Cation distribution in Ni-substituted Mn_(0.5)Zn_(0.5)Fe_2O_4 nanoparticles: A Raman, Moessbauer, X-ray diffraction and electron spectroscopy study

摘要

In this paper we report the structural, vibration, and electronic-structure parameters (bonding and valence of cations) of single phase cubic mixed spinel nanoparticles of (Zn_δMn_γFe_(1-(γ+δ))[Ni_xZn_(0.5-δ)Mn_(0.5-γ-x)Fe_(1+(γ+δ))]O_4 where x=0.05-0.45 with an aim to determine cation-distribution i.e. δ and γ in these samples. The Raman spectroscopy has established that only Fe and Zn cations occupy tetrahedral interstitial sites in a FCC anion lattice in nearly equal fraction, and Moessbauer spectra have shown that Fe~(3+) cations are present at both, tetrahedral and octahedral interstitial sites and Ni~(2+) cations are situated at the octahedral sites in all the substituted samples. The photoelectron spectra also revealed the presence of Fe~(3+) cations at both the interstitial sites. The best possible cationic distribution in Ni substituted Mn-Zn ferrites has been estimated by reiteratively calculating the intensity ratios of various pairs of X-ray diffraction peaks and matching with the observed intensity ratios.