Effect of sintering on X‐Ray and IR spectral behaviour of the MnAlxFe2‐xO4 ferrite system

Two series of the samples of the ferrite system MnAl x Fe 2-x O 4 were prepared using the usual ceramic technique and sintered at 1200 and 1350 °C for 6 h, respectively. X-ray and IR spectral analyses for the two series were studied. The true lattice parameters were calculated for the two series and were found to decrease with increasing Al substitution. The bulk and X-ray densities also decreased as the Al content increased due to the reduction of oxygen vacancies and the decreasing population of Fe 3+ in octahedral sites. The density of the sample sintered at 1350 °C is higher than that sintered at 1200°C. The porosity increased with increasing Al substitution. The distance between magnetic ions in both octahedral and tetrahedral sites decreased with increasing Al. The far-infrared spectra in the range 660 to 200cm -1 are reported. Two absorption bands v 1 600cm -1 , v 2 450 cm -1 appeared in the spectra which were assigned to the tetrahedral and octahedral complexes, respectively. Another band v 3 350 cm -1 is assigned to the divalent octahedral Fe 2+ -O 2- ion complex. A small band v 4 appears at higher concentration of Al which is attributed to the Al 3+ -O 2- complex at octahedral sites.