Neutron diffraction study of phase transitions in perovskite-type strontium molybdate SrMoO3

The structure of a polycrystalline sample of SrMoO3 has been investigated using powder neutron diffraction from 5 to 300K, to reveal two structural phase transitions, the first from the cubic Pm (3) over barm structure with a=3.97629(3)angstrom to a tetragonal structure in 14/mcm near 266K and the second to an orthorhombic Imma phase below 125 K. The average Mo-O distance is essentially independent of temperature. The temperature dependence of the octahedral tilting appears typical of a tricritical phase transition. (C) 2009 Elsevier Inc. All rights reserved.