稀土掺杂(K0.5Na0.5)NbO3基压电陶瓷的电可调荧光发射和光-电作用机理

Rare-earth doped lead-free piezoelectrics with the dual modes of luminescence and piezoelectricity have potential applications in new multifunctional luminescence and piezoelectricity integration devices by directly integrating or coupling their multiple functions. However, low luminous efficiency and piezoelectric property make it difficult to satisfy high performance requirements of new opto-electrical integration devices; the inherent correlation between piezoelectricity and luminescence is still unclear, then the effective control cannot be done. For this purpose, this application will study the rare-earth doped (K0.5Na0.5)NbO3-based piezoceramics. Through precisely tailoring the composition and process, the composition-controlled structure phase transitions would be achieved, and then new opto-electrical multifunctional materials with both the excellent piezoelectricity and luminescence would be obtained, and energy level transitions of 4f5d shell electrons of rare-earth elements, their relationships with structure phase transitions and energy transfer mechanism among different ions are clarified; meanwhile,the luminescent probe role of rare-earth ions is used to investigate the phase transition behaviors of KNN-based system at morphotropic phase boundary (MPB) or polymorphic phase transitions (PPT) under in situ applied electric fields. The influence of different types of structural phase transitions on luminescent properties would be determined, the inherent relationships between piezoelectricity and luminescence would be disclosed, and the external field-controlled emitting model would be estiblished, which would provide the foundation for the practical direction of KNN-based multifunctional materials.

稀土掺杂无铅压电材料兼有发光和压电的双重特性，利用其可直接集成或耦合的多功能特性，在新型多功能集成发光-铁电压电器件领域具有良好的应用前景。然而，低的发光效率和压电性能，难以满足光-电集成器件的高性能要求；压电-发光之间的内在关联尚不清楚，难以实现光-电之间的有效调控。为此，本项目以稀土掺杂(K0.5Na0.5)NbO3基压电陶瓷为研究对象，精确控制材料组分和工艺，实现对材料结构相变的调控，获得发光和压电性能俱佳的新型光-电多功能材料，阐明稀土元素4f5d壳层电子在KNN基体中的跃迁规律、与结构相变的关系及不同离子间的能量传递机理；同时利用稀土离子的荧光探针作用探讨原位电场作用下材料在准同型相界（MPB）或多型相变（PPT）区域内的相变行为，确立不同类型的相转变对发光性能影响的一般规律，揭示压电-发光性能之间的内在关联，建立电场可控的荧光发射模型，为此类光-电多功能材料的实用化奠定基础。

稀土掺杂的无铅压电材料具有优越的发光和铁电压电特性，使其在新型多功能集成发光-铁电压电器件领域具有良好的应用前景。系统探究稀土离子在铁电压电材料中的作用，对材料的发光和压电性能的影响规律是十分必要的。在项目实施的过程中，我们采用各种稀土离子，以单掺/共掺的方式引入到KNN基体中，通过控制材料组分和工艺，获得发光和压电性能俱佳的新型光-电多功能材料，揭示了KNN材料内部组分-结构-性能之间的关联。结果表明在外界光源的激励作用下，稀土离子的能级跃迁几率显著降低，表现出显著的荧光淬灭现象，荧光淬灭的程度达到90%以上，同时材料的极化强度明显降低。通过电流-电压的性能测试，揭示了稀土离子中的电子与KNN材料内部缺陷之间的能量转移机理，相关的研究结果发表在国际主流期刊上Journal of Materials Chemistry C等14篇，申请国家发明专利2项。