Nanocrystalline Magnesium ferrite has been prepared by chemical co-precipitation technique. Structural characterization has been performed by X-ray diffraction. Formation of ferrites has also been studied by using FTI...Nanocrystalline Magnesium ferrite has been prepared by chemical co-precipitation technique. Structural characterization has been performed by X-ray diffraction. Formation of ferrites has also been studied by using FTIR. Frequency dependence of real and imaginary part of initial permeability has been presented for the samples sintered at different temperatures. Real part of initial permeability, increases with the increase of grain growth. The loss component repre- sented by imaginary part of initial permeability decreases with frequency up to the measured frequency of this study of 13 MHz. Curie temperatures have been determined from the temperature dependence of permeability. Curie temperatures for the samples of this composition do not vary significantly with the variation of sintering temperatures. B-H loop measurements have been carried out by B-H loop tracer. Transport property measurements haven been carried out by electrometer and impedance analyzer.展开更多
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 cera...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.展开更多
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. Th...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￠ increases as the temperature increases exhibiting normal dielectric behaviour of the magnetic semiconductor ferrite. The observed variation of electrical and dielectric properties is explained on the basis of Fe2+/Fe3+ ionic concentration as well as the electronic hopping frequency between Fe3+ and Fe2+ ions in the present ferrite sample.展开更多
文摘Nanocrystalline Magnesium ferrite has been prepared by chemical co-precipitation technique. Structural characterization has been performed by X-ray diffraction. Formation of ferrites has also been studied by using FTIR. Frequency dependence of real and imaginary part of initial permeability has been presented for the samples sintered at different temperatures. Real part of initial permeability, increases with the increase of grain growth. The loss component repre- sented by imaginary part of initial permeability decreases with frequency up to the measured frequency of this study of 13 MHz. Curie temperatures have been determined from the temperature dependence of permeability. Curie temperatures for the samples of this composition do not vary significantly with the variation of sintering temperatures. B-H loop measurements have been carried out by B-H loop tracer. Transport property measurements haven been carried out by electrometer and impedance analyzer.
文摘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.
文摘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￠ increases as the temperature increases exhibiting normal dielectric behaviour of the magnetic semiconductor ferrite. The observed variation of electrical and dielectric properties is explained on the basis of Fe2+/Fe3+ ionic concentration as well as the electronic hopping frequency between Fe3+ and Fe2+ ions in the present ferrite sample.
