Crystal Structure of Ferroelectric PbZr_0.9Ti_0.1O₃ Studied by X-Ray and Neutron Diffraction Profile Analysis Method

Abstract

A previously proposed model of rhombohedral PbZr_0.9Ti_0.1O₃ (low temperature form) has been confirmed and refined at room temperature. X-ray diffraction data as well as neutron diffraction data of PbZr_0.9Ti_0.1O₃ powder have been analysed by profile analysis method. The result is in general agreement with that by Glazer and Mabud, and the structural parameters are now improved considerably. Rather unrealistic temperature parameters found in the previous study are corrected. Oxygen octahedra in the perovskite type unit cell rotate alternately clockwise and anticlockwise by 5.7 degrees about the polar axis, thus a superstructure appears. Additional atomic shifts (Pb 0.49 Å, Zr/Ti 0.22 Å with respect to oxygen) make the crystal ferroelectric, and the crystal is a structural hybrid of LaAlO₃ type and of rhombohedral ferroelectric BaTiO₃ type.