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Effect of Sintering Temperature on Structural and Magnetic Properties of Ni0.55Zn0.45Fe2O4 Ferrites  [PDF]
Robiul Islam, Md Obaidur Rahman, M. Abdul Hakim, Dilip Kumar Saha, Saiduzzaman Saiduzzaman, Saroaut Noor, Md Al-Mamun
Materials Sciences and Applications (MSA) , 2012, DOI: 10.4236/msa.2012.35048
Abstract: The effect of frequency and sintering temperature on initial permeability of Ni0.55Zn0.45Fe2O4 ferrites have been studied by using an impedance analyzer. The samples were prepared by conventional double sintering ceramic technique using oxide nanoparticles of grain size 30 - 50 nm. Single phase spinal structure has been confirmed for the prepared samples by X-ray diffraction. As the sintering temperatures increase from 1160℃ to 1300℃, the permeability gradually increases. The increase of permeability is ascribed to the increase of density and grain size. Grain size is expected to grow with the increase of sintering temperature. Ferrites with large average grain size posses higher initial permeability. The Curie temperatures determined from temperature dependence of permeability of the samples sintered at different temperatures are found to be Tc = (321 ± 1)℃ and independent of sintering temperature. At Ts = 1300℃, Tc is found to increase substantially which can be explained by the fact that Zn has evaporated from the surface layer.
Effect of Sintering Temperature on Structural and Magnetic Properties of Ni0.6Zn0.4Fe2O4 Ferrite: Synthesized from Nanocrystalline Powders  [PDF]
M. A. Ali,M. N. I. Khan,F. -U. -Z. Chowdhury,D. K. Saha,S. M. Hoque,S. I. Liba,S. Akhter,M. M. Uddin
Physics , 2015,
Abstract: The effect of sintering temperatures (Ts) on the structural and magnetic properties of Ni0.6Zn0.4Fe2O4 (NZFO) ferrites synthesized by conventional double sintering method has been reported. The samples are sintered at 1200, 1250 and 1300 {\deg}C. The X-ray diffraction (XRD) analysis reveals the formation of a single phase cubic spinel structure of the sample. The magnetic parameters such as saturation magnetization, Ms; coercive field, Hc; remanent magnetization, Mr and Bohr magneton, {\mu}B are determined and well compared with reported values. The obtained values are found to be 71.94 emu/gm and 1.2 Oe for Ms and Hc, respectively at Ts=1300 oC. Curie temperature (Tc) at various Ts has also been calculated. It is noteworthy to note that the sample with a very low Hc could be used in transformer core and inductor applications.
Influence of the sintering temperature on the magnetic and electric properties of NiFe2O4 ferrites
Zabotto, Fabio Luis;Gualdi, Alexandre José;Eiras, Jose Antonio;Oliveira, Adilson Jesus Aparecido de;Garcia, Ducinei;
Materials Research , 2012, DOI: 10.1590/S1516-14392012005000043
Abstract: this study evaluates the structural, microstructural, electric and magnetic properties of nickel ferrite samples prepared through the solid state reaction. it was observed that an increase in the sintering temperature produces a higher cation concentration in the a site when compared to the b site. the assessment of magnetic properties showed that an increase in grain size leads to a decrease in the coercive fields verging on superparamagnetic values, while the saturation magnetization increases up to 46.5 am2.kg-1 for samples sintered at 1200 oc. the dc electric resistivity behavior of samples was attributed to the increase in the cross-sectional area of grains as well as the different oxidation states and distribution of cations amongst the lattice sites of the spinel structure.
Synthesis, Structural and Magnetic Properties of Copper Substituted Nickel Ferrites by Sol-Gel Method  [PDF]
Gopathi Ravi Kumar, Katrapally Vijaya Kumar, Yarram Chetty Venudhar
Materials Sciences and Applications (MSA) , 2012, DOI: 10.4236/msa.2012.32013
Abstract: The Ni1–xCuxFe2O4 (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0) ferrites have been prepared by sol-gel method in order to obtain homogeneous crystal structure and they are sintered at high temperature. The effect of copper doping on the structural and magnetic properties of nickel ferrites sintered at 1000°C has been examined. The X-ray diffraction measurements clearly showed the formation of single phase spinel ferrite structure in all the prepared ferrite compositions. Because of the high sintering temperature the particle size is observed beyond the nano-scale range in all the compositions. The lattice parameters are found to increase with increasing doping concentration of the copper content. Magnetization results exhibit a non-collinear ferrimagnetic structure for x = 0.0 to 0.5 and Neel’s collinear ferrimagnetic structure for x = 0.5 to 0.9 suggesting a change in magnetic ordering.
Effect of Samarium Substitution on the Structural and Magnetic Properties of Nanocrystalline Cobalt Ferrite  [PDF]
Sheena Xavier,Smitha Thankachan,Binu P. Jacob,E. M. Mohammed
Journal of Nanoscience , 2013, DOI: 10.1155/2013/524380
Abstract: A series of samarium-substituted cobalt ferrites ( with , 0.05, 0.10, 0.15, 0.20, 0.25) was synthesized by the sol-gel method. The structural characterizations of all the prepared samples were done using XRD and FTIR. These studies confirmed the formation of single-phase spinel structure in all the compositions. The increase in the value of lattice parameter with increase in samarium concentration suggests the expansion of unit cell. The Hall-Williamson analysis is used for estimating the average crystallite size and lattice strain induced due to the substitution of samarium in the prepared samples. Crystallinity and the crystallite size are observed to increase with the concentration of samarium. The surface morphology and particle size of a typical sample were determined using SEM and TEM respectively. The substitution of samarium strongly influences the magnetic characteristics, and this is confirmed from the magnetization measurements at room temperature. 1. Introduction Spinel ferrite nanoparticles have attracted much attention in recent years because of their potential applications in high density magnetic recording, magnetic fluids, spintronics, data storage, and gas sensors [1–3]. Among the ferrite nanoparticles, cobalt ferrite has been widely studied due to its excellent chemical stability, mechanical hardness, reasonable saturation magnetization, and high magnetocrystalline anisotropy. These properties make it a promising candidate for many applications, namely, magnetic data storage, magnetic drug targeting, biosensors, and magnetic refrigeration [4–7]. Nanoferrites are simultaneously good magnetic and dielectric materials. These properties of the ferrites are governed by the choice of the cations and their distribution between tetrahedral and octahedral sites of the spinel lattice. The properties of the nanoferrites are also affected by the preparation conditions, chemical composition, sintering temperature, doping additives, and the method of preparation [8]. Several chemical and physical methods such as spray pyrolysis, sol-gel, coprecipitation, combustion technique, high energy milling, and so forth have been used for the fabrication of stoichiometric and chemically pure nanoferrite materials [9]. Among the available synthesis methods, sol-gel method has attracted much attention due to its inherent advantages of low processing temperature and homogenous reactant distribution. The products obtained by this method exhibit high crystalline quality, narrow size distribution, and uniform shape [10]. The substitution of rare-earth ions into the
Effect of Sintering Temperature and Zinc Content on Some Properties of Li-Zn Ferrites
AMEl-Saird SBHanna,

材料科学技术学报 , 1996,
Abstract: Li-Zn mixed ferrites with composition formula ZnxLi0.5-x/2Fe2.5-x/2O4 (0.2≤x≤0.8) were prepared by the usual ceramic method in 1000~1150℃. The effects of Zn substitution and sintering temperature on the formation, densification, microstructure and a.c. electrical conductivity have been studied. Under the effect of changing the firing temperature and Zn content, high sintered Li-Zn ferrite bodies are achieved. More fine structure bodies having high electrical resistance are obtained at high Zn content
Structural and Magnetic Properties of Cr3+ Doped Mg Ferrites  [PDF]
Faizun Nesa, A. K. M. Zakaria, M. A. Saeed Khan, S. M. Yunus, A. K. Das, S.-G. Eriksson, M. N. I. Khan, M. A. Hakim
World Journal of Condensed Matter Physics (WJCMP) , 2012, DOI: 10.4236/wjcmp.2012.21005
Abstract: The polycrystalline MgCrxFe2-xO4 ferrites (0.0 ? x ? 1.0) were prepared by conventional solid state ceramic sintering technique in air at 1300?C. X-ray diffraction experiments were carried out on all the samples in order to characterize the materials at room temperature. The X-ray diffraction patterns showed sharp peaks indicating the formation of single phased cubic spinel structure. The lattice parameters of the samples were determined from the X-ray diffraction data using Nelson-Riley extrapolation method. It was found that the lattice parameter decreased with increasing Cr concen- tration obeying Vegard’s law. Magnetic properties of the samples were measured using an Impedance Analyzer. Real and imaginary parts of the complex permeability, loss factor and quality factor were measured as the function of frequency at three different sintering temperatures 1250?C, 1300?C and 1350?C for all the samples in the frequency range 1 kHz to 13 MHz. Frequency stability of the real part of permeability increases with increasing Cr concentration and also with sintering temperature. Imaginary part of permeability decreases with increasing frequency and increased with increasing both of the Cr content and sintering temperature. Loss factor decreased with increasing frequency while the quality factor (Q) increased with increasing frequency for all the samples. The temperature de- pendence of initial permeability was measured for all the samples sintered at 1300?C. The Curie temperature (Tc) was determined from the -T curves. The values of Tc were found to be 733 K, 657 K, 583 K, 468 K, 400 K and 317 K for x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0, respectively.
Effect of Sintering Time on the Structural, Magnetic and Electrical Transport Properties of Mg0.35Cu0.20Zn0.45Fe1.94O4 Ferrites  [PDF]
M. Aliuzzaman, M. Manjurul Haque, M. Jannatul Ferdous, S. Manjura Hoque, M. Abdul Hakim
World Journal of Condensed Matter Physics (WJCMP) , 2014, DOI: 10.4236/wjcmp.2014.41003
Abstract:

Spinel-type Mg0.35Cu0.20Zn0.45Fe1.94O4 ferrites were synthesized by using the solid-state reaction technique. The XRD patterns of the sintered samples indicated the formation of single-phase cubic spinel structure. The apparent density of the sample is found to increase whereas porosity decreases with the increase in sintering time. The grain growth of the samples is enhanced with the increase in sintering time which is attributed to the liquid phase due to CuO during sintering. The initial permeability of the ferrite is found to increase with the increase in sintering time but the resonance frequency shifts towards the lower frequency. This increase in permeability is correlated to the increase of density and the grain size of the sample. The resistivity of the samples decreases with 103/T ensuring the semiconducting nature of the samples. Room temperature DC resistivity and activation energy of the samples decrease what is attributed to the increased Fe2+ ions content with the increase in sintering time. The dielectric constant (e) of the samples decreases with increasing frequency whereas e

Characterization and Electromagnetic Studies on NiZn and NiCuZn Ferrites Prepared by Microwave Sintering Technique  [PDF]
Matli Penchal Reddy, Il Gon Kim, Dong Sun Yoo, Wuppati Madhuri, Nagireddy R. Reddy, Kota Venkata Siva Kumar, Rajuru R. Reddy
Materials Sciences and Applications (MSA) , 2012, DOI: 10.4236/msa.2012.39091
Abstract: The low-temperature sintered NiZn and NiCuZn ferrites with the composition of Ni0.40Zn0.60Fe2O4 and Ni0.35Cu0.05Zn0.60 Fe2O4 were respectively synthesized by the microwave sintering method. These powders were calcined, compacted and sintered at 950℃ for 30 min. X-ray diffraction (XRD) patterns of the samples indicate the formation of single-phase cubic spinel structure. The grain size was estimated from SEM images which increase with CuO addition. The X-ray density is higher than the bulk density in both the ferrites. The temperature variation of the initial permeability of these samples was carried out from 30℃ to 250℃. The NiCuZn ferrite had higher initial permeability than that of the NiZn ferrite, which could be attributed to the microstructure. Saturation magnetization increases from 40 emug/g (NiZn) to 47 emug/g (NiCuZn). The dielectric constant and dielectric loss tangent of NiZn and NiCuZn ferrite samples decreases with increase in frequency exhibiting normal ferrimagnetic behavior. The NiCuZn ferrite had better electro- magnetic properties than the NiZn ferrite.
High temperature structural and magnetic properties of cobalt nanowires  [PDF]
Kahina Ait Atmane,Fatih Zighem,Yaghoub Soumare,Mona Ibrahim,Rym Boubekri,Thomas Maurer,Jérémie Margueritat,Jean-Yves Piquemal,Frédéric Ott,Grégory Chaboussant,Frédéric Schoenstein,Noureddine Jouini,Guillaume Viau
Physics , 2012, DOI: 10.1016/j.jssc.2012.08.009
Abstract: We present in this paper the structural and magnetic properties of high aspect ratio Co nanoparticles (~10) at high temperatures (up to 623 K) using in situ X ray diffraction (XRD) and SQUID characterizations. We show that the anisotropic shapes, the structural and texture properties are preserved up to 500 K. The coercivity can be modelled by u0Hc=2(Kmc+Kshape)/Ms with Kmc the magnetocrystalline anisotropy constant, Kshape the shape anisotropy constant and Ms the saturation magnetization. Hc decreases linearly when the temperature is increased due to the loss of the Co magnetocrystalline anisotropy contribution. At 500K, 50% of the room temperature coercivity is preserved corresponding to the shape anisotropy contribution only. We show that the coercivity drop is reversible in the range 300 - 500 K in good agreement with the absence of particle alteration. Above 525 K, the magnetic properties are irreversibly altered either by sintering or by oxidation.
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