X-ray absorption near edge structure and crystallographic studies of the mixed valence oxide SrRu0.8Ni0.2O3

Abstract

Neutron diffraction methods are used to refine the structure of SrRu 0.8 Ni 0.2 O 3 at room temperature and 4 K. X-ray absorption measurements at the Ru L-edge demonstrate that partial oxidation of the Ru 4+ to Ru 5+ occurs upon introducing Ni into the SrRuO 3 structure to form SrRu 0.8 Ni 0.2 O 3. Whilst the diffraction measurements show that SrRu 0.8 Ni 0.2 O 3 is isostructural with SrRuO 3, the Ni doped compound exhibits an unusual first order orthorhombic-cubic phase transition near 670 K as revealed by x-ray diffraction. The Curie temperature in SrRu 0.8 Ni 0.2 O 3 is lower than that found in SrRuO 3 as a consequence of local distortions reducing the p-d hybridization.