X-Ray Study on Lattice Strain and Domain Switching Induced in Rhombohedral PZT by Poling and External Loading

Abstract

The X-ray diffraction method was applied to measure the change of the lattice strain and domain switching in rhombohedral lead zirconate titanate (PZT) due to poling and external straining. The lattice strain was determined from the linear relation between the diffraction angle 2θ and sin2ψ (ψ is the angle between the normals of the specimen surface and of the diffraction plane). The lattice strain measured by X-rays is at most 15% of the macrostrain determined from the dimensional change due to poling. Domain switching caused a major part of the macrostrain. External loading induced domain switching and the lattice strain. The lattice strain induced by external loading was at most 25% of the applied strain. The amount of domain switching was evaluated by the change of the intensity ratio, I222/I222, of the 222 to 222 diffraction. The intensity ratio for the normal diffraction (ψ=0°) was decreased with increasing the applied strain, because the spontaneous polarization direction, the 222 direction, turned to the loading direction. The broadening of X-ray diffraction profiles obtained from the diffraction plane perpendicular to the poling direction was the maximum, indicating the largest microstrain in the poling direction.