is progress in modeling the effects of CNTs on fracture strength of SiC-based materials.

  12. Preparation of thin layer materials with macroporous microstructure for SOFC applications

    International Nuclear Information System (INIS)

    Marrero-Lopez, D.; Ruiz-Morales, J.C.; Pena-Martinez, J.; Canales-Vazquez, J.; Nunez, P.

    2008-01-01

    A facile and versatile method using polymethyl methacrylate (PMMA) microspheres as pore formers has been developed to prepare thin layer oxide materials with controlled macroporous microstructure. Several mixed oxides with fluorite and perovskite-type structures, i.e. doped zirconia, ceria, ferrites, manganites, and NiO-YSZ composites have been prepared and characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption and mercury porosimetry. The synthesised materials are nanocrystalline and present a homogeneous pore distribution and relatively high specific surface area, which makes them interesting for SOFC and catalysis applications in the intermediate temperature range. - Graphical abstract: Thin films materials of mixed oxides with potential application in SOFC devices have been prepared with macroporous microstructure using PMMA microspheres as pore formers. Display Omitted

  13. Strain rate sensitivity studies on bulk nanocrystalline aluminium by nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Varam, Sreedevi; Rajulapati, Koteswararao V., E-mail: kvrse@uohyd.ernet.in; Bhanu Sankara Rao, K.

    2014-02-05

    Nanocrystalline aluminium powder synthesized using high energy ball milling process was characterized by X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). The studies indicated the powder having an average grain size of ∼42 nm. The consolidation of the powder was carried out by high-pressure compaction using a uni-axial press at room temperature by applying a pressure of 1.5 GPa. The cold compacted bulk sample having a density of ∼98% was subjected to nanoindentation which showed an average hardness and elastic modulus values of 1.67 ± 0.09 GPa and 83 ± 8 GPa respectively at a peak force of 8000 μN and a strain rate of 10{sup −2} s{sup −1}. Achieving good strength along with good ductility is challenging in nanocrystalline metals. When enough sample sizes are not available to measure ductility and other mechanical properties as per ASTM standards, as is the case with nanocrystalline materials, nanoindentation is a very promising technique to evaluate strain rate sensitivity. Strain rate sensitivity is a good measure of ductility and in the present work it is measured by performing indentation at various loads with varying loading rates. Strain rate sensitivity values of 0.024–0.054 are obtained for nanocrystalline Al which are high over conventional coarse grained Al. In addition, Scanning Probe Microscopy (SPM) image of the indent shows that there is some plastically flown region around the indent suggesting that this nanocrystalline aluminium is ductile.

  14. Effect of Sr substitution on the room temperature electrical properties of La1-xSrxFeO3 nano-crystalline materials

    Science.gov (United States)

    Kafa, C. A.; Triyono, D.; Laysandra, H.

    2017-07-01

    LaFeO3 is a material with Perovskite structure which electrical properties got investigated a lot, because as a p-type semiconductor it showed good gas sensing behavior through resistivity comparison. Sr doping on LaFeO3 is able to improve the electrical conductivity through structural modification. Using the Sr atoms doping concentration (x) from 0.1 to 0.4, La1-xSrxFeO3 nanocrystal pellets were synthesized using sol-gel method, followed by gradual heat treatment and uniaxial compaction. Structural analysis from XRD characterization shows that the structure of the materials is Orthorhombic Perovskite. The topography of the sample by SEM reveals grain and grain boundary existence with emerging agglomeration. The electrical properties of the material, as functions of frequency, were measured by Impedance Spectroscopy method using RLC meter. Through the Nyquist plot and Bode plot, the electrical conductivity of La1-xSrxFeO3 is contributed by grain and grain boundaries. It is reported that La0.6Sr0.4FeO3 sample has the most superior electrical conductivity of all samples, and the electrical permittivity of both La0.8Sr0.2FeO3 and La0.7Sr0.3FeO3 are the most stable.

  15. Analyzing the scale of the bainitic ferrite plates by XRD, SEM and TEM

    International Nuclear Information System (INIS)

    Garcia-Mateo, Carlos; Jimenez, Jose A.; Lopez-Ezquerra, Belen; Rementeria, Rosalia; Morales-Rivas, Lucia; Kuntz, Matthias; Caballero, Francisca G.

    2016-01-01

    Since the major strengthening mechanisms in nanocrystalline bainitic steels arise from the exceptionally small size of the bainitc ferrite plate, accurate determination of this parameter is fundamental for quantitative relating the microstructure to the mechanical properties. In this work, the thickness of the bainitic ferrite subunits obtained by different bainitic heat treatments was determined in two steels, with carbon contents of 0.3 and 0.7 wt.%, from SEM and TEM micrographs. As these measurements were made on 2D images taken from random sections, the method includes some stereological correction factors to obtain accurate information. Finally, the determined thicknesses of bainitic ferrite plates were compared with the crystallite size calculated from the analysis of X-ray diffraction peak broadening. Although in some case the values obtained for crystallite size and plate thickness can be similar, this study confirms that indeed they are two different parameters. - Highlights: •Bainitic microstructure in a nanostructured and sub-micron steel •Bainitic ferrite plate thickness measured by SEM and TEM •Crystallite size determined by X-ray analysis

  16. Analyzing the scale of the bainitic ferrite plates by XRD, SEM and TEM

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Mateo, Carlos, E-mail: cgm@cenim.csic.es [Department of Physical Metallurgy, Spanish National Center for Metallurgical Research (CENIM-CSIC), Avda. Gregorio del Amo 8, E-28040 Madrid (Spain); Jimenez, Jose A.; Lopez-Ezquerra, Belen; Rementeria, Rosalia; Morales-Rivas, Lucia [Department of Physical Metallurgy, Spanish National Center for Metallurgical Research (CENIM-CSIC), Avda. Gregorio del Amo 8, E-28040 Madrid (Spain); Kuntz, Matthias [Robert-Bosch GmbH, Materials and Process Engineering Metals, Renningen, 70465 Stuttgart (Germany); Caballero, Francisca G. [Department of Physical Metallurgy, Spanish National Center for Metallurgical Research (CENIM-CSIC), Avda. Gregorio del Amo 8, E-28040 Madrid (Spain)

    2016-12-15

    Since the major strengthening mechanisms in nanocrystalline bainitic steels arise from the exceptionally small size of the bainitc ferrite plate, accurate determination of this parameter is fundamental for quantitative relating the microstructure to the mechanical properties. In this work, the thickness of the bainitic ferrite subunits obtained by different bainitic heat treatments was determined in two steels, with carbon contents of 0.3 and 0.7 wt.%, from SEM and TEM micrographs. As these measurements were made on 2D images taken from random sections, the method includes some stereological correction factors to obtain accurate information. Finally, the determined thicknesses of bainitic ferrite plates were compared with the crystallite size calculated from the analysis of X-ray diffraction peak broadening. Although in some case the values obtained for crystallite size and plate thickness can be similar, this study confirms that indeed they are two different parameters. - Highlights: •Bainitic microstructure in a nanostructured and sub-micron steel •Bainitic ferrite plate thickness measured by SEM and TEM •Crystallite size determined by X-ray analysis.

  17. Structural, magnetic and dielectric investigations in antimony doped nano-phased nickel-zinc ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Lakshmi, Ch.S. [Department of Physics, Regency Institute of Technology, Adivipolam Yanam 533464, Pondicherry (India); Sridhar, Ch.S.L.N. [Department of Physics, Vignana Bharathi Institute of Technology, Aushapur(v) Ghatkesar (M), Hyderabad 501301, Telangana (India); Govindraj, G. [Department of Physics, School of Physical, Chemical and Applied Sciences, Pondicherry University, R.V.Nagar, Kalapet, Pondicherry 605014 (India); Bangarraju, S. [Department of Physics, Andhra University, Visakhapatnam 530003, Andhrapradesh (India); Potukuchi, D.M., E-mail: potukuchidm@yahoo.com [Department of Physics, University College of Engineering, Jawaharlal Nehru Technological University:Kakinada, Kakinada 533003 (India)

    2015-02-15

    Nanocrystalline Ni–Zn–Sb ferrites synthesized by hydrothermal method are reported. Influence of Sb{sup 5+} ions on structural, magnetic and dielectric properties of ferrites is studied. Phase identification, lattice parameter and crystallite size studies are carried out using by X-ray diffraction (XRD). Addition of dopant resulted for decrease in lattice parameter. Crystallite size gets reduced from 62 nm to 38 nm with doping of Antimony. Crystallite size and porosity exhibit similar trends with doping. Morphological study is carried out by Field Emission Scanning Electron Microscopy (FESEM). Strong FTIR absorption bands at 400–600 cm{sup −1} confirm the formation of ferrite structure. Increase of porosity is attributed to the grain size. Doping with Antimony results for decrease in saturation magnetization and increase in coercivity. An initial increase of saturation magnetization for x=0.1 is attributed to the unusually high density. Reversed trend of coercivity with crystallite size are observed. Higher value of dielectric constant ε′(ω) is attributed to the formation of excess of Fe{sup 2+} ions caused by aliovalent doping of Sb{sup 5+} ions. Variation of dielectric constant infers hopping type of conductivity mechanism. The dielectric loss factor tanδ attains lower values of ∼10{sup −2}. High ac resistivity ρ(ω) of 10{sup 8} Ω cm is witnessed for antimony doped ferrites. Higher saturation magnetization and enhanced dielectric response directs for a possible utility as microwave oscillators and switches.

  18. Nanocrystalline diamond films for biomedical applications

    DEFF Research Database (Denmark)

    Pennisi, Cristian Pablo; Alcaide, Maria

    2014-01-01

    Nanocrystalline diamond films, which comprise the so called nanocrystalline diamond (NCD) and ultrananocrystalline diamond (UNCD), represent a class of biomaterials possessing outstanding mechanical, tribological, and electrical properties, which include high surface smoothness, high corrosion...... performance of nanocrystalline diamond films is reviewed from an application-specific perspective, covering topics such as enhancement of cellular adhesion, anti-fouling coatings, non-thrombogenic surfaces, micropatterning of cells and proteins, and immobilization of biomolecules for bioassays. In order...

  19. Electrophoretic Nanocrystalline Graphene Film Electrode for Lithium Ion Battery

    International Nuclear Information System (INIS)

    Kaprans, Kaspars; Bajars, Gunars; Kucinskis, Gints; Dorondo, Anna; Mateuss, Janis; Gabrusenoks, Jevgenijs; Kleperis, Janis; Lusis, Andrejs

    2015-01-01

    Graphene sheets were fabricated by electrophoretic deposition method from water suspension of graphene oxide followed by thermal reduction. The formation of nanocrystalline graphene sheets has been confirmed by scanning electron microscopy, X-ray diffraction and Raman spectroscopy. The electrochemical performance of graphene sheets as anode material for lithium ion batteries was evaluated by cycling voltammetry, galvanostatic charge-discharge cycling, and electrochemical impedance spectroscopy. Fabricated graphene sheets exhibited high discharge capacity of about 1120 mAh·g −1 and demonstrated good reversibility of lithium intercalation and deintercalation in graphene sheet film with capacity retention over 85 % after 50 cycles. Results show that nanocrystalline graphene sheets prepared by EPD demonstrated a high potential for application as anode material in lithium ion batteries

  20. Ferroelectric Polarization in Nanocrystalline Hydroxyapatite Thin Films on Silicon

    Science.gov (United States)

    Lang, S. B.; Tofail, S. A. M.; Kholkin, A. L.; Wojtaś, M.; Gregor, M.; Gandhi, A. A.; Wang, Y.; Bauer, S.; Krause, M.; Plecenik, A.

    2013-01-01

    Hydroxyapatite nanocrystals in natural form are a major component of bone- a known piezoelectric material. Synthetic hydroxyapatite is widely used in bone grafts and prosthetic pyroelectric coatings as it binds strongly with natural bone. Nanocrystalline synthetic hydroxyapatite films have recently been found to exhibit strong piezoelectricity and pyroelectricity. While a spontaneous polarization in hydroxyapatite has been predicted since 2005, the reversibility of this polarization (i.e. ferroelectricity) requires experimental evidence. Here we use piezoresponse force microscopy to demonstrate that nanocrystalline hydroxyapatite indeed exhibits ferroelectricity: a reversal of polarization under an electrical field. This finding will strengthen investigations on the role of electrical polarization in biomineralization and bone-density related diseases. As hydroxyapatite is one of the most common biocompatible materials, our findings will also stimulate systematic exploration of lead and rare-metal free ferroelectric devices for potential applications in areas as diverse as in vivo and ex vivo energy harvesting, biosensing and electronics. PMID:23884324

  1. Nanocrystalline SiC and Ti3SiC2 Alloys for Reactor Materials: Diffusion of Fission Product Surrogates

    Energy Technology Data Exchange (ETDEWEB)

    Henager, Charles H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jiang, Weilin [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-11-01

    MAX phases, such as titanium silicon carbide (Ti3SiC2), have a unique combination of both metallic and ceramic properties, which make them attractive for potential nuclear applications. Ti3SiC2 has been suggested in the literature as a possible fuel cladding material. Prior to the application, it is necessary to investigate diffusivities of fission products in the ternary compound at elevated temperatures. This study attempts to obtain relevant data and make an initial assessment for Ti3SiC2. Ion implantation was used to introduce fission product surrogates (Ag and Cs) and a noble metal (Au) in Ti3SiC2, SiC, and a dual-phase nanocomposite of Ti3SiC2/SiC synthesized at PNNL. Thermal annealing and in-situ Rutherford backscattering spectrometry (RBS) were employed to study the diffusivity of the various implanted species in the materials. In-situ RBS study of Ti3SiC2 implanted with Au ions at various temperatures was also performed. The experimental results indicate that the implanted Ag in SiC is immobile up to the highest temperature (1273 K) applied in this study; in contrast, significant out-diffusion of both Ag and Au in MAX phase Ti3SiC2 occurs during ion implantation at 873 K. Cs in Ti3SiC2 is found to diffuse during post-irradiation annealing at 973 K, and noticeable Cs release from the sample is observed. This study may suggest caution in using Ti3SiC2 as a fuel cladding material for advanced nuclear reactors operating at very high temperatures. Further studies of the related materials are recommended.

  2. Temperature-dependent impedance spectroscopy of La0.8Sr0.2FeO3 nano-crystalline material

    Science.gov (United States)

    Kafa, C. A.; Triyono, D.; Laysandra, H.

    2017-04-01

    LaFeO3 is a material with perovskite structure which electrical properties frequently investigated. Research are done due to the exhibition of excellent gas sensing behavior through resistivity comparison from the p-type semiconductor. Sr doping on LaFeO3 or La1-xSrxFeO3 are able to improve the electrical conductivity through structural modification. Using Sr dopant concentration (x) of 0.2, La0.8Sr0.2FeO3 nano-crystal pellet was synthesized. The synthesis used sol-gel method, followed by gradual heat treatment and uniaxial compaction. XRD characterization shows that the structure of the sample is Orthorhombic Perovskite. Topography of the sample by SEM reveals grain and grain boundary existence with emerging agglomeration. The electrical properties of the material, as functions of temperature and frequency, were measured by Impedance Spectroscopy method using RLC meter, for temperatures of 303-373K. Through the Nyquist plot and Bode plot, the electrical conductivity of La0.8Sr0.2FeO3 is contributed by the grain and grain boundary. Finally, the electrical permittivities of La0.8Sr0.2FeO3 are increasing with temperature increase, with the highest achieved when measured at 1 kHz frequency.

  3. THz generation from a nanocrystalline silicon-based photoconductive device

    International Nuclear Information System (INIS)

    Daghestani, N S; Persheyev, S; Cataluna, M A; Rose, M J; Ross, G

    2011-01-01

    Terahertz generation has been achieved from a photoconductive switch based on hydrogenated nanocrystalline silicon (nc-Si:H), gated by a femtosecond laser. The nc-Si:H samples were produced by a hot wire chemical vapour deposition process, a process with low production costs owing to its higher growth rate and manufacturing simplicity. Although promising ultrafast carrier dynamics of nc-Si have been previously demonstrated, this is the first report on THz generation from a nc-Si:H material

  4. Nanocrystalline SiC film thermistors for cryogenic applications

    Science.gov (United States)

    Mitin, V. F.; Kholevchuk, V. V.; Semenov, A. V.; Kozlovskii, A. A.; Boltovets, N. S.; Krivutsa, V. A.; Slepova, A. S.; Novitskii, S. V.

    2018-02-01

    We developed a heat-sensitive material based on nanocrystalline SiC films obtained by direct deposition of carbon and silicon ions onto sapphire substrates. These SiC films can be used for resistance thermometers operating in the 2 K-300 K temperature range. Having high heat sensitivity, they are relatively low sensitive to the magnetic field. The designs of the sensors are presented together with a discussion of their thermometric characteristics and sensitivity to magnetic fields.

  5. Stability of nanocrystalline electrochemically deposited layers

    DEFF Research Database (Denmark)

    Pantleon, Karen; Somers, Marcel A. J.

    2009-01-01

    have different microstructure and properties compared to bulk materials and the thermodynamic non-equilibrium state of as-deposited layers frequently results in changes of the microstructure as a function of time and/or temperature. The evolving microstructure affects the functionality and reliability......The technological demand for manufacturing components with complex geometries of micrometer or sub-micrometer dimensions and ambitions for ongoing miniaturization have attracted particular attention to electrochemical deposition methods. Thin layers of electrochemically deposited metals and alloys...... of electrodeposited components, which can be beneficial, as for the electrical conductivity of copper interconnect lines, or detrimental, as for reduced strength of nickel in MEMS applications. The present work reports on in-situ studies of the microstructure stability of as-deposited nanocrystalline Cu-, Ag- and Ni...

  6. Reinforced plastics and aerogels by nanocrystalline cellulose

    Energy Technology Data Exchange (ETDEWEB)

    Leung, Alfred C. W.; Lam, Edmond; Chong, Jonathan; Hrapovic, Sabahudin; Luong, John H. T., E-mail: john.luong@cnrc-nrc.gc.ca [National Research Council Canada (Canada)

    2013-05-15

    Nanocrystalline cellulose (NCC), a rigid rod-like nanoscale material, can be produced from cellulosic biomass in powder, liquid, or gel forms by acid and chemical hydrolysis. Owing to its unique and exceptional physicochemical properties, the incorporation of a small amount of NCC into plastic enhances the mechanical strength of the latter by several orders of magnitudes. Carbohydrate-based NCC poses no serious environmental concerns, providing further impetus for the development and applications of this green and renewable biomaterial to fabricate lightweight and biodegradable composites and aerogels. Surface functionalization of NCC remains the main focus of NCC research to tailor its properties for dispersion in hydrophilic or hydrophobic media. It is of uttermost importance to develop tools and protocols for imaging of NCC in a complex matrix and quantify its reinforcement effect.

  7. Arsenic removal by magnetic nanocrystalline barium hexaferrite

    International Nuclear Information System (INIS)

    Patel, Hasmukh A.; Byun, Jeehye; Yavuz, Cafer T.

    2012-01-01

    Nanoscale magnetite (Fe 3 O 4 ) ( 12 O 19 , BHF) is a well-known permanent magnet (i.e., fridge magnets) and attractive due to its low cost in making large quantities. BHF offers a viable alternative to magnetite nanocrystals for arsenic removal since it features surfaces similar to iron oxides but with much enhanced magnetism. Herein, we employ BHF nanocrystalline materials for the first time in arsenic removal from wastewater. Our results show better (75 %) arsenic removal than magnetite of the similar sizes. The BHF nanoparticles, 6.06 ± 0.52 nm synthesized by thermolysis method at 320 °C do not show hexagonal phase, however, subsequent annealing at 750 °C produced pure hexagonal BHF in >200 nm assemblies. By using BHF, we demonstrate that nanoparticle removal is more efficient and fixed bed type cartridge applications are more possible.

  8. 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.

  9. Evaluation of cost reduction method for manufacturing ODS ferritic claddings

    International Nuclear Information System (INIS)

    Fujiwara, Masayuki; Mizuta, Shunji; Ukai, Shigeharu

    2000-04-01

    For evaluating the fast reactor system technology, it is important to evaluate the practical feasibility of ODS ferritic claddings, which is the most promising materials to attain the goal of high coolant temperature and more than 150 GWd/t. Based on the results of their technology development, mass production process with highly economically benefit as well as manufacturing cost estimation of ODS ferritic claddings were preliminarily conducted. From the view point of future utility scale, the cost for manufacturing mother tubes has a dominant factor in the total manufacturing cost. The method to reduce the cost of mother tube manufacturing was also preliminarily investigated. (author)

  10. Impedimetric detection of alcohol vapours using nanostructured zinc ferrite.

    Science.gov (United States)

    Kannan, Padmanathan Karthick; Saraswathi, Ramiah

    2014-11-01

    A comparative study on the sensing characteristics of nanostructured zinc ferrite to three primary alcohols viz. methanol, ethanol and propanol has been carried out. The zinc ferrite has been prepared by a combustion method and characterized by XRD, FTIR, AFM and SEM. Impedance studies in the alcohol concentration range varying from 100 to 1000 ppm show definite variations in response to both the nature of the alcohol and its concentration. The nanostructured zinc ferrite shows the highest sensor response to methanol and least to propanol. Equivalent circuit modelling and calibration have been made for all the three alcohol sensors. The material shows a better selectivity to the alcohols compared to formaldehyde, ammonia and acetone vapours. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Nanocrystalline diamond coatings for machining

    Energy Technology Data Exchange (ETDEWEB)

    Frank, M.; Breidt, D.; Cremer, R. [CemeCon AG, Wuerselen (Germany)

    2007-07-01

    This history of CVD diamond synthesis goes back to the fifties of the last century. However, the scientific and economical potential was only gradually recognized. In the eighties, intensive worldwide research on CVD diamond synthesis and applications was launched. Industrial products, especially diamond-coated cutting tools, were introduced to the market in the middle of the nineties. This article shows the latest developments in this area, which comprises nanocrystalline diamond coating structures. (orig.)

  12. Bismuth Ferrite for Active Control of Surface Plasmon Polariton Modes

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Zhukovsky, Sergei; Lavrinenko, Andrei

    2014-01-01

    We propose and investigate several layouts of m etal-insulator-metal waveguide with active core which can be utilized for dynamic switching in photonic integrated circuits. The active material, bismuth ferrite (BiFeO3), is sandwiched between metal plates and changes i ts refractive index through...

  13. Development and application of dispersive soft ferrite models for time-domain simulation

    International Nuclear Information System (INIS)

    DeFord, J.F.; Kamin, G.; Craig, G.D.; Walling, L.

    1992-01-01

    Ferrite has a variety of applications in accelerator components, and the capability to model this magnetic material in the time domain is an important adjunct to currently available accelerator modeling tool. We describe in this report a material model we have developed for the magnetic characteristics of PE11BL, the ferrite found in the ETA-II (Experimental Test Accelerator-II) induction module. This model, which includes the important magnetic dispersion effects found in most soft ferrites, has been implemented in 1-D and 2-D finite-difference time-domain (FDTD) electromagnetic simulators, and comparisons with analytic and experimental results are presented

  14. Biologically inspired rosette nanotubes and nanocrystalline hydroxyapatite hydrogel nanocomposites as improved bone substitutes

    International Nuclear Information System (INIS)

    Zhang Lijie; Webster, Thomas J; Rodriguez, Jose; Raez, Jose; Myles, Andrew J; Fenniri, Hicham

    2009-01-01

    Today, bone diseases such as bone fractures, osteoporosis and bone cancer represent a common and significant public health problem. The design of biomimetic bone tissue engineering materials that could restore and improve damaged bone tissues provides exciting opportunities to solve the numerous problems associated with traditional orthopedic implants. Therefore, the objective of this in vitro study was to create a biomimetic orthopedic hydrogel nanocomposite based on the self-assembly properties of helical rosette nanotubes (HRNs), the osteoconductive properties of nanocrystalline hydroxyapatite (HA), and the biocompatible properties of hydrogels (specifically, poly(2-hydroxyethyl methacrylate), pHEMA). HRNs are self-assembled nanomaterials that are formed from synthetic DNA base analogs in water to mimic the helical nanostructure of collagen in bone. In this study, different geometries of nanocrystalline HA were controlled by either hydrothermal or sintering methods. 2 and 10 wt% nanocrystalline HA particles were well dispersed into HRN hydrogels using ultrasonication. The nanocrystalline HA and nanocrystalline HA/HRN hydrogels were characterized by x-ray diffraction, transmission electron microscopy, and scanning electron microscopy. Mechanical testing studies revealed that the well dispersed nanocrystalline HA in HRN hydrogels possessed improved mechanical properties compared to hydrogel controls. In addition, the results of this study provided the first evidence that the combination of either 2 or 10 wt% nanocrystalline HA and 0.01 mg ml -1 HRNs in hydrogels greatly increased osteoblast (bone-forming cell) adhesion up to 236% compared to hydrogel controls. Moreover, this study showed that HRNs stimulated HA nucleation and mineralization along their main axis in a way that is very reminiscent of the HA/collagen assembly pattern in natural bone. In summary, the presently observed excellent properties of the biomimetic nanocrystalline HA/HRN hydrogel composites

  15. Synthesis of Highly Uniform and Compact Lithium Zinc Ferrite Ceramics via an Efficient Low Temperature Approach.

    Science.gov (United States)

    Xu, Fang; Liao, Yulong; Zhang, Dainan; Zhou, Tingchuan; Li, Jie; Gan, Gongwen; Zhang, Huaiwu

    2017-04-17

    LiZn ferrite ceramics with high saturation magnetization (4πM s ) and low ferromagnetic resonance line widths (ΔH) represent a very critical class of material for microwave ferrite devices. Many existing approaches emphasize promotion of the grain growth (average size is 10-50 μm) of ferrite ceramics to improve the gyromagnetic properties at relatively low sintering temperatures. This paper describes a new strategy for obtaining uniform and compact LiZn ferrite ceramics (average grains size is ∼2 μm) with enhanced magnetic performance by suppressing grain growth in great detail. The LiZn ferrites with a formula of Li 0.415 Zn 0.27 Mn 0.06 Ti 0.1 Fe 2.155 O 4 were prepared by solid reaction routes with two new sintering strategies. Interestingly, results show that uniform, compact, and pure spinel ferrite ceramics were synthesized at a low temperature (∼850 °C) without obvious grain growth. We also find that a fast second sintering treatment (FSST) can further improve their gyromagnetic properties, such as higher 4πM s and lower ΔH. The two new strategies are facile and efficient for densification of LiZn ferrite ceramics via suppressing grain growth at low temperatures. The sintering strategy reported in this study also provides a referential experience for other ceramics, such as soft magnetism ferrite ceramics or dielectric ceramics.

  16. A study of the structure and crystallisation of nanocrystalline zirconia

    International Nuclear Information System (INIS)

    Tucker, M.

    1999-12-01

    Nanocrystalline zirconia, prepared via, calcination of the hydroxide, has been studied using a variety of experimental techniques. Two chemical routes, a precipitation and a sol-gel route, were used to prepare the hydroxide. Neutron and X-ray diffraction, EXAFS, NMR and SANS have been used to study the structure and crystallisation, during in-situ and ambient condition measurements. The structural information from the diffraction data has been complimented by the other techniques to provide information on the short, medium and longer range structure of nanocrystalline zirconia. Pure and yttrium doped samples were studied, this enabled the affects of doping and preparation routes to be investigated. The amorphous hydroxide was found to have a, monoclinic-like structure for all samples, independent of preparation route or yttrium content. The crystallisation temperature was lowest for the pure precipitation sample and was increased by the addition of yttrium or by preparation via, the sol-gel route. For the precipitation samples, in addition to the crystallisation temperature being raised, doping with yttrium also had an effect on the size of the crystallites obtained at high temperatures. Due to the different incorporation method of the yttrium into the sol-gel samples the effect on crystallite size and crystallisation temperature, as seen for the precipitation samples, were not evident for the sol-gel samples. The neutron and NMR data clearly show hydrogen remains in the samples well after crystallisation has become evident. The structural picture of nanocrystalline zirconia consisting of small crystallites surrounded by material containing, or terminated by, hydroxyl groups, is supported by all the results and methods used in this thesis. The in-situ and ambient conditions data is combined into a coherent growth picture of the nanocrystalline material from the hydroxide until at high enough temperatures the bulk or polycrystalline material is formed. (author)

  17. Effect of Yttrium Addition on the Microstructure and Mechanical Properties of Cu-Rich Nano-phase Strengthened Ferritic Steel

    Science.gov (United States)

    Liu, Hongyu; He, Jibai; Luan, Guoqing; Ke, Mingpeng; Fang, Haoyan; Lu, Jianduo

    2018-03-01

    Due to the brittle problem of Cu-rich nano-phase strengthened ferritic steel (CNSFS) after air aging, the effect of Y addition in CNSFS was systemically investigated in the present work. The microstructure, tensile fracture morphology and oxide layer of the steels were surveyed by optical microscope and scanning electron microscope. Transmission electron microscope with the combination of energy-dispersive x-ray spectroscopy and selected area electron diffraction was used to analyze the morphology, size, number density, chemical compositions and crystal structure for nano-crystalline precipitates. Microstructural examinations of the nano-crystalline precipitates show that Cu-rich precipitates and Y compounds in the range of 2-10 and 50-100 nm, respectively, form in the Y-containing steel; meanwhile, the average size of nano-crystalline precipitates in Y-containing steel is larger, but the number density is lower, and the ferritic grains are refined. Furthermore, the tensile strength and ductility of Y-containing steel after air aging are improved, whereas the tensile strength is enhanced and the ductility decreased after vacuum aging. The drag effect of Y makes the oxide layer thinner and be compacted. Tensile properties of CNSFS after air aging are improved due to the refined grains, antioxidation and purification by the addition of Y.

  18. Preparation, characterization and luminescence of nanocrystalline Y2O3:Ho

    International Nuclear Information System (INIS)

    Biljan, Tomislav; Gajovic, Andreja; Meic, Zlatko; Mestrovic, Ernest

    2007-01-01

    Nanocrystalline Y 2 O 3 :Ho was synthesized by solution combustion method with ethylene glycol as fuel. Material was characterized using powder X-ray diffraction and transmission electron microscopy (TEM). X-ray diffraction and TEM showed that the material is nanostructured. Luminescence properties were studied using Raman spectrometers with excitation in near infrared (NIR) and visible regions. The visible and NIR luminescence spectra of nanocrystalline Y 2 O 3 :Ho show some important differences from those of bulk material. The convenience of using Raman instruments for studying luminescence of lanthanide ions is demonstrated

  19. Dye-Sensitized Solar Cells Based on High Surface Area Nanocrystalline Zinc Oxide Spheres

    Directory of Open Access Journals (Sweden)

    Pavuluri Srinivasu

    2011-01-01

    Full Text Available High surface area nanocrystalline zinc oxide material is fabricated using mesoporous nanostructured carbon as a sacrificial template through combustion process. The resulting material is characterized by XRD, N2 adsorption, HR-SEM, and HR-TEM. The nitrogen adsorption measurement indicates that the materials possess BET specific surface area ca. 30 m2/g. Electron microscopy images prove that the zinc oxide spheres possess particle size in the range of 0.12 μm–0.17 μm. The nanocrystalline zinc oxide spheres show 1.0% of energy conversion efficiency for dye-sensitized solar cells.

  20. Grain boundary and triple junction diffusion in nanocrystalline copper

    Energy Technology Data Exchange (ETDEWEB)

    Wegner, M., E-mail: m.wegner@uni-muenster.de; Leuthold, J.; Peterlechner, M.; Divinski, S. V., E-mail: divin@uni-muenster.de [Institut für Materialphysik, Universität Münster, Wilhelm-Klemm-Straße 10, D-48149, Münster (Germany); Song, X., E-mail: xysong@bjut.edu.cn [College of Materials Science and Engineering, Beijing University of Technology, 100124 Beijing (China); Wilde, G. [Institut für Materialphysik, Universität Münster, Wilhelm-Klemm-Straße 10, D-48149, Münster (Germany); Institute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering, Shanghai University, 200444 Shanghai (China)

    2014-09-07

    Grain boundary and triple junction diffusion in nanocrystalline Cu samples with grain sizes, 〈d〉, of ∼35 and ∼44 nm produced by spark plasma sintering were investigated by the radiotracer method using the {sup 63}Ni isotope. The measured diffusivities, D{sub eff}, are comparable with those determined previously for Ni grain boundary diffusion in well-annealed, high purity, coarse grained, polycrystalline copper, substantiating the absence of a grain size effect on the kinetic properties of grain boundaries in a nanocrystalline material at grain sizes d ≥ 35 nm. Simultaneously, the analysis predicts that if triple junction diffusion of Ni in Cu is enhanced with respect to the corresponding grain boundary diffusion rate, it is still less than 500⋅D{sub gb} within the temperature interval from 420 K to 470 K.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. Structure and thermal stability of nanocrystalline materials

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    , ... Advances in nanoscience and nanotechnology are expected to have major impact on human .... faces, Baloghet al(2000) have reported that the grain boundary of ..... volume self-diffusion (Lu 1996; Krill et al 2001; Lu et al 1995) implies that ...

  7. Preparation of high-quality ultrathin transmission electron microscopy specimens of a nanocrystalline metallic powder.

    Science.gov (United States)

    Riedl, Thomas; Gemming, Thomas; Mickel, Christine; Eymann, Konrad; Kirchner, Alexander; Kieback, Bernd

    2012-06-01

    This article explores the achievable transmission electron microscopy specimen thickness and quality by using three different preparation methods in the case of a high-strength nanocrystalline Cu-Nb powder alloy. Low specimen thickness is essential for spatially resolved analyses of the grains in nanocrystalline materials. We have found that single-sided as well as double-sided low-angle Ar ion milling of the Cu-Nb powders embedded into epoxy resin produced wedge-shaped particles of very low thickness (coating on the sections consisting of epoxy deployed as the embedding material and considerable nanoscale thickness variations. Copyright © 2011 Wiley Periodicals, Inc.

  8. Dynamic recovery in nanocrystalline Ni

    International Nuclear Information System (INIS)

    Sun, Z.; Van Petegem, S.; Cervellino, A.; Durst, K.; Blum, W.; Van Swygenhoven, H.

    2015-01-01

    The constant flow stress reached during uniaxial deformation of electrodeposited nanocrystalline Ni reflects a quasi-stationary balance between dislocation slip and grain boundary (GB) accommodation mechanisms. Stress reduction tests allow to suppress dislocation slip and bring recovery mechanisms into the foreground. When combined with in situ X-ray diffraction it can be shown that grain boundary recovery mechanisms play an important role in producing plastic strain while hardening the microstructure. This result has a significant consequence for the parameters of thermally activated glide of dislocations, such as athermal stress and activation volume, which are traditionally derived from stress/strain rate change tests

  9. The effects of laser welding parameters on the microstructure of ferritic and duplex stainless steels welds

    Science.gov (United States)

    Pekkarinen, J.; Kujanpää, V.

    This study is focused to determine empirically, which microstructural changes occur in ferritic and duplex stainless steels when heat input is controlled by welding parameters. Test welds were done autogenously bead-on-plate without shielding gas using 5 kW fiber laser. For comparison, some gas tungsten arc welds were made. Used test material were 1.4016 (AISI 430) and 1.4003 (low-carbon ferritic) type steels in ferritic steels group and 1.4162 (low-alloyed duplex, LDX2101) and 1.4462 (AISI 2205) type steels in duplex steels group. Microstructural changes in welds were identified and examined using optical metallographic methods.

  10. Uncertainty propagation in a multiscale model of nanocrystalline plasticity

    International Nuclear Information System (INIS)

    Koslowski, M.; Strachan, Alejandro

    2011-01-01

    We characterize how uncertainties propagate across spatial and temporal scales in a physics-based model of nanocrystalline plasticity of fcc metals. Our model combines molecular dynamics (MD) simulations to characterize atomic-level processes that govern dislocation-based-plastic deformation with a phase field approach to dislocation dynamics (PFDD) that describes how an ensemble of dislocations evolve and interact to determine the mechanical response of the material. We apply this approach to a nanocrystalline Ni specimen of interest in micro-electromechanical (MEMS) switches. Our approach enables us to quantify how internal stresses that result from the fabrication process affect the properties of dislocations (using MD) and how these properties, in turn, affect the yield stress of the metallic membrane (using the PFMM model). Our predictions show that, for a nanocrystalline sample with small grain size (4 nm), a variation in residual stress of 20 MPa (typical in today's microfabrication techniques) would result in a variation on the critical resolved shear yield stress of approximately 15 MPa, a very small fraction of the nominal value of approximately 9 GPa. - Highlights: → Quantify how fabrication uncertainties affect yield stress in a microswitch component. → Propagate uncertainties in a multiscale model of single crystal plasticity. → Molecular dynamics quantifies how fabrication variations affect dislocations. → Dislocation dynamics relate variations in dislocation properties to yield stress.

  11. Size-dependent deformation behavior of nanocrystalline graphene sheets

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhi [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Huang, Yuhong [College of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062, Shaanxi (China); Ma, Fei, E-mail: mafei@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Sun, Yunjin [Faculty of Food Science and Engineering, Beijing University of Agriculture, Beijing Key Laboratory of Agricultural Product Detection and Control of Spoilage Organisms and Pesticide Residue, Beijing Laboratory of Food Quality and Safety, Beijing 102206 (China); Xu, Kewei, E-mail: kwxu@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Department of Physics and Opt-electronic Engineering, Xi’an University of Arts and Science, Xi’an 710065, Shaanxi (China); Chu, Paul K., E-mail: paul.chu@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

    2015-08-15

    Highlights: • MD simulation is conducted to study the deformation of nanocrystalline graphene. • Unexpectedly, the elastic modulus decreases with the grain size considerably. • But the fracture stress and strain are nearly insensitive to the grain size. • A composite model with grain domains and GBs as two components is suggested. - Abstract: Molecular dynamics (MD) simulation is conducted to study the deformation behavior of nanocrystalline graphene sheets. It is found that the graphene sheets have almost constant fracture stress and strain, but decreased elastic modulus with grain size. The results are different from the size-dependent strength observed in nanocrystalline metals. Structurally, the grain boundaries (GBs) become a principal component in two-dimensional materials with nano-grains and the bond length in GBs tends to be homogeneously distributed. This is almost the same for all the samples. Hence, the fracture stress and strain are almost size independent. As a low-elastic-modulus component, the GBs increase with reducing grain size and the elastic modulus decreases accordingly. A composite model is proposed to elucidate the deformation behavior.

  12. Investigation of microstructure thermal evolution in nanocrystalline Cu

    International Nuclear Information System (INIS)

    Zhou Kai; Li Hui; Pang Jinbiao; Wang Zhu

    2011-01-01

    The microstructure of nanocrystalline Cu prepared by compacting nanoparticles (50-60 nm in diameter) under high pressures has been studied by means of positron lifetime spectroscopy and X-ray diffraction. These nanoparticles were produced by two different methods. We found that there are order regions interior to the grains and disorder regions at the grain boundaries with a wide distribution of interatomic distances. The mean grain sizes of the nanocrystalline Cu samples decrease after being annealed at 900 o C and increase during aging at 180 o C, which are observed by X-ray diffraction, revealing that the atoms exchange between the two regions. The positron lifetime results clearly indicate that the vacancy clusters formed in the annealing process are unstable and decomposed at the aging time below 6 hours. In addition, the partially oxidized surfaces of the nanoparticles hinder grain growth when the samples age at 180 o C, and the vacancy clusters inside the disorder regions, which are related to Cu 2 O, need longer aging time to decompose. The disorder regions remain after the heat treatment in this work, in spite of the grain growth, which will be good for the samples keeping the properties of nanocrystalline material. -- Research highlights: → We use a digital positron lifetime spectrometer correlated with XRD to study the microstructure evolution of nanocrystalline Cu during thermal treatment. → An atomic scale microstructure of grain boundary is characterized. Further, the surface oxidation of the nanoparticles is considered. → The disorder regions remain after the heat treatment in this work, in spite of grain growth.

  13. Effects of oxide distributed in grain boundaries on microstructure stability of nanocrystalline metals

    Science.gov (United States)

    Zhou, Kai; Li, Hui; Biao Pang, Jin; Wang, Zhu

    2013-06-01

    Nanocrystalline copper and zinc prepared by high-pressure compaction method have been studied by positron lifetime spectroscopy associated with X-ray diffraction. For nanocrystalline Cu, mean grain sizes of the samples decrease after being annealed at 900 °C and increase during aging at 180 °C, revealing that the atoms exchange between the two regions. The positron lifetime results indicate that the vacancy clusters formed in the annealing process are unstable and decomposed at the aging time below 6 hours. In addition, the partially oxidized surfaces of the nanoparticles hinder the grain growth during the ageing at 180 °C, and the vacancy clusters inside the disorder regions which are related to Cu2O need longer aging time to decompose. In the case of nanocrystalline Zn, the open volume defect (not larger than divacancy) is dominant according to the high relative intensity for the short positron lifetime (τ1). The oxide (ZnO) inside the grain boundaries has been found having an effect to hinder the decrease of average positron lifetime (τav) during the annealing, which probably indicates that the oxide stabilizes the microstructure of the grain boundaries. For both nanocrystalline copper and zinc, the oxides in grain boundaries enhance the thermal stability of the microstucture, in spite of their different crystal structures. This effect is very important for the nanocrystalline materials using as radiation resistant materials.

  14. Effects of oxide distributed in grain boundaries on microstructure stability of nanocrystalline metals

    International Nuclear Information System (INIS)

    Zhou Kai; Li Hui; Pang Jinbiao; Wang Zhu

    2013-01-01

    Nanocrystalline copper and zinc prepared by high-pressure compaction method have been studied by positron lifetime spectroscopy associated with X-ray diffraction. For nanocrystalline Cu, mean grain sizes of the samples decrease after being annealed at 900 °C and increase during aging at 180 °C, revealing that the atoms exchange between the two regions. The positron lifetime results indicate that the vacancy clusters formed in the annealing process are unstable and decomposed at the aging time below 6 hours. In addition, the partially oxidized surfaces of the nanoparticles hinder the grain growth during the ageing at 180 °C, and the vacancy clusters inside the disorder regions which are related to Cu 2 O need longer aging time to decompose. In the case of nanocrystalline Zn, the open volume defect (not larger than divacancy) is dominant according to the high relative intensity for the short positron lifetime (τ 1 ). The oxide (ZnO) inside the grain boundaries has been found having an effect to hinder the decrease of average positron lifetime (τ av ) during the annealing, which probably indicates that the oxide stabilizes the microstructure of the grain boundaries. For both nanocrystalline copper and zinc, the oxides in grain boundaries enhance the thermal stability of the microstucture, in spite of their different crystal structures. This effect is very important for the nanocrystalline materials using as radiation resistant materials.

  15. Sputtered tungsten-based ternary and quaternary layers for nanocrystalline diamond deposition.

    Science.gov (United States)

    Walock, Michael J; Rahil, Issam; Zou, Yujiao; Imhoff, Luc; Catledge, Shane A; Nouveau, Corinne; Stanishevsky, Andrei V

    2012-06-01

    Many of today's demanding applications require thin-film coatings with high hardness, toughness, and thermal stability. In many cases, coating thickness in the range 2-20 microm and low surface roughness are required. Diamond films meet many of the stated requirements, but their crystalline nature leads to a high surface roughness. Nanocrystalline diamond offers a smoother surface, but significant surface modification of the substrate is necessary for successful nanocrystalline diamond deposition and adhesion. A hybrid hard and tough material may be required for either the desired applications, or as a basis for nanocrystalline diamond film growth. One possibility is a composite system based on carbides or nitrides. Many binary carbides and nitrides offer one or more mentioned properties. By combining these binary compounds in a ternary or quaternary nanocrystalline system, we can tailor the material for a desired combination of properties. Here, we describe the results on the structural and mechanical properties of the coating systems composed of tungsten-chromium-carbide and/or nitride. These WC-Cr-(N) coatings are deposited using magnetron sputtering. The growth of adherent nanocrystalline diamond films by microwave plasma chemical vapor deposition has been demonstrated on these coatings. The WC-Cr-(N) and WC-Cr-(N)-NCD coatings are characterized with atomic force microscopy and SEM, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and nanoindentation.

  16. 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.

  17. Irradiation creep in ferritic steels

    International Nuclear Information System (INIS)

    Vandermeulen, W.; Bremaecker, A. de; Burbure, S. de; Huet, J.J.; Asbroeck, P. van

    Pressurized and non-pressurized capsules of several ferritic steels have been irradiated in Rapsodie between 400 and 500 0 C up to 3.7 x 10 22 n/cm 2 (E>0.1 MeV). Results of the diameter measurements are presented and show that the total in-pile deformation is lower than for austenitic steels

  18. Stability of ferritic steel to higher doses: Survey of reactor pressure vessel steel data and comparison with candidate materials for future nuclear systems

    International Nuclear Information System (INIS)

    Blagoeva, D.T.; Debarberis, L.; Jong, M.; Pierick, P. ten

    2014-01-01

    This paper is illustrating the potential of the well-known low alloyed clean steels, extensively used for the current light water Reactor Pressure Vessels (RPV) steels, for a likely use as a structural material also for the new generation nuclear systems. This option would provide, especially for large components, affordable, easily accessible and a technically more convenient solution in terms of manufacturing and joining techniques. A comprehensive comparison between several sets of surveillance and research data available for a number of RPV clean steels for doses up to 1.5 dpa, and up to 12 dpa for 9%Cr steels, is carried out in order to evaluate radiation stability of the currently used RPV clean steels even at higher doses. Based on the numerous data available, positive preliminary conclusions are drawn regarding the eventual use of clean RPV steels for the massive structural components of the new reactor systems. - Highlights: • Common embrittlement trend between RPV and advanced steels till intermediate doses. • For doses >1.5 dpa, damage rate saturation tendency is observed for RPV steels. • RPV steels might be conveniently utilised also outside their foreseen dose range

  19. In-situ TEM observation of the response of ultrafine- and nanocrystalline-grained tungsten to extreme irradiation environments.

    Science.gov (United States)

    El-Atwani, O; Hinks, J A; Greaves, G; Gonderman, S; Qiu, T; Efe, M; Allain, J P

    2014-05-06

    The accumulation of defects, and in particular He bubbles, can have significant implications for the performance of materials exposed to the plasma in magnetic-confinement nuclear fusion reactors. Some of the most promising candidates for deployment into such environments are nanocrystalline materials as the engineering of grain boundary density offers the possibility of tailoring their radiation resistance properties. In order to investigate the microstructural evolution of ultrafine- and nanocrystalline-grained tungsten under conditions similar to those in a reactor, a transmission electron microscopy study with in situ 2 keV He(+) ion irradiation at 950 °C has been completed. A dynamic and complex evolution in the microstructure was observed including the formation of defect clusters, dislocations and bubbles. Nanocrystalline grains with dimensions less than around 60 nm demonstrated lower bubble density and greater bubble size than larger nanocrystalline (60-100 nm) and ultrafine (100-500 nm) grains. In grains over 100 nm, uniform distributions of bubbles and defects were formed. At higher fluences, large faceted bubbles were observed on the grain boundaries, especially on those of nanocrystalline grains, indicating the important role grain boundaries can play in trapping He and thus in giving rise to the enhanced radiation tolerance of nanocrystalline materials.

  20. Development of FEMAG. Calculation code of magnetic field generated by ferritic plates in the tokamak devices

    Energy Technology Data Exchange (ETDEWEB)

    Urata, Kazuhiro [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

    2003-03-01

    In design of the future fusion devises in which low activation ferritic steel is planned to use as the plasma facing material and/or the inserts for ripple reduction, the appreciation of the error field effect against the plasma as well as the optimization of ferritic plate arrangement to reduce the toroidal field ripple require calculation of magnetic field generated by ferritic steel. However iterative calculations concerning the non-linearity in B-H curve of ferritic steel disturbs high-speed calculation required as the design tool. In the strong toroidal magnetic field that is characteristic in the tokamak fusion devices, fully magnetic saturation of ferritic steel occurs. Hence a distribution of magnetic charges as magnetic field source is determined straightforward and any iteration calculation are unnecessary. Additionally objective ferritic steel geometry is limited to the thin plate and ferritic plates are installed along the toroidal magnetic field. Taking these special conditions into account, high-speed calculation code ''FEMAG'' has been developed. In this report, the formalization of 'FEMAG' code, how to use 'FEMAG', and the validity check of 'FEMAG' in comparison with a 3D FEM code, with the measurements of the magnetic field in JFT-2M are described. The presented examples are numerical results of design studies for JT-60 modification. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-09-08

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

  2. Determination of delta ferrite volumetric fraction in austenitic stainless steel

    International Nuclear Information System (INIS)

    Almeida Macedo, W.A. de.

    1983-01-01

    Measurements of delta ferrite volumetric fraction in AISI 304 austenitic stainless steels were done by X-ray diffraction, quantitative metallography (point count) and by means of one specific commercial apparatus whose operational principle is magnetic-inductive: The Ferrite Content Meter 1053 / Institut Dr. Foerster. The results obtained were comparated with point count, the reference method. It was also investigated in these measurements the influence of the martensite induced by mechanical deformation. Determinations by X-ray diffraction, by the ratio between integrated intensities of the ferrite (211) and austenite (311) lines, are in excelent agreement with those taken by point count. One correction curve for the lectures of the commercial equipment in focus was obtained, for the range between zero and 20% of delta ferrite in 18/8 stainless steels. It is demonstrated that, depending on the employed measurement method and surface finishing of the material to be analysed, the presence of martensite produced by mechanical deformation of the austenitic matrix is one problem to be considered. (Author) [pt

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

    Energy Technology Data Exchange (ETDEWEB)

    Amiri, S.; Shokrollahi, H., E-mail: Shokrollahi@sutech.ac.ir

    2013-01-01

    The nanotechnology industry is rapidly growing and promises that the substantial changes that will have significant economic and scientific impacts be applicable to a wide range of areas, such as aerospace engineering, nano-electronics, environmental remediation and medical healthcare. In this area, cobalt ferrite nanoparticles have been regarded as one of the competitive candidates because of their suitable physical, chemical and magnetic properties like the high anisotropy constant, high coercivity and high Curie temperature, moderate saturation magnetization and ease of synthesis. This paper introduces the magnetic properties, synthesis methods and some medical applications, including the hyperthermia, magnetic resonance imaging (MRI), magnetic separation and drug delivery of cobalt ferrite nanoparticles. Highlights: Black-Right-Pointing-Pointer Cobalt ferrite nanoparticles are one of the most important materials for nanomedicine. Black-Right-Pointing-Pointer They have high coercivity and moderate saturation magnetization. Black-Right-Pointing-Pointer Cobalt ferrite nanoparticles are synthesized easily. Black-Right-Pointing-Pointer They are a good candidate for hyperthermia and magnetic resonance imaging.

  4. Determination of delta ferrite volumetric fraction in austenitic stainless steels

    International Nuclear Information System (INIS)

    Almeida Macedo, W.A. de.

    1983-01-01

    Measurements of delta ferrite volumetric fraction in AISI 304 austenitic stainless steels were done by X-ray difraction, quantitative metallography (point count) and by means of one specific commercial apparatus whose operational principle is magnetic-inductive: The Ferrite Content Meter 1053 / Institut Dr. Forster. The results obtained were comparated with point count, the reference method. It was also investigated in these measurements the influence of the martensite induced by mechanical deformation. Determinations by X-ray diffraction, by the ratio between integrated intensities of the ferrite (211) and austenite (311) lines, are in excelent agreement with those taken by point count. One correction curve for the lectures of the commercial equipment in focus was obtained, for the range between zero and 20% of delta ferrite in 18/8 stainless steels. It is demonstrated that, depending on the employed measurement method and surface finishing of the material to be analysed, the presence of martensite produced by mechanical deformation of the austenitic matrix is one problem to be considered. (Author) [pt

  5. Influence of ferrite phase in alite-calcium sulfoaluminate cements

    Science.gov (United States)

    Duvallet, Tristana Yvonne Francoise

    Since the energy crisis in 1970's, research on low energy cements with low CO2- emissions has been increasing. Numerous solutions have been investigated, and the goal of this original research is to create a viable hybrid cement with the components of both Ordinary Portland cement (OPC) and calcium sulfoaluminate cement (CSAC), by forming a material that contains both alite and calcium sulfoaluminate clinker phases. Furthermore, this research focuses on keeping the cost of this material reasonable by reducing aluminum requirements through its substitution with iron. The aim of this work would produce a cement that can use large amounts of red mud, which is a plentiful waste material, in place of bauxite known as an expensive raw material. Modified Bogue equations were established and tested to formulate this novel cement with different amounts of ferrite, from 5% to 45% by weight. This was followed by the production of cement from reagent chemicals, and from industrial by-products as feedstocks (fly ash, red mud and slag). Hydration processes, as well as the mechanical properties, of these clinker compositions were studied, along with the addition of gypsum and the impact of a ferric iron complexing additive triisopropanolamine (TIPA). To summarize this research, the influence of the addition of 5-45% by weight of ferrite phase, was examined with the goal of introducing as much red mud as possible in the process without negatively attenuate the cement properties. Based on this PhD dissertation, the production of high-iron alite-calcium sulfoaluminateferrite cements was proven possible from the two sources of raw materials. The hydration processes and the mechanical properties seemed negatively affected by the addition of ferrite, as this phase was not hydrated entirely, even after 6 months of curing. The usage of TIPA counteracted this decline in strength by improving the ferrite hydration and increasing the optimum amount of gypsum required in each composition

  6. 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.

  7. 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.

  8. Isolation of bacterial cellulose nanocrystalline from pineapple peel waste: Optimization of acid concentration in the hydrolysis method

    Science.gov (United States)

    Anwar, Budiman; Rosyid, Nurul Huda; Effendi, Devi Bentia; Nandiyanto, Asep Bayu Dani; Mudzakir, Ahmad; Hidayat, Topik

    2016-02-01

    Isolation of needle-shaped bacterial cellulose nanocrystalline with a diameter of 16-64 nm, a fiber length of 258-806 nm, and a degree of crystallinity of 64% from pineapple peel waste using an acid hydrolysis process was investigated. Experimental showed that selective concentration of acid played important roles in isolating the bacterial cellulose nanocrystalline from the cellulose source. To achieve the successful isolation of bacterial cellulose nanocrystalline, various acid concentrations were tested. To confirm the effect of acid concentration on the successful isolation process, the reaction conditions were fixed at a temperature of 50°C, a hydrolysis time of 30 minutes, and a bacterial cellulose-to-acid ratio of 1:50. Pineapple peel waste was used as a model for a cellulose source because to the best of our knowledge, there is no report on the use of this raw material for producing bacterial cellulose nanocrystalline. In fact, this material can be used as an alternative for ecofriendly and cost-free cellulose sources. Therefore, understanding in how to isolate bacterial cellulose nanocrystalline from pineapple peel waste has the potential for large-scale production of inexpensive cellulose nanocrystalline.

  9. 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.)

  10. Corrosion of an austenite and ferrite stainless steel weld

    Directory of Open Access Journals (Sweden)

    BRANIMIR N. GRGUR

    2011-07-01

    Full Text Available Dissimilar metal connections are prone to frequent failures. These failures are attributed to the difference in the mechanical properties across the weld, the coefficients of thermal expansion of the two types of steels and the resulting creep at the interface. For the weld analyzed in this research, it was shown that corrosion measurements can be used for a proper evaluation of the quality of weld material and for the prediction of whether or not the material, after the applied welding process, can be in service without failures. It was found that the corrosion of the weld analyzed in this research resulted from the simultaneous activity of different types of corrosion. In this study, electrochemical techniques including polarization and metallographic analysis were used to analyze the corrosion of a weld material of ferrite and austenitic stainless steels. Based on surface, chemical and electrochemical analyses, it was concluded that corrosion occurrence was the result of the simultaneous activity of contact corrosion (ferrite and austenitic material conjuction, stress corrosion (originating from deformed ferrite structure and inter-granular corrosion (due to chromium carbide precipitation. The value of corrosion potential of –0.53 V shows that this weld, after the thermal treatment, is not able to repassivate a protective oxide film.

  11. Transformation of Goethite to Hematite Nanocrystallines by High Energy Ball Milling

    Directory of Open Access Journals (Sweden)

    O. M. Lemine

    2014-01-01

    Full Text Available α-Fe2O3 nanocrystallines were prepared by direct transformation via high energy ball milling treatment for α-FeOOH powder. X-ray diffraction, Rietveld analysis, TEM, and vibrating sample magnetometer (VSM are used to characterize the samples obtained after several milling times. Phase identification using Rietveld analysis showed that the goethite is transformed to hematite nanocrystalline after 40 hours of milling. HRTEM confirm that the obtained phase is mostly a single-crystal structure. This result suggested that the mechanochemical reaction is an efficient way to prepare some iron oxides nanocrystallines from raw materials which are abundant in the nature. The mechanism of the formation of hematite is discussed in text.

  12. High-pressure X-ray diffraction study of bulk- and nanocrystalline GaN

    DEFF Research Database (Denmark)

    Jorgensen, J.E.; Jakobsen, J.M.; Jiang, Jianzhong

    2003-01-01

    Bulk- and nanocrystalline GaN have been studied by high-pressure energy-dispersive X-ray diffraction. Pressure-induced structural phase transitions from the wurtzite to the NaCl phase were observed in both materials. The transition pressure was found to be 40 GPa for the bulk-crystalline GaN, while...... the wurtzite phase was retained up to 60 GPa in the case of nanocrystalline GaN. The bulk moduli for the wurtzite phases were determined to be 187 ( 7) and 319 ( 10) GPa for the bulk- and nanocrystalline phases, respectively, while the respective NaCl phases were found to have very similar bulk moduli [ 208...

  13. Characteristics of W Doped Nanocrystalline Carbon Films Prepared by Unbalanced Magnetron Sputtering.

    Science.gov (United States)

    Park, Yong Seob; Park, Chul Min; Kim, Nam-Hoon; Kim, Jae-Moon

    2016-05-01

    Nanocrystalline tungsten doped carbon (WC) films were prepared by unbalanced magnetron sputtering. Tungsten was used as the doping material in carbon thin films with the aim of application as a contact strip in an electric railway. The structural, physical, and electrical properties of the fabricated WC films with various DC bias voltages were investigated. The films had a uniform and smooth surface. Hardness and frication characteristics of the films were improved, and the resistivity and sheet resistance decreased with increasing negative DC bias voltage. These results are associated with the nanocrystalline WC phase and sp(2) clusters in carbon networks increased by ion bombardment enhanced with increasing DC bias voltage. Consequently, the increase of sp(2) clusters containing WC nanocrystalline in the carbon films is attributed to the improvement in the physical and electrical properties.

  14. Ferrite measurements for SNS accelerating cavities

    International Nuclear Information System (INIS)

    Bendall, R.G.; Church, R.A.

    1979-03-01

    The RF system for the SNS has six double accelerating cavities each containing seventy ferrite toroids. Difficulties experienced in obtaining toroids to the required specifications are discussed and the two toroid test cavity built to test those supplied is described. Ferrite measurements are reported which were undertaken to measure; (a) μQf as a function of frequency and RF field level and (b) bias current as a function of frequency for different ranges of ferrite permeability μ. (U.K.)

  15. 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.

  16. Microstructural characterization of ODS ferritic steels at different processing stages

    Energy Technology Data Exchange (ETDEWEB)

    Gil, E., E-mail: egil@ceit.es; Ordás, N.; García-Rosales, C.; Iturriza, I., E-mail: iiturriza@ceit.es

    2015-10-15

    Highlights: • ODS ferritic stainless steel produced by new route without mechanical alloying. • Fully dense ferritic stainless steels containing Y and Ti were obtained by HIPping. • Y and Ti-rich precipitates prevent grain growth during heat treatment up to 1320 °C. • HIPping at 1220 °C dissolves the metastable oxides on PPBs. - Abstract: Nanostructured Oxide Dispersion Strengthened Reduced Activation Ferritic Stainless Steels (ODS RAF) are promising structural materials for fusion reactors, due to their ultrafine microstructure and the presence of a dispersion of Y–Ti–O nanoclusters that provide excellent creep strength at high temperatures (up to 750 °C). The traditional powder metallurgical route to produce these steels is based on Gas Atomization (GA) + Mechanical Alloying (MA) + HIP + ThermoMechanical Treatments (TMTs). Recently, alternative methods have arisen to avoid the MA step. In line with this new approach, ferritic stainless steel powders were produced by gas atomization and HIPped, after adjusting their oxygen, Y and Ti contents to form Y–Ti–O nanoclusters during subsequent heat treatments. The microstructure of as-HIPped steels mainly consists of ferrite grains, Y–Ti precipitates, carbides and oxides on Prior Particle Boundaries (PPBs). Post-HIP heat treatments performed at high temperatures (1270 and 1300 °C) evaluated the feasibility of achieving a complete dissolution of the oxides on PPBs and a precipitation of ultrafine Ti- and Y-rich oxides in the Fe14Cr2W matrix. FEG-SEM with extensive EDS analysis was used to characterize the microstructure of the atomized powders and the ODS-RAF specimens after HIP consolidation and post-HIP heat treatments. A deeper characterization of atomized powder was carried out by TEM.

  17. Epitaxial Garnets and Hexagonal Ferrites.

    Science.gov (United States)

    1982-04-20

    guide growth of the epitaxial YIG films. Aluminum or gallium substitu- tions for iron were used in combination with lanthanum substitutions for yttrium... gallate spinel sub- strates. There was no difficulty with nucleation in the melt and film quality appeared to be similar to that observed previously...hexagonal ferrites. We succeeded in growing the M-type lead hexaferrite (magnetoplumbite) on gallate spinel substrates. We found that the PbO-based

  18. Defects level evaluation of LiTiZn ferrite ceramics using temperature dependence of initial permeability

    Science.gov (United States)

    Malyshev, A. V.; Petrova, A. B.; Sokolovskiy, A. N.; Surzhikov, A. P.

    2018-06-01

    The method for evaluating the integral defects level and chemical homogeneity of ferrite ceramics based on temperature dependence analysis of initial permeability is suggested. A phenomenological expression for the description of such dependence was suggested and an interpretation of its main parameters was given. It was shown, that the main criterion of the integral defects level of ferrite ceramics is relation of two parameters correlating with elastic stress value in a material. An indicator of structural perfection can be a maximum value of initial permeability close to Curie point as well. The temperature dependences of initial permeability have analyzed for samples sintered in laboratory conditions and for the ferrite industrial product. The proposed method allows controlling integral defects level of the soft ferrite products and has high sensitivity compare to typical X-ray methods.

  19. 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.

  20. Ferrite-guided cyclotron-resonance maser

    International Nuclear Information System (INIS)

    Jerby, Eli; Kesar, A.; Aharony, A.; Breitmeier, G.

    2002-01-01

    The concept of a cyclotron-resonance maser (CRM) with a ferrite loading incorporated in its waveguide is proposed. The CRM interaction occurs between the rotating electron beam and the em wave propagating along a longitudinally magnetized ferrite medium. The ferrite anisotropic permeability resembles the CRM susceptibility in many aspects, and particularly in their similar response to the axial magnetic field (the ferrite susceptibility can be regarded as a passive analog of the active CRM interaction). The ferrite loading slows down the phase velocity of the em wave and thus the axial (Weibel) mechanism of the CRM interaction dominates. The ferrite loading enables also a mechanism of spectral tunability for CRM's. The ferrite loading is proposed, therefore, as a useful ingredient for high-power CRM devices. A linear model of the combined ferrite-guided CRM interaction reveals its useful features. Future schemes may also incorporate ferrite sections functioning as isolators, gyrators, or phase shifters within the CRM device itself for selective suppression of backward waves and spurious oscillations, and for gain and efficiency enhancement

  1. Thermal transport in nanocrystalline Si and SiGe by ab initio based Monte Carlo simulation.

    Science.gov (United States)

    Yang, Lina; Minnich, Austin J

    2017-03-14

    Nanocrystalline thermoelectric materials based on Si have long been of interest because Si is earth-abundant, inexpensive, and non-toxic. However, a poor understanding of phonon grain boundary scattering and its effect on thermal conductivity has impeded efforts to improve the thermoelectric figure of merit. Here, we report an ab-initio based computational study of thermal transport in nanocrystalline Si-based materials using a variance-reduced Monte Carlo method with the full phonon dispersion and intrinsic lifetimes from first-principles as input. By fitting the transmission profile of grain boundaries, we obtain excellent agreement with experimental thermal conductivity of nanocrystalline Si [Wang et al. Nano Letters 11, 2206 (2011)]. Based on these calculations, we examine phonon transport in nanocrystalline SiGe alloys with ab-initio electron-phonon scattering rates. Our calculations show that low energy phonons still transport substantial amounts of heat in these materials, despite scattering by electron-phonon interactions, due to the high transmission of phonons at grain boundaries, and thus improvements in ZT are still possible by disrupting these modes. This work demonstrates the important insights into phonon transport that can be obtained using ab-initio based Monte Carlo simulations in complex nanostructured materials.

  2. Phase-pure Nanocrystalline Li4Ti5O12 for Lithium ion Battery

    Czech Academy of Sciences Publication Activity Database

    Kalbáč, Martin; Zukalová, Markéta; Kavan, Ladislav

    2003-01-01

    Roč. 8, č. 1 (2003), s. 2-6 ISSN 1432-8488 R&D Projects: GA MŠk OC D14.10 Institutional research plan: CEZ:AV0Z4040901 Keywords : phase purity * Li4Ti5O12 * nanocrystalline materials Subject RIV: CG - Electrochemistry Impact factor: 1.195, year: 2003

  3. Controllable chemical vapor deposition of large area uniform nanocrystalline graphene directly on silicon dioxide

    DEFF Research Database (Denmark)

    Sun, Jie; Lindvall, Niclas; Cole, Matthew T.

    2012-01-01

    Metal-catalyst-free chemical vapor deposition (CVD) of large area uniform nanocrystalline graphene on oxidized silicon substrates is demonstrated. The material grows slowly, allowing for thickness control down to monolayer graphene. The as-grown thin films are continuous with no observable pinholes...

  4. An investigation into the room temperature mechanical properties of nanocrystalline austenitic stainless steels

    International Nuclear Information System (INIS)

    Eskandari, Mostafa; Zarei-Hanzaki, Abbas; Abedi, Hamid Reza

    2013-01-01

    Highlights: ► Strength of nanocrystalline specimens follows a trend of a remarkable rise along with a small drop in ductility in comparison to the coarse-grained one. ► Universal correlation of linear type (UTS = mτ max ) between shear punch test data and the tensile strength may be unreliable for the nanocrystalline materials. ► Actual relation between the maximum shear and ultimate tensile strength follows an empirical formula of UTS=0.013τ max 2 -25.62τ max +13049. -- Abstract: The present work has been conducted to evaluate the mechanical properties of nanostructured 316L and 301 austenitic stainless steels. The nanocrystalline structures were produced through martensite treatment which includes cold rolling followed by annealing treatment. The effect of equivalent rolling strain and annealing parameters on the room temperature mechanical behavior of the experimental alloys have been studied using the shear punch testing technique. The standard uniaxial tension tests were also carried out to adapt the related correlation factors. The microstructures and the volume fraction of phases were characterized by transmission electron microscopy and feritscopy methods, respectively. The results indicate that the strength of nanocrystalline specimens remarkably increases, but the ductility in comparison to the coarse-grained one slightly decreases. In addition the strength of nanocrystalline specimens has been increased by decreasing the annealing temperature and increasing the equivalent rolling strain. The analysis of the load–displacement data has also disclosed that the universal correlation of linear type (UTS = mτ max ) between shear punch test data and the tensile strength is somehow unreliable for the nanocrystalline materials. The results suggest that the actual relation between the maximum shear strength and ultimate tensile strength follows a second order equation of type UTS=aτ max 2 -bτ max +c.

  5. Internal stresses in an austeno-ferritic duplex stainless steel

    International Nuclear Information System (INIS)

    Verhaeghe, B.; Brechet, Y.; Louchet, F.; Massoud, J.P.; Touzeau, D.

    1996-04-01

    Austeno-ferritic duplex steels possess microstructures containing comparable volume fractions of hard and soft phases which are bi-percolated. They are therefore liable to develop large internal stresses during straining. The evolution and the relaxation of these stresses and the occurrence of damage are characterized using Bauschinger tests. Thermally aged and non-aged material behaviour are compared. Plastic flow in the hard phase is shown to be significantly efficient in releasing these internal stresses. (authors). 15 refs., 8 figs

  6. Assessment of delta ferrite in multipass TIG welds of 40 mm thick SS 316L plates: a comparative study of ferrite number (FN) prediction and experimental measurements

    International Nuclear Information System (INIS)

    Buddu, Ramesh Kumar; Shaikh, Shamsuddin; Raole, Prakash M.; Sarkar, Biswanath

    2015-01-01

    Austenitic stainless steels are widely used in the fabrication of fusion reactor major systems like vacuum vessel, divertor, cryostat and other major structural components development. AISI SS316L materials of different thicknesses are utilized due to the superior mechanical properties, corrosion resistance, fatigue and stability at high temperature operation. The components are developed by using welding techniques like TIG welding with suitable filler material. Like in case of vacuum vessel, the multipass welding is unavoidable due to the use of high thickness plates (like in case of ITER and DEMO reactors). In general austenitic welds contains fraction of delta ferrite phase in multipass welds. The quantification depends on the weld thermal cycles like heat input and cooling rates associated with process conditions and chemical composition of the welds. Due to the repeated weld thermal passes, the microstructure adversely alters due to the presence of complex phases like austenite, ferrite and delta ferrite and subsequently influence the mechanical properties like tensile and impact toughness of joints. Control of the delta ferrite is necessary to hold the compatible final properties of the joints and hence its evaluation vital before the fabrication process. The present paper reports the detail analysis of delta ferrite phase in welded region and heat affected zones of 40 mm thick SS316L plates welded by special design multipass narrow groove TIG welding process under three different heat input conditions (1.67 kJ/mm, 1.78 kJ/mm, 1.87 kJ/mm). The correlation of delta ferrite microstructure with optical microscope and high resolution SEM has been carried out and different type of acicular and vermicular delta ferrite structures is observed. This is further correlated with the non destructive magnetic measurement using Ferrite scope. The measured ferrite number (FN) is correlated with the formed delta ferrite phase. The chemical composition of weld samples is

  7. Cofiring behavior and interfacial structure of NiCuZn ferrite/PMN ferroelectrics composites for multilayer LC filters

    International Nuclear Information System (INIS)

    Miao Chunlin; Zhou Ji; Cui Xuemin; Wang Xiaohui; Yue Zhenxing; Li Longtu

    2006-01-01

    The cofiring behavior, interfacial structure and cofiring migration between NiCuZn ferrite and lead magnesium niobate (PMN)-based relaxor ferroelectric materials were investigated via thermomechanical analyzer (TMA), X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Mismatched sintering shrinkage between NiCuZn ferrite and PMN was modified by adding an appropriate amount of sintering aids, Bi 2 O 3 , into NiCuZn ferrite. Pyrochlore phase appeared in the mixture of NiCuZn ferrite and PMN, which is detrimental to the final electric properties of LC filters. EDS results indicated that the interdiffusion at the heterogeneous interfaces in the composites, such as Fe, Pb, Zn, existed which can strengthen combinations between ferrite layers and ferroelectrics layers

  8. Ferrite control--Measurement problems and solutions during stainless steel fabrication

    International Nuclear Information System (INIS)

    Pickering, E.W.

    1986-01-01

    Ferrite is one of the magnetic phases found in many grades of otherwise nonmagnetic austenitic stainless steel weldments. Control of ferrite during the fabrication of cryogenic component parts is necessary to produce a reliable product, free of cracking and microfissuring. This is accomplished by balancing compositions in order to produce a small amount of ferrite which is generally accompanied with reduced toughness. Control of ferrite is essential during the fabrication of component parts. The means to accomplish this will vary with the type of material being welded, thickness, welding process, method of measurement and fabrication procedures. An application used during the fabrication of component parts for the Fast Flux Test Facility (FFTF) required specially formulated shielded manual arc welding (SMAW) electrodes and consumable inserts. Control of ferrite measurements and shop welding procedures were essential. The special materials and techniques were used to weld Type 316 stainless steel pipe joints, 28 in. (0.71 m) in diameter. By using three lots of electrodes, each with a different ferrite level, a compatible range of ferrite was achieved throughout the layers of weld metal. By extensive use of the Schaeffler and DeLong modified constitution diagrams for stainless steel weld metal, E-16-8-2 SMAW electrodes were developed with ''0'' ferrite level. The electrodes were used during fabrication of the Liquid Metal Fast Breader Reactor (LMFBR) component parts of Type 316 stainless steel. Metallographic evaluation of laboratory specimens, control of shop welding techniques and individual laboratory training of shop welders combined to produce a quality product

  9. Thermodynamic and kinetic characteristics of the austenite-to-ferrite transformation under high magnetic field in medium carbon steel

    International Nuclear Information System (INIS)

    Zhang Yudong; He Changshu; Zhao Xiang; Zuo Liang; Esling, Claude

    2005-01-01

    The thermodynamic and kinetic characteristics of austenite-to-ferrite phase transformation in medium carbon steel in the high magnetic fields were investigated. Results showed that the magnetic field could obviously change the γ/α+γ phase equilibrium-by increasing the amount of ferrite obtained during cooling-and greatly accelerate the transformation. Thus the microstructure obtained under fast cooling with high magnetic field was still ferritic and pearlitic, while that obtained without the magnetic field under the same cooling conditions was bainitic. Exploration in this area contributes both to enriching the new theory on electromagnetic processing of materials (EPM) and in establishing new techniques for materials processing

  10. Ferrite thin films: Synthesis, characterization and gas sensing properties towards LPG

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Pratibha; Godbole, R.V. [Department of Physics, Abasaheb Garware College, Karve Road, Pune 411 004 (India); Phase, D.M. [UGC-DAE CSR Centre, Indore (India); Chikate, R.C. [Department of Chemistry, Abasaheb Garware College, Karve Road, Pune 411 004 (India); Bhagwat, Sunita, E-mail: smb.agc@gmail.com [Department of Physics, Abasaheb Garware College, Karve Road, Pune 411 004 (India)

    2015-01-15

    Nanocrystalline (Co, Cu, Ni, Zn) ferrite thin films have been deposited onto the Si (100) and alumina substrates by spray pyrolysis deposition technique. Respective metal chlorides and iron chloride were used as precursors. The structural properties of (Co, Cu, Ni, Zn) ferrite thin films were investigated by X-ray diffraction (XRD) technique which confirms polycrystalline nature and single phase spinel structure. The surface morphology was studied using scanning electron microscopy (SEM) which reveals spherical morphology for these films except NiFe{sub 2}O{sub 4} films that exhibit petal like structure. The optical transmittance and reflectance measurements were recorded using a double beam spectrophotometer. The optical studies reveal that the transition is direct band gap energy. The VSM analyzes reveal the predominant ferrimagnetic nature for CuFe{sub 2}O{sub 4} films. The gas sensing properties towards Liquid Petroleum Gas (LPG) revealed that ZnFe{sub 2}O{sub 4} films are sensitive at lower temperature while NiFe{sub 2}O{sub 4} films show steep rise at higher temperature. - Highlights: • (Co, Cu, Ni, Zn) ferrite thin films are synthesized by simple spray pyrolysis technique. • Homogenization of substituent within ferrite structure. • CuFe{sub 2}O{sub 4} film exhibits predominantly ferrimagnetic nature. • LPG sensing at lower temperature for ZnFe{sub 2}O{sub 4} film. • High sensitivity for NiFe{sub 2}O{sub 4} film at higher temperature due to defects created in the structure.

  11. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-06-15

    Nanosized copper ferrite-type materials (Cu{sub x}Fe{sub 3–x}O{sub 4}, 0 ≤ x ≤ 1) have been prepared by combination of co-precipitation and mechanochemical activation and/or thermal treatment. The crystalline structure and morphology of the obtained ferrite nanopowders have been characterized by different instrumental methods, such as Powder X-ray diffraction (PXRD), Mössbauer and FT-IR spectroscopies, specific surface area and porosity measurements, thermal analyses (Differential Thermal Analysis and Thermogravimetric Analysis) and Temperature-Programmed Reduction. The average crystallite size of copper ferrites ranged between 7.8 and 14.7 nm and show a superparamagnetic and collective magnetic excitations nature. The photocatalytic decolorization of Malachite green oxalate under different UV illumination intervals was examined using these copper ferrites as photocatalysts. The results indicate that the prepared nanostructured copper ferrites showed enhanced photocatalytic activity and amount adsorbed Malachite Green dye. The co-precipitated nanosized copper ferrite powder with a low content of copper metal ions in a magnetite host structure (Cu{sub 0.25}Fe{sub 2.75}O{sub 4}) showed an apparent pseudo-first-order rate constant 15.4 × 10{sup −3} min{sup −1} and an amount adsorbed Malachite Green as model organic dye pollutant per 1 g catalyst of 33.4 ppm/g after the dark period. The results confirm that the copper ferrites can be suitable for photocatalytic treatment of wastewaters containing organic dyes. The new aspect of presented investigations is to study the influence of different degree of incorporation of copper ions into the magnetite host structure and preparation methods on the photocatalytic properties of nanosized copper ferrite materials and obtaining of potential photocatalyst (Cu{sub 0.25}Fe{sub 2.75}O{sub 4}) with higher photocatalytic activity (15.4 × 10{sup −3} min{sup −1}) than that of the standard referent Degussa P25 (12 × 10

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

    International Nuclear Information System (INIS)

    Zaharieva, Katerina; Rives, Vicente; Tsvetkov, Martin; Cherkezova-Zheleva, Zara; Kunev, Boris; Trujillano, Raquel; Mitov, Ivan; Milanova, Maria

    2015-01-01

    Nanosized copper ferrite-type materials (Cu x Fe 3–x O 4 , 0 ≤ x ≤ 1) have been prepared by combination of co-precipitation and mechanochemical activation and/or thermal treatment. The crystalline structure and morphology of the obtained ferrite nanopowders have been characterized by different instrumental methods, such as Powder X-ray diffraction (PXRD), Mössbauer and FT-IR spectroscopies, specific surface area and porosity measurements, thermal analyses (Differential Thermal Analysis and Thermogravimetric Analysis) and Temperature-Programmed Reduction. The average crystallite size of copper ferrites ranged between 7.8 and 14.7 nm and show a superparamagnetic and collective magnetic excitations nature. The photocatalytic decolorization of Malachite green oxalate under different UV illumination intervals was examined using these copper ferrites as photocatalysts. The results indicate that the prepared nanostructured copper ferrites showed enhanced photocatalytic activity and amount adsorbed Malachite Green dye. The co-precipitated nanosized copper ferrite powder with a low content of copper metal ions in a magnetite host structure (Cu 0.25 Fe 2.75 O 4 ) showed an apparent pseudo-first-order rate constant 15.4 × 10 −3 min −1 and an amount adsorbed Malachite Green as model organic dye pollutant per 1 g catalyst of 33.4 ppm/g after the dark period. The results confirm that the copper ferrites can be suitable for photocatalytic treatment of wastewaters containing organic dyes. The new aspect of presented investigations is to study the influence of different degree of incorporation of copper ions into the magnetite host structure and preparation methods on the photocatalytic properties of nanosized copper ferrite materials and obtaining of potential photocatalyst (Cu 0.25 Fe 2.75 O 4 ) with higher photocatalytic activity (15.4 × 10 −3 min −1 ) than that of the standard referent Degussa P25 (12 × 10 −3 min −1 ) for degradation of organic dye

  14. Corrosion-resistant coating technique for oxide-dispersion-strengthened ferritic/martensitic steel

    International Nuclear Information System (INIS)

    Sakasegawa, Hideo; Tanigawa, Hiroyasu; Ando, Masami

    2014-01-01

    Oxide-dispersion-strengthened (ODS) steels are attractive materials for application as fuel cladding in fast reactors and first-wall material of fusion blanket. Recent studies have focused more on high-chromium ferritic (12-18 wt% Cr) ODS steels with attractive corrosion resistance properties. However, they have poor material workability, require complicated heat treatments for recrystallization, and possess anisotropic microstructures and mechanical properties. On the other hand, low-chromium ferritic/martensitic (8-9 wt% Cr) ODS steels have no such limitations; nonetheless, they have poor corrosion resistance properties. In our work, we developed a corrosion-resistant coating technique for a low-chromium ferritic/martensitic ODS steel. The ODS steel was coated with the 304 or 430 stainless steel, which has better corrosion resistances than the low-chromium ferritic/martensitic ODS steels. The 304 or 430 stainless steel was coated by changing the canning material from mild steel to stainless steel in the conventional material processing procedure for ODS steels. Microstructural observations and micro-hardness tests proved that the stainless steels were successfully coated without causing a deterioration in the mechanical property of the low-chromium ferritic/martensitic ODS steel. (author)

  15. Nanocrystalline zinc oxide for the decontamination of sarin

    Energy Technology Data Exchange (ETDEWEB)

    Mahato, T.H. [Defense R and D Establishment, Jhansi Road, 474002, Gwalior, MP (India); Prasad, G.K., E-mail: gkprasad@lycos.com [Defense R and D Establishment, Jhansi Road, 474002, Gwalior, MP (India); Singh, Beer; Acharya, J.; Srivastava, A.R.; Vijayaraghavan, R. [Defense R and D Establishment, Jhansi Road, 474002, Gwalior, MP (India)

    2009-06-15

    Nanocrystalline zinc oxide materials were prepared by sol-gel method and were characterized by X-ray diffraction, scanning electron microscopy, thermogravimetry, nitrogen adsorption and infrared spectroscopy techniques. The data confirmed the formation of zinc oxide materials of zincite phase with an average crystallite size of {approx}55 nm. Obtained material was tested as destructive adsorbent for the decontamination of sarin and the reaction was followed by GC-NPD and GC-MS techniques. The reaction products were characterized by GC-MS and the data explored the role of hydrolysis reaction in the detoxification of sarin. Sarin was hydrolyzed to form surface bound non-toxic phosphonate on the surface of nano-zinc oxide. The data also revealed the values of rate constant and half-life to be 4.12 h{sup -1} and 0.16 h in the initial stages of the reaction and 0.361 h{sup -1} and 1.9 h at the final stages of the reaction for the decontamination reaction on nanocrystalline ZnO.

  16. Nanocrystalline zinc oxide for the decontamination of sarin

    International Nuclear Information System (INIS)

    Mahato, T.H.; Prasad, G.K.; Singh, Beer; Acharya, J.; Srivastava, A.R.; Vijayaraghavan, R.

    2009-01-01

    Nanocrystalline zinc oxide materials were prepared by sol-gel method and were characterized by X-ray diffraction, scanning electron microscopy, thermogravimetry, nitrogen adsorption and infrared spectroscopy techniques. The data confirmed the formation of zinc oxide materials of zincite phase with an average crystallite size of ∼55 nm. Obtained material was tested as destructive adsorbent for the decontamination of sarin and the reaction was followed by GC-NPD and GC-MS techniques. The reaction products were characterized by GC-MS and the data explored the role of hydrolysis reaction in the detoxification of sarin. Sarin was hydrolyzed to form surface bound non-toxic phosphonate on the surface of nano-zinc oxide. The data also revealed the values of rate constant and half-life to be 4.12 h -1 and 0.16 h in the initial stages of the reaction and 0.361 h -1 and 1.9 h at the final stages of the reaction for the decontamination reaction on nanocrystalline ZnO.

  17. 2. Home 3. Journals 4. Bulletin of Materials Science 5. Volume 29 6 ...

    Indian Academy of Sciences (India)

    Sr0⋅5Ba0⋅5–xBixTiO3 thin films. 523. Bilayer ... High coercivity in nanostructured Co-ferrite thin films 573 ..... Surface characterization of sol–gel derived indium tin oxide films on .... Surface plasmon effect in nanocrystalline copper/DLC com-.

  18. Radiation induced microstructural evolution in ferritic/martensitic steels

    International Nuclear Information System (INIS)

    Kohno, Y.; Kohyama, A.; Asakura, K.; Gelles, D.S.

    1993-01-01

    R and D of ferritic/martensitic steels as structural materials for fusion reactor is one of the most important issues of fusion technology. The efforts to characterize microstructural evolution under irradiation in the conventional Fe-Cr-Mo steels as well as newly developed Fe-Cr-Mn or Fe-Cr-W low activation ferritic/ martensitic steels have been continued. This paper provides some of the recent results of heavy irradiation effects on the microstructural evolution of ferritic/martensitic steels neutron irradiated in the FFTF/MOTA (Fast Flux Test Facility/Materials Open Test Assembly). Materials examined are Fe-10Cr-2Mo dual phase steel (JFMS: Japanese Ferritic/Martensitic Steel), Fe-12Cr-XMn-1Mo manganese stabilized martensitic steels and Fe-8Cr-2W Tungsten stabilized low activation martensitic steel (F82H). JFMS showed excellent void swelling resistance similar to 12Cr martensitic steel such as HT-9, while the manganese stabilized steels and F82H showed less void swelling resistance with small amount of void swelling at 640-700 K (F82H: 0.14% at 678 K). As for irradiation response of precipitate behavior, significant formation of intermetallic χ phase was observed in the manganese stabilized steels along grain boundaries which is though to cause mechanical property degradation. On the other hand, precipitates identified were the same type as those in unirradiated condition in F82H with no recognition of irradiation induced precipitates, which suggested satisfactory mechanical properties of F82H after the irradiation. (author)

  19. 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.

  20. Ni_0_,_5Zn_0_,_5Fe_2O_3 ferrite synthesized by combustion and Pechini method for use in nanomedicine: methods evaluation

    International Nuclear Information System (INIS)

    Albuquerque, I.L.T. de; Nascimento, A.L.C.; Costa, A.C.F.M.

    2016-01-01

    The objective of this work was to synthesize the Ni0.5Zn0.5Fe2O3 ferrite by combustion reaction and Pechini method, and to evaluate structural characteristics and magnetic behavior for its use in nanomedicine. The synthesized ferrite was characterized by DRX, BET, TG and magnetic properties. According to the results of XRD, the Ni_0_,_5Zn_0_,_5Fe_2O_3 ferrite synthesized by both methods presented nano crystallite sizes, high crystallinity, surface area, stable at high temperatures and with high saturation magnetization, being higher in the ferrite synthesized by combustion reaction. Both methods produced materials that could be used in nanomedicine

  1. Effect of degassing temperature on the microstructure of a nanocrystalline Al-Mg alloy

    International Nuclear Information System (INIS)

    Ahn, Byungmin; Newbery, A. Piers; Lavernia, Enrique J.; Nutt, Steven R.

    2007-01-01

    The microstructural evolution of a nanocrystalline Al-Mg alloy was investigated to determine the effects of degassing temperature. Al 5083 powder was ball-milled in liquid nitrogen to obtain a nanocrystalline structure, then vacuum degassed to remove contaminants. The degassed powder was consolidated by cold isostatic pressing and then forged to produce bulk, low-porosity material. The material microstructure was analyzed at different stages using optical microscopy, transmission electron microscopy, and density measurements. The impurity concentration of the final product was also measured. The forged material exhibited a bimodal grain size distribution, consisting of both ultra fine and coarse grains. The bimodal distribution was attributed to the presence of residual coarse grains in the as-milled powder. Higher degassing temperatures resulted in higher density values and lower hydrogen content in the consolidated materials, although these materials also exhibited more extensive grain growth

  2. Chromium Enrichment on P11 Ferritic Steel by Pack Cementation

    Directory of Open Access Journals (Sweden)

    Fauzi F. A.

    2016-01-01

    Full Text Available The future thermal power plant is expected to operate at higher temperature to improve its efficiency and to reduce greenhouse gas emission. This target requires better corrosion properties of ferritic steels, which commonly used as materials for superheater and reheater of boiler tubes. In this work, chromium enrichment on the surface of ferritic steel is studied. The deposited chromium is expected to become a reservoir for the formation of chromia protective layer. Chromium was deposited on the substrate of steel by pack cementation process for two hours at the temperature of 850ºC, 950ºC and 1050ºC, respectively. XRD analysis indicated that chromium was successfully deposited at all temperatures. Somehow, SEM cross sectional image showed that continuous layer of chromium was not continuously formed at 850oC. Therefore, this research clarify that chromium enrichment by pack cementation may be conducted at the temperature above 950°C.

  3. Electromagnetic properties of photodefinable barium ferrite polymer composites

    Science.gov (United States)

    Sholiyi, Olusegun; Lee, Jaejin; Williams, John D.

    2014-07-01

    This article reports the magnetic and microwave properties of a Barium ferrite powder suspended in a polymer matrix. The sizes for Barium hexaferrite powder are 3-6 μm for coarse and 0.8-1.0 μm for the fine powder. Ratios 1:1 and 3:1 (by mass) of ferrite to SU8 samples were characterized and analyzed for predicting the necessary combinations of these powders with SU8 2000 Negative photoresist. The magnetization properties of these materials were equally determined and were analyzed using Vibrating Sample Magnetometer (VSM). The Thru, Reflect, Line (TRL) calibration technique was employed in determining complex relative permittivity and permeability of the powders and composites with SU8 between 26.5 and 40 GHz.

  4. Electromagnetic properties of photodefinable barium ferrite polymer composites

    Directory of Open Access Journals (Sweden)

    Olusegun Sholiyi

    2014-07-01

    Full Text Available This article reports the magnetic and microwave properties of a Barium ferrite powder suspended in a polymer matrix. The sizes for Barium hexaferrite powder are 3–6 μm for coarse and 0.8–1.0 μm for the fine powder. Ratios 1:1 and 3:1 (by mass of ferrite to SU8 samples were characterized and analyzed for predicting the necessary combinations of these powders with SU8 2000 Negative photoresist. The magnetization properties of these materials were equally determined and were analyzed using Vibrating Sample Magnetometer (VSM. The Thru, Reflect, Line (TRL calibration technique was employed in determining complex relative permittivity and permeability of the powders and composites with SU8 between 26.5 and 40 GHz.

  5. Residual stress studies of austenitic and ferritic steels

    International Nuclear Information System (INIS)

    Chrenko, R.M.

    1978-01-01

    Residual studies have been made on austenitic and ferritic steels of the types used as structural materials. The residual stress results presented here will include residual stress measurements in the heat-affected zone on butt welded Type 304 stainless steel pipes, and the stresses induced in Type 304 austenitic stainless steel and Type A508 ferritic steel by several surface preparations. Such surface preparation procedures as machining and grinding can induce large directionality effects in the residual stresses determined by X-ray techniques and some typical data will be presented. A brief description is given of the mobile X-ray residual stress apparatus used to obtain most of the data in these studies. (author)

  6. Tribological properties of nanocrystalline diamond films

    Energy Technology Data Exchange (ETDEWEB)

    Erdemir, A.; Fenske, G.R.; Krauss, A.R.; Gruen, D.M.; McCauley, T.; Csencsits, R.T. [Argonne National Lab., IL (United States). Energy Technology Div.

    1999-11-01

    In this paper, we present the friction and wear properties of nanocrystalline diamond (NCD) films grown in Ar-fullerene (C{sub 60}) and Ar-CH{sub 4} microwave plasmas. Specifically, we will address the fundamental tribological issues posed by these films during sliding against Si{sub 3}N{sub 4} counterfaces in ambient air and inert gases. Grain sizes of the films grown by the new method are very small (10-30 nm) and are much smoother (20-40 nm, root mean square) than those of films grown by the conventional H{sub 2}-CH{sub 4} microwave-assisted chemical vapor deposition process. Transmission electron microscopy (TEM) revealed that the grain boundaries of these films are very sharp and free of nondiamond phases. The microcrystalline diamond films grown by most conventional methods consist of large grains and a rough surface finish, which can cause severe abrasion during sliding against other materials. The friction coefficients of films grown by the new method (i.e. in Ar-C{sub 60} and Ar-CH{sub 4} plasmas) are comparable with those of natural diamond, and wear damage on counterface materials is minimal. Fundamental tribological studies indicate that these films may undergo phase transformation during long-duration, high-speed and/or high-load sliding tests and that the transformation products trapped at the sliding interfaces can intermittently dominate friction and wear performance. Using results from a combination of TEM, electron diffraction, Raman spectroscopy, and electron energy loss spectroscopy, we describe the structural chemistry of the debris particles trapped at the sliding interfaces and elucidate their possible effects on friction and wear of NCD films in dry N{sub 2}. Finally, we suggest a few potential applications in which NCD films can improve performance and service lives. (orig.)

  7. Study of LiTiMg-ferrite radome for the application of satellite communication

    International Nuclear Information System (INIS)

    Saxena, Naveen Kumar; Kumar, Nitendar; Pourush, P.K.S.

    2010-01-01

    In this paper the characteristics of LiTiMg-ferrite radome are presented. A thin layer of LiTiMg-ferrite is used as superstrate or radome, which controls the radiation, reception, and scattering from a printed antenna or array by applying a dc magnetic bias field in the plane of the ferrite, orthogonal to the RF magnetic field. In this analysis absorbing and transmission power coefficients are calculated to obtain the power loss and transmitted power through the radome layer respectively. The absorbing power coefficient verifies the switching behavior of radome for certain range of applied external magnetic field (Ho), which depends on the resonance width parameter (ΔH) of ferrite material. By properly choosing the bias field, electromagnetic wave propagation in the ferrite layer can be made zero or negligible over a certain frequency range, resulting in switching behavior of the ferrite layer. In this communication we also show precise preparation of radome layer and present its electric and magnetic properties along with its Curie temperature, which shows the working efficiency of layer under extreme situation. This radome layer can be very useful for the sensitive and smart communication systems.

  8. Mechanism and experimental research on ultra-precision grinding of ferrite

    Science.gov (United States)

    Ban, Xinxing; Zhao, Huiying; Dong, Longchao; Zhu, Xueliang; Zhang, Chupeng; Gu, Yawen

    2017-02-01

    Ultra-precision grinding of ferrite is conducted to investigate the removal mechanism. Effect of the accuracy of machine tool key components on grinding surface quality is analyzed. The surface generation model of ferrite ultra-precision grinding machining is established. In order to reveal the surface formation mechanism of ferrite in the process of ultraprecision grinding, furthermore, the scientific and accurate of the calculation model are taken into account to verify the grinding surface roughness, which is proposed. Orthogonal experiment is designed using the high precision aerostatic turntable and aerostatic spindle for ferrite which is a typical hard brittle materials. Based on the experimental results, the influence factors and laws of ultra-precision grinding surface of ferrite are discussed through the analysis of the surface roughness. The results show that the quality of ferrite grinding surface is the optimal parameters, when the wheel speed of 20000r/mm, feed rate of 10mm/min, grinding depth of 0.005mm, and turntable rotary speed of 5r/min, the surface roughness Ra can up to 75nm.

  9. 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.

  10. Preparation of porous nano barium ferrite and its adsorption properties on uranium

    International Nuclear Information System (INIS)

    Xiong Guoxuan; Huang Haiqing; Zhang Zhibin

    2012-01-01

    The porous nano barium ferrite was made of Fe(NO 3 ) 3 and Ba(NO 3 ) 2 as raw materials, CTAB as surfactant by method of sol-gel and self-propagating combustion. The composition, morphology and magnetic properties of nano-rod barium ferrite were characterized by XRD, SEM and vibrating sample magnetometer. The adsorption properties of porous nano barium ferrite on uranium were studied with static adsorption and the effects of pH, adsorption temperature and oscillation time on adsorption properties were discussed. The results indicate that the average particle size of porous nano barium ferrite is 45-65 nm, the saturation magnetization and coercivity are 62.83 emu/g and 5481.0 Oe, respectively. Under the condition of the porous nano barium ferrite amount of 0.02 g, pH of 6, adsorption temperature of 25℃ and oscillation time of 30 min, the adsorption capacity of uranium on the porous nano barium ferrite reaches 921 μg/g. (authors)

  11. Formation of oxides particles in ferritic steel by using gas-atomized powder

    International Nuclear Information System (INIS)

    Liu Yong; Fang Jinghua; Liu Donghua; Lu Zhi; Liu Feng; Chen Shiqi; Liu, C.T.

    2010-01-01

    Oxides dispersion strengthened (ODS) ferritic steel was prepared by using gas-atomized pre-alloyed powder, without the conventional mechanical alloying process. By adjusting the volume content of O 2 in the gas atmosphere Ar, the O level in the ferritic powder can be well controlled. The O dissolves uniformly in the ferritic powder, and a very thin layer of oxides forms on the powder surface. After hot deformation, the primary particle boundaries, which retain after sintering, can be disintegrated and near fully dense materials can be obtained. The oxide layer on the powder surface has a significant effect on the microstructural evolution. It may prevent the diffusion in between the primary particles during sintering, and may dissolve and/or induce the nucleation of new oxides in the ferritic matrix during recrystallization. Two kinds of oxide particles are found in the ferritic steel: large (∼100 nm) Ti-rich and fine (10-20 nm) Y-Ti-rich oxides. The hardness of the ferritic steel increases with increasing annealing temperatures, however, decreases at 1400 deg. C, due to the coarsening of precipitates and the recrystallization microstructure.

  12. The radiation response of mesoporous nanocrystalline zirconia thin films

    Energy Technology Data Exchange (ETDEWEB)

    Manzini, Ayelén M.; Alurralde, Martin A. [Comisión Nacional de Energía Atómica, Centro Atómico Constituyentes, Av. General Paz 1499, 1650 San Martin, Provincia de Buenos Aires (Argentina); Giménez, Gustavo [Instituto Nacional de Tecnología Industrial - CMNB, Av. General Paz 5445, 1650 San Martín, Provincia de Buenos Aires (Argentina); Luca, Vittorio, E-mail: vluca@cnea.gov.ar [Comisión Nacional de Energía Atómica, Centro Atómico Constituyentes, Av. General Paz 1499, 1650 San Martin, Provincia de Buenos Aires (Argentina)

    2016-12-15

    The next generation of nuclear systems will require materials capable of withstanding hostile chemical, physical and radiation environments over long time-frames. Aside from its chemical and physical stability, crystalline zirconia is one of the most radiation tolerant materials known. Here we report the first ever study of the radiation response of nanocrystalline and mesoporous zirconia and Ce{sup 3+}-stabilized nanocrystalline zirconia (Ce{sub 0.1}Zr{sub 0.9}O{sub 2}) thin films supported on silicon wafers. Zirconia films prepared using the block copolymer Brij-58 as the template had a thickness of around 60–80 nm. In the absence of a stabilizing trivalent cation they consisted of monoclinic and tetragonal zirconia nanocrystals with diameters in the range 8–10 nm. Films stabilized with Ce{sup 3+} contained only the tetragonal phase. The thin films were irradiated with iodine ions of energies of 70 MeV and 132 keV at low fluences (10{sup 13} - 10{sup 14} cm{sup −2}) corresponding to doses of 0.002 and 1.73 dpa respectively, and at 180 keV and high fluences (2 × 10{sup 16} cm{sup −2}) corresponding to 82.4 dpa. The influence of heavy ion irradiation on the nanocrystalline structure was monitored through Rietveld analysis of grazing incidence X-ray diffraction (GIXRD) patterns recorded at angles close to the critical angle to ensure minimum contribution to the diffraction pattern from the substrate. Irradiation of the mesoporous nanocrystalline zirconia thin films with 70 MeV iodine ions, for which electronic energy loss is dominant, resulted in slight changes in phase composition and virtually no change in crystallographic parameters as determined by Rietveld analysis. Iodine ion bombardment in the nuclear energy loss regime (132–180 keV) at low fluences did not provoke significant changes in phase composition or crystallographic parameters. However, at 180 keV and high fluences the monoclinic phase was totally eliminated from the GIXRD

  13. Study of the sintering behavior of fine, ultrafine and nanocrystalline WC-CO mixtures obtained by high energy milling

    International Nuclear Information System (INIS)

    Salvador, M. D.; Bonache, V.; Amigo, V.; Busquets, D.

    2008-01-01

    In this work the sintering behaviour of fine, ultrafine and nanocrystalline WC-12Co mixtures obtained by high energy milling, as well commercial nano powders, have been studied, in order to evaluate the effect of the particle size and the powder processing, in the densification, microstructural development and mechanical properties of the final product. The consolidation of the mixtures has been made by uniaxial pressing and sintering in vacuum, and by hot isostatic pressing. The sintered materials have been evaluated by measures of density, hardness and indentation fracture toughness, and micro structurally characterized by optical microscopy and scanning and transmission electronic microscopy (SEM and TEM). The results show the improvements in resistant behaviour of the materials obtained from nanocrystalline powders, in spite of the grain growth experienced during the sintering. The best results were obtained for the milling nanocrystalline material, which presents values of hardness higher than 180 HV. (Author) 46 refs

  14. The magnetic properties of aligned M hexa-ferrite fibres

    International Nuclear Information System (INIS)

    Pullar, R.C.; Bhattacharya, A.K.

    2006-01-01

    Aligned and random fibres of strontium hexa ferrite (SrM, SrFe 12 O 19 ) and barium hexaferrite (BaM, BaFe 12 O 19 ) were manufactured by blow spinning from an aqueous inorganic sol-gel precursor, which was then fired to give the hexagonal ferrite fibre. Their magnetic properties were studied by VSM, investigating the evolution of these properties with firing and measurement temperature, and in particular the effects of fibre alignment. It has been predicted that aligned ferrite fibres will demonstrate an enhanced magnetisation along the axis of alignment with respect to perpendicular to the axis, and this has been demonstrated here for the first time. The optimum firing temperature was 1000 deg. C, at which point they still had submicron grains. In BaM random fibres M s =63.8 emu g -1 and H c =428.1 kA m -1 , and in SrM random fibres M s =63.3 emu g -1 and H c =452.8 kA m -1 , high values for polycrystalline materials. Fibres aligned parallel to the applied field had saturation magnetisation (M s ) values equal to those of the random fibres, whilst fibres aligned perpendicular to the field had M s values 62% and 75% lower, for BaM and SrM, respectively. There was no change in coercivity (H c ) between random or aligned fibres of any orientation, and fibres aligned 45 deg. and parallel to H appeared identical. Therefore, properties along the axis of alignment were superior when compared to measurements perpendicular to the axis of alignment, giving a directionality to the magnetisation in an otherwise randomly oriented ferrite material

  15. Mechanical properties of nanocrystalline palladium prepared by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Castrup, Anna; Hahn, Horst [Forschungszentrum Karlsruhe (Germany); Technical University of Darmstadt (Germany); Scherer, Torsten; Ivanisenko, Yulia; Choi, In-Suk; Kraft, Oliver [Forschungszentrum Karlsruhe (Germany)

    2009-07-01

    Nanocrystalline metals and alloys with grain sizes well below 100 nm often demonstrate unique deformation behaviour and therefore attract a great interest in material science. The understanding of deformation mechanisms operating in nanocrystalline materials is important to predict their mechanical properties. In the present study Pd films of 1{mu}m thickness were prepared using UHV rf magnetron sputtering on dog bone shaped Kapton substrates and on Si/SiO2 wafers. The films were sputtered using multilayer technology with an individual layer thickness of 10 nm. This resulted in grain sizes of about 20 nm. Initial microstructure and texture were characterized using conventional XRD measurements and transmission electron microscopy (TEM) in both cross section- and plane view. The mechanical properties were investigated using tensile testing and nanoindentation at several strain rates. An increased hardness and strength as compared to coarse grained Pd was observed, as well as high strain rate sensitivity. The microstructure in the gauge section after tensile testing was again analyzed using TEM in order to reveal signatures of deformation mechanisms like dislocation motion or twinning.

  16. Influence of grain boundaries on elasticity and thermal conductivity of nanocrystalline diamond films

    International Nuclear Information System (INIS)

    Mohr, Markus; Daccache, Layal; Horvat, Sebastian; Brühne, Kai; Jacob, Timo; Fecht, Hans-Jörg

    2017-01-01

    Diamond combines several outstanding material properties such as the highest thermal conductivity and highest elastic moduli of all materials. This makes diamond an interesting candidate for a multitude of applications. Nonetheless, nanocrystalline diamond films, layers and coatings, usually show properties different to those of single crystalline diamond. This is usually attributed to the larger volume fraction of the grain boundaries with atomic structure different from the single crystal. In this work we measured Young's modulus and thermal conductivity of nanocrystalline diamond films with average grain sizes ranging from 6 to 15 nm. The measured thermal conductivities are modeled considering the thermal boundary conductance between grains as well as a grain size effect on the phonon mean free path. We make a comparison between elastic modulus and thermal boundary conductance of the grain boundaries G_k for different nanocrystalline diamond films. We conclude that the grain boundaries thermal boundary conductance G_k is a measure of the cohesive energy of the grain boundaries and therefore also of the elastic modulus of the nanocrystalline diamond films.

  17. Nanocrystalline Ni-Zn ferrites prepared by sol-gel method

    Czech Academy of Sciences Publication Activity Database

    Popovici, M.; Savii, C.; Nižňanský, Daniel; Šubrt, Jan; Boháček, Jaroslav; Becherescu, D.; Caizer, C.; Enache, C.; Ionescu, C.

    2003-01-01

    Roč. 5, č. 1 (2003), s. 251-256 ISSN 1454-4164 R&D Projects: GA MŠk LN00A028 Institutional research plan: CEZ:AV0Z4032918 Keywords : nanostructures * sol-gel processing * XRD Subject RIV: CA - Inorganic Chemistry Impact factor: 0.996, year: 2003

  18. Neutron depolarization in compressed ferrite powders

    International Nuclear Information System (INIS)

    Rekveldt, M.Th.; Kraan, W.H.

    1976-01-01

    The polarization change of a polarized neutron beam after transmission through a partly magnetized ferromagnetic material can be described by a (3x3) depolarization matrix. This matrix can be expressed in terms of domain quantities such as the reduced mean magnetization M, the mean domain size delta and the mean square direction cosinus γsub(y) of the inner magnetization within the domain, and can be used for measuring magnetic properties of ferromagnetic materials. In the underlying depolarization theory it is assumed that no correlations exist between the direction of the spontaneous magnetization Bs in neighbouring domains, and between the direction of Bs and the individual domain sizes. In order to extend the measuring method for ferromagnetic materials, measurements have been made with different compressed ferrite powders assuming that the mean domain size is equal to the mean particle size. The neutron depolarization matrix is measured as a function of an alternative external magnetic field and interpreted in terms of m, γsub(y), and delta. The possibilities and limitations of the measuring method are discussed

  19. 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.

  20. Science at the interface : grain boundaries in nanocrystalline metals.

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, Mark Andrew; Follstaedt, David Martin; Knapp, James Arthur; Brewer, Luke N.; Holm, Elizabeth Ann; Foiles, Stephen Martin; Hattar, Khalid M.; Clark, Blythe B.; Olmsted, David L.; Medlin, Douglas L.

    2009-09-01

    Interfaces are a critical determinant of the full range of materials properties, especially at the nanoscale. Computational and experimental methods developed a comprehensive understanding of nanograin evolution based on a fundamental understanding of internal interfaces in nanocrystalline nickel. It has recently been shown that nanocrystals with a bi-modal grain-size distribution possess a unique combination of high-strength, ductility and wear-resistance. We performed a combined experimental and theoretical investigation of the structure and motion of internal interfaces in nanograined metal and the resulting grain evolution. The properties of grain boundaries are computed for an unprecedented range of boundaries. The presence of roughening transitions in grain boundaries is explored and related to dramatic changes in boundary mobility. Experimental observations show that abnormal grain growth in nanograined materials is unlike conventional scale material in both the level of defects and the formation of unfavored phases. Molecular dynamics simulations address the origins of some of these phenomena.

  1. Ordered mesoporous MFe(2)O(4) (M = Co, Cu, Mg, Ni, Zn) thin films with nanocrystalline walls, uniform 16 nm diameter pores and high thermal stability: template-directed synthesis and characterization of redox active trevorite.

    Science.gov (United States)

    Haetge, Jan; Suchomski, Christian; Brezesinski, Torsten

    2010-12-20

    In this paper, we report on ordered mesoporous NiFe(2)O(4) thin films synthesized via co-assembly of hydrated ferric nitrate and nickel chloride with an amphiphilic diblock copolymer, referred to as KLE. We establish that the NiFe(2)O(4) samples are highly crystalline after calcination at 600 °C, and that the conversion of the amorphous inorganic framework comes at little cost to the ordering of the high quality cubic network of pores averaging 16 nm in diameter. We further show that the synthesis method employed in this work can be readily extended to other ferrites, such as CoFe(2)O(4), CuFe(2)O(4), MgFe(2)O(4), and ZnFe(2)O(4), which could pave the way for innovative device design. While this article focuses on the self-assembly and characterization of these materials using various state-of-the-art techniques, including electron microscopy, grazing incidence small-angle X-ray scattering (GISAXS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), X-ray photoelectron spectroscopy (XPS), as well as UV-vis and Raman spectroscopy, we also examine the electrochemical properties and show the benefits of combining a continuous mesoporosity with nanocrystalline films. KLE-templated NiFe(2)O(4) electrodes exhibit reasonable levels of lithium ion storage at short charging times which stem from facile pseudocapacitance.

  2. Synthesis and luminescence properties of nanocrystalline LiF:Mg,Cu,P phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Sahare, P.D., E-mail: pdsahare@physics.du.ac.i [Department of Physics and Astrophysics, University of Delhi, Delhi 110 007 (India); Bakare, J.S. [SSGM College of Engineering, Amravati University, Shegaon 444 203, Maharashtra (India); Dhole, S.D. [Department of Physics, University of Pune, Ganeshkhind, Pune 411 007 (India); Ingale, N.B. [Department of Physics, Professor Ram Meghe Institute of Technology and Research, Badnera-Amravati 444 605, Maharashtra (India); Rupasov, A.A. [P. N. Lebedev Physical Institute, Russian Academy of Sciences, Leninsky pr-t 53, Moscow (Russian Federation)

    2010-02-15

    Nanocrystalline LiF:Mg,Cu,P phosphor material of different shapes and sizes (microcrystalline cubic shape, nanorod shape and nanocrystalline cubical shaped) have been prepared by the chemical co-precipitation method. Thermoluminescence (TL) and other dosimetric characteristics of the phosphor are studied and presented here. The formation of the materials was confirmed by the X-ray diffraction (XRD). Its shapes and sizes were also observed using scanning electron microscope (SEM). The TL glow curve of the microcrystalline powder shows a prominent single peak at 408 K along with another peak of lesser intensity at around 638 K. On the contrary, the nanocrystalline rod shaped particles show a peak of low intensity at 401 K and a prominent peak around 700 K while the nanocrystalline particles in cubical shapes again show two peaks, one at around 407 K and the other at around 617 K, of which the lower temperature (407 K) peak is more prominent. The glow curve structure changes at very high doses (100 kRad) and some new peaks appear at around 525 and 637 K also the first peak appearing at around 401 K becomes prominent. The observed changes in TL due to the change in the shape and sizes of the nanophosphor have been reported. The PL has also been studied and various excitation and emission peaks observed due to the presence of various impurities are explained. The observed results have been explained in the light of asymmetrical crystal field effects due to asymmetrical shapes of the nanocrystalline phosphor. The comparison of these properties with the microcrystalline material prepared by the same co-precipitation method is also done.

  3. High-strength bulk nano-crystalline silver prepared by selective leaching combined with spark plasma sintering

    Czech Academy of Sciences Publication Activity Database

    Marek, I.; Vojtěch, D.; Michalcová, A.; Kubatík, Tomáš František

    2015-01-01

    Roč. 627, March (2015), s. 326-332 ISSN 0921-5093 Institutional support: RVO:61389021 Keywords : Nano-crystalline material * Selective leaching * Silver * Spark plasma sintering * Strength Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 2.647, year: 2015 http://dx.doi.org/10.1016/j.msea.2015.01.014

  4. Nanocrystalline permanent magnets with enhanced properties

    International Nuclear Information System (INIS)

    Leonowicz, M.

    2002-01-01

    Parameters of permanent magnets result from the combination of intrinsic properties such as saturation magnetization, magnetic exchange, and magnetocrystalline energy, as well as microstructural parameters such as phase structure, grain size, and orientation. Reduction of grain size into nanocrystalline regime (∼ 50 nm) leads to the enhanced remanence which derives from ferromagnetic exchange coupling between highly refined grains. In this study the fundamental phenomena, quantities, and structure parameters, which define nanophase permanent magnets are presented and discussed. The theoretical considerations are confronted with experimental data for nanocrystalline Sm-Fe-N type permanent magnets. (author)

  5. Effect of residual stress on fatigue crack propagation at 200 C in a welded joint austenitic stainless steel - ferritic steel

    International Nuclear Information System (INIS)

    Zahouane, A.I.; Gauthier, J.P.; Petrequin, P.

    1988-01-01

    Fatigue resistance of heterogeneous welded joints between austenitic stainless steels and ferritic steels is evaluated for reactor components and more particularly effect of residual stress on fatigue crack propagation in a heterogeneous welded joint. Residual stress is measured by the hole method in which a hole is drilled through the center of a strain gage glued the surface of the materials. In the non uniform stress field a transmissibility function is used for residual stress calculation. High compression residual stress in the ferritic metal near the interface ferritic steel/weld slow down fatigue crack propagation. 5 tabs., 15 figs., 19 refs [fr

  6. Enzymatic-assisted preparation of nanocrystalline cellulose from non-wood fibers

    OpenAIRE

    Beltramino Heffes, Facundo

    2016-01-01

    In the current scenario of growing environmental concerns, the search for innovative, renewable, non-polluting materials has never been as intensive as it is today. Cellulose, being the most abundant polymer on earth, offers a wide range of possibilities for fulfilling current and potential future needs for novel materials. In this direction, research in the field of nanocrystalline cellulose (NCC) has attracted a great interest in recent years. However, this great interest has been shadowed ...

  7. Characterization of SrCo1.5Ti1.5Fe9O19 hexagonal ferrite synthesized by sol-gel combustion and solid state route

    International Nuclear Information System (INIS)

    Vinaykumar, R.; Mazumder, R.; Bera, J.

    2017-01-01

    Co-Ti co-substituted SrM hexagonal ferrite (SrCo 1.5 Ti 1.5 Fe 9 O 19 ) was synthesized by sol-gel combustion and solid state route. The effects of sources of TiO 2 raw materials; titanium tetra-isopropoxide (TTIP) and titanyl nitrate (TN) on the phase formation behavior and properties of the ferrite were studied. The thermal decomposition behavior of the gel was studied using TG-DSC. The phase formation behavior of the ferrite was studied by using X-ray powder diffraction and FTIR analysis. Phase formation was comparatively easier in the TN-based sol-gel process. The morphology of powder and sintered ferrite was investigated using scanning electron microscope. Magnetic properties like magnetization, coercivity, permeability, tan δ µ and dielectric properties were investigated. The ferrite synthesized by sol-gel based chemical route showed higher saturation magnetization, permeability and permittivity compared to the ferrite synthesized by solid state route. - Highlights: • SrCo 1.5 Ti 1.5 Fe 9 O 19 ferrite was successfully prepared by sol–gel combustion process. • Sol-gel synthesis of the ferrite using titanyl nitrate has been reported first time. • Phase formation was easier in the titanyl nitrate based sol-gel process. • Better magneto-dielectric properties were observed in sol-gel processed ferrite.

  8. Growth modes of individual ferrite grains in the austenite to ferrite transformation of low carbon steels

    International Nuclear Information System (INIS)

    Li, D.Z.; Xiao, N.M.; Lan, Y.J.; Zheng, C.W.; Li, Y.Y.

    2007-01-01

    The mesoscale deterministic cellular automaton (CA) method and probabilistic Q-state Potts-based Monte Carlo (MC) model have been adopted to investigate independently the individual growth behavior of ferrite grain during the austenite (γ)-ferrite (α) transformation. In these models, the γ-α phase transformation and ferrite grain coarsening induced by α/α grain boundary migration could be simulated simultaneously. The simulations demonstrated that both the hard impingement (ferrite grain coarsening) and the soft impingement (overlapping carbon concentration field) have a great influence on the individual ferrite growth behavior. Generally, ferrite grains displayed six modes of growth behavior: parabolic growth, delayed nucleation and growth, temporary shrinkage, partial shrinkage, complete shrinkage and accelerated growth in the transformation. Some modes have been observed before by the synchrotron X-ray diffraction experiment. The mesoscopic simulation provides an alternative tool for investigating both the individual grain growth behavior and the overall transformation behavior simultaneously during transformation

  9. Structural and electrical properties of nickel substituted cadmium ferrite

    Science.gov (United States)

    Chethan, B.; Raj Prakash, H. G.; Vijayakumari, S. C.; Ravikiran, Y. T.

    2018-05-01

    Spinal nano-sized Cadmium ferrite (CD) and Nickel substituted cadmium ferrite (NSCF) were fabricated by sol-gel auto combustion method. The formation of spinal structure of ferrite materials was confirmed by X-ray diffraction (XRD) analysis. The crystallites size of CF and NSCF as determined by Scherrer's formula were found to be 24.73 nm and 17.70 nm respectively. comparative study of Fourier transform infrared spectroscopy (FTIR) of CF and NSCF revealed tetrahedral absorption bands shifted slightly towards higher frequency where as octahedral bands shifted towards lower frequency side confirming interfacial interaction between Ni and CF. The AC conductivity (σ), loss tangent (tan δ) and complex plane impedance plots for both CF and NSCF are determined at various frequencies ranging from 50 kHz to 5 MHz and comparatively analyzed. The increase in AC conductivity of the NSCF nano particles as compared to CF was explained in the light of hopping model. The impedance measurement of NSCF show presence of a semi-circle corresponding to the grain boundary resistance and hence shows that the conductivity takes place largely through grain boundaries.

  10. 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)

  11. Bulletin of Materials Science | News

    Indian Academy of Sciences (India)

    scale grain growth of two nanocrystalline materials, Pd81Zr19 and RuAl. ... Structural, optical and electrical properties of chemically deposited copper selenide films .... Effect of substitution of titanium by magnesium and niobium on structure and ...

  12. Mechanically alloyed PrFeB nanocrystalline magnets

    International Nuclear Information System (INIS)

    Kaszuwara, W.; Leonowicz, M.

    1998-01-01

    Mechanically alloyed PrFeB nanocrystalline magnets were prepared by extensive ball milling of Pr, Fe and Fe 80 B 20 powders, followed by diffusion annealing. After milling, the material consisted of nanocrystalline α-Fe crystallites embedded in amorphous Pr-rich matrix. Thermomagnetic and calorimetric investigations of the transformations which occurred during annealing showed that the amorphous phase crystallised at 240 C, leading to the formation of crystalline Pr having lattice constants 10% greater than those shown in the ASTM data. This fact indicated that mechanical alloying and low temperature annealing led to the formation of a solid solution of either Fe or B in Pr, which does not exist in the equilibrium state. The Pr 2 Fe 14 B phase was subsequently formed within a temperature range of 420-620 C. The magnetic properties of magnets depend on the phase structure and grain size. Milling time appears to be a decisive processing parameter for the tailoring of the magnetic properties. Depending on the phase structure, the coercivities varied from 100 to 1200 kA/m and, respectively, the remanences from 0.98 T to 0.6 T. The highest maximum energy product was 80 kJ/m 3 . (orig.)

  13. Stability of nanocrystalline Ni-based alloys: coupling Monte Carlo and molecular dynamics simulations

    Science.gov (United States)

    Waseda, O.; Goldenstein, H.; Silva, G. F. B. Lenz e.; Neiva, A.; Chantrenne, P.; Morthomas, J.; Perez, M.; Becquart, C. S.; Veiga, R. G. A.

    2017-10-01

    The thermal stability of nanocrystalline Ni due to small additions of Mo or W (up to 1 at%) was investigated in computer simulations by means of a combined Monte Carlo (MC)/molecular dynamics (MD) two-steps approach. In the first step, energy-biased on-lattice MC revealed segregation of the alloying elements to grain boundaries. However, the condition for the thermodynamic stability of these nanocrystalline Ni alloys (zero grain boundary energy) was not fulfilled. Subsequently, MD simulations were carried out for up to 0.5 μs at 1000 K. At this temperature, grain growth was hindered for minimum global concentrations of 0.5 at% W and 0.7 at% Mo, thus preserving most of the nanocrystalline structure. This is in clear contrast to a pure Ni model system, for which the transformation into a monocrystal was observed in MD simulations within 0.2 μs at the same temperature. These results suggest that grain boundary segregation of low-soluble alloying elements in low-alloyed systems can produce high-temperature metastable nanocrystalline materials. MD simulations carried out at 1200 K for 1 at% Mo/W showed significant grain boundary migration accompanied by some degree of solute diffusion, thus providing additional evidence that solute drag mostly contributed to the nanostructure stability observed at lower temperature.

  14. Rapid rate sintering of nanocrystalline ZrO2-3 mol% Y2O3

    International Nuclear Information System (INIS)

    Chen, D.J.; Mayo, M.J.

    1996-01-01

    Conventional ramp-and-hold sintering with a wide range of heating rates was conducted on submicrometer and nanocrystalline ZrO 2 -3 mol% Y 2 O 3 powder compacts. Although rapid heating rates have been reported to produce high density/fine grain size products for many submicrometer and smaller starting powders, the application of this technique to ZrO 2 -3 mol% Y 2 O 3 produced mixed results. In the case of submicrometer ZrO 2 -3 mol% Y 2 O 3 , neither densification nor grain growth was affected by the heating rate used. In the case of nanocrystalline ZrO 2 -3 mol% Y 2 O 3 , fast heating rates severely retarded densification and had a minimal effect on grain growth. The large adverse effect of fast heating rates on the densification of the nanocrystalline powder was traced to a thermal gradient/differential densification effect. Microstructural evidence suggests that the rate of densification greatly exceeded the rate of heat transfer in this material; consequently, the sample interior was not able to densify before being geometrically constrained by a fully dense shell which formed at the sample exterior. This finding implies that rapid rate sintering will meet severe practical constraints in the manufacture of bulk nanocrystalline ZrO 2 -3 mol% Y 2 O 3 specimens

  15. Influence of particle size on the magnetic spectrum of NiCuZn ferrites for electromagnetic shielding applications

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Xiaohan; Yan, Shuoqing; Liu, Weihu [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei (China); Feng, Zekun, E-mail: fengzekun@mail.hust.edu.cn [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei (China); Chen, Yajie; Harris, Vincent G. [Center for Microwave Magnetic Materials and Integrated Circuits, and Department of Electrical and Computer Engineering, Northeastern University, Boston, MA 02115 (United States)

    2016-03-01

    The effect of ferrite particle size on the magnetic spectra (1 MHz to 1 GHz) of NiCuZn polycrystalline ferrites doped with Co{sub 2}O{sub 3} and Bi{sub 2}O{sub 3} were systematically investigated. The experiments indicate that the ferrite particle size tailored by grinding time and corresponding sintering temperatures is crucial to achieving high permeability, high Q-factor and low magnetic loss, at 13.56 MHz for electromagnetic shielding applications especially in the near field communication (NFC) field. It is evident that high-performance NiZnCu ferrite materials are strongly tailored by morphology and microstructure. It is conclusive that fine ferrite particles and relatively low sintering temperatures are favorable to lowering magnetic loss and enhancing permeability. This work has built a foundation for improvement of the ferrite slurry used for fabrication of large area tape-casting ferrite sheets. - Highlights: • Fine particles are favorable to lowering magnetic loss and enhancing permeability.

  16. Development of oxide dispersion strengthened 9Cr ferritic-martensitic steel clad tube for fast reactor

    International Nuclear Information System (INIS)

    Laha, K.; Saroja, S.; Mathew, M.D.; Jayakumar, T.; Vijay, R.; Venugopal Reddy, A.; Lakshminarayana, B.; Kapoor, Komal; Jha, S.K.; Tonpe, S.S.

    2012-01-01

    One of the key issues in the economical operation of FBR is to achieve high burn-up of fuel (200-250 GWd/t) which considerably reduces the fuel cycle cost. This imposes stringent requirements of void swelling resistance upto 200 dpa for the core structural materials. Presently used alloy 09 (a modified austenitic stainless steel, 15Cr-15Ni-Ti) for PFBR has void swelling limit less than 150 dpa. Because of the inherent void swelling resistance, 9-12Cr steels ferritic/martensitic steels are qualified for irradiation upto 200 dpa but their low creep strength at temperatures above 600 deg C restricts their application as a clad material. Oxide dispersion strengthening is found to be promising means of extending the creep resistance of ferritic/martensitic steels beyond 650 deg C without sacrificing the inherent advantages of high thermal conductivity and low swelling of ferritic steels

  17. Feasibility of low-cost magnetic rail designs by integrating ferrite magnets and NdFeB magnets for HTS Maglev systems

    Science.gov (United States)

    Sun, R. X.; Deng, Z. G.; Gou, Y. F.; Li, Y. J.; Zheng, J.; Wang, S. Y.; Wang, J. S.

    2015-09-01

    Permanent magnet guideway (PMG) is an indispensable part of high temperature superconducting (HTS) Maglev systems. Present PMGs are made of NdFeB magnets with excellent performance and cost much. As another permanent magnet material, the ferrite magnet is weak at magnetic energy product and coercive force, but inexpensive. So, it is a possible way to integrate the ferrite and NdFeB magnets for cutting down the cost of present PMGs. In the paper, the equivalent on magnetic field intensity between ferrite magnets and NdFeB magnets was evaluated by finite element simulation. According to the calculation results, the magnetic field of the PMG integrating ferrite magnets and NdFeB magnets can be increased remarkably comparing with the pure ferrite PMG. It indicates that low-cost PMG designs by integrating the two permanent magnet materials are feasible for the practical HTS Maglev system.

  18. Chemical vapor deposition of nanocrystalline diamond films

    International Nuclear Information System (INIS)

    Vyrovets, I.I.; Gritsyna, V.I.; Dudnik, S.F.; Opalev, O.A.; Reshetnyak, O.M.; Strel'nitskij, V.E.

    2008-01-01

    The brief review of the literature is devoted to synthesis of nanocrystalline diamond films. It is shown that the CVD method is an effective way for deposition of such nanostructures. The basic technological methods that allow limit the size of growing diamond crystallites in the film are studied.

  19. Multiphase Nanocrystalline Ceramic Concept for Nuclear Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Mecartnery, Martha [Univ. of California, Irvine, CA (United States); Graeve, Olivia [Univ. of California, San Diego, CA (United States); Patel, Maulik [Univ. of Liverpool (United Kingdom)

    2017-05-25

    The goal of this research is to help develop new fuels for higher efficiency, longer lifetimes (higher burn-up) and increased accident tolerance in future nuclear reactors. Multiphase nanocrystalline ceramics will be used in the design of simulated advanced inert matrix nuclear fuel to provide for enhanced plasticity, better radiation tolerance, and improved thermal conductivity

  20. Multiphase Nanocrystalline Ceramic Concept for Nuclear Fuel

    International Nuclear Information System (INIS)

    Mecartnery, Martha; Graeve, Olivia; Patel, Maulik

    2017-01-01

    The goal of this research is to help develop new fuels for higher efficiency, longer lifetimes (higher burn-up) and increased accident tolerance in future nuclear reactors. Multiphase nanocrystalline ceramics will be used in the design of simulated advanced inert matrix nuclear fuel to provide for enhanced plasticity, better radiation tolerance, and improved thermal conductivity

  1. Characterization of nanocrystalline silicon germanium film and ...

    African Journals Online (AJOL)

    The nanocrystalline silicon-germanium films (Si/Ge) and Si/Ge nanotubes have low band gaps and high carrier mobility, thus offering appealing potential for absorbing gas molecules. Interaction between hydrogen molecules and bare as well as functionalized Si/Ge nanofilm and nanotube was investigated using Monte ...

  2. Synthesis and characterization of a nanocrystalline diamond aerogel

    Energy Technology Data Exchange (ETDEWEB)

    Pauzauskie, Peter J.; Crowhurst, Jonathan C.; Worsley, Marcus A.; Laurence, Ted A.; Kilcoyne, A. L. David; Wang, Yinmin; Willey, Trevor M.; Visbeck, Kenneth S.; Fakra, Sirine C.; Evans, William J.; Zaug, Joseph M.; Satcher, Jr., Joe H.

    2011-07-06

    Aerogel materials have myriad scientific and technological applications due to their large intrinsic surface areas and ultralow densities. However, creating a nanodiamond aerogel matrix has remained an outstanding and intriguing challenge. Here we report the high-pressure, high-temperature synthesis of a diamond aerogel from an amorphous carbon aerogel precursor using a laser-heated diamond anvil cell. Neon is used as a chemically inert, near-hydrostatic pressure medium that prevents collapse of the aerogel under pressure by conformally filling the aerogel's void volume. Electron and X-ray spectromicroscopy confirm the aerogel morphology and composition of the nanodiamond matrix. Time-resolved photoluminescence measurements of recovered material reveal the formation of both nitrogen- and silicon- vacancy point-defects, suggesting a broad range of applications for this nanocrystalline diamond aerogel.

  3. Mesoporous nanocrystalline film architecture for capacitive storage devices

    Science.gov (United States)

    Dunn, Bruce S.; Tolbert, Sarah H.; Wang, John; Brezesinski, Torsten; Gruner, George

    2017-05-16

    A mesoporous, nanocrystalline, metal oxide construct particularly suited for capacitive energy storage that has an architecture with short diffusion path lengths and large surface areas and a method for production are provided. Energy density is substantially increased without compromising the capacitive charge storage kinetics and electrode demonstrates long term cycling stability. Charge storage devices with electrodes using the construct can use three different charge storage mechanisms immersed in an electrolyte: (1) cations can be stored in a thin double layer at the electrode/electrolyte interface (non-faradaic mechanism); (2) cations can interact with the bulk of an electroactive material which then undergoes a redox reaction or phase change, as in conventional batteries (faradaic mechanism); or (3) cations can electrochemically adsorb onto the surface of a material through charge transfer processes (faradaic mechanism).

  4. Preparation and characterization of polyol assisted ultrafine Cu–Ni–Mg–Ca mixed ferrite via co-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Boobalan, T. [Park College of Engineering and Technology, Coimbatore (India); Pavithradevi, S. [Department of Physics, Government College of Technology, Coimbatore (India); Suriyanarayanan, N., E-mail: nsuri22@gmail.com [Department of Physics, PSG Polytechnic College, Coimbatore (India); Manivel Raja, M. [Defence Metallurgical Research Laboratory, Ministry of Defence, Govt. of India, Hyderabad (India); Ranjith Kumar, E., E-mail: ranjueaswar@gmail.com [Dr. NGP Institute of Technology, Coimbatore (India)

    2017-04-15

    Nanocrystalline spinel ferrite of composition Cu{sub 0.2}Ni{sub 0.2}Mg{sub 0.2}Ca{sub 0.4}Fe{sub 2}O{sub 4} is synthesized by wet hydroxyl co-precipitation method in ethylene glycol as chelating agent and sodium hydroxide as precipitator at pH 8. Ethylene glycol is utilized as the medium which serves as the dissolvable and in addition a complexing specialist. The synthesized particles are annealed at various temperatures. Thermogravimetric investigation affirms that at 280 °C ethylene glycol is dissipated totally and stable phase arrangement happens over 680 °C. FTIR spectra of as synthesized and annealed at 1050 °C recorded between 400 cm{sup −1} and 4000 cm{sup −1}. Structural characterizations of all the samples are carried out by X-ray diffraction (XRD) technique. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) affirm that the particles are spherical and cubic shape with the crystallite size of 12 nm to 32 nm. Magnetic measurements are performed utilizing vibrating sample magnetometer at room temperature. - Highlights: • Polyol improves purity of the spinel ferrite. • TG curves confirm the single phase ferrite is obtained above 680 °C. • Super paramagnetic behavior is seen at lower annealing temperature. • Soft ferromagnetic behavior is obtained at 1050 °C.

  5. Effect of Zn addition on structural, magnetic properties, antistructural modeling of Co1-xZnxFe2O4 nano ferrite

    Science.gov (United States)

    Raghuvanshi, S.; Kane, S. N.; Tatarchuk, T. R.; Mazaleyrat, F.

    2018-05-01

    Effect of Zn addition on cationic distribution, structural properties, magnetic properties, antistructural modeling of nanocrystalline Co1-xZnxFe2O4 (0.08 ≤ x ≤ 0.56) ferrite is reported. XRD confirms the formation of single phase cubic spinel nano ferrites with average grain diameter ranging between 41.2 - 54.9 nm. Coercivity (Hc), anisotropy constant (K1) decreases with Zn addition, but experimental, theoretical saturation magnetization (Ms, Ms(t)) increases upto x = 0.32, then decreases, attributed to the breaking of collinear ferrimagnetic phase. Variation of magnetic properties is correlated with cationic distribution. A new antistructural modeling for describing active surface centers is discussed to explain change in concentration of donor's active centers Zn'B, Co'B, acceptor's active centers Fe*A are explained.

  6. Large zinc cation occupancy of octahedral sites in mechanically activated zinc ferrite powders

    Energy Technology Data Exchange (ETDEWEB)

    Oliver, S. A. [Center for Electromagnetic Research, Northeastern University, Boston, Massachusetts 02115 (United States); Harris, V. G. [Complex Materials Section, Code 6342, Naval Research Laboratory, Washington, DC 20375 (United States); Hamdeh, H. H. [Department of Physics, Wichita State University, Wichita, Kansas 67260 (United States); Ho, J. C. [Department of Physics, Wichita State University, Wichita, Kansas 67260 (United States)

    2000-05-08

    The cation site occupancy of a mechanically activated nanocrystalline zinc ferrite powder was determined as (Zn{sub 0.55}{sup 2+}Fe{sub 0.18}{sup 3+}){sub tet}[Zr{sub 0.45}{sup 2+}Fe{sub 1.82}{sup 3+}]{sub oct}O{sub 4} through analysis of extended x-ray absorption fine structure measurements, showing a large redistribution of cations between sites compared to normal zinc ferrite samples. The overpopulation of cations in the octahedral sites was attributed to the ascendance in importance of the ionic radii over the crystal energy and bonding coordination in determining which interstitial sites are occupied in this structurally disordered powder. Slight changes are observed in the local atomic environment about the zinc cations, but not the iron cations, with respect to the spinel structure. The presence of Fe{sup 3+} on both sites is consistent with the measured room temperature magnetic properties. (c) 2000 American Institute of Physics.

  7. Characterization of Ni ferrites powders prepared by plasma arc discharge process

    Energy Technology Data Exchange (ETDEWEB)

    Safari, A. [Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University, Ahvaz (Iran, Islamic Republic of); Gheisari, Kh., E-mail: khgheisari@scu.ac.ir [Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University, Ahvaz (Iran, Islamic Republic of); Farbod, M. [Physics Department, Shahid Chamran University, Ahvaz (Iran, Islamic Republic of)

    2017-01-01

    The aim of this work was to synthesize a single-phase spinel structure from a mixture of zinc, iron and nickel powders by plasma arc discharge method. A mixture of zinc, iron and nickel powders with the appropriate molar ratio was prepared and formed into a cylindrical shape. The synthesis process was performed in air, oxygen and argon atmospheres with the applied arc current of 400 A and pressure of 1 atm. After establishing an arc between the electrodes, the produced powders were collected and their structure and magnetic properties were examined by XRD and VSM, respectively. ZnO as an impurity was appeared in the as-produced powders owing to the high reactivity of zinc atoms, preventing the formation of Ni–Zn ferrite. A pure spinel structure with the highest saturation magnetization (43.8 emu/g) was observed as zinc powders removed completely from the initial mixture. Morphological evaluations using field emission scanning electron microscopy showed that the mean size of fabricated nanoparticles was in the range 100–200 nm and was dependent on the production conditions. - Highlights: • Nanocrystalline Ni ferrite powders are prepared by plasma arc discharge process. • The mean particle size of the as-synthesized ceramic powders is about 100 nm. • The highest saturation magnetization is observed as zinc powders removed completely from the initial mixture.

  8. Advanced Magnetic Materials for Aircraft Power Applications

    National Research Council Canada - National Science Library

    McHenry, Michael

    2003-01-01

    ... new materials with improved magnetic and mechanical properties at high temperature. The group worked on the refinement of existing soft bulk materials while conducting research on novel nanocrystalline magnets in parallel...

  9. Computational materials science: Nanoscale plasticity

    DEFF Research Database (Denmark)

    Jacobsen, Karsten Wedel; Schiøtz, Jakob

    2002-01-01

    How does plastic deformation of polycrystalline materials with grain sizes less than 100 nm look at the atomic scale? A large-scale molecular dynamics simulation of nanocrystalline alluminium reveals some surprising behaviour.......How does plastic deformation of polycrystalline materials with grain sizes less than 100 nm look at the atomic scale? A large-scale molecular dynamics simulation of nanocrystalline alluminium reveals some surprising behaviour....

  10. Optimization and testing results of Zr-bearing ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Lizhen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yang, Ying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Tyburska-Puschel, Beata [Univ. of Wisconsin, Madison, WI (United States); Sridharan, K. [Univ. of Wisconsin, Madison, WI (United States)

    2014-09-01

    The mission of the Nuclear Energy Enabling Technologies (NEET) program is to develop crosscutting technologies for nuclear energy applications. Advanced structural materials with superior performance at elevated temperatures are always desired for nuclear reactors, which can improve reactor economics, safety margins, and design flexibility. They benefit not only new reactors, including advanced light water reactors (LWRs) and fast reactors such as sodium-cooled fast reactor (SFR) that is primarily designed for management of high-level wastes, but also life extension of the existing fleet when component exchange is needed. Developing and utilizing the modern materials science tools (experimental, theoretical, and computational tools) is an important path to more efficient alloy development and process optimization. Ferritic-martensitic (FM) steels are important structural materials for nuclear reactors due to their advantages over other applicable materials like austenitic stainless steels, notably their resistance to void swelling, low thermal expansion coefficients, and higher thermal conductivity. However, traditional FM steels exhibit a noticeable yield strength reduction at elevated temperatures above ~500°C, which limits their applications in advanced nuclear reactors which target operating temperatures at 650°C or higher. Although oxide-dispersion-strengthened (ODS) ferritic steels have shown excellent high-temperature performance, their extremely high cost, limited size and fabricability of products, as well as the great difficulty with welding and joining, have limited or precluded their commercial applications. Zirconium has shown many benefits to Fe-base alloys such as grain refinement, improved phase stability, and reduced radiation-induced segregation. The ultimate goal of this project is, with the aid of computational modeling tools, to accelerate the development of a new generation of Zr-bearing ferritic alloys to be fabricated using conventional

  11. Ferrite HOM Absorber for the RHIC ERL

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-10-01

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

  12. Focused Application Software for Ferrite Patch Antennas

    National Research Council Canada - National Science Library

    Trott, Keith

    1999-01-01

    ... (brick and tetrahedral elements) are combined by MRC via a graphical user interface (GUI) into a user friendly code capable of modeling conformal antennas with ferrite sub and superstrates recessed in planar surfaces.

  13. Micromagnetic simulations of spinel ferrite particles

    International Nuclear Information System (INIS)

    Dantas, Christine C.; Gama, Adriana M.

    2010-01-01

    This paper presents the results of simulations of the magnetization field ac response (at 2-12 GHz) of various submicron ferrite particles (cylindrical dots). The ferrites in the present simulations have the spinel structure, expressed here by M 1 - n Zn n Fe 2 O 4 (where M stands for a divalent metal), and the parameters chosen were the following: (a) for n=0: M={Fe, Mn, Co, Ni, Mg, Cu }; (b) for n=0.1: M = {Fe, Mg} (mixed ferrites). These runs represent full 3D micromagnetic (one-particle) ferrite simulations. We find evidences of confined spin waves in all simulations, as well as a complex behavior nearby the main resonance peak in the case of the M = {Mg, Cu} ferrites. A comparison of the n=0 and n=0.1 cases for fixed M reveals a significant change in the spectra in M = Mg ferrites, but only a minor change in the M=Fe case. An additional larger scale simulation of a 3 by 3 particle array was performed using similar conditions of the Fe 3 O 4 (magnetite; n=0, M = Fe) one-particle simulation. We find that the main resonance peak of the Fe 3 O 4 one-particle simulation is disfigured in the corresponding 3 by 3 particle simulation, indicating the extent to which dipolar interactions are able to affect the main resonance peak in that magnetic compound.

  14. Resistance to pitting corrosion in ferritic and austenitic/ferritic steels

    International Nuclear Information System (INIS)

    De Bouvier, O.

    1995-01-01

    Stainless steel tubes carrying raw water are potentially vulnerable to pitting corrosion. With a view to minimizing the corrosion risk in the river-water-cooled condensers at PWR power plant, a study was conducted to determine initiation conditions and incubation durations for pitting corrosion in stagnant water. As a result, condenser tubes in Z2 CI 18 (439) or Z2 CT 18-10 (304L) steels were phased out in favour of Z2 CND 16-32 (316L) stainless steel. The same question can be yield for other applications and especially for all types of exchangers for use in electrical applications. This study sought to assess alternative methods for estimating pitting corrosion, and to check the results of these methods against the actual behaviour of studied steels. The study covered ferritic steels (439, 444, 290Mo), austenitic steel (316L) and austenitic/ferritic steels (Uranus 35N, 45N, 47N, 52N). Two approaches were adopted: laboratory tests to compare pitting corrosion risks on different materials, and tests for characterizing the behaviour of steels exposed to river water. The study begins with a laboratory tests that yield an arbitrary parameter for quantifying pitting corrosion resistance. One method involves measuring the pitting temperature in an aggressive ferric chloride solution. Other methods measure the pitting potential, either statistically (Multipit method) or deterministically (polarization curve). We then go on to discuss tests under simulated life-like conditions, involving repeated immersions in water from the Seine. (author). 9 refs., 13 figs, 9 tabs

  15. Resolving the nanostructure of plasma-enhanced chemical vapor deposited nanocrystalline SiOx layers for application in solar cells

    Science.gov (United States)

    Klingsporn, M.; Kirner, S.; Villringer, C.; Abou-Ras, D.; Costina, I.; Lehmann, M.; Stannowski, B.

    2016-06-01

    Nanocrystalline silicon suboxides (nc-SiOx) have attracted attention during the past years for the use in thin-film silicon solar cells. We investigated the relationships between the nanostructure as well as the chemical, electrical, and optical properties of phosphorous, doped, nc-SiO0.8:H fabricated by plasma-enhanced chemical vapor deposition. The nanostructure was varied through the sample series by changing the deposition pressure from 533 to 1067 Pa. The samples were then characterized by X-ray photoelectron spectroscopy, spectroscopic ellipsometry, Raman spectroscopy, aberration-corrected high-resolution transmission electron microscopy, selected-area electron diffraction, and a specialized plasmon imaging method. We found that the material changed with increasing pressure from predominantly amorphous silicon monoxide to silicon dioxide containing nanocrystalline silicon. The nanostructure changed from amorphous silicon filaments to nanocrystalline silicon filaments, which were found to cause anisotropic electron transport.

  16. Micromechanical modelling of nanocrystalline and ultrafine grained metals: A short overview

    DEFF Research Database (Denmark)

    Mishnaevsky, Leon; Levashov, Evgeny

    2015-01-01

    An overview of micromechanical models of strength and deformation behaviour of nanostructured and ultrafine grained metallic materials is presented. Composite models of nanomaterials, polycrystal plasticity based models, grain boundary sliding, the effect of non-equilibrium grain boundaries...... and nanoscale properties are discussed and compared. The examples of incorporation of peculiar nanocrystalline effects (like large content of amorphous or semi-amorphous grain boundary phase, partial dislocation GB emission/glide/GB absorption based deformation mechanism, diffusion deformation, etc.......) into the continuum mechanical approach are given. The possibilities of using micromechanical models to explore the ways of the improving the properties of nanocrystalline materials by modifying their structures (e.g., dispersion strengthening, creating non-equilibrium grain boundaries, varying the grain size...

  17. Fracture toughness of ferritic alloys irradiated at FFTF

    International Nuclear Information System (INIS)

    Huang, F.H.

    1986-05-01

    Ferritic compact tension specimens loaded in the Material Open Test Assembly (MOTA) for irradiation during FFTF Cycle 4 were tested at temperatures ranging from room temperature to 428/degree/C. The electrical potential single specimen method was used to measure the fracture toughness of the specimens. Results showed that the fracture toughness of both HT-9 and 9Cr-1Mo decreases with increasing test temperature and that the toughness of HT-9 was about 30% higher than that of 9Cr-1Mo. In addition, increasing irradiation temperature resulted in an increase in tearing modulus for both alloys. 4 refs., 5 figs., 1 tab

  18. Embrittlement of a 17Cr ferritic steel irradiated in Phenix

    International Nuclear Information System (INIS)

    Allegraud, G.; Boutard, J.L.; Boyer, J.M.

    1987-01-01

    Charpy V and tensile tests have been performed with samples made of 17Cr ferritic steel irradiated in Phenix at temperatures between 390 and 540C up to a maximum dose of 83.3 dpaF. All over the temperature and dose ranges, irradiation leads to an increase of the ductile brittle transition temperature (DBTT). The DBTT and hardening are decreasing functions of the irradiation temperature. Fast neutron flux at 390C hardens the material more than a sole thermal ageing does

  19. Enlargement of Tuning Range in a Ferrite-Tuned Cavity Through Superposed Orthogonal and Parallel Magnetic Bias

    CERN Document Server

    Vollinger, C

    2013-01-01

    Conventional ferrite-tuned cavities operate either with bias fields that are orthogonal or parallel to the magnetic RF-field. For a cavity that tunes rapidly over an overall frequency range around 100-400 MHz with high Q, we use ferrite garnets exposed to an innovative new biasing method consisting of a superposition of perpendicular and parallel magnetic fields. This method leads to a significant enlargement of the high-Q cavity tuning range by defining an operation point close to the magnetic saturation and thus improving ferrite material behaviour. A further advantage of this technique is the fast tuning speed resulting from the fact that tuning is carried out either with pure parallel biasing, or together with a very small change of operating point from perpendicular bias. In this paper, several scaled test models of ferrite-filled resonators are shown; measurements on the set-ups are compared and discussed.

  20. Formation of austenite in high Cr ferritic/martensitic steels by high fluence neutron irradiation

    Science.gov (United States)

    Lu, Z.; Faulkner, R. G.; Morgan, T. S.

    2008-12-01

    High Cr ferritic/martensitic steels are leading candidates for structural components of future fusion reactors and new generation fission reactors due to their excellent swelling resistance and thermal properties. A commercial grade 12%CrMoVNb ferritic/martensitic stainless steel in the form of parent plate and off-normal weld materials was fast neutron irradiated up to 33 dpa (1.1 × 10 -6 dpa/s) at 400 °C and 28 dpa (1.7 × 10 -6 dpa/s) at 465 °C, respectively. TEM investigation shows that the fully martensitic weld metal transformed to a duplex austenite/ferrite structure due to high fluence neutron irradiation, the austenite was heavily voided (˜15 vol.%) and the ferrite was relatively void-free; whilst no austenite phases were detected in plate steel. Thermodynamic and phase equilibria software MTDATA has been employed for the first time to investigate neutron irradiation-induced phase transformations. The neutron irradiation effect is introduced by adding additional Gibbs free energy into the system. This additional energy is produced by high energy neutron irradiation and can be estimated from the increased dislocation loop density caused by irradiation. Modelling results show that neutron irradiation reduces the ferrite/austenite transformation temperature, especially for high Ni weld metal. The calculated results exhibit good agreement with experimental observation.

  1. 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

  2. Ferritic insertion for reduction of toroidal magnetic field ripple on JT-60U

    International Nuclear Information System (INIS)

    Shinohara, K.; Sakurai, S.; Ishikawa, M.; Tsuzuki, K.; Suzuki, Y.; Masaki, K.; Naito, O.; Kurihara, K.; Suzuki, T.; Koide, Y.; Fujita, T.; Miura, Y.

    2007-01-01

    Ferritic steel tiles (FSTs) have been installed to improve the energetic ion confinement by reducing a toroidal magnetic field ripple. Aiming at cost-effective installation, orbit-following calculations of energetic ions were carried out for a design of the installation of ferritic steel on the JT-60U by using the fully three dimensional magnetic field orbit-following Monte-Carlo (F3D OFMC) code, which had been developed for ferritic insert experiments on the JFT-2M and can treat the complex magnetic field structure produced by ferritic inserts. The installed FSTs add a non-linear magnetic field on magnetic sensors for plasma control and an equilibrium calculation. The code for real-time control has been modified to take into account the magnetic field by the FSTs. The plasma operation was successfully resumed after usual conditioning processes and real-time plasma control was successfully carried out. The heat load measurement indicates the improved confinement of energetic ions. These results are important for practical application of the ferritic steel, which is a leading candidate of a structural material on a DEMO reactor

  3. Moessbauer study of Mn-Zn and Mn ferrites prepared by wet method

    International Nuclear Information System (INIS)

    Michalk, C.

    1985-01-01

    Moessbauer spectroscopy was employed to study Mn-Zn ferrites before and after low-temperature annealing. The unannealed Mn-Zn ferrite prepared by a wet method and also the sintered material after annealing at 400 deg C in air show the presence of paramagnetic clusters. These findings are explained as being due to nonrandom ordering of Fe 3+ and Zn 2+ ions caused by local charge compensation in the neighbourhood of cation vacancies. A change of cation distribution after annealing at relatively low temperatures was observed. 10 refs., 3 figs. (author)

  4. Oxidation Kinetics of Ferritic Alloys in High-Temperature Steam Environments

    Science.gov (United States)

    Parker, Stephen S.; White, Josh; Hosemann, Peter; Nelson, Andrew

    2018-02-01

    High-temperature isothermal steam oxidation kinetic parameters of several ferritic alloys were determined by thermogravimetric analysis. The oxidation kinetic constant ( k) was measured as a function of temperature from 900°C to 1200°C. The results show a marked increase in oxidation resistance compared to reference Zircaloy-2, with kinetic constants 3-5 orders of magnitude lower across the experimental temperature range. The results of this investigation supplement previous findings on the properties of ferritic alloys for use as candidate cladding materials and extend kinetic parameter measurements to high-temperature steam environments suitable for assessing accident tolerance for light water reactor applications.

  5. 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

  6. 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)

  7. Characteristics of Laser Beam and Friction Stir Welded AISI 409M Ferritic Stainless Steel Joints

    Science.gov (United States)

    Lakshminarayanan, A. K.; Balasubramanian, V.

    2012-04-01

    This article presents the comparative evaluation of microstructural features and mechanical properties of friction stir welded (solid-state) and laser beam welded (high energy density fusion welding) AISI 409M grade ferritic stainless steel joints. Optical microscopy, microhardness testing, transverse tensile, and impact tests were performed. The coarse ferrite grains in the base material were changed to fine grains consisting duplex structure of ferrite and martensite due to the rapid cooling rate and high strain induced by severe plastic deformation caused by frictional stirring. On the other hand, columnar dendritic grain structure was observed in fusion zone of laser beam welded joints. Tensile testing indicates overmatching of the weld metal relative to the base metal irrespective of the welding processes used. The LBW joint exhibited superior impact toughness compared to the FSW joint.

  8. Fatigue Crack Growth Behavior of Gas Metal Arc Welded AISI 409 Grade Ferritic Stainless Steel Joints

    Science.gov (United States)

    Lakshminarayanan, A. K.; Shanmugam, K.; Balasubramanian, V.

    2009-10-01

    The effect of filler metals such as austenitic stainless steel, ferritic stainless steel, and duplex stainless steel on fatigue crack growth behavior of the gas metal arc welded ferritic stainless steel joints was investigated. Rolled plates of 4 mm thickness were used as the base material for preparing single ‘V’ butt welded joints. Center cracked tensile specimens were prepared to evaluate fatigue crack growth behavior. Servo hydraulic controlled fatigue testing machine with a capacity of 100 kN was used to evaluate the fatigue crack growth behavior of the welded joints. From this investigation, it was found that the joints fabricated by duplex stainless steel filler metal showed superior fatigue crack growth resistance compared to the joints fabricated by austenitic and ferritic stainless steel filler metals. Higher yield strength and relatively higher toughness may be the reasons for superior fatigue performance of the joints fabricated by duplex stainless steel filler metal.

  9. Comment on "Mitigating grain growth in binary nanocrystalline alloys through solute selection based on thermodynamic stability maps"

    Czech Academy of Sciences Publication Activity Database

    Lejček, Pavel; Hofmann, S.

    2015-01-01

    Roč. 107, Sep (2015), s. 235-237 ISSN 0927-0256 R&D Projects: GA ČR GBP108/12/G043 Institutional support: RVO:68378271 Keywords : nanocrystalline materials * grain size * grain boundary energy * grain boundary segregation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.086, year: 2015

  10. THERMALLY STABLE NANOCRYSTALLINE TIO2 PHOTOCATALYSTS SYNTHESIZED VIA SOL-GEL METHODS MODIFIED WITH IONIC LIQUID AND SURFACTANT MOLECULES

    Science.gov (United States)

    Recently, sol-gel methods employing ionic liquids (ILs) have shown significant implications for the synthesis of well-defined nanostructured inorganic materials. Herein, we synthesized nanocrystalline TiO2 particles via an alkoxide sol-gel method employing a water-immi...

  11. Low dielectric loss in nano-Li-ferrite spinels prepared by sol–gel ...

    Indian Academy of Sciences (India)

    ... Refresher Courses · Symposia · Live Streaming. Home; Journals; Bulletin of Materials Science; Volume 39; Issue 1. Low dielectric loss in nano-Li-ferrite spinels prepared by sol–gel auto-combustion technique. Mamata Maisnam Nandeibam Nilima Maisnam Victory Sumitra Phanjoubam. Volume 39 Issue 1 February 2016 ...

  12. Constraint Effects at Brittle Fracture Initiation in a Cast Ferritic Steel

    Czech Academy of Sciences Publication Activity Database

    Dlouhý, Ivo; Chlup, Zdeněk; Kozák, Vladislav

    č. 71 (2004), s. 873-883 ISSN 0013-7944 R&D Projects: GA AV ČR IAA2041003 Institutional research plan: CEZ:AV0Z2041904 Keywords : Cast ferritic steel * transition behaviour * fracture toughness Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.299, year: 2004 www.sciencedirect.com

  13. Synthesis of nanocrystalline hydroxyapatite by using precipitation method

    International Nuclear Information System (INIS)

    Mobasherpour, I.; Heshajin, M. Soulati; Kazemzadeh, A.; Zakeri, M.

    2007-01-01

    In this investigation, hydroxyapatite powder has been synthesized from the calcium nitrate hydrated and di-ammonium hydrogen phosphate solution by precipitation method and heat treatment of hydroxyapatite powders. In order to study the structural evolution, the Fourier transform infrared spectroscopy (FTIR), the X-ray diffraction (XRD) and simultaneous thermal analysis (STA) were used. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to estimate the particle size of the powder and observe the morphology and agglomeration state of the powder. Results show that hydroxyapatite nanocrystalline can successfully be produced by precipitation technique from raw materials. Hydroxyapatite grain gradually increased in size when temperature increased from 100 to 1200 o C, and the hydroxyapatite hexagonal-dipyramidal phase was not transformed to the other calcium phosphates phases up to 1200 o C

  14. Synthesis of nanocrystalline Zn0.5Mn0.5Fe2O4 via in situ polymerization technique

    International Nuclear Information System (INIS)

    Liu Xianming; Fu Shaoyun

    2007-01-01

    Nanocrystalline Zn 0.5 Mn 0.5 Fe 2 O 4 was synthesized through the pyrolysis of polyacrylate salt precursors prepared via in situ polymerization of the metal salts and acrylic acid. The pyrolysis behavior of the polymeric precursors was studied by use of thermal analysis. The as-obtained product was characterized by powder X-ray diffraction (XRD), transmission electron microscope (TEM), electron diffraction (ED) pattern, scanning electron microscopy (SEM) and electron dispersive X-ray (EDX) analysis. The results revealed that the particle size is in the range of 15-25 nm for Zn-Mn ferrites with good crystallinity. Magnetic properties of the sample at 300 K were measured using a vibrating sample magnetometer, which showed that the sample exhibited characteristics of superparamagnetism

  15. Characterization of Austempered Ferritic Ductile Iron

    Science.gov (United States)

    Dakre, Vinayak S.; Peshwe, D. R.; Pathak, S. U.; Likhite, A. A.

    2018-04-01

    The ductile iron (DI) has graphite nodules enclose in ferrite envelop in pearlitic matrix. The pearlitic matrix in DI was converted to ferritic matrix through heat treatment. This heat treatment includes austenitization of DI at 900°C for 1h, followed by furnace cooling to 750°C & hold for 1h, then again furnace cooling to 690°C hold for 2h, then samples were allowed to cool in furnace. The new heat treated DI has graphite nodules in ferritic matrix and called as ferritic ductile iron (FDI). Both DIs were austenitized at 900°C for 1h and then quenched into salt bath at 325°C. The samples were soaked in salt bath for 60, 120, 180, 240 and 300 min followed by air cooling. The austempered samples were characterized with help of optical microscopy, SEM and X-ray diffraction analysis. Austempering of ferritic ductile iron resulted in finer ausferrite matrix as compared to ADI. Area fraction of graphite, ferrite and austenite were determining using AXIOVISION-SE64 software. Area fraction of graphite was more in FDI than that of as cast DI. The area fraction of graphite remains unaffected due to austempering heat treatment. Ausferritic matrix coarsened (feathered) with increasing in austempering time for both DI and FDI. Bulk hardness test was carried on Rockwell Hardness Tester with load of 150 kgf and diamond indenter. Hardness obtained in as cast DI is 28 HRC which decreased to 6 HRC in FDI due conversion of pearlitic matrix to ferritic matrix. Hardness is improved by austempering process.

  16. Corrosion resistance improvement of ferritic steels through hydrogen additions to the BWR coolant

    International Nuclear Information System (INIS)

    Gordon, B.M.; Jewett, C.W.; Pickett, A.E.; Indig, M.E.

    1984-01-01

    Motivated by the success of oxygen suppression for mitigation of intergranular stress corrosion cracking (IGSCC) in weld sensitized austenitic materials used in Boiling Water Reactors (BWRs), oxygen suppression, through hydrogen additions to the feedwater was investigated to determine its affect on the corrosion resistance of ferritic and martensitic BWR structural materials. The results of these investigations are presented in this paper, where particular emphasis is placed on the corrosion performance of BWR pressure vessel low alloy steels, carbon steel piping materials and martensitic pump materials. It is important to note that the corrosion resistance of these materials in the BWR environment is excellent. Consequently this investigation was also motivated to determine whether there were any detrimental effects of hydrogen additions, as well as to identify any additional margin in ferritic/martensitic materials corrosion performance

  17. Radiation influence on properties of nanocrystalline alloy

    International Nuclear Information System (INIS)

    Holkova, D.; Sitek, J.; Novak, P.; Dekan, J.

    2016-01-01

    Our work is focused on the studied of structural changes amorphous and nanocrystalline alloys after irradiation with electrons. For the analysis of these alloy we use two spectroscopic methods: Moessbauer spectroscopy and XRD. Measurements of nanocrystalline (Fe 3 Ni 1 ) 81 Nb 7 B 12 samples before and after electrons irradiation by means of Moessbauer spectroscopy and XRD showed that the electrons causes changes in magnetic structure which is reflected changes of direction of net magnetic moment. Structural changes occurs in the frame of error indicated by both spectroscopic methods. We can confirm that this kind alloys a resistive again electrons irradiation up to doses of 4 MGy. We observed in this frame only beginning of the radiation damage. (authors)

  18. Ultrafast Terahertz Conductivity of Photoexcited Nanocrystalline Silicon

    DEFF Research Database (Denmark)

    Cooke, David; MacDonald, A. Nicole; Hryciw, Aaron

    2007-01-01

    The ultrafast transient ac conductivity of nanocrystalline silicon films is investigated using time-resolved terahertz spectroscopy. While epitaxial silicon on sapphire exhibits a free carrier Drude response, silicon nanocrystals embedded in glass show a response that is best described by a class...... in the silicon nanocrystal films is dominated by trapping at the Si/SiO2 interface states, occurring on a 1–100 ps time scale depending on particle size and hydrogen passivation......The ultrafast transient ac conductivity of nanocrystalline silicon films is investigated using time-resolved terahertz spectroscopy. While epitaxial silicon on sapphire exhibits a free carrier Drude response, silicon nanocrystals embedded in glass show a response that is best described...

  19. 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

  20. Effect of phase transitions on thermoluminescence characteristics of nanocrystalline alumina

    International Nuclear Information System (INIS)

    Rani, Geeta; Sahare, P.D.

    2013-01-01

    Highlights: •Synthesis of Al 2 O 3 nanocrystalline TLD phosphor. •Material characterizations by XRD, TEM and TL. •Change in structure and morphology of the phase transition alumina. •Change in glow curve structures and trapping parameters on phase transitions. -- Abstract: Nanocrystalline boehmite (γ-AlOOH) was synthesized by hydrothermal method using AlCl 3 ·6H 2 O and Urea as precursors. The material gets decomposed to form the γ-Al 2 O 3 phase at around 873 K on annealing in air. On annealing further at higher temperatures it gets converted into different phases, such as, δ, θ and the most stable α-phase. Not only the phase changes but the annealing has also changed the morphology of the nanomaterial, i.e. it has changed from spindle like edges to vermicular structures and also grew bigger in sizes. The formations of different phases were confirmed by the X-ray diffraction (XRD) patterns and the changes in the morphology were seen through the TEM images. Further the effect of different phases on the thermoluminescence (TL) glow curve structures was studied and it is also shown that the TL glow curves structures do change due to phase transformations. To investigate further and to determine trapping parameters, different glow curves have been theoretically deconvoluted using computerized glow curve deconvolution (CGCD method) into simple glow peaks. The values of different trapping parameters also change as the glow curve structures on phase transformations due to reorganization of energy levels and the stress/strain generated by some intermediate phases

  1. Solubility of Carbon in Nanocrystalline -Iron

    OpenAIRE

    Alexander Kirchner; Bernd Kieback

    2012-01-01

    A thermodynamic model for nanocrystalline interstitial alloys is presented. The equilibrium solid solubility of carbon in -iron is calculated for given grain size. Inside the strained nanograins local variation of the carbon content is predicted. Due to the nonlinear relation between strain and solubility, the averaged solubility in the grain interior increases with decreasing grain size. The majority of the global solubility enhancement is due to grain boundary enrichment however. Therefor...

  2. 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 ...

  3. Effect of Gd"3"+ substitution on structural, magnetic, dielectric and optical properties of nanocrystalline CoFe_2O_4

    International Nuclear Information System (INIS)

    Joshi, Seema; Kumar, Manoj; Chhoker, Sandeep; Kumar, Arun; Singh, Mahavir

    2017-01-01

    Nanoparticles of CoGd_xFe_2_−_xO_4 with x=0.0, 0.03, 0.05, 0.07, 0.10 and 0.15 were synthesized by co-precipitation method. Gd"3"+ substitution effect on different properties of nanocrystalline CoFe_2O_4 has been studied. X-ray diffraction and Raman spectroscopy confirmed the formation of single phase cubic mixed spinel structure. Cation distribution has been proposed from Rietveld refined data. Mössbauer spectra at room temperature showed two ferrimagnetic Zeeman sextets with one superparamagnetic doublet. Mössbauer parameters suggested that Gd"3"+ ions occupy the octahedral site in CoFe_2O_4. Room temperature magnetic measurements exhibited that the saturation magnetization decreased from 91 emu/gm to 54 emu/gm for x=0.0 to 0.15 samples. The coercivity decreased from 1120 Oe to 340 Oe for x=0.0 to 0.07 samples and increased from 400 Oe to 590 Oe for x=0.10 and 0.15 samples, respectively. Raman analysis showed that the degree of inversion with Gd"3"+ substitution supporting the variation of coercivity. Electron spin resonance spectra revealed the dominancy of superexchange interactions in these samples. Optical band gap measurement suggested that all samples are indirect band gap materials and band gap has been decreased with Gd"3"+ substitution. Both dielectric constant and dielectric loss is found to decrease because of the decrease in hopping rate with the Gd"3"+ substitution for Fe"3"+ at the octahedral sites. Low dielectric loss suggested the applicability of Gd"3"+ doped CoFe_2O_4 nanoparticles for high frequency microwave device applications. - Highlights: • Gd"3"+ ions were successfully added in to the spinel lattice of CoFe_2O_4. • Magnetic hysteresis loss is influenced by Gd"3"+ doping. • All doped samples exhibit normal dielectric dispersion behaviour of spinel ferrites. • UV–vis diffuse spectroscopy concludes band gap is reduced by Gd"3"+ doping.

  4. The influence of delta ferrite in the AISI 416 stainless steel hot workability

    International Nuclear Information System (INIS)

    Cardoso, P.H.S.; Kwietniewski, C.; Porto, J.P.; Reguly, A.; Strohaecker, T.R.

    2003-01-01

    Delta ferrite in martensitic stainless steels may have an adverse effect on the mechanical properties of these materials at high temperature. The occurrence of such phase is determined by the material chemical composition (mainly Cr and C), as-received microstructure condition and hot working temperature. The aim of this investigation is to assess the influence of delta ferrite on the hot workability of the martensitic AISI 416 stainless steel. Hence, different heats of this material (differing in chemical composition and as-received microstructure) were submitted to heating tests in order to observe the microstructural transformations that take place at high temperature and then examine the influence of these transformations on the mechanical behaviour. Phase characterisation and quantification were carried out using scanning electron microscopy/energy-dispersive X-ray microanalysis and image analysis. The heating tests were performed in the temperature range of 1100-1350 deg. C and hot workability in two heats with different delta ferrite content was assessed by hot torsion tests in the temperature range of 1000-1250 deg. C. The results have indicated that chemical composition and as-received microstructure strongly affect delta ferrite formation, which in turn deteriorates hot workability of the martensitic AISI 416 stainless steel

  5. Studies on nanocrystalline zinc coating

    Indian Academy of Sciences (India)

    Wintec

    The particles size was also characterized by TEM analysis. Keywords. Electrochemical ... netic materials for magnetic recording, and electrocatalyst for hydrogen .... polarization behaviour was studied in the test electrolyte for zinc deposit of ...

  6. Compact, low-loss and broadband photonic crystal circulator based on a star-type ferrite rod

    Directory of Open Access Journals (Sweden)

    Xiang Xi

    Full Text Available We propose and investigate a compact, low-loss and broadband circulator based on a star-type ferrite rod in two-dimensional square-lattice photonic crystals. Only one ferrite rod is required to be inserted in our structure. Firstly, the performances of circulator based on the star-type, circle, and square ferrite rod are compared, showing that the circulator with the star-type ferrite rod performs better than the other two ones. And then, based on the star-type ferrite rod circulator, four cases of improvement, in which the background rods around the center ferrite rod are replaced respectively by the backward-triangle, forward-triangle, backward-semicircle, and forward-semicircle rods, are investigated to modulate the coupling between the center magneto-optical micro-cavity and the corresponding waveguides. The results show that, with proper parameters, all the four cases can greatly improve the output properties of the circulator, and different cases have its own advantages. The mechanism behind these improvements is also discussed. Finite-element method is used to calculate the characteristics of the circulator and Nelder-Mead optimization method is employed to obtain the optimized parameters. The ideas presented here are useful for designing broadband, low insertion loss, and high-isolation circulators which have potential application in integrated photonic crystal devices. Keywords: Photonic crystals, Circulator, Magneto-optical material, Photonic crystal waveguides

  7. Ferrite LTCC based phased array antennas

    KAUST Repository

    Ghaffar, Farhan A.

    2016-11-02

    Two phased array antennas realized in multilayer ferrite LTCC technology are presented in this paper. The use of embedded bias windings in these designs allows the negation of external magnets which are conventionally employed with bulk ferrite medium. This reduces the required magnetostatic field strength by 90% as compared to the traditional designs. The phase shifters are implemented using the SIW technology. One of the designs is operated in the half mode waveguide topology while the other design is based on standard full mode waveguide operation. The two phase shifter designs are integrated with two element patch antenna array and slotted SIW array respectively. The array designs demonstrate a beam steering of 30° and ±19° respectively for a current excitation of 200 mA. The designs, due to their small factor can be easily integrated in modern communication systems which is not possible in the case of bulk ferrite based designs.

  8. Highly conducting p-type nanocrystalline silicon thin films preparation without additional hydrogen dilution

    Science.gov (United States)

    Patra, Chandralina; Das, Debajyoti

    2018-04-01

    Boron doped nanocrystalline silicon thin film has been successfully prepared at a low substrate temperature (250 °C) in planar inductively coupled RF (13.56 MHz) plasma CVD, without any additional hydrogen dilution. The effect of B2H6 flow rate on structural and electrical properties of the films has been studied. The p-type nc-Si:H films prepared at 5 ≤ B2H6 (sccm) ≤ 20 retains considerable amount of nanocrystallites (˜80 %) with high conductivity ˜101 S cm-1 and dominant crystallographic orientation which has been correlated with the associated increased ultra- nanocrystalline component in the network. Such properties together make the material significantly effective for utilization as p-type emitter layer in heterojunction nc-Si solar cells.

  9. Characterisation of nanocrystalline CdS thin films deposited by CBD

    International Nuclear Information System (INIS)

    Devi, R.; Sarma, B.K.

    2006-01-01

    Nanocrystalline thin films of CdS are deposited on glass substrates by chemical bath deposition using polyvinyl alcohol (PVA) matrix solution. Crystallite sizes of the films are determined from X-ray diffraction and are found to vary from 5.4 nm to 7 nm. The band gaps of the nanocrystalline material is determined from the U-V spectrograph and are found to be within the range from 2.6 eV to 2.8 eV as grain size decreases. The band gaps are also determined from the dependence of electrical conductivity of the films with temperature. An increase of molarity decreases the grain size which in turn increases the band gap. (author)

  10. Photoacoustic study of nanocrystalline silicon produced by mechanical grinding

    Energy Technology Data Exchange (ETDEWEB)

    Poffo, C.M. [Departamento de Engenharia Mecanica, Universidade Federal de Santa Catarina, Campus Universitario Trindade, C.P. 476, 88040-900 Florianopolis, Santa Catarina (Brazil); Lima, J.C. de, E-mail: fsc1jcd@fisica.ufsc.b [Departamento de Fisica, Universidade Federal de Santa Catarina, Campus Trindade, C.P. 476, 88040-900 Florianopolis, Santa Catarina (Brazil); Souza, S.M.; Triches, D.M. [Departamento de Engenharia Mecanica, Universidade Federal de Santa Catarina, Campus Universitario Trindade, C.P. 476, 88040-900 Florianopolis, Santa Catarina (Brazil); Grandi, T.A. [Departamento de Fisica, Universidade Federal de Santa Catarina, Campus Trindade, C.P. 476, 88040-900 Florianopolis, Santa Catarina (Brazil); Biasi, R.S. de [Secao de Engenharia Mecanica e de Materiais, Instituto Militar de Engenharia, 22290-270 Rio de Janeiro, RJ (Brazil)

    2011-04-01

    Mechanical grinding (MG) was used to produce nanocrystalline silicon and its thermal and transport properties were investigated by photoacoustic absorption spectroscopy (PAS). The experimental results suggest that in as-milled nanocrystalline silicon for 10 h the heat transfer through the crystalline and interfacial components is similar, and after annealed at 470 {sup o}C the heat transfer is controlled by crystalline component.

  11. Photoacoustic study of nanocrystalline silicon produced by mechanical grinding

    International Nuclear Information System (INIS)

    Poffo, C.M.; Lima, J.C. de; Souza, S.M.; Triches, D.M.; Grandi, T.A.; Biasi, R.S. de

    2011-01-01

    Mechanical grinding (MG) was used to produce nanocrystalline silicon and its thermal and transport properties were investigated by photoacoustic absorption spectroscopy (PAS). The experimental results suggest that in as-milled nanocrystalline silicon for 10 h the heat transfer through the crystalline and interfacial components is similar, and after annealed at 470 o C the heat transfer is controlled by crystalline component.

  12. The Linear Thermal Expansion of Bulk Nanocrystalline Ingot Iron from Liquid Nitrogen to 300 K.

    Science.gov (United States)

    Wang, S G; Mei, Y; Long, K; Zhang, Z D

    2009-09-17

    The linear thermal expansions (LTE) of bulk nanocrystalline ingot iron (BNII) at six directions on rolling plane and conventional polycrystalline ingot iron (CPII) at one direction were measured from liquid nitrogen temperature to 300 K. Although the volume fraction of grain boundary and residual strain of BNII are larger than those of CPII, LTE of BNII at the six measurement directions were less than those of CPII. This phenomenon could be explained with Morse potential function and the crystalline structure of metals. Our LTE results ruled out that the grain boundary and residual strain of BNII did much contribution to its thermal expansion. The higher interaction potential energy of atoms, the less partial derivative of interaction potential energy with respect to temperature T and the porosity free at the grain boundary of BNII resulted in less LTE in comparison with CPII from liquid nitrogen temperature to 300 K. The higher LTE of many bulk nanocrystalline materials resulted from the porosity at their grain boundaries. However, many authors attributed the higher LTE of many nanocrystalline metal materials to their higher volume fraction of grain boundaries.

  13. The Linear Thermal Expansion of Bulk Nanocrystalline Ingot Iron from Liquid Nitrogen to 300 K

    Directory of Open Access Journals (Sweden)

    Mei Y

    2009-01-01

    Full Text Available Abstract The linear thermal expansions (LTE of bulk nanocrystalline ingot iron (BNII at six directions on rolling plane and conventional polycrystalline ingot iron (CPII at one direction were measured from liquid nitrogen temperature to 300 K. Although the volume fraction of grain boundary and residual strain of BNII are larger than those of CPII, LTE of BNII at the six measurement directions were less than those of CPII. This phenomenon could be explained with Morse potential function and the crystalline structure of metals. Our LTE results ruled out that the grain boundary and residual strain of BNII did much contribution to its thermal expansion. The higher interaction potential energy of atoms, the less partial derivative of interaction potential energy with respect to temperature T and the porosity free at the grain boundary of BNII resulted in less LTE in comparison with CPII from liquid nitrogen temperature to 300 K. The higher LTE of many bulk nanocrystalline materials resulted from the porosity at their grain boundaries. However, many authors attributed the higher LTE of many nanocrystalline metal materials to their higher volume fraction of grain boundaries.

  14. Preparation and characterization of nanocrystalline porous TiO2/WO3 composite thin films

    International Nuclear Information System (INIS)

    Hsu, C.-S.; Lin, C.-K.; Chan, C.-C.; Chang, C.-C.; Tsay, C.-Y.

    2006-01-01

    TiO 2 materials possessing not only photocatalytic but also electrochromic properties have attracted many research and development interests. Though WO 3 exhibits excellent electrochromic properties, the much higher cost and water-sensitivity of WO 3 as compared with the TiO 2 may restrict the practical application of WO 3 materials. In the present study, the feasibility of preparing nanocrystalline porous TiO 2 /WO 3 composite thin films was investigated. Precursors of sols TiO 2 and/or WO 3 and polystyrene microspheres were used to prepare nanocrystalline pure TiO 2 , WO 3 , and composite TiO 2 /WO 3 thin films by spin coating. The spin-coated thin films were amorphous and, after heat treating at a temperature of 500 o C, nanocrystalline TiO 2 , TiO 2 /WO 3 , and WO 3 thin films with or without pores were prepared successfully. The heat-treated thin films were colorless and coloration-bleaching phenomena can be observed during cyclic voltammetry tests. The heat-treated thin films exhibited good reversible electrochromic behavior while the porous TiO 2 /WO 3 composite film exhibited improved electrochromic properties

  15. Carbonate effects on hexavalent uranium removal from water by nanocrystalline titanium dioxide

    International Nuclear Information System (INIS)

    Wazne, Mahmoud; Meng, Xiaoguang; Korfiatis, George P.; Christodoulatos, Christos

    2006-01-01

    A novel nanocrystalline titanium dioxide was used to treat depleted uranium (DU)-contaminated water under neutral and alkaline conditions. The novel material had a total surface area of 329 m 2 /g, total surface site density of 11.0 sites/nm 2 , total pore volume of 0.415 cm 3 /g and crystallite size of 6.0 nm. It was used in batch tests to remove U(VI) from synthetic solutions and contaminated water. However, the capacity of the nanocrystalline titanium dioxide to remove U(VI) from water decreased in the presence of inorganic carbonate at pH > 6.0. Adsorption isotherms, Fourier transform infrared (FTIR) spectroscopy, and surface charge measurements were used to investigate the causes of the reduced capacity. The surface charge and the FTIR measurements suggested that the adsorbed U(VI) species was not complexed with carbonate at neutral pH values. The decreased capacity of titanium dioxide to remove U(VI) from water in the presence of carbonate at neutral to alkaline pH values was attributed to the aqueous complexation of U(VI) by inorganic carbonate. The nanocrystalline titanium dioxide had four times the capacity of commercially available titanium dixoide (Degussa P-25) to adsorb U(VI) from water at pH 6 and total inorganic carbonate concentration of 0.01 M. Consequently, the novel material was used to treat DU-contaminated water at a Department of Defense (DOD) site

  16. Amorphous and nanocrystalline Fe-Ni-Zr-B ribbons as sensing elements in magnetic field sensors

    International Nuclear Information System (INIS)

    Vertesy, G.; Idzikowski, B.

    2006-01-01

    Fe 81-x Ni x Zr 7 B 12 (x=20, 30, 40) melt-spun alloys were investigated as potential new material applied as a sensing element of a fluxgate-type high-sensitivity magnetic field sensor. The sensitivity of the magnetometer was increased by about 60% by using the amorphous or nanocrystalline Fe 41 Ni 40 Zr 7 B 12 alloy, compared with a standard reference sensing material. Application of this material can also extend the temperature range of the operation of the device

  17. Amorphous and nanocrystalline Fe-Ni-Zr-B ribbons as sensing elements in magnetic field sensors

    Energy Technology Data Exchange (ETDEWEB)

    Vertesy, G. [Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences, H-1525 Budapest, P.O.B. 49 (Hungary)]. E-mail: vertesyg@mfa.kfki.hu; Idzikowski, B. [Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, PL 60-179 Poznan (Poland)

    2006-04-15

    Fe{sub 81-x}Ni{sub x}Zr{sub 7}B{sub 12} (x=20, 30, 40) melt-spun alloys were investigated as potential new material applied as a sensing element of a fluxgate-type high-sensitivity magnetic field sensor. The sensitivity of the magnetometer was increased by about 60% by using the amorphous or nanocrystalline Fe{sub 41}Ni{sub 40}Zr{sub 7}B{sub 12} alloy, compared with a standard reference sensing material. Application of this material can also extend the temperature range of the operation of the device.

  18. Toward a quantitative understanding of mechanical behavior of nanocrystalline metals

    International Nuclear Information System (INIS)

    Dao, M.; Lu, L.; Asaro, R.J.; Hosson, J.T.M. de; Ma, E.

    2007-01-01

    Focusing on nanocrystalline (nc) pure face-centered cubic metals, where systematic experimental data are available, this paper presents a brief overview of the recent progress made in improving mechanical properties of nc materials, and in quantitatively and mechanistically understanding the underlying mechanisms. The mechanical properties reviewed include strength, ductility, strain rate and temperature dependence, fatigue and tribological properties. The highlighted examples include recent experimental studies in obtaining both high strength and considerable ductility, the compromise between enhanced fatigue limit and reduced crack growth resistance, the stress-assisted dynamic grain growth during deformation, and the relation between rate sensitivity and possible deformation mechanisms. The recent advances in obtaining quantitative and mechanics-based models, developed in line with the related transmission electron microscopy and relevant molecular dynamics observations, are discussed with particular attention to mechanistic models of partial/perfect-dislocation or deformation-twin-mediated deformation processes interacting with grain boundaries, constitutive modeling and simulations of grain size distribution and dynamic grain growth, and physically motivated crystal plasticity modeling of pure Cu with nanoscale growth twins. Sustained research efforts have established a group of nanocrystalline and nanostructured metals that exhibit a combination of high strength and considerable ductility in tension. Accompanying the gradually deepening understanding of the deformation mechanisms and their relative importance, quantitative and mechanisms-based constitutive models that can realistically capture experimentally measured and grain-size-dependent stress-strain behavior, strain-rate sensitivity and even ductility limit are becoming available. Some outstanding issues and future opportunities are listed and discussed

  19. Dielectric and impedance study of praseodymium substituted Mg-based spinel ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Farid, Hafiz Muhammad Tahir, E-mail: tahirfaridbzu@gmail.com [Department of Physics, Bahauddin Zakariya, University Multan, 60800 (Pakistan); Ahmad, Ishtiaq; Ali, Irshad [Department of Physics, Bahauddin Zakariya, University Multan, 60800 (Pakistan); Ramay, Shahid M. [College of Science, Physics and Astronomy Department, King Saud University, P.O. Box 2455, 11451 Riyadh (Saudi Arabia); Mahmood, Asif [Chemical Engineering Department, College of Engineering, King Saud University, Riyadh (Saudi Arabia); Murtaza, G. [Centre for Advanced Studies in Physics, GC University, Lahore 5400 (Pakistan)

    2017-07-15

    Highlights: • Magnesium based spinel ferrites were successfully synthesized by sol-gel method. • Dielectric constant shows the normal spinel ferrites behavior. • The dc conductivity are found to decrease with increasing temperature. • The samples with low conductivity have high values of activation energy. • The Impedance decreases with increasing frequency of applied field. - Abstract: Spinel ferrites with nominal composition MgPr{sub y}Fe{sub 2−y}O{sub 4} (y = 0.00, 0.025, 0.05, 0.075, 0.10) were prepared by sol-gel method. Temperature dependent DC electrical conductivity and drift mobility were found in good agreement with each other, reflecting semiconducting behavior. The dielectric properties of all the samples as a function of frequency (1 MHz–3 GHz) were measured at room temperature. The dielectric constant and complex dielectric constant of these samples decreased with the increase of praseodymium concentration. In the present spinel ferrite, Cole–Cole plots were used to separate the grain and grain boundary’s effects. The substitution of praseodymium ions in Mg-based spinel ferrites leads to a remarkable rise of grain boundary’s resistance as compared to the grain’s resistance. As both AC conductivity and Cole–Cole plots are the functions of concentration, they reveal the dominant contribution of grain boundaries in the conduction mechanism. AC activation energy was lower than dc activation energy. Temperature dependence normalized AC susceptibility of spinel ferrites reveals that MgFe{sub 2}O{sub 4} exhibits multi domain (MD) structure with high Curie temperature while on substitution of praseodymium, MD to SD transitions occurs. The low values of conductivity and low dielectric loss make these materials best candidate for high frequency application.

  20. Forming limit and fracture mechanism of ferritic stainless steel sheets

    International Nuclear Information System (INIS)

    Xu Le; Barlat, Frederic; Ahn, Deok Chan; Bressan, Jose Divo

    2011-01-01

    Research highlights: → Forming limit curves of two ferritic stainless steel sheets were well predicted. → Failure occurs by necking in uniaxial and plane strain tension for both materials. → Failure occurs by shearing in balanced biaxial tension for both materials. → Strain rate sensitivity does not affect the limit strains a lot for both materials. → Strain rate sensitivity likely influences the failure mode for both materials. - Abstract: In this work, the forming limit curves (FLCs) of two ferritic stainless steel sheets, AISI409L and AISI430, were predicted with the Marciniak-Kuczynski (MK) and Bressan-William-Hill (BWH) models, combined with the Yld2000-2d yield function and the Swift hardening law. Uniaxial tension, disk compression and hydraulic bulge tests were performed to determine the yield loci and hardening curves of both materials. Meanwhile, the strain rate sensitivity (SRS) coefficient was measured through uniaxial tension tests carried out at different strain rates. Out-of-plane stretching tests were conducted in sheet specimens to obtain the surface limit strains under different linear strain paths. Micrographs of the specimens fractured in different stress states were obtained by optical and scanning electron microscopy. The overall results show that the BWH model can predict the FLC better than the MK model, and that the SRS does not have much effect on the limit strains for both materials. The predicted FLCs and micrograph analysis both indicate that failure occurs by surface localized necking in uniaxial and plane strain tension states, whereas it occurs by localized shearing in the through thickness direction in balanced biaxial tension state.

  1. Recrystallization induced plasticity in austenite and ferrite

    International Nuclear Information System (INIS)

    Huang Mingxin; Pineau, André; Bouaziz, Olivier; Vu, Trong-Dai

    2012-01-01

    Highlights: ► Plasticity can be induced by recrystallization in austenite and ferrite. ► Strain rate is proportional to recrystallization kinetics. ► Overall atomic flux selects a preferential direction may be the origin. - Abstract: New experimental evidences are provided to demonstrate that plastic strain can be induced by recrystallization in austenite and ferrite under an applied stress much smaller than their yield stresses. Such Recrystallization Induced Plasticity (RIP) phenomenon occurs because the overall atomic flux during recrystallization follows a preferential direction imposed by the applied stress.

  2. 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.

  3. Simulation of non-linear coaxial line using ferrite beads

    International Nuclear Information System (INIS)

    Furuya, S.; Matsumoto, H.; Tachi, K.; Takano, S.; Irisawa, J.

    2002-01-01

    A ferrite sharpener is a non-linear coaxial line using ferrite beads, which produces high-voltage, high-dV/dt pulses. We have been examining the characteristics of ferrite sharpeners experimentally, varying various parameters. Also we have made the simulation of the ferrite sharpener and compared the predictions with the experimental results in detail to analyze the characteristics of the sharpener. In this report, calculating the magnetization M of the ferrite bead, we divide the bead into n sections radially instead of adopting M at the average radius in the previous report. (author)

  4. Ammonia Gas Sensing Properties of Nanocrystalline Zn1-xCuxFe2O4 Doped with Noble Metal

    Directory of Open Access Journals (Sweden)

    S. V. JAGTAP

    2010-11-01

    Full Text Available The sensors are required basically for monitoring of trace gases in environment. In order to detect, measure and control these gases; one should know the amount and type of gases present in the environment. Among the most toxic and hazardous gases, it is necessary to detect and monitor the ammonia gas because this is enhance in the agricultural sector by the addition of large amounts of NH3 to cultivated farmland in the form of fertilizers. Nanocrystalline spinel type Zn1-xCuxFe2O4 (x=0, 0.2, 0.4 0.6 & 0.8 has been synthesized by sol-gel citrate method. The synthesized powders were characterized by XRD and SEM. The results revealed that the particle size is in the range of 40–45 nm for Cu–Zn ferrite with good crystallinity. The gas sensing properties were studied towards reducing gases like CO, LPG, NH3 and H2S and it is observed that Cu–Zn ferrite shows high response to ammonia gas at relatively lower operating temperature. The Zn0.6Cu0.4Fe2O4 nanomaterial shows better sensitivity towards NH3 gas at an operating temperature 300 0C. Incorporation of Pd improved the sensitivity, selectivity, response time and reduced the operating temperature from 300 0C to 250 0C for NH3 sensor.

  5. Auto-combustion synthesis, Mössbauer study and catalytic properties of copper-manganese ferrites

    International Nuclear Information System (INIS)

    Velinov, N.; Petrova, T.; Tsoncheva, T.; Genova, I.; Koleva, K.; Kovacheva, D.; Mitov, I.

    2016-01-01

    Spinel ferrites with nominal composition Cu _0_._5Mn _0_._5Fe _2O_4 and different distribution of the ions are obtained by auto-combustion method. Mössbauer spectroscopy, X-ray Diffraction, Thermogravimetry-Differential Scanning Calorimetry, Scanning Electron Microscopy and catalytic test in the reaction of methanol decomposition is used for characterization of synthesized materials. The spectral results evidence that the phase composition, microstructure of the synthesized materials and the cation distribution depend on the preparation conditions. Varying the pH of the initial solution microstructure, ferrite crystallite size, cation oxidation state and distribution of ions in the in the spinel structure could be controlled. The catalytic behaviour of ferrites in the reaction of methanol decomposition also depends on the pH of the initial solution. Reduction transformations of mixed ferrites accompanied with the formation of Hägg carbide χ-Fe _5C_2 were observed by the influence of the reaction medium.

  6. Auto-combustion synthesis, Mössbauer study and catalytic properties of copper-manganese ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Velinov, N., E-mail: nikivelinov@ic.bas.bg; Petrova, T. [Institute of Catalysis, Bulgarian Academy of Sciences (Bulgaria); Tsoncheva, T.; Genova, I. [Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences (Bulgaria); Koleva, K. [Institute of Catalysis, Bulgarian Academy of Sciences (Bulgaria); Kovacheva, D. [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences (Bulgaria); Mitov, I. [Institute of Catalysis, Bulgarian Academy of Sciences (Bulgaria)

    2016-12-15

    Spinel ferrites with nominal composition Cu {sub 0.5}Mn {sub 0.5}Fe {sub 2}O{sub 4} and different distribution of the ions are obtained by auto-combustion method. Mössbauer spectroscopy, X-ray Diffraction, Thermogravimetry-Differential Scanning Calorimetry, Scanning Electron Microscopy and catalytic test in the reaction of methanol decomposition is used for characterization of synthesized materials. The spectral results evidence that the phase composition, microstructure of the synthesized materials and the cation distribution depend on the preparation conditions. Varying the pH of the initial solution microstructure, ferrite crystallite size, cation oxidation state and distribution of ions in the in the spinel structure could be controlled. The catalytic behaviour of ferrites in the reaction of methanol decomposition also depends on the pH of the initial solution. Reduction transformations of mixed ferrites accompanied with the formation of Hägg carbide χ-Fe {sub 5}C{sub 2} were observed by the influence of the reaction medium.

  7. Tem study of thermal ageing of ferrite in cast duplex stainless steel

    International Nuclear Information System (INIS)

    Nenonen, P.; Massoud, J.P.; Timofeev, B.T.

    2002-01-01

    The changes in the microstructure and composition of ferrite in two types of cast duplex stainless steels and in an austenitic-ferritic weld metal after long term thermal ageing has been studied using analytical transmission electron microscope (FEGTEM). A cast test steel containing Mo was investigated first as a reference material in three different conditions: as solution annealed, aged at 300 C and aged at 400 C. This investigation was carried out to gain experience of how EDS (X-ray analyser) analyser and TEM (transmission electron microscope) can be used to study elemental inhomogeneity, which is usually investigated with an atom probe (APFIM). The two other materials, an austenitic-ferritic weld metal and a cast duplex Ti-stabilised stainless steel used for long time at NPP operation temperature were investigated using the experience obtained with the test steel. The results showed that analytical TEM can be used to investigate elemental inhomogeneity of ferrite, but there are several important things to be taken into account when the spectra for this purpose are collected. These things are, such as the thickness of the specimen, probe size, contamination rate, 'elemental background' of the spectrum and possible enrichment of certain alloying elements in the surface oxide layer of the TEM-specimens. If minor elements are also analysed, it may increase the scattering of the results. (authors)

  8. A study of the suitability of ferrite for use in low-field insertion devices

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, K.; Hassenzahl, W.V.

    1995-02-01

    Most insertion devices built to date use rare-earth permanent-magnet materials, which have a high remanent field and are more expensive than many other permanent-magnet materials. Low-field insertion devices could use less-expensive, lower performance magnetic materials if they had suitable magnetic characteristics. These materials must be resistant to demagnetization during construction and operation of the insertion device, have uniform magnetization, possess low minor-axis magnetic moments, and have small minor field components on the surfaces. This paper describes an investigation to determine if ferrite possesses magnetic qualities suitable for insertion device applications. The type of ferrite investigated, MMPA Ceramic 8 from Stackpole Inc., was found to be acceptable for insertion device applications.

  9. Statistical study to determine the effect of carbon, silicon, nickel and other alloying elements on the mechanical properties of as-cast ferritic ductile irons

    International Nuclear Information System (INIS)

    Lacaze, J.; Sertucha, J.; Larranaga, P.; Suarez, R.

    2016-01-01

    There is a great interest in fully ferritic ductile irons due to their structural homogeneity, remarkable ductility and good response when machining. On the other hand the wide variety of raw materials available in foundry plants becomes a problem when controlling the chemical composition of the manufactured alloys. The present work shows a statistical study about the effect of different C, Si, Ni contents and other minor elements on structural and mechanical properties of a group of ferritic ductile iron alloys. A set of equations are finally presented to predict room temperature mechanical properties of ferritic ductile irons by means of their chemical composition and pearlite content. (Author)

  10. Statistical study to determine the effect of carbon, silicon, nickel and other alloying elements on the mechanical properties of as-cast ferritic ductile irons

    Energy Technology Data Exchange (ETDEWEB)

    Lacaze, J.; Sertucha, J.; Larranaga, P.; Suarez, R.

    2016-10-01

    There is a great interest in fully ferritic ductile irons due to their structural homogeneity, remarkable ductility and good response when machining. On the other hand the wide variety of raw materials available in foundry plants becomes a problem when controlling the chemical composition of the manufactured alloys. The present work shows a statistical study about the effect of different C, Si, Ni contents and other minor elements on structural and mechanical properties of a group of ferritic ductile iron alloys. A set of equations are finally presented to predict room temperature mechanical properties of ferritic ductile irons by means of their chemical composition and pearlite content. (Author)

  11. Determination of local texture and stress distributions on submicro-/nanocrystalline multiphase gradient materials by means of two-dimensional X-ray diffraction as well by means of analytical and numerical modeling approaches

    International Nuclear Information System (INIS)

    Eschke, Andy

    2015-01-01

    Examination object of the present thesis was the determination of local distributions of crystallographic texture and mechanical (eigen-)stresses in submicro-/nan0crystalline many-phase gradient materials. For this at the one hand experimental methods of the two-dimensional X-ray diffraction were applied as well as at the other hand theoretical calculations performed by means of analytical and numerical modeling approaches. The interest for the material is founded on the fact that ultrafine-granular materials because of their mechanical propertier (for instance hardness, ductility) ar to be stressed for advanced engineering application purposes. Furthermore the application of many-phase gradient materials makes to some extent possible a manufacture for measure concerning physical properties and by this a manifold of application potentials as well as a tuning of the material properties to the differential requirements in the application fields. This measure tailoring is related both to the degree of gradiation and to the special composition of the composite materials by the chosen starting materials. The work performed in the framework of the excellence cluster ''European Centre for Emerging Materials and Processes Dresden (ECEMP)'' of the Saxonian excellence initiative aimed especially to the analysis of an especially processed, ultrafine-granular Ti/Al composite, which was and is research object of the partial ECEMP project ''High strength metallic composites'' (HSMetComp). Thereby were process as well as materials in the focus of the above mentioned (indirect) examination methods. which were adapted and further developed for these purposes. The results of the experimental as well as theoretical studies could contribute to an increased understanding of the technological process as well as the material behaviour and can by this also used for hints concerning process- and/or material-sided optimizations. Altogether they

  12. Characterization of SrCo{sub 1.5}Ti{sub 1.5}Fe{sub 9}O{sub 19} hexagonal ferrite synthesized by sol-gel combustion and solid state route

    Energy Technology Data Exchange (ETDEWEB)

    Vinaykumar, R., E-mail: vinaykumar.r1984@gmail.com; Mazumder, R., E-mail: ranabrata@nitrkl.ac.in; Bera, J., E-mail: jbera@nitrkl.ac.in

    2017-05-01

    Co-Ti co-substituted SrM hexagonal ferrite (SrCo{sub 1.5}Ti{sub 1.5}Fe{sub 9}O{sub 19}) was synthesized by sol-gel combustion and solid state route. The effects of sources of TiO{sub 2} raw materials; titanium tetra-isopropoxide (TTIP) and titanyl nitrate (TN) on the phase formation behavior and properties of the ferrite were studied. The thermal decomposition behavior of the gel was studied using TG-DSC. The phase formation behavior of the ferrite was studied by using X-ray powder diffraction and FTIR analysis. Phase formation was comparatively easier in the TN-based sol-gel process. The morphology of powder and sintered ferrite was investigated using scanning electron microscope. Magnetic properties like magnetization, coercivity, permeability, tan δ{sub µ} and dielectric properties were investigated. The ferrite synthesized by sol-gel based chemical route showed higher saturation magnetization, permeability and permittivity compared to the ferrite synthesized by solid state route. - Highlights: • SrCo{sub 1.5}Ti{sub 1.5}Fe{sub 9}O{sub 19} ferrite was successfully prepared by sol–gel combustion process. • Sol-gel synthesis of the ferrite using titanyl nitrate has been reported first time. • Phase formation was easier in the titanyl nitrate based sol-gel process. • Better magneto-dielectric properties were observed in sol-gel processed ferrite.

  13. Magnetic properties of nanostructured spinel ferrites and ...

    Indian Academy of Sciences (India)

    exchange interaction strength because of an increase in the magnetic ion concentration in the A-site on milling, ... By using a copper wheel, rotating with the ... Zn ferrite with a small applied field of 4 mT for two different grain sizes. The Néel ... By varying the concentration of the oxidant (KNO3) or ferric ions, we could achieve.

  14. Structural properties of Cd–Co ferrites

    Indian Academy of Sciences (India)

    36, No. 5, October 2013, pp. 919–922. c Indian Academy of Sciences. Structural properties of Cd–Co ferrites. S P DALAWAIa,∗. , T J SHINDEb, A B GADKARIc and P N VASAMBEKARa. aDepartment of Electronics, Shivaji University, Kolhapur 416 004, India. bDepartment of Physics, KRP Kanya Mahavidyalaya, Islampur ...

  15. Neutron diffraction in a frustrated ferrite

    International Nuclear Information System (INIS)

    Mirebeau, I.; Iancu, G.; Gavoille, G.; Hubsch, J.

    1994-01-01

    The competition between a long range ordered ferrimagnetic lattice and small fluctuating clusters have been probed by neutron diffraction in a titanium magnesium frustrated ferrite. The description of the system is then compared to the predictions of several theoretical models for frustrated systems. 3 figs., 8 refs

  16. Synthesis of lithium ferrites from polymetallic carboxylates

    Directory of Open Access Journals (Sweden)

    STEFANIA STOLERIU

    2008-10-01

    Full Text Available Lithium ferrite was prepared by the thermal decomposition of three polynuclear complex compounds containing as ligands the anions of malic, tartaric and gluconic acid: (NH42[Fe2.5Li0.5(C4H4O53(OH4(H2O2]×4H2O (I, (NH46[Fe2.5Li0.5(C4H4O63(OH8]×2H2O (II and (NH42[Fe2.5Li0.5(C6H11O73(OH7] (III. The polynuclear complex precursors were characterized by chemical analysis, IR and UV–Vis spectra, magnetic measurements and thermal analysis. The obtained lithium ferrites were characterized by XRD, scanning electron microscopy, IR spectra and magnetic measurements. The single α-Li0.5Fe2.5O4 phase was obtained by thermal decomposition of the tartarate complex annealed at 700 °C for 1 h. The magnetization value ≈ 50 emu g-1 is lower than that obtained for the bulk lithium ferrite due to the nanostructural character of the ferrite. The particle size was smaller than 100 nm.

  17. Transparent nanocrystalline diamond coatings and devices

    Science.gov (United States)

    Sumant, Anirudha V.; Khan, Adam

    2017-08-22

    A method for coating a substrate comprises producing a plasma ball using a microwave plasma source in the presence of a mixture of gases. The plasma ball has a diameter. The plasma ball is disposed at a first distance from the substrate and the substrate is maintained at a first temperature. The plasma ball is maintained at the first distance from the substrate, and a diamond coating is deposited on the substrate. The diamond coating has a thickness. Furthermore, the diamond coating has an optical transparency of greater than about 80%. The diamond coating can include nanocrystalline diamond. The microwave plasma source can have a frequency of about 915 MHz.

  18. Simulations of intergranular fracture in nanocrystalline molybdenum

    DEFF Research Database (Denmark)

    Frederiksen, Søren Lund; Jacobsen, Karsten Wedel; Schiøtz, Jakob

    2004-01-01

    Using molecular dynamics simulations we investigate the plastic deformation of nanocrystalline molybdenum with a grain size of 12 nm at high strain rates. The simulations are performed with an interatomic potential which is obtained through matching of atomic forces to a database generated...... with density-functional calculations. The simulations show the plastic deformation to involve both grain boundary processes and dislocation migration which in some cases lead to twin boundary formation. A large component of the strain is accommodated through the formation of cracks in the grain boundaries...

  19. Microstructure and mechanical properties of unirradiated low activation ferritic steel

    International Nuclear Information System (INIS)

    Hsu, C.Y.; Lechtenberg, T.A.

    1986-01-01

    Transmission electron micrographs of normalized and tempered 9Cr-2.5W-0.3V-0.15C low activation ferritic steel showed tempered lath-type martensite with precipitation of rod and plate-like carbides at lath and grain boundaries. X-ray diffraction analysis of the extracted replicas revealed nearly 100% M 23 C 6 carbides (a=1.064 nm), with no indication of Fe 2 W-type Laves phase even after thermal aging at 600 0 C/1000 h. Thermal aging increased the number density of rod-like M 23 C 6 along prior austenite grain boundaries and martensite lath boundaries. The elevated-temperature tensile strengths of this steel are about 10% higher than the average strengths of commercial heats of 9Cr-1Mo and modified 9Cr-1Mo steels up to 650 0 C, with equivalent uniform elongation and ∝50% decrease in total elongation. The DBTT was determined to be -25 0 C which is similar to other 9Cr-1Mo steels. Fractographic examination of tensile tested specimens shows a mixed mode of equiaxed and elongated dimples at test temperatures above 400 0 C. Modification of the Ga3X alloy composition for opimization of materials properties is discussed. However, the proposed low activation ferritic steel shows the promise of improved mechanical properties over 9Cr-1Mo steels. (orig.)

  20. Magnetic and electrical properties of Cr substituted Ni nano ferrites

    Directory of Open Access Journals (Sweden)

    Katrapally Vijaya Kumar

    2018-03-01

    Full Text Available Nano-ferrites with composition NiCrxFe2-xO4 (where x = 0.1, 0.3, 0.5, 0.7, 0.9, 1.0 were synthesized through citrate-gel auto combustion technique at moderately low temperature. X-ray analysis shows cubic spinel structure single phase without any impurity peak and average crystallite size in the range 8.5–10.5 nm. Magnetic properties were measured using a vibrating sample magnetometer at room temperature in the applied field of ±6 KOe. The obtained M-H loop area is very narrow, hence the synthesized nano ferrites are soft magnetic materials with small coercivity. Magnetic parameters such as saturation magnetization (Ms, coercivity (Hc, remanent magnetization (Mr and residual magnetization were measured and discussed with regard to Cr3+ ion concentration. Electrical properties were measured using two probe method from room temperature to well beyond transition temperature. The DC resistivity variation with temperature shows the semiconductor nature. Resistivity, drift mobility and activation energy values are measured and discussed with regard to composition. The Curie temperature was determined using DC resistivity data and Loria-Sinha method. The observed results can be explained in detail on the basis of composition.

  1. Magnetic loss analysis in Mn-Zn ferrite cores

    International Nuclear Information System (INIS)

    Beatrice, C.; Bottauscio, O.; Chiampi, M.; Fiorillo, F.; Manzin, A.

    2006-01-01

    Magnetic losses have been measured and analyzed upon a wide range of frequencies in Mn-Zn ferrite ring cores. Exploiting the concept of loss separation and modeling the conductivity process in the heterogeneous material as a function of frequency, the role of the different energy dissipation mechanisms has been elucidated. It is shown, in particular, that eddy current effects can be appreciated, in standard materials and cores, only on approaching and overcoming the MHz range. The basic mechanism for hysteresis and low-frequency losses is therefore identified with the domain wall relaxation engendered by spin damping processes. Resonant absorption of energy associated with magnetization rotation is in turn deemed to chiefly contribute to the loss upon the practical range of frequencies going from a few 10 4 Hz to a few MHz

  2. High purity ferritic Cr-Mo stainless steel

    International Nuclear Information System (INIS)

    Knoth, J.

    1977-01-01

    In five years, E-BRITE 26-1 ferritic stainless steel has won an important place in the spectrum of materials suitable for use in chemical process equipment. It provides, in stainless steel, performance-capability characteristics comparable to more expensive alloys. It has demonstrated cost-effectiveness in equipment used for caustic, nitric-urea, organic chemicals, pulping liquors, refinery streams, and elsewhere. User confidence in the reliability and integrity of Grade XM 27 has increased to the point where large critical systems are now routinely specified in the alloy. The market acceptance of this material has attracted attempts to produce substitute versions of the alloy. Imitation, should be viewed with caution. Stabilized 26-IS must be examined over a lengthy period of time to determine if its own corrosion resistance, ductility, fabricability and reproducibility properties could ever be likened to those of E-BRITE 26-1. (orig.) [de

  3. 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)

  4. Thermal Stability of Nanocrystalline Copper for Potential Use in Printed Wiring Board Applications

    Science.gov (United States)

    Woo, Patrick Kai Fai

    Copper is a widely used conductor in the manufacture of printed wiring boards (PWB). The trends in miniaturization of electronic devices create increasing challenges to all electronic industries. In particular PWB manufacturers face great challenges because the increasing demands in greater performance and device miniaturization pose enormous difficulties in manufacturing and product reliability. Nanocrystalline and ultra-fine grain copper can potentially offer increased reliability and functionality of the PWB due to the increases in strength and achievable wiring density by reduction in grain size. The first part of this thesis is concerned with the synthesis and characterization of nanocrystalline and ultra-fine grain-sized copper for potential applications in the PWB industry. Nanocrystalline copper with different amounts of sulfur impurities (25-230ppm) and grain sizes (31-49nm) were produced and their hardness, electrical resistivity and etchability were determined. To study the thermal stability of nanocrystalline copper, differential scanning calorimetry and isothermal heat treatments combined with electron microscopy techniques for microstructural analysis were used. Differential scanning calorimetry was chosen to continuously monitor the grain growth process in the temperature range from 40?C to 400?C. During isothermal annealing experiments samples were annealed at 23?C, 100?C and 300?C to study various potential thermal issues for these materials in PWB applications such as the long-term room temperature thermal stability as well as for temperature excursions above the operation temperature and peak temperature exposure during the PWB manufacturing process. From all annealing experiments the various grain growth events and the overall stability of these materials were analyzed in terms of driving and dragging forces. Experimental evidence is presented which shows that the overall thermal stability, grain boundary character and texture evolution of

  5. Effect of Mo Ion Implantation on Stability of Nanocrystalline Copper Surface Layers

    Directory of Open Access Journals (Sweden)

    XI Yang

    2016-08-01

    Full Text Available The surface of pure copper was modified using the surface mechanical attrition treatment (SMAT method, and molybdenum ions were implanted in the nanosurface using a metal vapor vacuum arc (MEVVA. The results of the SMAT were observed by optical microscopy (OM, X-ray diffraction (XRD and scanning electron microscopy (SEM. An obvious nanocrystalline layer and a deformation region exist on the surface. The size of the nanocrystalline layer was characterized using atomic force microscopy (AFM. The results indicate remarkable suppression on grain size, the nanocrystalline layer grows to 163nm after annealing and reduces to only 72nm due to the Mo ion implantation. In addition, the hardness of the topmost surface of the material is 3.5 times that of the SMATed copper, which is about 7 times of the value of the matrix. The above improvements most likely result from the dispersion of the Mo ions and the reactions of the crystal defects due to the SMAT and ion implantation.

  6. The electrochemical characteristics of Mg2Ni nanocrystalline hydrogen storage alloy

    International Nuclear Information System (INIS)

    Zhang Ling; Zhou Xiaosong; Peng Shuming

    2008-06-01

    The nanocrystalline Mg 2 Ni materials were prepared by mechanical alloying. The cyclic voltametry results indicated that the potential of oxidation peak was shift as the scan rate increased and the absorption property of Mg 2 Ni prepared by mechanical alloying was increased even at ambient temperature. The absorption and desorption of hydrogen in Mg 2 Ni alloy were remarkably accelerated with the rising temperature. Small angel X-ray scattering results indicated that the Mg 2 Ni powder have 1-5 nm and 5-10 nm particle size distribution, which increased the acting sites of hydrogen absorption/desorption reaction and decreased the diffusion path of hydrogen desorption. It was induced to the enhanced performance of Mg 2 Ni nanocrystalline powder. The cycle life investigated results indicated that the activation property of Mg 2 Ni nanocrystal-line hydrogen storage alloy electrode was excellent, the capacitance maintenance ration was 66% after 200 cycles. The coating of epoxy resin on one side of the electrode had no effect on the activation property and the capacitance maintenance ration was better than the uncoating one. But the anode peak current value and the cathodic peak current value were decreased remarkably which indicated that the hydrogen absorption/desorption rate and the charge/discharge degree had decreased. (authors)

  7. Influence of coating on nanocrystalline magnetic properties during high temperature thermal ageing

    Energy Technology Data Exchange (ETDEWEB)

    Lekdim, Atef, E-mail: atef.lekdim@univ-lyon1.fr; Morel, Laurent; Raulet, Marie-Ange

    2017-05-15

    Since their birth or mergence the late 1980s, the nanocrystalline ultrasoft magnetic materials are taking a great importance in power electronic systems conception. One of the main advantages that make them more attractive nowadays is their ability to be packaged since the reduction of the magnetostrictive constant to almost zero. In aircraft applications, due to the high component compactness and to their location (for example near the jet engine), the operating temperature increases and may reach easily 200 °C and more. Consequently, the magnetic thermal ageing may occur but is, unfortunately, weakly studied. This paper focuses on the influence of the coating (packaging type) on the magnetic nanocrystalline performances during a thermal ageing. This study is based on monitoring the magnetic characteristics of two types of nanocrystalline cores (naked and coated) during a thermal activated ageing (100, 150 and 200 °C). Based on a dedicated monitoring protocol, a large magnetic characterization has been done and analyzed. Elsewhere, X-Ray Diffraction and magnetostriction measurements were carried out to support the study of the anisotropy energies evolution with ageing. This latter is discussed in this paper to explain and give hypothesis about the ageing phenomena. - Highlights: • The coating impacts drastically the magnetic properties during thermal ageing. • Irreversible ageing phenomena after the total coating breakage. • The deteriorations are related to the storage of the magnetoelastic anisotropy.

  8. Fe(Co)SiBPCCu nanocrystalline alloys with high Bs above 1.83 T

    Science.gov (United States)

    Liu, Tao; Kong, Fengyu; Xie, Lei; Wang, Anding; Chang, Chuntao; Wang, Xinmin; Liu, Chain-Tsuan

    2017-11-01

    Fe84.75-xCoxSi2B9P3C0.5Cu0.75 (x = 0, 2.5 and 10) nanocrystalline alloys with excellent magnetic properties were successfully developed. The fully amorphous alloy ribbons exhibit wide temperature interval of 145-156 °C between the two crystallization events. It is found that the excessive substitution of Co for Fe greatly deteriorates the magnetic properties due to the non-uniform microstructure with coarse grains. The alloys with x = 0 and 2.5 exhibit high saturation magnetization (above 1.83 T), low core loss and relatively low coercivity (below 5.4 A/m) after annealing. In addition, the Fe84.75Si2B9P3C0.5Cu0.75 nanocrystalline alloy also exhibits good frequency properties and temperature stability. The excellent magnetic properties were explained by the uniform microstructure with small grain size and the wide magnetic domains of the alloy. Low raw material cost, good manufacturability and excellent magnetic properties will make these nanocrystalline alloys prospective candidates for transformer and motor cores.

  9. Ultra-nanocrystalline diamond electrodes: optimization towards neural stimulation applications.

    Science.gov (United States)

    Garrett, David J; Ganesan, Kumaravelu; Stacey, Alastair; Fox, Kate; Meffin, Hamish; Prawer, Steven

    2012-02-01

    Diamond is well known to possess many favourable qualities for implantation into living tissue including biocompatibility, biostability, and for some applications hardness. However, conducting diamond has not, to date, been exploited in neural stimulation electrodes due to very low electrochemical double layer capacitance values that have been previously reported. Here we present electrochemical characterization of ultra-nanocrystalline diamond electrodes grown in the presence of nitrogen (N-UNCD) that exhibit charge injection capacity values as high as 163 µC cm(-2) indicating that N-UNCD is a viable material for microelectrode fabrication. Furthermore, we show that the maximum charge injection of N-UNCD can be increased by tailoring growth conditions and by subsequent electrochemical activation. For applications requiring yet higher charge injection, we show that N-UNCD electrodes can be readily metalized with platinum or iridium, further increasing charge injection capacity. Using such materials an implantable neural stimulation device fabricated from a single piece of bio-permanent material becomes feasible. This has significant advantages in terms of the physical stability and hermeticity of a long-term bionic implant.

  10. Synthesis of bulk nanocrystalline Pb-Sn-Te alloy under high pressure

    International Nuclear Information System (INIS)

    Zhu, P W; Chen, L X; Jia, X; Ma, H A; Ren, G Z; Guo, W L; Liu, H J; Zou, G T

    2002-01-01

    Pb-Sn-Te bulk nanocrystalline (NC) materials are prepared successfully by quenching melts under high pressure. The mean particle size is about 100 nm and the crystal structure is NaCl type. The mechanism of formation of the bulk NC alloy is explained: there is an increasing of the nucleation rate and a decrease in the growth rate of nuclei with increase of pressure during the solidification processes. The thermoelectric properties of Pb-Sn-Te bulk NC alloy are enhanced. This method is promising for producing thermoelectric materials with improved high-energy conversion efficiency

  11. Strength of "Light" Ferritic and Austenitic Steels Based on the Fe - Mn - Al - C System

    Science.gov (United States)

    Kaputkina, L. M.; Svyazhin, A. G.; Smarygina, I. V.; Kindop, V. E.

    2017-01-01

    The phase composition, the hardness, the mechanical properties at room temperature, and the resistance to hot (950 - 1000°C) and warm (550°C) deformation are studied for cast deformable "light" ferritic and austenitic steels of the Fe - (12 - 25)% Mn - (0 - 15)% Al - (0 - 2)% C system alloyed additionally with about 5% Ni. The high-aluminum high-manganese low-carbon and carbonless ferritic steels at a temperature of about 0.5 T melt have a specific strength close to that of the austenitic steels and may be used as weldable scale-resistant and wear-resistant materials. The high-carbon Fe - (20 - 24)% Mn - (5 - 9)% Al - 5% Ni - 1.5% C austenitic steels may be applied as light high-strength materials operating at cryogenic temperatures after a solution treatment and as scale- and heat-resistant materials in an aged condition.

  12. 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.

  13. 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

  14. New stainless steels of ferrite-martensite grade and perspectives of their application in thermonuclear facilities and fast reactors

    International Nuclear Information System (INIS)

    Ajtkhozhin, Eh.S.; Maksimkin, O.P.

    2007-01-01

    Review of scientific literature for last 5 years in which results on study of radiation effect on ferrite-martensite steels - construction materials of fast reactors and most probable candidates for first wall and blanket of the thermonuclear facilities ITER and Demo - are presented. Alongside with this a prior experimental data on study of microstructure changing and physical- mechanical properties of ferrite-martensite steel EhP-450 - the material of hexahedral case of spent assembly of BN-350 fast reactor- are cited. Principal attention was paid to considering of radiation effects of structural components content changing and ferrite-martensite steel swelling irradiated at comparatively low values of radiation damage climb rate

  15. Synthesis of metal-doped Mn-Zn ferrite from the leaching solutions of vanadium slag using hydrothermal method

    Science.gov (United States)

    Liu, Shiyuan; Wang, Lijun; Chou, Kuochih

    2018-03-01

    Using vanadium slag as raw material, Metal-doped Mn-Zn ferrites were synthesized by multi-step processes including chlorination of iron and manganese by NH4Cl, selective oxidation of Fe cation, and hydrothermal synthesis. The phase composition and magnetic properties of synthesized metal-doped Mn-Zn ferrite were characterized by X-ray powder diffraction, Raman spectroscopy, transmission electron microscopy (TEM), X-ray photon spectra (XPS) and physical property measurement. It was found that Mn/Zn mole ratio significantly affected the magnetic properties and ZnCl2 content significantly influenced the purity of the phase of ferrite. Synthesized metal-doped Mn-Zn ferrite, exhibiting a larger saturation magnetization (Ms = 60.01 emu/g) and lower coercivity (Hc = 8.9 Oe), was obtained when the hydrothermal temperature was controlled at 200 °C for 12 h with a Mn/Zn mole ratio of 4. The effect of ZnCl2 content, Mn/Zn mole ratio and temperature on magnetic properties of the synthesized metal-doped Mn-Zn ferrite were systemically investigated. This process provided a new insight to utilize resources in the aim of obtaining functional materials.

  16. Processing–microstructure–properties relationship in a CuNiZn ferrite

    International Nuclear Information System (INIS)

    Clausell, C.; Barba, A.

    2018-01-01

    CuNiZn ferrites are polycrystalline ceramic materials that are used widely in electronic devices for a number of reasons, including their high permeability in the RF frequency region, electrical resistivity, mechanical hardness and chemical stability. One of their main applications is in the production of specimens to prevent possible interferences between electronic devices, thanks to their ability to absorb electromagnetic waves. However, their electromagnetic properties are not solely dependent on their chemical composition, but also on the microstructure of the final piece (relative density or total porosity, grain size distribution, pore size distribution, the nature of the grain boundary, presence of secondary phases, dopants, etc.) and, therefore, on the morphology and size of the starting particles, and the processing method. The microstructure of the sintered specimens was designed in such a way as to optimize the electromagnetic properties of this ferrite. The solid-state sintering stage was also modeled with this optimization in mind. This sintering model enabled to propose the material transport mechanisms that controlled the densification and grain-growth rates, as well as the relative rates of these two simultaneous processes. The established relationships facilitate the design of a thermal cycle suitable for the manufacture of ferrite pieces with maximum relative density and the necessary microstructure. Together with the pre-configured chemical composition, the idea is that this ensures a strong set of final electromagnetic properties. The electromagnetic properties of the sintered ferrites were observed to improve as sintered relative density and average grain size increased, provided there was no evidence of exaggerated grain growth. In this sense, it seems there is a threshold of the grain size as of which the electromagnetic properties of the sintered specimens get worse. A linear relationship was observed between the imaginary part of the

  17. Microwave processed NiMg ferrite: Studies on structural and magnetic properties

    International Nuclear Information System (INIS)

    Chandra Babu Naidu, K.; Madhuri, W.

    2016-01-01

    Ferrites are magnetic semiconductors realizing an important role in electrical and electronic circuits where electrical and magnetic property coupling is required. Though ferrite materials are known for a long time, there is a large scope in the improvement of their properties (vice sintering and frequency dependence of electrical and magnetic properties) with the current technological trends. Forth coming technology is aimed at miniaturization and smart gadgets, electrical components like inductors and transformers cannot be included in integrated circuits. These components are incorporated into the circuit as surface mount devices whose fabrication involves low temperature co-firing of ceramics and microwave monolithic integrated circuits technologies. These technologies demand low temperature sinter-ability of ferrites. This article presents low temperature microwave sintered Ni–Mg ferrites of general chemical formula Ni_1_−_xMg_xFe_2O_4 (x=0, 0.2, 0.4, 0.5, 0.6, 0.8, 1) for potential applications as transformer core materials. The series of ferrites are characterized using X-ray diffractometer, scanning electron microscopy, Fourier transform infrared and vibrating sample magnetometer for investigating structural, morphological and magnetic properties respectively. The initial permeability is studied with magnesium content, temperature and frequency in the temperature range of 308 K–873 K and 42 Hz–5 MHz. - Highlights: • First article on microwave processed NiMgFe_2O_4 giving. • The article gives systematic magnetic studies. • Cation distribution is discussed based on magnetic moments from VSM. • Promising candidates for transformer core and soft magnet manufacturing.

  18. Microwave processed NiMg ferrite: Studies on structural and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Chandra Babu Naidu, K.; Madhuri, W., E-mail: madhuriw12@gmail.com

    2016-12-15

    Ferrites are magnetic semiconductors realizing an important role in electrical and electronic circuits where electrical and magnetic property coupling is required. Though ferrite materials are known for a long time, there is a large scope in the improvement of their properties (vice sintering and frequency dependence of electrical and magnetic properties) with the current technological trends. Forth coming technology is aimed at miniaturization and smart gadgets, electrical components like inductors and transformers cannot be included in integrated circuits. These components are incorporated into the circuit as surface mount devices whose fabrication involves low temperature co-firing of ceramics and microwave monolithic integrated circuits technologies. These technologies demand low temperature sinter-ability of ferrites. This article presents low temperature microwave sintered Ni–Mg ferrites of general chemical formula Ni{sub 1−x}Mg{sub x}Fe{sub 2}O{sub 4} (x=0, 0.2, 0.4, 0.5, 0.6, 0.8, 1) for potential applications as transformer core materials. The series of ferrites are characterized using X-ray diffractometer, scanning electron microscopy, Fourier transform infrared and vibrating sample magnetometer for investigating structural, morphological and magnetic properties respectively. The initial permeability is studied with magnesium content, temperature and frequency in the temperature range of 308 K–873 K and 42 Hz–5 MHz. - Highlights: • First article on microwave processed NiMgFe{sub 2}O{sub 4} giving. • The article gives systematic magnetic studies. • Cation distribution is discussed based on magnetic moments from VSM. • Promising candidates for transformer core and soft magnet manufacturing.

  19. Small polaron conduction in lead modified lanthanum ferrite ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Bhargav, K.K.; Ram, S.; Majumder, S.B., E-mail: subhasish@matsc.iitkgp.ernet.in

    2015-07-25

    Highlights: • La{sub 0.8}Pb{sub 0.2}FeO{sub 3} (ε{sub r} ∼ 30,000) shows higher dielectric constant than LaFeO{sub 3} (∼14,000). • Lower A-site dopant content, the dielectric maxima shift to higher temperature. • The frequency dependence of ε{sub r} and tan δ vs. temperature exhibit CDC like behavior. • R{sub g} and R{sub gb} of Pb modified LaFeO{sub 3} follow small polaron hopping conduction model. - Abstract: In the present work we have illustrated the physics of the electrical characteristics of nanocrystalline La{sub 1−x}Pb{sub x}FeO{sub 3,} (0 ⩽ x ⩽ 0.2) powder prepared using auto-combustion synthesis. The effect of lead doping on the dielectric, impedance and ac conductivity characteristics of lanthanum ferrite has systematically been investigated. The synthesized powders were phase pure and crystallized into centro-symmetric Pnma space group. As compared to pure LaFeO{sub 3} ceramics (dielectric constant ∼ 14,000), the dielectric constant is grossly increased (∼30,000) in Pb doped LaFeO{sub 3}. The temperature dependence of dielectric constant of 10.0 at.% Pb doped LaFeO{sub 3} exhibits dielectric maxima similar to that observed in ferroelectric ceramics with non-centrosymmetric point group. For La{sub 0.8}Pb{sub 0.2}FeO{sub 3} ceramics, the frequency dependence of the dielectric constant and loss tangent at various temperatures (300–450 K) exhibit typical colossal dielectric constant (CDC) like behavior. From the impedance spectroscopy we have estimated the grain and grain boundary resistance and capacitance of Pb doped LaFeO{sub 3} that follow a small polaron hopping conduction model. Long range movement of the charge carriers govern the CDC behavior.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-12-01

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