LAUSR

Abstract The temperature dependence of the structure of a polycrystalline sample of AgTaO3 has been determined using in-situ Synchrotron X-ray powder diffraction methods. This work finds no evidence for the presence of a monoclinic phase, rather three phase transitions have been identified, namely R 3 c ↔ 390 ° C Cmcm ↔ 465 ° C P 4 / mbm ↔ 580 ° C Pm 3 m . The rhombohedral phase was further studied at room temperature by neutron powder diffraction. The co-existence of the rhombohedral and orthorhombic phases around 380–400 ° C indicates that the transition between these is first order, and gives rise to unusual peak shapes in the diffraction patterns.