EXAFS studies of SrSn1-xSbxO3 and BaPb1-xBixO3

Abstract

EXAFS is used to study changes in local structure which occur on doping at the B site in two related perovskite oxides, SrSn _1-x Sb _x O ₃ and BaPb _1-x Bi _x O ₃ . In the case of the stannate, data is taken at the Sr K, Sb K and Sn K edges. A combination of near-edge XAS and EXAFS measurements show that Sb dopes into the material as Sb ^V . In the case of the bismuthate, data is taken at the low-intensity Bi L _I and Pb L _II edges, with the aim of resolving controversy surrounding the interpretation of EXAFS data taken at the overlapping L _III edges. In BaBiO ₃ , two Bi–O bond lengths are observed, suggesting the presence of a charge density wave. In this material, equal proportions of these two bond lengths are present. However, as Pb is doped into the material, the proportion of oxygen bonded to Bi at the shorter of the two distances increases progressively.