Neutron difraction investigation of the F_RL−F_RH transition in Nb doped PbZr_1−xTI_xO₃ with x=0.035

Abstract

Neutron powder diffraction data have been collected in order to characterize the F_RL-F_RH transition of Nb-doped, Zr-rich PZT. Data for the first few diffraction peaks were obtained in the temperature range 270<T<350 K in order to make a detailed characterization of the F_RL-F_RH transition, which takes place for this composition at T_LT≅323 K. The temperature dependence of the Pb and Zr/Ti(Nb) atomic shifts, and the rotation and distortion of the oxygen octahedra through the transition was derived. The results are compared with published data for PZT with x=0.10, and indicate that (a) the change in Zr/Ti(Nb) shift through T_LH becomes more pronounced, and (b) the distortion and tilt of the oxygen octahedra below T_LH become more important for x=0.035 than for x=0.10. It has been concluded that the increment in the variation of the spontaneous polarization through T_LH with increasing Zr amount is mainly caused by the increase of the Zr/Ti(Nb) displacement in the low temperature rhombohedral phase.