格位可调的双钙钛矿结构中Er3+离子的局域晶场环境对其上转换发光的影响机理

由于Er离子的上转换发光是一种非线性过程，导致其发光效率偏低。改变Er离子的局域晶场环境是提升其上转换发光性能的重要途径之一。针对目前材料的微观结构与Er离子上转换发光之间关系缺乏规律性认识的问题，本项目以双钙钛矿基质为研究对象，利用其结构上的特点，通过改变基质的组成，有效调控Er离子在晶格中进入的格位及等价或不等价取代，从而能够采用横向和纵向对比分析Er离子在基质中所处格位的局域晶场环境(格位对称性、晶胞参数、晶场强度及不等价取代形成的缺陷)对其上转换发光的影响，揭示Er离子的上转换发光强度与Er离子局域晶场环境参数的定量关系，形成直观的规律性认识，在此基础上建立原子结构模型并结合能级图探讨实际局域晶场环境下Er离子的上转换发光过程和机理，解决目前采用单纯的能级图模型分析Er离子上转换发光机理带来的理论与实验不一致的弊端。项目研究可以为新型高效上转换发光材料的探索提供一定的理论指导作用。

Upconversion emission of Er3+ ion is a nonlinear optical process which results in the low efficiency of emission. One of the way to improve the upconversion emission properties is changing the local crystal field environment of Er3+ ion. For the absence of regular relationship between micro structure of materials and upconversion emissions of Er3+ ion, the double perovskite structure hosts are chosen to be the object based on the particular characterization of its structure. The Er3+ ion can be incorporated to the specific lattice site and equivalence substitution or nonequivalence substitution in the materials by adjusting the composition of host, which is beneficial to investigate the effect of local crystal field environment (lattice symmetry, cell parameters, strength of crystal field and defects caused by the equivalence substitution) of Er3+ site in the matrix on the upconversion properties of Er3+ ion horizontally or longitudinally. And then quantitative relationship between upconversion emission intensity and local crystal environment parameters of Er3+ ion can be revealed as well as the direct regularity. Furthermore, the upconversion process and mechanism will be discussed by establishing the atom structure model combining with the energy level diagram based on the above results. The conclusion can be used to solve the problem about the inconformity between theory and experimental results caused by the analysis of upconversion mechanism using energy level diagram in isolation. This program is beneficial to the exploration of novel and high efficient upconversion emission materials in theory.