OPTIMUM FIRING TEMPERATURES FOR FABRICATION OF SOFT FERROMAGNETIC Ni0.475Zn0.475Li0.025Al0.025Fe2O4 CERAMICS VIA THE SOLID-STATE COMBUSTION TECHNIQUE

The optimum conditions for fabricating Ni0.475Zn0.475Li0.025Al0.025Fe2O4 (NZLAF) ceramics prepared by the solid-state combustion technique with glycine as fuel were investigated. The NZLAF samples were calcined and sintered in the temperature range of 850-1,050°C (in 50°C increments) for 2 h and 1,150-1,350°C (in 50°C increments) for 4 h, respectively. A pure cubic spinel phase was obtained in the NZLAF powders calcined above 900°C for 2 h, as well as in all of the NZLAF ceramics. Rietveld refinement analysis indicated that the lattice parameter a of the NZLAF ceramics decreased from 8.3803 to 8.3663 Å when the sintering temperature increased from 1,150 to 1,300°C, then increased. The grain morphology of the NZLAF ceramics exhibited a polygonal grain shape, and the average grain size increased with increasing sintering temperatures. The NZLAF ceramic produced with the optimum firing condition (1,300°C for 4 h) showed good crystalline and morphology, the highest density (5.31 g/cm3), the highest dielectric constant at 1 kHz (e ~ 130,987) and good ferromagnetic properties (Ms ~ 82.40 emu/g, Mr ~ 0.05 emu/g, and Hc ~ 3.65 Oe).