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 or...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.展开更多
The polycrystalline spinel oxides NiX?Co1-X?Fe2O4 with composition x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 were prepared by conventional solid state ceramic sintering technique in air at 1300°C. X-ray diffraction exp...The polycrystalline spinel oxides NiX?Co1-X?Fe2O4 with composition x = 0.0, 0.2, 0.4, 0.6, 0.8 and 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 at room temperature in order to characterize the materials. X-ray diffraction patterns showed sharp peaks indicating the formation of single phase cubic spinel structure. The neutron diffraction experiments were performed on all samples at room temperature, with an incident monochromatic neutron beam of wavelength λ = 1.5656 Å. The experimental neutron diffraction data were analyzed using the computer program FullProf in the Reitveld method. Reitveld refinement of the neutron diffraction data reveals that the samples possess cubic symmetry corresponding to the space group F d-3m. Cation distribution between the two sublattices of the spinel structure has been found from the analysis of the neutron diffraction data. Lattice parameters, oxygen position parameters, and overall temperature factors have also been determined from the analysis of neutron diffraction data. The lattice parameter decreases and oxygen position parameter increases with increasing Ni content in the system. Sublattices and net magnetic moments have been determined from the refinement of neutron diffraction data. The magnetic structure at room temperature was found to be ferrimagnetic for all the samples.展开更多
文摘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.
文摘The polycrystalline spinel oxides NiX?Co1-X?Fe2O4 with composition x = 0.0, 0.2, 0.4, 0.6, 0.8 and 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 at room temperature in order to characterize the materials. X-ray diffraction patterns showed sharp peaks indicating the formation of single phase cubic spinel structure. The neutron diffraction experiments were performed on all samples at room temperature, with an incident monochromatic neutron beam of wavelength λ = 1.5656 Å. The experimental neutron diffraction data were analyzed using the computer program FullProf in the Reitveld method. Reitveld refinement of the neutron diffraction data reveals that the samples possess cubic symmetry corresponding to the space group F d-3m. Cation distribution between the two sublattices of the spinel structure has been found from the analysis of the neutron diffraction data. Lattice parameters, oxygen position parameters, and overall temperature factors have also been determined from the analysis of neutron diffraction data. The lattice parameter decreases and oxygen position parameter increases with increasing Ni content in the system. Sublattices and net magnetic moments have been determined from the refinement of neutron diffraction data. The magnetic structure at room temperature was found to be ferrimagnetic for all the samples.
