The structural phase transitions in strontium zirconate revisited

The structures of SrZrO3 have been studied in fine temperature steps, from room temperature to 1230 degreesC, by very high resolution neutron powder d iffraction. It has been concluded that SrZrO3, orthorhombic in space group Pnma at room temperature, changes by a continuous transition to a pseudo-te tragonal structure in Imma at about 750 degreesC, then by a discontinuous t ransformation to tetragonal I4/mcm at about 840 degreesC, and finally, cont inuously, to cubic at 1070 degreesC. The sequence of structures is rational ised by reference to a recent group theoretical analysis.