Anomalous change in electron density at nuclear sites in nanosize zinc ferrite

摘要

Nanosize samples of zinc ferrite with different particle sizes synthesized by citrate precursor route have been studied by x-ray diffraction, transmission electron microscopy and Mossbauer spectroscopy. The observations suggest that the electronic processes depend sensitively on size, and a big variation occurs in the pattern of temperature dependence of isomer shift on changing the size from 5 nm to 6 nm and from 6 nm to 7 nm. The electron density at the nuclear sites first increases, then decreases and again increases as the temperature of the nanosize samples is increased from 12 K to 400 K. The electric-field gradient varies considerably as the size is changed, but remains almost independent of temperature for a particular size. It is concluded that different aspects of hyperfine interactions in nanophase become significant at different sizes. (C) 2004 American Institute of Physics.