A high temperature neutron diffraction study of the double perovskite Ba2154SmMoO6

doi:10.1016/j.jssc.2012.06.030

Journal of Solid State Chemistry

Volume 196, December 2012, Pages 379-383

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Abstract

Ba₂LnMoO₆ double perovskites have been recently shown to display a wide range of interesting magnetic and structural properties; Ba₂¹⁵⁴SmMoO₆ exhibits simultaneous antiferromagnetic order and a Jahn–Teller distortion. Here we report a high temperature neutron diffraction study of Ba₂¹⁵⁴SmMoO₆ from 353 to 877 K. The results evidence a tetragonal to cubic phase transition at 423 K. Above this temperature the thermal displacement parameters of the oxygen atoms are modelled anisotropically as a result of a transverse vibration of the bridging oxygen. A smooth increase in the cell parameter a is observed with temperature for Ba₂¹⁵⁴SmMoO₆.

Graphical abstract

The high temperature crystal structure of Ba₂¹⁵⁴SmMoO₆ evidencing a transverse oxygen vibration.

Highlights

► A high temperature neutron diffraction study has been performed on an isotopically enriched sample of Ba₂¹⁵⁴SmMoO₆. ► A cubic–tetragonal phase transition occurs below 423 K. ► The thermal displacement parameters of the bridging oxygens are modelled anisotropically. ► There is a transverse vibration of the bridging oxygen.

Keywords

Double perovskite

Phase transition

Neutron diffraction