A high temperature neutron diffraction study of the double perovskite Ba2154SmMoO6

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.