Abstract
Compounds in the double perovskites series Ba 2 LnSn x Sb 1− x O 6− δ ( Ln=Pr and Tb) have been synthesised and structurally characterised using synchrotron X-ray and neutron powder diffraction. It was found that the two end-members of the Ba 2PrSn x Sb 1− x O 6− δ series both adopt rhombohedral symmetry but the antimonate is a fully ordered double perovskite while the stannate has no B-site cation ordering. X-ray absorption near-edge structure (XANES) and near-infrared spectroscopy indicate that the Pr cations gradually change oxidation state from Pr 3+ to Pr 4+ with increasing x and that this is likely to be the cause of the loss of B-site ordering. Similarly, both Ba 2TbSbO 6 and Ba 2TbSnO 6− δ are cubic with B-site ordering present in the former but absent in the latter due to the oxidation state change of the Tb from Tb 3+ to Tb 4+. Multiple linear regression analysis of the Pr and Tb L III-edge XANES indicates that the rate of Ln 3+ transforming to Ln 4+ is such that there are no oxygen vacancies in Ba 2PrSn x Sb 1− x O 6− δ but in Ba 2TbSn x Sb 1− x O 6− δ there is a small amount of oxygen vacancies, with a maximum of δ≈0.05 present.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
