Synthesis, structural characterization and Mِssbauer study of LnV0.5Fe0.5O3 perovskites (Ln = Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho and Er)

Perovskites LnV0.5Fe0.5O3 (Ln = Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho and Er) were synthesized by rapid solidification from arc-melted samples and characterized by the study of their crystal structure and hyperfine properties. These metastable solid solutions crystallized in the Pbnm symmetry, with the iron and vanadium cations randomly distributed in the transition metal octahedral sites. Depending on the lanthanide present at the A site of the perovskite, iron is present with two valences (i.e., Fe3+ and Fe2+). The volume of the unit cell for these perovskites increases linearly with the lanthanide ionic radius, as the perovskite approaches its ideal structure. At room temperature, the quadrupolar splitting of the trivalent paramagnetic Mِssbauer component works as an indirect measurement for the Goldshmidt tolerance factor. Close to or below 100 K, these perovskites undergo a crystallographic phase transformation, probably due to orbital ordering of the V3+ cations, originating two different magnetic iron sites.