Structural, magnetic, and electrical properties of microwave-sintered Cr < sup > 3+ < /sup > -Doped Sr hexaferrites

Abstract

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°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 ρ) decreased linearly with increasing temperature up to a certain temperature known as the transition temperature (Tc), and Tc decreased with further increase (x > 0.5) of the Cr3+ content. This decrease in log ρ and the activation energy (Eg) 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.