Behaviour of polyhedra in Sr2NiMoO6 at high pressure and temperature

Abstract

The high-pressure behaviour of Sr2NiMoO6 has been measured up to ∼6 ​GPa using neutron powder diffraction. With increasing pressure the tetragonal (I4/m) symmetry is maintained and the structure becomes more distorted. The distortion is a result of increased octahedral tilting away from the idealised cubic symmetry by rotation around the c-axis in the ab plane. The pressure equation of state has been determined and gives values of V0 ​= ​243.10(2) Å3, B0 ​= ​155(2) GPa and B’ ​= ​3.1(6). We also report the high temperature behaviour at ambient pressure and observe a transition from tetragonal to cubic symmetry at ∼ 573 ​K.