Structural analysis and cations distribution of nanocrystalline Ni1-xZnxFe1.7Ga0.3O4

Abstract

Nanostructured Ni1-xZnxFe1.7Ga0.3O4, with x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5 were prepared by citrate method and were investigated using X-ray diffraction and Mossbauer spectroscopy. The structure characterized using X-ray powder diffraction and Rietveld method showed that upon increasing Zn2+ content, the lattice parameter gradually increases from a = 8.3493 to 8.390 angstrom and also the crystallite size increases from 4 to 8 nm for x = 0.0 and x = 0.5 respectively. Furthermore, the Mossbauer spectra, measured at 20 K showing spinel magnetic ordering in all the samples, whereas at room temperature, are superposition of collapsing broadened sextet and doublet because of the dependency of particle size. The cation distribution was estimated from the analysis of the Mossbauer spectra as well as Bertaut method, and then confirmed by Rietveld analysis. The results showed that both Zn and Ga ions exclusively occupy the A-site while Ni and Fe ions are distributed over the A- and B-sites.