AN X Ray Diffraction STUDY ON THE ULTRA-HIGH ELECT-ROMECHANICAL ANISOTROPY IN (Pb 0.85 Sm 0.10 )(Ti 0.98 Mn 0.02 )O 3 PIEZOELECTRIC CERAMICS

XRD technique was employed to examine Sm-modified PbTiO 3 piezoelectric ceramics with typical ultra-high electromechanical anisotropy. By introducing crystal plane orientation density ρ (hkl) and establishing wall translation model for 90°ferroelectric domain switching, a quantitative analysis and discussion on the domain texture change within the ceramic disks poled at various electric forces has been carried out. The results indicate that 90°domain walls in the modified PbTiO 3 ceramics show a strong spatial orientation preference, and little changes in their orientation can result from poling treatment but noticeable wall displacement appears. Another noteworthy result is that the thickness electromechanical coupling coefficient K t develops with poling field almost at the same pace as the orientation density gain △ρ(002) of the crystal plane (002).