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Influence of Time and Temperature on Resistivity and Microstructure of CuX Co1-X Fe2 O4 Mixed Ferrites
Bantesh Kempanna Bammannavar;Lalasing Ratnu Naik;Rangappa Basappa Pujar;Baburao Kallappa Chougule
PIER Letters , 2008, DOI: 10.2528/PIERL08061101
Abstract: Copper-cobalt ferrites with general chemical formula CuCoFeO (with x = 0.0, 0.4, 0.6 & 1.0) were prepared by ceramic method. The solid state reaction was confirmed by XRD patterns. DC conductivity was measured by two probe method. Electrical resistivity is found to increase on lowering of sintering temperature and time. At x = 1.0, the conduction is mainly due to hopping of electrons leading to n-type conductivity while at x = 0.0, conduction is due to holes leading to P-type conductivity. The lowest conduction at x = 0.4 is attributed to the electron hole compensation. SEM micrographs were obtained from JEOL scanning electron microscope. The micrographs reveal that an average grain size increases with sintering temperature and time as a result of decrease in porosity. This leads to the decrease in resistivity with sintering temperature and time. One of the factors for higher conductivity in ferrites is an increase in average grain size and decrease in pore concentration during the heat treatment.
Structural Ordering and Magnetic Property of Complex Perovskite Solid Solution (1―x)Pb(Fe2/3W1/3)O3―xPb(Mg1/2W1/2)O3  [PDF]
YAO Chun-Fa, LI Cai-Fu, LIU Zhi-Quan, SHANG Jian-Ku
无机材料学报 , 2011, DOI: 10.3724/sp.j.1077.2011.00649
Abstract: Pb(Fe2/3W1/3)O3 was modified by doping Pb(Mg1/2W1/2)O3 with Sol―Gel method using inorganic salts as precursors. At calcination temperature of 700 , the resulted solid solution (1―x)Pb(Fe2/3W1/3)O3―xPb(Mg1/2W1/2)O3 kept a perovskite structure in the whole doping range of 0≤x≤1. The obtained Pb(Mg1/2W1/2)O3 (x=1) is fully ordered with a unit cell as two times as that of Pb(Fe2/3W1/3)O3 (x=0). Solid solution (1―x)Pb(Fe2/3W1/3)O3― xPb(Mg1/2W1/2)O3 (0
Influence of Mn substitution on crystal structure and magnetocrystalline anisotropy of nanocrystalline Co1 x Mn x Fe2 2x Mn2x O4
Lawrence Kumar,Pawan Kumar,Manoranjan Kar
Applied Nanoscience , 2013, DOI: 10.1007/s13204-012-0071-2
Abstract: Nanocrystalline Mn substituted cobalt ferrite Co1 x Mn x Fe2 2x Mn2x O4 (x = 0.0–0.4) has been synthesized by the standard citrate–gel method. The structural and magnetic characteristics of all samples have been studied using powder X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscope (FE-SEM) and VSM techniques. Distributions of cations between the two interstitial sites (tetrahedral and octahedral site) have been estimated qualitatively by analyzing the powder X-ray diffraction patterns by employing the Rietveld refinement technique. All samples are found to be mixed spinel with cubic structure ( $ Fd\mathop 3\limits^{ - } m $ space group). The FT-IR study shows the presence of absorption bands in the range of 390–750 cm 1, which confirm the spinel structure of the sample. The stoichiometry of Co, Fe, Mn and O ions in the sample has been obtained by using energy-dispersive spectrum with help of an FE-SEM. The magnetizations in saturation have been analyzed by employing the “law of approach” technique. The saturation magnetization, coercivity and magnetocrystalline anisotropy constant depend upon Mn ion concentration and crystallite size.
Novel Applications of Ferrites  [PDF]
Raúl Valenzuela
Physics Research International , 2012, DOI: 10.1155/2012/591839
Abstract: The applications of ferrimagnetic oxides, or ferrites, in the last 10 years are reviewed, including thin films and nanoparticles. The general features of the three basic crystal systems and their magnetic structures are briefly discussed, followed by the most interesting applications in electronic circuits as inductors, in high-frequency systems, in power delivering devices, in electromagnetic interference suppression, and in biotechnology. As the field is considerably large, an effort has been made to include the original references discussing each particular application on a more detailed manner. 1. Introduction Ferrites are a large class of oxides with remarkable magnetic properties, which have been investigated and applied during the last ~50 years [1]. Their applications encompass an impressive range extending from millimeter wave integrated circuitry to power handling, simple permanent magnets, and magnetic recording. These applications are based upon the very basic properties of ferrites: a significant saturation magnetization, a high electrical resistivity, low electrical losses, and a very good chemical stability. Ferrites can be obtained in three different crystal systems by many methods, and the feasibility to prepare a virtually unlimited number of solid solutions opens the means to tailor their properties for many applications. For many applications, ferrites cannot be substituted by ferromagnetic metals; for other, ferrites often compete with metals on economic reasons. The possibility of preparing ferrites in the form of nanoparticles has open a new and exciting research field, with revolutionary applications not only in the electronic technology but also in the field of biotechnology. In this paper, the applications of ferrites developed in the last 10 years are briefly described. 2. Ferrites 2.1. Spinels Spinel ferrites possess the crystal structure of the natural spinel MgAl2O4, first determined by Bragg [2]. This structure is particularly stable, since there is an extremely large variety of oxides which adopt it, fulfilling the conditions of overall cation-to-anion ratio of 3/4, a total cation valency of 8, and relatively small cation radii. Spinel structure is shown in Figure 1. Cation valency combinations known are 2, 3 (as in Ni2+Fe3+2O4); 2, 4 (as in Co2GeO4); 1, 3, 4 (as in LiFeTiO4); 1, 3 (as in Li0.5Fe2.5O4); 1, 2, 5 (as in LiNiVO4); 1, 6 (as in Na2WO4). In ferrites with applications as magnetic materials, Al3+ has usually been substituted by Fe3+. An important ferrite is magnetite, Fe2+Fe3+2O4 (typically referred as Fe3O4),
Magnetoelectric and converse magnetoelectric responses in Tb x Dy1 x Fe2 y alloy & Pb(Mg1/3Nb2/3)(1 x)TixO3 crystal laminated composites
YanMin Jia,HaoSu Luo,Siu Wing Or,YaoJin Wang,Helen L. W. Chan
Chinese Science Bulletin , 2008, DOI: 10.1007/s11434-008-0274-9
Abstract: Measured results of magnetoelectric (ME) and converse magnetoelectric (CME) effects of Tb x Dy1 x Fe2 y /Pb(Mg1/3Nb2/3)(1 x)TixO3/TbxDy1 x Fe2 y (TD/PMNT/TD) and PMNT/TD/PMNT laminated composites are presented. ME effect was determined by measuring laminate voltage output under a Helmholtz-generated AC field biased by a DC field (0–1 kOe) (1 Oe = 79.58 A/m). The CME effect was measured by recording the voltage induced in a solenoid encompassing the ME sample while exposed to a DC bias field and PMNT layer driven by a 10 V AC source. The ME and CME responses in the two laminated structure are linear. The highest values of ME coefficients in TD/PMNT/TD and PMNT/TD/PMNT composites are 384 mV/Oe and 158 mV/Oe, respectively, while the highest values of CME coefficients in the two composites are 118 mG/V and 162 mG/V (1 G=10 4 T), respectively.
X-ray Diffraction and Site Preference Analysis of Ni-Substituted MgFe2O4 Ferrites  [PDF]
Mazhar U. rana,Misbah-ul-Islam,Tahir Abbas
Journal of Applied Sciences , 2002,
Abstract: A series of Mg1-x NixFe2O4 spinel ferrites with x = 0.0, 0.25, 0.50, 0.75 and 1.0 have been prepared using standard ceramic method. The relationship between structural parameters and concentration of the substituted Ni-ions has been studied. A determination of crystal structure, oxygen positional parameter and cation distribution using X-ray Diffraction (XRD) and R-factor method revealed that these ferrites belong to the familty of mixed of partially inverse spinels.
Magnetic Properties of Magnesium Doped Li-Cr Ferrites
International Journal of Materials and Chemistry , 2012, DOI: 10.5923/j.ijmc.20120202.05
Abstract: Mixed ferrites Cr1.05 Li0.5 Mg x Fe1.45-(2/3)x O4 (0 ≤ x ≤ 0.4) doped with Magnesium have been studied using x-ray diffraction, M ssbauer spectroscopy and magnetic measurements. X-ray diffraction patterns show that all samples have single phase cubic spinel structure. The temperature-dependent magnetic measurements revealed that magnetic compensation disappears when Fe3+ in A-site is partially replaced by Mg2+. Moreover, below the compensation temperature the observed magnetic moment of these ferrites increases with magnesium content. The magnetization data at all concentrations are discussed in the light of Néel’s molecular field model taking into account the cations distribution obtained using the analysis of M ssbauer spectra.
Novel Applications of Ferrites  [PDF]
Raúl Valenzuela
Physics Research International , 2012, DOI: 10.1155/2012/591839
Abstract: The applications of ferrimagnetic oxides, or ferrites, in the last 10 years are reviewed, including thin films and nanoparticles. The general features of the three basic crystal systems and their magnetic structures are briefly discussed, followed by the most interesting applications in electronic circuits as inductors, in high-frequency systems, in power delivering devices, in electromagnetic interference suppression, and in biotechnology. As the field is considerably large, an effort has been made to include the original references discussing each particular application on a more detailed manner.
Synthesis of lithium ferrites from polymetallic carboxylates  [PDF]
DANA GINGASU,IOANA MINDRU,LUMINITA PATRON,STEFANIA STOLERIU
Journal of the Serbian Chemical Society , 2008,
Abstract: Lithium ferrite was prepared by the thermal decomposition of three polynuclear complex compounds containing as ligands the anions of malic, tartaric and gluconic acid: (NH4)2[Fe2.5Li0.5(C4H4O5)3(OH)4(H2O)2]×4H2O (I), (NH4)6[Fe2.5Li0.5(C4H4O6)3(OH)8]×2H2O (II) and (NH4)2[Fe2.5Li0.5(C6H11O7)3(OH)7] (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.
M?SSBAUER STUDY OF MAGNETIC STPUCTURE IN LITHIUM-ZINC FERRITES
LiZn铁氧体磁结构的穆斯堡尔研究

YANG XIE-LONG,GU YUAN-JI,TANG HUAN,HE RUI-YUN,HE PI-MO,
杨燮龙
,顾元吉,唐焕,何瑞芸,何丕模

物理学报 , 1985,
Abstract: The M?ssbauer spectra of the ferrite system, Li(0.5(1-x))ZnxFe(2.5-0.5x)O4, were studied at 77 K, 195 K and room temperature in an external magnetic field parallel to the gamma-ray direction. With increasing x and decreasing temperature, the second and the fifth lines of the six magnetic splittings were observed to become clearer, which proves convincingly the existence of canting of the moment of Fe3+ populated in the (B)-sublattice of the LiZn-ferrites. The agreement between magnetizations calculated on the basis of M?ssbauer parameters and measured by the magnetic experiment is satis-factory.
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