深紫外非线性光学晶体RbBa2(PO3)5的提拉法生长和性能研究

China has traditional advantages on the researches and associated industries of UV and deep-UV nonlinear optical (NLO) crystals. Nowadays, the commonly used UV and deep-UV NLO crystals are grown by the flux method, which always costs a long time during the growth period. Recently, we discovered a new crystal RbBa2(PO3)5 that possesses the shortest UV absorption edge and the largest powder second-harmonic generation (SHG) response (among deep-UV transparent phosphates), both which are comparable to those of the sole available deep-UV NLO crystal KBBF. Furthermore, this crystal melts congruently, indicating that it could be grown by the Czochralski method, a method with relatively short growth period. Therefore, the RbBa2(PO3)5 crystal has potential prospects as a NLO material in UV, in particular, deep-UV region. This project will make microscopic observations on the growth morphologies and the mechanisms of defect production for the RbBa2(PO3)5 crystal, and then find out the key factor with respect to the growth of bulk single crystals, thereby realizing the rapid growth of bulk RbBa2(PO3)5 crystals by the Czochralski method. Using the as-grown bulk crystals, the thermal properties will be systematically measured. As the RbBa2(PO3)5 crystal has a low crystallographic symmetry, we will combine different measurement methods to accurately measure the optical properties including refringence, SHG coefficients, and so on, and then manufacture the SHG devices according to the as-obtained optical parameters. Finally, the SHG devices will be used to carry out primary laser SHG experiments, for the sake of the prospect evaluation of this crystal. We believe that this project will put forward the researches on UV and deep-UV NLO crystals to the direction of rapid production.

紫外、深紫外非线性光学（NLO）晶体研究及相关产业属于我国传统优势领域。目前常用的紫外、深紫外NLO晶体都采用助熔剂法生长，生长周期较长。我们发现的RbBa2(PO3)5晶体具有已知深紫外磷酸盐中最短的紫外吸收边和最大的粉末倍频效应，这两项性能均和目前唯一可用的深紫外NLO晶体KBBF相当；同时，该晶体同成分熔融，可采用生长周期较短的提拉法生长，作为紫外特别是深紫外NLO 晶体具有潜在应用前景。本项目拟对该晶体的生长形貌和缺陷形成机制等进行微观观察，找到影响其生长的关键因素，实现其大尺寸单晶的提拉法快速生长；利用生长的大尺寸单晶，测试其各项热学性质；针对该晶体的晶体学低对称性，结合不同测量方法精确测试其折射率、倍频系数等光学性质，进而制作出其倍频器件；利用该器件开展初步的激光倍频实验，评估其应用前景。本项目的顺利实施，有望推动我国紫外、深紫外NLO晶体研究向可快速制备方向发展。

紫外、深紫外非线性光学（NLO）晶体研究及相关产业属于我国传统优势领域。我们发现的RbBa2(PO3)5（RBPO）晶体具有已知深紫外磷酸盐中最短的紫外吸收边和最大的粉末倍频效应，这两项性能均和目前唯一可用的深紫外NLO晶体KBBF相当；同时，该晶体同成分熔融，利于大尺寸晶体生长，作为紫外、深紫外NLO晶体具有潜在应用前景。本项目采用高纯原料合成得到了纯相的RBPO多晶，掌握了其纯相粉末的宏量制备技术；针对RBPO晶体析晶温度范围窄的问题，采用助熔剂法深入研究了其生长工艺，获得了生长该晶体的最优助熔剂配比以及适合大其尺寸晶体生长的温场梯度；最终得到了厘米级的无色透明RBPO晶体，顺利表征了该晶体的相关性能，为其实际应用奠定了良好基础。RBPO晶体的相关生长技术已申请中国发明专利。我们基于该晶体生长的有益技术手段和经验，成功开发并生长出几例高性能的非线性光学晶体，并对相关光学、热学性能进行了系统研究，加深了我们对相关结构基元和性能关系的认识。项目相关研究成果发表在Coord. Chem. Rev.、J. Am. Chem. Soc.、Angew. Chem.、J. Mater. Chem. C、Inorg. Chem.等国际期刊上，包括43篇SCI学术论文（影响因子大于4.0的34篇），获福建省自然科学学术论文一等奖（第一完成人）1项，申请中国发明专利5项。在项目执行期间培养培养硕士毕业生2名、博士毕业生2名。