Structural and vibrational studies of NiAlxFe2−xO4 ferrites (0≤x≤1)

Nickel–Aluminium ferrites with the general formula NiAlxFe2−xO4 (0≤x≤1) were synthesized using the solid-state reaction technique and characterized using X-ray diffraction, FT-Infra Red and Raman spectroscopy. XRD diffraction patterns show that all samples have a pure single-phase cubic spinel structure over the whole composition range. From these patterns, the lattice parameter, bonds length, crystallite size, density and porosity have been calculated. Infra Red spectra showed two significant absorption bands, the high band corresponds to tetrahedral (A) sites and the lower band to octahedral [B] sites, thus confirming the single phase spinel structure. The force constants Kt and Ko for the two sites have been deduced from IR band frequencies and compared with the trend of bond lengths. For all compositions, Raman spectra show the five active modes A1g+E1g+3 T2g of the motion of O2− ions and both the A-site and B-site ions. The Raman frequencies trend with aluminium content show a blue shift for all modes consistent with the replacement of Fe3+ by lower mass Al3+.