Lu2O3激光透明陶瓷的晶界偏析行为研究

Rare earth doped lutetium (III) oxide (RE3+:Lu2O3), with excellent physical and optical properties, has emerged as a promising candidate for ceramic scintillators and the laser gain medium used in the short-pulsed laser and high-power laser. However, ceramic is intrinsically different from a single crystal. The grain boundaries of a ceramic laser gain medium could introduce doping non-uniformity into the ceramic laser materials, which give rise to phenomena that more doped ions, are in the grain boundary region than in the grain. The doping non-uniformity further makes the refractive index of the laser ceramic becomes non-uniform, which in return causes grain boundary segregation. The project selected cubic Lu2O3 as host material, through the wet chemistry method, prepared a series of different rare earth ions doped high quality transparent ceramic laser materials. Through adopting characterization methods of laser scanning confocal raman spectrometer, fluorescence spectrometer, high resolution transmission electron microscopy and energy spectrometer, this project systematically investigated uniform distribution of rare earth ions in host and grain boundary segregation phenomenon by changing different experimental process conditions. By establishing thermodynamic model and using the atomic fitting simulation calculation together with the experimental data, we investigated the effects of process parameters on grain boundary segregation phenomenon, such as sizes of rare earth ions, concentration, heat treatment temperature, grain size and etc. In addition, this project investigated the relationship between grain boundary segregation and laser output performance, such as laser beam quality and efficiency of laser output.

稀土掺杂的氧化镥透明陶瓷材料因其具有优良的物理性能和光学特性，是作为陶瓷闪烁体和高功率激光器以及短脉冲激光器增益介质的理想材料。然而，与单晶不同的是，陶瓷增益介质的晶界可能会在陶瓷激光材料中引入不均匀掺杂，导致晶界处的掺杂离子浓度高于晶粒内部，产生晶界偏析。本项目以立方相的Lu2O3为基质，通过湿化学法制备一系列不同稀土离子掺杂高质量透明激光陶瓷。本项目通过采用扫描共聚焦拉曼/荧光光谱分析技术和高分辨率透射电镜、能谱等表征手段，系统研究不同实验工艺条件下，稀土离子在基质中均一分布情况和晶界偏析现象。通过建立热力学模型，采用拟合模拟计算与实验数据相结合的方法，研究不同稀土掺杂离子、掺杂浓度、热处理温度、晶粒大小等因素对于晶界偏析现象的影响。在此基础上进一步研究晶界偏析对于激光光束质量、斜效率等激光输出性能的影响。

自1995年Ikesue博士制备出世界上首块激光陶瓷以来，激光陶瓷正以其优异和独特的性能异军突起，成为固体激光领域新的发展方向。然而陶瓷的多晶特性使得其晶界上存在掺杂离子偏析行为，从而导致掺杂离子在晶界处的浓度要比晶粒内部要高，进而产生额外的散射损耗，限制激光输出性能。针对这一问题，本项目通过激光共聚焦拉曼光谱仪、透射电子显微镜、扫描电子显微镜、取向成像显微技术等表征设备，系统研究不同陶瓷制备工艺条件下，稀土离子掺杂在基质中均一性分布情况和晶界偏析行为；基于原子拟合模拟计算与实验数据相结合的方法，研究不同陶瓷制备工艺参数对于晶界偏析现象的影响，并对晶界偏析现象方面取得了规律性认识。在基础上，通过优化陶瓷制备工艺，成功制备了高质量稀土掺杂倍半氧化物，并成功实现了Er：Lu2O3激光陶瓷3微米波段的室温激光输出。