Investigation of Structural, Magnetic and Electrical Properties of Chromium Substituted Nickel Ceramic Nanopowders

Nano-ceramic of NiCrxFe2-xO4 (0.1 ≤ x ≤ 1.0) ferrites were synthesized by citrate-gel auto combustion method. The structural parameter such as lattice parameter, X-ray density, bulk density and porosity variations with Cr doping were studied. The average crystallite size is in the range 8.5–10.5 nm. The surface morphology and elemental analysis was studied with SEM (EDAX) spectrum and the structural information analyzed with FTIR spectra. Magnetic properties were discussed with Cr3+ion concentration. Electrical parameters like dc resistivity and drift mobility were reported with function of temperature and dopent concentration from room temperature to well beyond Curie temperature and explained with hopping mechanism between Fe2+↔Fe3+ ions. The activation energies in ferri and para magnetic regions were investigated. Dielectric parameters like dielectric constant, dielectric loss and ac conductivity were investigated variation with frequency and composition

Effect of low oxygen pressure on structural and magnetic properties of quenched SrFe12O19 thin films

Strontium hexaferrite thin films have been grown on glass substrates at room temperature in oxygen environment by pulsed laser deposition method. The effect of oxygen pressure (p(o2)) on the structural and magnetic properties has been investigated. The as-deposited films were found to be amorphous in nature. The crystallization of these films was achieved by annealing at a temperature of 850 A degrees C in air. The thickness of the film increased with p(o2). The film grown at p(o2) = 0.455 Pa had a clear hexagonal structure. The values of coercivity for the films were found to increase with p(o2)

Structural, Magnetic, and Electrical Properties of Microwave-Sintered Cr3+-Doped Sr Hexaferrites

SrCrxFe12-xO19 (x = 0.0, 0.1, 0.3, 0.5, 0.7, 0.9) hexaferrites were prepared by a microwave-hydrothermal method and subsequently sintered at 950 degrees C for 90 min using the microwave sintering method. The results show that, with increasing Cr3+ content, the lattice parameters changed anisotropically. The average grain sizes of sintered samples were in the range of 280 nm to 660 nm. The saturation magnetization systematically decreased with increasing Cr3+ doping, but the coercivity values increased. The electrical resistivity (log rho) decreased linearly with increasing temperature up to a certain temperature known as the transition temperature (T-c), and T-c decreased with further increase (x>0.5) of the Cr3+ content. This decrease in log rho and the activation energy (E-g) is due to electron hopping and occupancy of doped ions at different lattice sites. We found that the dielectric constant and dielectric loss for all the samples decreased with the Cr3+ content. The structural, magnetic, and electrical properties of Cr3+-doped SrFe12O19 hexaferrites have thus been investigated

Synthesis and Characterization of Cu–Mn Substituted SrFe12O19 Hexaferrites

In this study, bimetallic (Cu-Mn) substituted SrFe12O19 hexaferrites [Sr1-2xMnxCuxFe12O19 (0.0 <= x <= 0.1)] were synthesized via sol-gel auto-combustion approach. The effect of bimetallic substitution on structure, morphology and magnetism of SrFe12O19 was investigated. SEM images divulge the nano-size of the prepared products with speck morphology. X-ray powder diffraction analysis affirmed their complete conversion to SrFe12O19 hexagonal crystal phase. The results from Fe-57 Mossbauer suggested that all five important sextets of Sr1-2xMnxCuxFe12O19 hexaferrites effected due to the substitution of Cu and Mn ions. Cation distribution calculation showed that as the percentage of Mn and Cu increased in Sr1-2xMnxCuxFe12O19 (0.0 <= x <= 0.1), particularly for x = 0.03 the relative area of 12k and 4f(2) site increased. This indicates that Fe ions are migrated towards 12k and 4f(2) octahedral site

Electrical and Dielectric Properties of Y3+-Substituted Barium Hexaferrites

In this study, Y3+ ion-substituted M-type barium hexaferrites (BaM; BaFe12O19) were fabricated via facile ceramic route. As-prepared powders were characterized by X-ray powder diffractometry (XRD), Fourier transform infrared (FT-IR) spectroscopy, and impedance spectroscopy. XRD (Rietveld) analyses confirmed the presence of a single characterization of all samples (except x = 0.0 and 0.1 samples). The crystallite sizes of products are found in the range of 47.2-63.2 nm. Spectral analysis (FT-IR) also presented the formation of spinel structure for all products. The ac conductivity of the substituted samples was found to initially decrease slightly with increase in Y3+ compared with unsubstituted, and then variation tendency changes at the medium substitution ranges are observed with a different attitude against temperature. In the end, the lower conductivity for high substitutions is recorded and increases as functions of frequency while it also increases with the elevation of temperature. It was observed that ac conductivities of products increased by increasing frequency which indicate that observed ac conductivity is due to both electronic and polaron hopping mechanism