Effects of ZnO on the dielectric, conductive and piezoelectric properties of low-temperature-sintered PMnN-PZT based hard piezoelectric ceramics

摘要

The ZnO-doped Pb_(0.98)Ca_(0.01)Sr_(0.01)[(Mn_(1/3)Nb_(2/3))_(0.06)-(Zr_(0.52)Ti_(0.48))_(0.94)]O_3+ 0.15 wt.% CuO for varying amounts of ZnO (x wt.%) ceramics were prepared. Their structure evolutions and electrical properties were systematically investigated. A dc and ac conductivity analysis was conducted. It demonstrated that the probability of ZnO dopants entered the A and/or B-site of the perovskite structure, which affected the dielectric relaxation, activation energy, and piezoelectric properties. Experimental results showed that the tetragonality of the perovskite structure and electro-mechanical energy transformation ratio (k~2 value) were increased with increasing the ZnO contents for 0.1 <= x <= 0.5. As ZnO contents increased for 0.1 <= x <= 2, the diffused phase transition (DPT) characteristic was gradually disappeared. And, the ac activation energy calculated was also decreased due to the conduction mechanism. In addition, the frequency dependence of the ac conductivity was complied with the Jonscher power law, for x=0.5, 1, and 1.5 at measured temperature.