Investigation of the effect of sintering temperatures on the structural and magnetic properties of (Bi0.90Sm0.10Fe0.93Cr 0.07O3) ferrite

Rare earth samarium (Sm) and transition metal chromium (Cr) doped bismuth ferrites (Bi0.90Sm0.10Fe0.93Cr 0.07O3) are successfully fabricated using a solid state reaction method at various sintering temperatures (Ts). The distorted rhombohedral structure was confirmed by X-ray diffraction with R3c space group for 800 and 850 degrees C sintered compositions with some impurity peaks. The distorted rhombohedral phase changes slightly in the pseudo-cubic phase at 900 degrees C Ts with a nominal reduction in the percentage of some secondary phases. The average crystallite size of compositions is decreased from 71 to 23 nm and lattice strain is increased from 0.108 to 0.313% with increasing Ts. The value of the Gold-Schmidt tolerance factor is 0.84 which indicates the stabilized form of the ferrites. Field Emission Scanning Electron Microscopy images reveal the surface morphology of the compositions, and it is found that the grain size increases from 0.868 to 1.29 mu m with increasing Ts. Increasing trends and a long range of frequency stable permeability suggest these compositions to use in high frequency devices. In magnetic hysteresis loops, the exchange bias effect in the negative axis direction is observed that is gradually increased with Ts. Saturation magnetization is increased from 1.780 to 1.975 emu/g following the increment trend of Bhor magnetic moment from 0.256 to 0.320 mu B. The squareness ratio suggests the formation of a multidomain structure in the polycrystalline ferrites.