Home About us Contact
|
Home About us Contact | ||
|
|
||
Ferrite
Terms modified by Ferrite Selected AbstractsUnraveling Deterministic Mesoscopic Polarization Switching Mechanisms: Spatially Resolved Studies of a Tilt Grain Boundary in Bismuth FerriteADVANCED FUNCTIONAL MATERIALS, Issue 13 2009Brian J. Rodriguez Abstract The deterministic mesoscopic mechanism of ferroelectric domain nucleation is probed at a single atomically-defined model defect: an artificially fabricated bicrystal grain boundary (GB) in an epitaxial bismuth ferrite film. Switching spectroscopy piezoresponse force microscopy (SS-PFM) is used to map the variation of local hysteresis loops at the GB and in its immediate vicinity. It is found that the the influence of the GB on nucleation results in a slight shift of the negative nucleation bias to larger voltages. The mesoscopic mechanisms of domain nucleation in the bulk and at the GB are studied in detail using phase-field modeling, elucidating the complex mechanisms governed by the interplay between ferroelectric and ferroelastic wall energies, depolarization fields, and interface charge. The combination of phase-field modeling and SS-PFM allows quantitative analysis of the mesoscopic mechanisms for polarization switching, and hence suggests a route for unraveling the mechanisms of polarization switching at a single defect level and ultimately optimizing materials properties through microstructure engineering. [source] Enhanced Permeability and Dielectric Constant of NiZn Ferrite Synthesized in Nanocrystalline Form by a Combustion MethodJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2007Sasanka Deka The performance parameters of Ni0.5Zn0.5Fe2O4, synthesized in the nanocrystalline form by an autocombustion method, have been investigated. The sample sintered at 1200°C, with Bi2O3 as additive shows a very high value of initial permeability ,,i of >400 at 1 MHz, with low loss. Similarly, a very high dielectric constant is obtained at lower frequencies. The results show that optimum magnetic and electrical properties can be achieved for the NiZn ferrite nanocrystalline powders synthesized by the present autocombustion method and sintered at a relatively lower temperature of 1200°C when compared with a temperature of 1400°C required for the materials synthesized by the conventional ceramic method. [source] Polymer Bonded Ferrite Materials as EMC ComponentsMATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 7 2003J. Töpfer Polymergebundene Ferrite; Ferritabsorber; Permeabilität; Dämpfung Abstract Polymer bonded ferrites composed of a mixture of Mn-Zn ferrites or Ni-Zn ferrites in a polymer binder (PE, PA) were prepared and tested as electromagnetic-wave absorbing materials. Test samples and cases were prepared by hot or injection molding. Permeability spectra show loss contributions in the frequency range 100-1000,MHz. Absorption measurements of injection molded polymer-ferrite cases display a 3-5,dB better attenuation characteristics compared to graphite-loaded polyamide housings. Polymer-gebundene Ferritwerkstoffe für EMV-Anwendungen Polymer-gebundene Ferritwerkstoffe auf der Basis von Ferrit (Mn-Zn oder Ni-Zn Ferrite) , Thermoplast Mischungen wurden präpariert und hinsichtlich ihrer Eignung zur Absorption elektromagnetischer Strahlung untersucht. Es wurden sowohl Testproben wie auch komplette Gehäusekomponenten durch Heißpressen oder Spritzgießen hergestellt. Die Permeabilitätsspektren weisen verlustbehaftete Komponenten im Frequenzbereich von 100-1000,MHz auf. Schirmdämpfungsmessungen an spritzgegossenen Gehäuseteilen zeigen eine um 3-5,dB bessere Dämpfung im Vergleich zu Graphit-gefüllten Polyamid-Gehäusen. [source] ChemInform Abstract: Heck Reaction over Palladium Supported on Nickel Ferrite as an Efficient and Inexpensive Catalyst.CHEMINFORM, Issue 6 2009Sanjay R. Borhade Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Study of Substitution Limit, Structural, Bulk Magnetic and Electrical Properties of Ca2+ Substituted Magnesium Ferrite.CHEMINFORM, Issue 48 2004S. D. Chhaya Abstract For Abstract see ChemInform Abstract in Full Text. [source] Physical and Electrical Properties of Nanosized Mn- and Cr-Doped Strontium Y-Type Hexagonal FerritesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2010Muhammad Javed Iqbal Nanometer-sized crystallites of Y-type strontium hexaferrite, Sr2Ni2Fe12O22 and its Mn- and Cr-doped derivatives have been synthesized by the sol,gel method. Y-type phase formation was achieved at a considerably lower temperature of 950°C than is required in the traditional solid-state method (1200°C). The effect of doping of manganese at the tetrahedral site, Sr2Ni2,xMnx Fe12O22 (x=0.0,2.0), and chromium at octahedral site, Sr2Ni2 Fe12,yCryO22 (y=0.0,1.5), has been studied. The crystal structure remains unaffected by the substitutions. The crystallite size in the range of 13,45 nm is calculated from the X-ray diffraction data. The energy-dispersive X-ray fluorescence analysis shows that Y-type hexaferrites can be prepared with a base of strontium. The extent of doped Cr+3 ions at the octahedral site has been increased from the reported maximum value of y=1.5. Scanning electron micrographs of the samples showed a homogenous microstructure. The dc electrical resistivity studies show that these hexaferrites exhibit high resistivity at room temperature. Cr-doped samples have comparatively higher resistivity than Mn-doped samples. The doubly doped (Cr+Mn) samples possess high resistivity (7.37 × 109,-cm), a low dielectric constant (33.88 at 3000 Hz), and a high Curie temperature (>698 K). The dielectric energy losses are minimized by increasing the Mn and Cr contents of the synthesized samples. [source] Synthesis, Structure and Physical Properties of Ru Ferrites: BaMRu5O11 (M: Li and Cu) and BaM,2Ru4O11 (M,: Mn, Fe, and Co).CHEMINFORM, Issue 17 2006M. L. Foo Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Ion-Electron Transport in Strontium Ferrites: Relationships with Structural Features and Stability.CHEMINFORM, Issue 44 2004M. V. Patrakeev Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Crystal Structure, Electronic Structure, and Magnetic Properties of Bismuth-Strontium Ferrites.CHEMINFORM, Issue 20 2001J. Li Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Low-Fire Processing and Properties of Ferrite+Dielectric Ceramic CompositeJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2006Te-Ming Peng A low-fire Ni,Cu,Zn ferrite+dielectric ceramic composite and its multilayer integrated laminate, which can be densified at temperatures below 900°C, is prepared. To densify Ni,Cu,Zn ferrite at low temperatures, the dielectric needs to contain an effective sintering flux of Bi2O3 or PbO to the Ni,Cu,Zn ferrite. This enables densification of the resulting ceramic composite or multilayer integrated dielectric/ferrite laminate at temperatures close to those of pure ferrite and dielectric. The dielectric constant decreases but the initial permittivity increases with increasing amount of ferrite existing in the ferrite+dielectric ceramic composite. [source] Influence of the starting powders on the synthesis of nickel ferriteCRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2006F. Kenfack Abstract The thermal decomposition of freeze-dried nickel(II)-iron(III) formate was investigated by means of DTA, TG, mass spectrometry and X-ray powder diffractometry. For the preparation of homogeneous freeze-dried nickel(II)-iron(III) formate precursors, a rigorous control of nickel ion concentration in the precursor solution was required. The decomposition of the reactive nickel(II)-iron(III) formate does not only reflect aspects of single formates, but also an interaction between components which lowers the decomposition temperature. Crystalline nickel ferrite powders were obtained at 600-800°C. This temperature is quite lower than 1100°C employed for the ceramic method. In the presence of air, the regeneration of nickel ferrite from the taenite phase (,Ni,Fe) is accomplished at 800°C. This temperature is also 300°C below the temperature employed when the mixtures NiO:,-Fe2O3 or Ni:2Fe are the starting powders. The main reason for the high reactivity of the freeze-dried formates and the taenite alloy is the large homogeneity of these precursors. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Microstructure of a genuine Damascus sabreCRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2005A. A. Levin Abstract The surface and cross-section of a genuine Damascus sword was characterised by means of wide-angle X-ray scattering techniques complemented by optical and transmisssion electron microscopy. Position-resolved X-ray phase analysis revealed that, unlike ferrite and martensite, the distribution of cementite is inhomogeneous in different spatial zones parallel to the cutting edge of the blade. For the first time a quantitative X-ray phase and texture analysis was made possible by averaging all spatial zones of the surface and the cross-section of the sword and applying the Rietveld method with code TOPAS. Differences concerning texture and structure characteristics of ferrite, martensite and cementite are discussed. More evidence for the structure of cementite nanowires is supplied. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A study of copper recovery from copper-contaminated sludge with ferrite and selective leaching processesENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2007S.H. Hu Abstract The purpose of this study was to develop an effective resource recovery and leached residue stabilization process for copper-contaminated sludge. To this end, a treatment procedure utilizing ferrite and selective leaching processes was developed. The XRD examination of ferrite complex revealed the crystalline phases to be mainly Fe3O4, CuO, and 6CuO·Cu2O. A selective leaching process was followed to recover the copper content of the ferrite complex. To promote the dissolution percentage of copper and repress that of iron, additional 0.5 N sulfuric acid was added at intervals to the suspension in the second step of the selective leaching process. The purpose of this operation was to return the suspension pH back to 3 to promote the dissolution of copper oxide and repress the dissolution of iron. Finally, the heavy metal (i.e., Cu, Pb, Cr, and Cd) dissolution of the above residue was examined with toxicity characteristic leaching procedure (TCLP) testing and all met the regulatory standard. © 2007 American Institute of Chemical Engineers Environ Prog 26:104,112, 2007 [source] Microstructure Evolution and Mechanical Properties of Linear Friction Welded 45 Steel JointADVANCED ENGINEERING MATERIALS, Issue 8 2007J. Ma Linear friction welding (LFW) is an emerging solid-state joining process to extend the current applications of welding. The microstructure evolution and mechanical properties of LFW 45 steel joint were investigated. The microstructures from the weld center to the parent metal were the superfine ferrite+pearlite in the weld center, the deformed fine ferrite + pearlite in the thermomechanically affected zone, the tempered sorbite, troosite and martensite in the heat affected zone. The microhardness of the joint decreased gradually from the parent metal to the weld center. The tensile properties of the joint were significantly improved in both the strength and ductility. The microstructure evolution, microhardness variation and fracture position are attributed to the various thermal histories of different positions. [source] Fabrication and Structural Evaluation of Beaded Inorganic Nanostructures Using Soft-Electron-Beam Lithography,ADVANCED MATERIALS, Issue 1 2007S. Donthu Soft electron-beam lithography, a simple high-resolution patterning technique, is used to fabricate single-grain-wide nanostructures, as seen in the figure, of functional ceramic materials, such as zinc oxide and bismuth ferrite. Structural characterization of these nanostructures reveal that average grain size decreases with line width (see the plot in the figure). [source] Design and measurement of microstrip ferrite coupled line circulatorsINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 3 2001C. S. Teoh Abstract The design of microstrip ferrite coupled line (MFCL) circulators using normal mode theory and the first proof-of-principle experiments are described. The longitudinally magnetized ferrite slab is positioned on top of a pair of microstrip lines to form the FCL and this is used with a T -junction and a novel hybrid coupler to form a three-port and a four-port circulator, respectively. The results show MFCL circulator behavior for the first time, and impedance levels and discontinuities are discussed. © 2001 John Wiley & Sons, Inc. Int J RF and Microwave CAE 11: 121,130, 2001 [source] TLM modelling of microstrip patch antenna on ferrite substrateINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 3 2001M. I. Sobhy Abstract A new TLM modelling method has been developed for patch antennas on magnetized ferrite substrate. The antenna has magnetically controllable resonance frequency and beam direction. The anisotropic permeability tensor of ferrite is modelled by state equations derived from the Polder tensor. Simulation results agree with measurement. © 2001 John Wiley & Sons, Inc. Int J RF and Microwave CAE 11: 131,139, 2001. [source] A small-angle neutron scattering study of fine-scale NbC precipitation kinetics in the ,-Fe,Nb,C systemJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 4 2006F. Perrard The fine-scale precipitation of NbC in ferrite has been quantitatively characterized in the temperature range 873,1073,K for two alloy compositions, containing respectively 800,p.p.m. Nb and 400,p.p.m. Nb (by weight). Transmission electron microscopy (TEM) has revealed that the precipitates are located on dislocations, and have a plate-like morphology with an average aspect ratio between 2 and 3. Small-angle neutron scattering (SANS) has been systematically used to determine the precipitation kinetics. The validity of the quantitative SANS measurements of size and volume fraction has been assessed by TEM image analysis and chemical dissolution experiments. The precipitation kinetics is observed to depend strongly on temperature but to be similar for the two alloy compositions. From the measurements, it is inferred that precipitate nucleation is extremely rapid, in relation to the nature of the nucleation sites. A time,temperature transformation diagram is built from the kinetic data, showing a maximum reaction rate between 973 and 1073,K. [source] Comparative evaluation of heating ability and biocompatibility of different ferrite-based magnetic fluids for hyperthermia applicationJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2007Pallab Pradhan Abstract In this study, lauric acid-coated, superparamagnetic, nanoparticle-based magnetic fluids of different ferrites (Fe3O4, MnFe2O4, and CoFe2O4) were prepared and compared in terms of heating ability and biocompatibility to evaluate the feasibility of use in hyperthermia treatment of cancer. All the magnetic fluids prepared had particles of average sizes 9,11 nm. Heating ability of these magnetic fluids was evaluated by calorimetric measurement of specific absorption rate (SAR) at 300 kHz frequency and 15 kA/m field. Fe3O4 and MnFe2O4 showed higher SAR (120 and 97 W/g of ferrite, respectively) than CoFe2O4 (37 W/g of ferrite). In vitro study on BHK 21 cell lines showed dose-dependent cell viability for all the magnetic fluids. Threshold-biocompatible ferrite concentration for all the magnetic fluids was 0.1 mg/mL. Above 0.2 mg/mL, CoFe2O4 was more toxic than the other magnetic fluids. On intravenous injection of different doses (50, 200, and 400 mg/kg body weight) of magnetic fluids in mice, no significant changes in hematological and biochemical parameters were observed for Fe3O4 and MnFe2O4. With CoFe2O4, an increase in SGPT levels at a dose rate of 400 mg/kg body weight was observed, indicating its mild hepatotoxic effect. However, histology of different vital organs showed no pathological changes for all the three magnetic fluids. Further, long term in vivo evaluation of biocompatibility of the lauric acid-coated ferrites is warranted. This study shows that lauric acid-coated, superparamagnetic Fe3O4 and MnFe2O4 may be used for hyperthermia treatment and are to be preferred over CoFe2O4. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source] Preparation of Unsintered Spherical BaFe12O19 Nanoparticles via an Alcohol-Assisted Spray-Pyrolysis RouteJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2008Hye Moon Lee Unsintered spherical barium ferrite (BaFe12O19) nanoparticles were successfully prepared by the alcohol-assisted spray-pyrolysis (AASP) method without any postannealing processes. Ethyl alcohol (EtOH) in the precursor solution for BaFe12O19 particles was very effective not only in its capacity to decrease the particle size, but also in enhancing crystallization into barium ferrite hexagonal phase. As the vol% of EtOH increased from 0 to 20, a decrease of particle size from 136 to 111 nm and an increase of crystallinity were clearly observed. The AASP method was optimized by adjusting the chemical concentration in the precursor solution, and finally, unsintered spherical BaFe12O19 particles, with a geometric mean diameter of 72 nm, a geometric SD of 1.4, and an intrinsic coercivity of 4510 Oe, were successfully prepared. [source] Composition-Size Effects in Nickel,Zinc Ferrite Nanoparticles Prepared by Aqueous CoprecipitationJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2008Brian T. Naughton Nickel,zinc ferrite nanoparticles across the solid solution range, Ni1,xZnxFe2O4, from nickel ferrite to zinc ferrite were prepared by aqueous precipitation of mixed nitrate solutions at the same pH of 12.3. There is a linear relationship between the nanoparticle diameter and composition, decreasing with increasing zinc concentration across the solid solution. The nanoparticles are highly resistant to coarsening and some of them are faceted, suggesting that they are close to thermodynamic equilibrium. Measurements of the surface charge density of the nanoparticles, based on simultaneous conductimetric and potentiometeric titration, are presented as a function of composition for the zinc-rich compositions. A trend exists between the surface charge density and the zinc concentration, suggesting that they may be stabilized by charge. [source] Magneto-Dielectric Properties of Mg,Cu,Co Ferrite Ceramics: I. Densification Behavior and Microstructure DevelopmentJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2007L. B. Kong The densification, grain growth, and microstructure development of Mg,Cu,Co ferrite ceramics (MgFe1.98O4, Mg1,xCuxFe1.98O4, with x=0.10,0.30 and Mg0.90,xCoxCu0.10Fe1.98O4, with x=0.05,0.20) were studied. The primary objective was to develop magneto-dielectric materials for miniaturization of high frequency and very-high frequency antennas. It was found that magnesium ferrite (MgFe1.98O4) is a promising magneto-dielectric material. However, due to its poor densification, it could not be fully sintered at a temperature below 1200°C. High-temperature sintering resulted in undesirable electrical and dielectric properties, due to the formation of Fe2+ ions. The poor densification and slow grain growth rate of MgFe1.98O4 can be considerably improved by incorporating Cu, due to the occurrence of liquid-phase sintering at a high temperature. A critical concentration of Cu was observed for Mg1,xCuxFe1.98O4, above which both densification and grain growth were maximized or saturated. The presence of Co did not have a significant influence on the densification and grain growth of the Mg-based ferrite ceramics. [source] Low-Fire Processing and Properties of Ferrite+Dielectric Ceramic CompositeJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2006Te-Ming Peng A low-fire Ni,Cu,Zn ferrite+dielectric ceramic composite and its multilayer integrated laminate, which can be densified at temperatures below 900°C, is prepared. To densify Ni,Cu,Zn ferrite at low temperatures, the dielectric needs to contain an effective sintering flux of Bi2O3 or PbO to the Ni,Cu,Zn ferrite. This enables densification of the resulting ceramic composite or multilayer integrated dielectric/ferrite laminate at temperatures close to those of pure ferrite and dielectric. The dielectric constant decreases but the initial permittivity increases with increasing amount of ferrite existing in the ferrite+dielectric ceramic composite. [source] Dispersion characteristics of LiTi-Ferrite radomeMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 1 2010Naveen Kumar Saxena Abstract The dispersion characteristics of a magnetically switchable LiTi-Ferrite radome is presented. A thin layer of LiTi-ferrite is used as superstrate or radome layer, which control 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 in radome layer and transmitted power, 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 (,H) of ferrite material. By properly choosing the bias field, quasi TEM wave propagation in the ferrite layer can be made to be zero or negative over a certain frequency range, results in a switching behavior in the ferrite layer. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 52,54, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24828 [source] Microwave dielectric properties of NiFe2O4 nanoparticles ferritesMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2007C. P. L. Rubinger Abstract Nickel ferrite (NiFe2O4) was synthesized by the micelles mixing method, using lyophilized coconut oil. The method leads to the formation of ferrite nanoparticles. Nickel ferrite was prepared in coconut oil suspension and annealed during 4 h, at 400, 600, 800, 1000, and 1200°C. The X-ray diffraction (XRD) was applied to investigate the nanoparticle size dependence on the annealing temperature. Complex permittivity measurements were carried out in cavity resonators at 5.0 and 9.0 GHz, using the small perturbation theory. The main result is that the real part of the permittivity decreases with increasing annealing temperatures (3.6,2.4), while the imaginary part of the permittivity varies only for the lowest annealing temperatures, remaining low for the other samples (about 10,3). The X-ray diffractograms indicates that the nanoparticle size increase with annealing temperature, allowed the correlation between the nanoparticle size and the observed microwave dielectric response. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1341,1343, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22402 [source] The influence of substrate on the magnetic properties of MnZn ferrite thin film fabricated by alternate sputteringPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 10 2008Lanxi Wang Abstract Mn0.5Zn0.5Fe2O4 film which has the highest saturation magnetization among Mn1,xZnx Fe2O4 thin films was prepared by the alternate rf sputtering method from two targets with compositions of MnFe2O4 and ZnFe2O4, respectively. The films were deposited on single-crystal Si(100), MgO(100) and SiO2/Si(100) substrates. The as-deposited films were amorphous, and after annealing in a vacuum furnace at 550 °C, polycrystalline MnZn ferrite films with residual amorphous matrix were obtained. The coercivity of all films is low, and the film on the MgO(100) substrate shows a coercivity as low as 27 Oe. The grain size of all films is about 20 nm and is less than the ferromagnetic exchange length (160 nm), so magnetic anisotropies are averaged to lower effective values. Furthermore, the negative magnetostriction constant of crystalline MnZn ferrite and the positive magnetostriction constant of amorphous Fe-based matrix will cancel out and may lead to a low or vanishing saturation magnetostriction constant. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] X-ray diffraction and Raman study of nanogranular BaTiO3,CoFe2O4 thin films deposited by laser ablation on Si/Pt substratesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2007J. Barbosa Abstract Nanocomposite thin films composed by (BaTiO3)1,x,(CoFe2O4)x with different cobalt ferrite concentrations (x) have been deposited by pulsed laser ablation on platinum covered Si(001) substrates. The films structure was studied by X-ray diffraction and Raman spectroscopy. It was found that the CoFe2O4 phase unit cell was compressed along the growth direction of the films, and it relaxed with increasing x. The opposite behavior was observed in the BaTiO3 phase where the lattice parameters obtained from the X-ray measurements presented a progressive distortion of its unit cell with increasing x. The presence of the strain in the films induced a blueshift of the Raman peaks of CoFe2O4 that decreased with increasing CoFe2O4 concentration. Cation disorder in the cobalt ferrite was observed for lower x, where the nanograins are more isolated and subjected to more strain, which was progressively decreased for higher CoFe2O4 content in the films. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Flexomagnetoelectric effect in bismuth ferritePHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 8 2009Anatoly K. Zvezdin Abstract There is a profound analogy between the inhomogeneous magnetoelectric effect in multiferroics and the flexoelectric effect in liquid crystals. This similarity gives rise to the flexomagnetoelectric polarization induced by spin modulation. The theoretical estimations of flexomagnetoelectric polarization agree with the value of jumps of magnetoelectric dependences (,20 ,C/m2) observed at spin cycloid suppression in a critical magnetic field of 200 kOe. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Microstructure and humidity sensitive properties of MgFe2O4 ferrite with Ni and Mn substitutionsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2004E. Rezlescu Abstract It was studied the effect of manganese and nickel ions on the microstructure and humidity sensitivity of the electrical resistivity of Mg ferrite. The humidity sensitivity depends on composition. The MgMn0.2Fe1.8O4 is sensitive in a wide humidity range, between 11% and 85%RH. The other compositions are sensitive at high humidities only, between 43% and 98%. The response time of a.c. resistivity to the humidity variations was measured to be about 120 seconds for all compositions. This sensor element can be used for controlling the humidity in microwave ovens. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Design of an energy conversion system with decomposition of H2O and CO2 using ferritesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2004H. C. Shin Abstract The energy conversion system was designed in order to reduce the green-house effect and to get energy resources by decomposition of CO2 and H2O. This system is consisted of two parts, one is CO2 decomposition with the reduced ferrite by H2 and the other is H2O decomposition with reduced ferrite by CH4. CH4 could be synthesized in this system by methanation reaction using carbon, which was deposited on the ferrite surface in the CO2 decomposition process. Also, CH4 was used as reducing gas to reduce the ferrite for H2O decomposition. H2O was decomposed by oxidation of oxygen-deficient ferrite. In this energy conversion system, the reduced Cu-ferrite easily decomposed CO2 and H2O into the useful gases such as CO and H2, respectively. Cu-ferrite is a suitable material to apply to this system because it showed excellent redox reactivity on the energy conversions. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||||||||