Structures and crystal chemistry of the double perovskites Ba(2)LnB'O6 (Ln = lanthanide B'=Nb5+ and Ta5+), Part I - investigation of Ba(2)LnTaO(6) using synchrotron x-ray and neutron powder diffraction

Saines, PJ; Spencer, JR; Kennedy, BJ; Avdeev, M

Structures and crystal chemistry of the double perovskites Ba(2)LnB'O6 (Ln = lanthanide B'=Nb5+ and Ta5+), Part I - investigation of Ba(2)LnTaO(6) using synchrotron x-ray and neutron powder diffraction

Date

2007-11

Authors

Publisher

Elsevier

Abstract

The structure of 14 compounds in the series Ba(2)LnTaO(6) have been examined using synchrotron X-ray diffraction and found to undergo a sequence of phase transitions from I2/m monoclinic to I4/m tetragonal to Fm (3) over barm cubic symmetry with decreasing ionic radii of the lanthanides. Ba2LaTaO6 is an exception to this with variable temperature neutron diffraction being used to establish that the full series of phases adopted over the range of 15-500 K is P2(1)/n monoclinic to I2/m monoclinic to R (3) over bar rhombohedral. The chemical environments of these compounds have also been investigated and the overbonding to the lanthanide cations is due to the unusually large size for the B-site in these perovskites. © 2007, Elsevier Ltd.

Keywords

Perovskites, Phase transformations, X-ray diffraction, Neutron diffraction, Rare earths, Synchrotrons

Citation

Saines, P. J., Spencer, J. R., Kennedy, B. J., & Avdeev, M. (2007). Structures and crystal chemistry of the double perovskites Ba(2)LnB'O6 (Ln = lanthanide B'=Nb5+ and Ta5+), Part I - investigation of Ba(2)LnTaO(6) using synchrotron x-ray and neutron powder diffraction. Journal of Solid State Chemistry, 180(11), 2991-3000. doi:10.1016/j.jssc.2007.08.009