Phase transformation in unpoled bulk Pb(Zn1/3Nb2/3)O3-8%PbTiO3 single crystals revealed by the fracturing technique

Polished-and-annealed surfaces of bulk Pb(Zn1/3Nb2/3)O-3-PbTiO3 (PZN-PT) single crystals were covered with a deformed layer and, hence, were unsuitable for structural study by means of x-ray diffraction technique. In contrast, fractured surfaces of bulk single crystals were relatively strain-free giving rise to distinctive diffraction patterns. Using the fracturing technique and high-resolution synchrotron x-ray diffraction, the present work shows that unpoled (annealed) PZN-8%PT single crystal undergoes a (M-C)-T-C transformation upon heating under zero field condition, where T and C are the tetragonal and cubic phases, respectively. The symbol (M-C) indicates an "apparent" type-C monoclinic phase, which in fact may be a rhombohedral phase of complicated domain structures. (C) 2008 American Institute of Physics.