钽酸镓镧压电晶体高温电阻率的掺杂改性研究

The low resistivity of traditional LGT crystal at high temperature is the main bottleneck of its application in ultra-high temperature piezoelectric devices. In the early research work, the new Mo:LGT crystals have been grown and its resistivity at 500℃ than traditional LGT crystal is increased by 2 orders of magnitude. The new Mo:LGT crystal is successful application of the high temperature acceleration sensor for the first time. However, its resistivity at higher temperatures remained low, resulting in that the material cann’t be applied to the higher temperature environment. This project intends to use the hole-electronic compensation mechanism to grow series of new R:LGT (R = Al、Er、Yb、Mo and Nb) piezoelectric crystals by Czochralaski method. By the study of the dependence of the structural factors of R doping ions such as valence,ionic radius, electronegative and its concentration on the performance of the high-temperature resistivity, the carrier concentration and the mobility of the R:LGT crystals, the high-temperature conduction mechanism of the new R:LGT crystals was then revealed. It can provide 3 inch new R:LGT crystal material and theoretical basis for the ultrahigh temperature piezoelectric device applications at 800℃.

传统LGT晶体高温电阻率偏低是其难以应用于超高温压电器件的主要瓶颈。申请人在前期预研工作中采用熔体提拉法生长出新型Mo:LGT晶体，初步结果表明其500℃的电阻率比传统LGT晶体提高了2个数量级，并在高温加速度传感器中首次获得成功应用。但在超过600℃环境时，Mo:LGT晶体电阻率仍然偏低，极大地限制了其在更高温度环境的实际应用。基于电荷补偿调控机制，本项目拟设计Al3+、Er3+、Yb3+补偿离子以及Mo5+、Nb5+施主离子掺杂传统LGT晶体，并采用熔体提拉法生长出这类掺杂型R:LGT（R= Al、Er、Yb、Mo和Nb）压电晶体。通过系统研究掺杂离子、掺杂量以及生长气氛等因素对R:LGT压电晶体的高温电阻率、载流子浓度及迁移率的影响规律，重点揭示R:LGT压电晶体的高温导电机理，为最终稳定获得3英寸可应用于800℃超高温环境的掺杂型高电阻率R:LGT压电晶体产品及其相关超高温压电器件

高温压电晶体作为压电晶体材料的一个重要分支，可应用于发动机和舰载燃轮机的监测、油田探井、蒸镀和溅射系统的膜厚控制等航空航天高技术领域及国防国民经济的各部门中，因此，发展性能优异的高温压电晶体一直是压电材料重要的研究方向和热点。本项目通过选择性掺杂提高LGT晶体高温电阻率，揭示了LGT类晶体的高温导电机理，发现通过Al3+离子和Mo5+离子掺杂可降低晶体中氧空位浓度及其迁移率，从而实现晶体的高温电阻率提高一个量级以上；同时结合一致熔融组分的控制技术，实现晶体性能的均匀一致性，基于此晶体研制的高温压电加速度传感器最高使用温度达到704oC，达到国际水平。在此基础上，指导生长性能更优异、电阻率更高的新型BTS、CTAGS和CNAGS，获得了853.2ºC时电阻率保持在1.10×107Ω·cm的新型高温压电晶体，这为研制使用温度超过900ºC的超高温压电加速度传感器提供了保障。因此，本项目研究不仅具有很好的学术价值和创新性，而且研究成果有明确的应用前景。