Phase transformations in poled PZN-4.5%PT single crystal revealed by combined property measurements and high-resolution diffraction technique

The phase transformation of annealed and poled 0.955Pb(Zn1/3Nb2/3)O-3-0.045PbTiO(3) (PZN-4.5%PT) single crystals has been studied by means of combined bulk property measurements (dielectric permittivity and thermal current density measurements) and microstructural characterization (polarized light microscope and high-resolution x-ray diffraction). Our results showed that upon heating under zero-field condition, poled PZN-4.5%PT undergoes a R-(R+R-NT +T+T-NT)-(T+T-NT)-C transformation sequence, where (R+R-NT) and (T+T-NT) denote that the rhombohedral and tetragonal phases present consist of a mixture of microscopic (R, T) and nanotwin (R-NT, T-NT) domains and C denotes the cubic phase. The R-NT and T-NT nanotwin domains were detected only in the temperature vicinity of the R-T transformation, possibly as a means to alleviate the transformation stress in the material. These nanotwin diffractions can be easily mistaken as monoclinic diffractions. (C) 2008 American Institute of Physics.