氮掺杂对ABO3钙钛矿型铁电材料结构与性能的影响研究

ABO3 perovskite-type materials play a critical role in ferro/piezoelectric and photoelectric fields, in which doping modification can effectively improve their properties. Previous investigations have shown that doping modification in A-/B-site enables significant improvement of the performance of these materials, but there are still many troublesome problems to be solved. Recent investigations have indicated that O-site doping modification can not only improve ferroelectric properties significantly, but also lead to ferromagnetism in room temperature, which will greatly broaden the scope of application of perovskite-type ferroelectric materials. In this project, the method of sintering or annealing ceramics at low temperature under ammonia atmosphere will be taken to introduce N3+ ions at O-site of perovskite-type ferroelectrics , and then the variation of ferroelectric and magnetic properties after nitrogen-doping will be investigated. Meanwhile, the crystal structure after nitrogen-doping should be analyzed to explain the fundamental causes of changed ferroelectric properties. the nitrogen doping concentration threshold which resulting in ferromagnetism at room temperature will be obtained by adopting different ammonia concentration or sintering time, and domain configuration observation will be carried out to combine analysis of microcosmic level with macroscopical performance. Finally, the physical mechanism and theoretical model of the electromagnetic response for single-phase perovskite ferroelectric ceramics caused by nitrogen doping are proposed, and a new method of regulating and optimizing the material performance will be established.

ABO3钙钛矿型材料在铁电压电以及光电领域有着非常重要的地位，掺杂改性是提高这种材料性能最直接有效的方法。以往的研究表明，采用常规的A位或B位改性虽然能提高材料的性能，但还存在着许多待解决的难题。近阶段的一些研究表明，氧位改性法不但可以提高材料的铁电性能，还能引进室温铁磁性，因此深化氮掺杂钙钛矿铁电体的研究具有重要的科学意义。在本项目中，我们采取在氨气气氛中低温烧结或退火陶瓷样品的方法在氧位引入氮离子，研究单相ABO3钙钛矿型铁电陶瓷铁电性和磁性的变化，对其结构进行解析以阐明其铁电性改变的根本原因；调节通入的氨气氛浓度以确定铁磁性产生的氮掺杂浓度阈值；同时结合畴组态观察以进行微观层面上的分析。最后，提出氮掺杂引起单相钙钛矿铁电陶瓷电磁响应行为变化的物理机制和理论模型，建立调控和优化材料性能的新方法。

ABO3钙钛矿型铁电材料是当前应用最为广泛的信息功能材料，但是其光电性能还有待进一步提升，本项目拟采用A/B位掺杂的方式来调控ABO3钙钛矿型铁电陶瓷的光电性能。在本项目中利用常规固相合成技术成功制备了ABO3钙钛矿型铁电体Bi(Ni2/3Ta1/3)O3‐PbTiO3陶瓷以及稀土La掺杂的Bi(Ni2/3Ta1/3)O3-PbTiO3陶瓷。在此基础上，系统地调查了该体系的结构转变、电学性能和光伏性能，利用压电力显微镜研究了此类陶瓷的畴结构，并对其光学、电学性能和结构变化机制进行了深入的探查，揭示了ABO3钙钛矿型铁电陶瓷铁电、压电、介电性能与微观结构的内在关联及调控规律，从宏观和微观两个角度阐明了此类材料铁电性与光伏特性的内在构效关系，为ABO3钙钛矿型铁电陶瓷在光电器件中的应用提供了科学依据。