Chiang Mai Journal of Science

Piezoelectric materials are presently being extensively developed for applications such as ultrasonic motors and piezoelectric transformers. In this study, the dielectric, piezoelectric, and ferroelectric properties of  MnO₂-doped 0.2Pb(Zn_1/3 Nb_2/3)O₃ -0.8Pb(Zr_1/2Ti_1/2)O₃ (here after 0.2PZN - 0.8PZT), which is the morphotropic phase boundary composition of  the PZN-PZT system, were investigated. It was found that crystal structure moved to rhombohedral side when increasing MnO₂  content.  With the addition of  MnO₂ , Curie temperature T_c , the piezoelectric constant d₃₃ , and electromechanical coupling factor k_p  were slightly decreased, but the mechanical quality factor Q_m  was significantly increased. The P–E  and  s-E loop demonstrated decreased P_r and strain level but increased E_c with addition of  MnO₂ These. results clearly showed the significance of  MnO₂ addition on the electrical properties of  the PZN–PZT system with ‘‘hard’’ characteristics.