B位取代钛酸铋钠基压电陶瓷的结构与性能

采用传统固相反应制备出了0.80Na0.5Bi0.5TiO3-0.20K0.5Bi0.5TiO3(NKBT)基无铅压电陶瓷材料,研究了高化合价离子(Sb5+, Nb5+,W6+) B位掺杂对NKBT基无铅压电陶瓷结构与性能的影响.结果表明,掺杂等量Sb3+、Nb5+和W6+后,NKBT基陶瓷的主晶相仍然为钙钛矿相结构,其中掺杂Sb5+和Nb5+时,陶瓷中分别出现少量Sb6O13和Nb2O5相.掺杂离子的相对原子质量越大,陶瓷的压电常数d33越大.W6+为最优掺杂离子.不同W6+含量的NKBT陶瓷的主晶相均为钙钛矿相,当W6+摩尔分数为8%时,出现焦绿石相Bi14W2O27.W6+的固然极限为4%.随着W6+摩尔分数的增加,材料的介电常数εr、d33及居里温度TC减小,介电损耗tan δ增加.当W6+的摩尔分数为1%时,陶瓷的性能达到最佳,其d33、εr、tan δ、TC分别为123 pC/N,1 352、0.042 9,318 ℃.

Effects of B-site Substitution on Microstructure and Piezoelectric Properties of (NaK)0.5Bi0.5TiO3-based Ceramics

The lead-free piezoelectric 0.80Na0.5Bi0.5TiO3-0.20K0.5Bi0.5TiO3 (NKBT) ceramics were synthesized by the conventional solid state reaction method. The effect of high valence ions (Sb5+, Nb5+, W6+) B-site substitution on the microstructure and piezoelectric properties of NKBT-based ceramics has been investigated. The results showed that the main phase of NKBT-based ceramics was still the perovskite phase. With Sb3+and Nb5+ doping, there were a small amount of the cubic phase of Sb6O13 and monoclinic phase Nb2O5 which coexisted with the perovskite phase in the samples respectively. The doping ions with larger atomic weight could make the ceramics obtain higher piezoelectric constant of d33. The W6+ was the optimal doping ion. The main phase of NKBT-based ceramics with different content of W6+ was the perovskite phase. However, when the content of W6+ reached to 8mol%, the pyrochlore phase of Bi14W2O27 appeared. The solubility limit of W6+existed at 4mol% of W6+ content. The dielectric constant (ε), the piezoelectric constant (d33) and the Curie temperature (TC) decreased and the dielectric loss increased with the content of W6+ increasing. When the mole fraction of W6+ was 1mol%, the properties of the NKBT-based ceramic were optimal, in which d33, εr , tan δ and TC were 123 pC/N, 1 352, 0.042 9 and 318 ℃ respectively.