The structural phase transitions in strontium zirconate revisited

The structures of SrZrO3 have been studied in fine temperature steps, from room temperature to 1230 °C, by very high resolution neutron powder diffraction. It has been concluded that SrZrO3, orthorhombic in space group Pnma at room temperature, changes by a continuous transition to a pseudo-tetragonal structure in Imma at about 750 °C, then by a discontinuous transformation to tetragonal I4/mcm at about 840 °C, and finally, continuously, to cubic at 1070 °C. The sequence of structures is rationalised by reference to a recent group theoretical analysis (Howard C J and Stokes H T 1998 Acta Crystallogr. B 54 782).