A high temperature neutron diffraction study of the double perovskite Ba2154SmMoO6

► 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.