Structural and infra-red studies of Ni1+xPbxFe2-2xO4 system

The structural properties and IR absorption spectra of Pb4+ substituted nickel ferrites, having general formula Ni1+xPbxFe2-2xO4 (where x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5), were investigated. Samples of Ni-Pb-Fe system were prepared by the ceramic technique. X-ray analysis confirmed the single phase formation of the samples. The lattice parameter was found to increase linearly with composition (x), which is attributed to ionic size difference of the cations involved. The X-ray density was also found to increase linearly with composition (x). X-ray intensity ratio calculations show that Pb4+ occupies A and B sites, which replace Fe3+ ions and added Ni2+ ions substitute for B site iron ions. The IR spectra were analysed in the frequency range 200- 800 cm-1. The IR bands show a shift towards the lower frequency side with the addition of Pb4+ for x = 0.0-0.2, which can be attributed to an increase in lattice parameter. The bond lengths R(A) and R(B) were found to increase with composition (x). 16 refs.