铋掺杂铌镁酸铅陶瓷的制备及其有序现象研究

采用二步固相合成法制备钙钛矿相的掺铋铌镁酸铅陶瓷，利用ＸＲＤ和ＴＥＭ选区电子衍射技术对Ｂ位离子非计量有序排列结构进行了表征．研究表明，当为施主掺杂而提高Ｍｇ^２＋、Ｎｂ^５＋离子比例时，铌酸镁前驱体中逐渐出现六方Ｍｇ_４Ｎｂ_９Ｏ_６相．施主Ｂｉ^３＋离子能够有效促进有序微区长大，提高系统有序度．利用Ｘ射线衍射线宽法对ＸＲＤ慢扫描谱进行处理，求得当掺入５％Ｂｉ^３＋离子时，有序微区平均尺寸由纯ＰＭＮ的５nｍ提高到２２ｎｍ．

Fabrication and Ordering Behavior of Lead Magnesium Niobate Ceramics Doped with Bismuth Cations

The pyrochlore-free Bi_2O_3 doped lead magnesium niobate ceramics were fabricatedthrough columbite precursor method and their B-site ordering structures were characterized byXRD and SAED techniques. With the increase of the ratio between Mg~2 and Nb~5 cationcontent, hexagonal Mg_4Nb_9O_6 becomes coexisting with orthorhombic MgNb_2O_6 in the columbiteprecursor. The donor doping with Bi~3 can compensate for the space charge generated by thenonstoichiometric order and thus promotes the growth of ordering regions. Moreover, the orderingdegree of PMN can be increased pronouncedly with the increase of bismuth cation content of thespecimen. The average size of ordering microdomains estimated in PMN-0.05Bi specimen is about22nm.