Mössbauer effect study of Li21+Me4+Fe63+O122−spinels

Abstract

Mossbauer effect spectra are obtained for the cubic ferrites Li2 Me Fe6 O12 (where Me4+ is one of the tetravalent elements Ge, Si and Ti) at 78K up to their magnetic transition temperatures. In a rather large temperature range they clearly are a broadened six lines pattern. Each spectrum is successfully analysed to two sets of magnetic hyperfine splitting Zeeman patterns with isomer shifts corresponding to ferric ions in both tetrahedral and octahedral sites. The tendency of the present non-magnetic elements to occupy the octahedral site led to an antiparallel Neel spin structure. Debye and Neel temperatures of these substituted lithium ferrites are determined and their hyperfine parameters are discussed.