无籽固相生长工艺制备KNN基无铅压电单晶

KNN-based lead-free piezoelectric single crystal prepared by seed-free solid-state growth method

采用无籽固相生长技术,成功制备了低含量LiBiO_3(LB)掺杂的K_(0.5)Na_(0.5)NbO_3(KNN)单晶,并系统地研究LB的掺杂量和烧结工艺(烧结温度、保温时间)对KNN晶体生长行为的影响。研究结果表明:在较窄的烧结温度范围内,通过在KNN基陶瓷中引入微量的LB,可以从基体中成功获得大的KNN单晶颗粒;当在同一烧结温度和相同保温时间条件下,随着LB掺杂量的增加,KNN陶瓷基体的晶体异常长大的转化面积逐渐减少;当样品的成分和烧结温度相同时,延长保温时间,晶粒可以继续长大。所生长的铌酸钾钠单晶最大一维尺寸达到厘米级。掺杂量为0.45at%的KNN晶体的结构和电学性能被测试分析,结果表明:所制备的KNN晶体的综合性能高于目前大部分采用的布里奇曼法、顶部籽晶生长法、浮区法等溶液/熔体法生长的KNN晶体,具有极大的潜在应用价值。

K0.5sNa0.5sNbO3（KNN） single crystals were successfully prepared by a seed-free solidstate growth method with low content of LiBiO3 （LB） as a sintering aid. The effects of LB doping content and sintering process including the dwelling temperature and time on the growth behavior of KNN single crystal were systematically studied. The research results show that within a narrow sintering temperature range, KNN single crystal grains can be successful obtained by doping low content of LB in the ceramic matrix. Under the same sintering temperature and holding time, the crystalliza- tion area of the KNN single crystals in the ceramic matrix gradually reduces with the increasing of LB content. For the samples with the same composition and sintering temperature, prolonging the dwell- ing time can make single crystal grain to continue growing. The largest size of KNN single crystal can reach centimeter-scale. In addition, the microstructure and electrical properties of KNN-0. 45 at% LB single crystal were tested and analyzed. The comprehensive performance of KNN crystal prepared by seed-free solid-state growth method is higher than that of many KNN crystals prepared by other methods such as the solution or melt growth methods, including the Bridgman, the top-seeded solution growth, the floating zone method. This research shows that the KNN single crystal present in this paper has a great promising application in many relative devices.