稀土掺杂铋基弛豫铁电单晶的上转换发光及其外场调控机理研究

As a source of all-solid-state short wavelength laser, up-conversion (UC) laser is widely applied in optical data storage, color display, marine exploration, etc. It is significant to develop single crystals with high UC photoluminescence efficiency for UC laser. In this project, relaxor ferroelectric NBT-BT single crystals doped with rare earths are grown by top seed solution growth method. The quality and property of single crystal can be improved through the optimization of growth parameters, formula composition and after-treatment. Base on the converse piezoelectric effect, the UC intensity can be in-situ controlled by external electric field. The UC property as functions of external electric field and temperature variation are characterized. The characteristic and dynamic evolution of microstructure, including the morphology of ferroelectric domains and the phase structure, as functions of external electric field and temperature variation are investigated by the in-situ photoluminescence spectra combined with the in-situ Raman and XRD, which reveals the microscopic mechanism of the UC property. Finally, to establish the relationship between UC property and crystal field symmetries with various microstructures. The mechanism of enhanced UC property by electric field in NBT-BT crystal doped with rare earth will be clarified based on the experiment results and J-O theoretical calculation, which will guide the developing development of host ferroelectrics with high UC efficiency.

上转换激光作为一种全固态短波长激光光源，在光数据存储、彩色显示、海洋探测等方面具有广泛应用。探求高效的上转换发光单晶材料，对于研制上转换激光器具有重要意义。本研究将以铋基弛豫铁电体NBT-BT为基质材料，采用顶部籽晶法生长稀土掺杂NBT-BT单晶。通过调节生长参数、配方组成与后处理工艺，优化单晶的质量和性能。基于逆压电效应，利用外电场原位调控上转换发光，测定在电场和温度作用下发光性能的变化；利用稀土离子的发光特征谱，辅以原位拉曼、x射线衍射技术，研究电场和温度场作用下，单晶沿特定取向的微结构特征（如铁电畴形态、相结构）及其随外场的动态演变，从而揭示对上转换发光性能影响的微观机制。将实验结果与J-O理论计算进行对比研究，建立不同微观结构下晶体场对称性与上转换发光特性的关系，揭示单晶上转换发光的外场增强机理，为探索新型高上转换发光效率的铁电基质材料提供理论指导。

上转换激光作为一种全固态短波长激光光源，在光数据存储、彩色显示、海洋探测等方面具有广泛应用。探求高效的上转换发光单晶材料，对于研制上转换激光器具有重要意义。本项目通过改进后的TSSG 法及晶体后处理工艺，成功生长出具有高质量、高上转换发光效率的稀土掺杂铋基压电单晶；同时项目还制备了多种稀土掺杂铋基光（荧光）-电（压电）多功能陶瓷。获得了单晶、陶瓷材料的微观结构、电性能与光致发光性能的变化关系，揭示原位电场调控上转换发光的性能与结构机理：确定稀土掺杂单晶的上转换发光效率的电场增强机理，获得铁电基质材料中高上转换发光效率的形成条件。在国家自然基金资助下，项目在国内外知名期刊上共发表学术论文17篇，被SCI收录16篇（其中SCI二区top期刊8篇、其他国内外知名SCI期刊8篇）；另外，获授权国家发明专利1项，获2017年省物理学会优秀论文二等奖，2018年中韩国际铁电材料会议最佳poster奖，申请人晋升副教授职称，并入选2019年江西省青年井冈学者，培养硕士研究生8名。项目完成结果远超过2-3篇学术论文，培养研究生1-2名的预计目标。