Effect of Impurities Pinning on the Domains of PSTZT Ceramics

(1-x)Pb(Sc_0.5Ta_0.5)O₃-xPb(Zr_0.52Ti_0.48)O₃ (PSTZT-100x) ceramics were prepared by using conventional oxide processing, and their piezoelectric and ferroelectric properties studied. The results of X-ray diffraction (XRD) suggest that PSTZT-100x ceramics formed a single-phase perovskite structure when 0.1=x=0.8. The ceramics exhibit relatively good piezoelectric and ferroelectric properties: piezoelectric constant, d₃₃=117 pC/N; planar electromechanical coupling factor, k_p=45%, remnant polarization, P_r=14 muC/cm², coercive field, E_c=0.65 kV/mm. When x>0.70, the polarization-field hysteresis curves of PSTZT ceramics show "pinched" shapes instead of the normal square-like P-E loops when tested at room temperature and different frequency. In the meantime, the coercive field, polarization and internal bias field of PSTZT ceramics are strongly dependent on frequency or temperature. A defect pinning may induces the unsaturated hysteresis loop of PSTZT ceramics.