Temperature dependent lattice distortion in aerogel-produced Fe-Mo oxides

摘要

Moessbauer studies have been made to evaluate the temperature dependence of lattice distortion in two aerogel-synthesized iron-molybdenum oxides having different atomic ratios Fe:Mo=1: 1 and 2:3, but both with a β-FeMoO_4 structure. The experimentally obtained spectra discern three distinctive iron ions, _OFe~(2+), _(PT)Fe~(2+), and _(O/T)Fe~(3+). The subscripts refer to octahedral, pseudotetra-hedral, and unresolved octahedral and tetrahedral lattice sites, respectively. As anticipated, only the quadrupole splitting (QS) of both ferrous ions shows a measurable dependence on temperature. However, the remarkable sensitivity of the _(PT)Fe~(2+) QS indicates a temperature induced asymmetric lattice distortion on the pseudotetrahedral sites.