铬掺杂对PZT-PMN陶瓷材料性能的影响

采用ＴＥＭ、ＳＥＭ、ＥＳＲ（电子自旋共振）结合常规压电性能测试手段研究了Ｃｒ_２Ｏ_３掺杂对ＰＺＴ－ＰＭＮ陶瓷的压电性能、微结构及畴态的影响．压电性能测试结果表明，当Ｃｒ_２Ｏ_３含量低于０．０６Ｗｔ％时，可使Ｋ_ｐ和Ｑ_ｍ同时提高，这说明铬掺杂同时兼具“软掺杂”与“硬掺杂”的双重特性．此外，还发现随着烧结温度的提高，材料性能“硬化”明显．ＥＳＲ谱分析表明，Ｃｒ离子主要以Ｃｒ^３＋和 Ｃｒ^５＋的方式共存，随着烧结温度的提高，它有从高价态 Ｃｒ^５＋或Ｃｒ^６＋向低价态转变的趋势，这一价态变化被认为是材料性能随烧结温度提高而“变硬”的主要原因之一．ＴＥＭ图片显示，随着掺杂的Ｃｒ_２Ｏ_３的浓度的增大，由于氧空位或受主离子与氧空位构成的缺陷复合体对畴壁的钉扎，电畴将从正规带状畴向波纹状畴转变．

Effects of Cr_2O_3 Addition on the Properties of PZT-PMN Ceramics

The effects of Cr2O3 addition on piezoelectric properties，microstructure and morphology of the domain of PZT-PMN ceramics were studied by TEM,SEM,ESR and other conventional electrical methods. The measurement results of piezoelectric properties showed that the Cr2O3 addition was effective in increasing the Kp and Qm when its concentration was below 0.06wt%,which indicated that Cr-doped PZTMN ceramics possessed the properties of “soft” and and“hard” piezoelectrics simultaneously. Furthermore,the properties were found to get “hard” with the increase of sintering temperature even for the ceramics with the same compositions. Electron Spin Resonance (ESR) analysis showed that Cr ion coexisted in both Cr3+ and Cr5+,and the valence change from Cr5+ or Cr6+ to Cr3+ happened when the sintering temperature was increased,which was believed to be one of the reasons for its hardness of the properties. TEM images revealed that,with the increment in Cr content,the normal stripe-like domain changed to wavy domain due to the domain pinning by the defect complexes of acceptor impurities and oxygen vacancies.