【作者】 张帆；

【导师】 沈德忠；

【作者基本信息】 清华大学 ， 化学， 2008， 博士

【摘要】 由于能够扩展现有激光器的输出频率,无机非线性光学（NLO）晶体材料在光通讯、信号传输等领域有广泛的应用。探索具有大的倍频系数、宽的透光范围、高的光损伤阈值、稳定的物化性能的晶体,具有重要的理论意义和应用价值。本论文的主要研究目的是探索新型硼酸盐非线性光学晶体。首先,对Cd₃Zn₃B₄O₁₂晶体进行了系统研究。分别采用固相法和液相法合成了Cd₃Zn₃B₄O₁₂纯相多晶原料,解决了单相原料的合成难题。采用助熔剂法,试验了二十四种助熔剂,六十个比例的样品,对Cd₃Zn₃B₄O₁₂晶体的生长进行了探索研究。以B₂O₃自助熔剂,按照Cd:Zn:B=1:1:1.5的配比,获得了Cd₃Zn₃B₄O₁₂毫米级单晶;以PbO-0.85PbF2作为助熔剂,得到了较大尺寸的晶体。对晶体进行的差热、红外和拉曼分析、粉末倍频效应、化学稳定性等测试表明,Cd₃Zn₃B₄O₁₂晶体有较强的倍频效应,性能稳定不潮解,具有较好的潜在应用前景。其次,对不同配比的硼酸锌镉化合物,进行了晶体生长及其性能的研究。采用固相法和液相法合成了CdZn₂B₂O₆的纯相多晶原料,并分别用泡生法和坩埚下降法生长出CdZn₂B₂O₆单晶,证实了CdZn₂B₂O₆的存在。研究结果表明CdZn₂B₂O₆与Cd₃Zn₃B₄O₁₂的晶体结构相似,且XRD、红外和拉曼谱图十分接近。单晶结构解析表明,Cd²⁺离子和Zn²⁺离子占据晶胞中的相同位置,随机无序分布,Cd和Zn占位度的不同导致形成不同比例的硼酸锌镉。从实验和理论上证实两种化合物都存在,也解释了两者性质相似的原因,从而解决了CdZn₂B₂O₆和Cd₃Zn₃B₄O₁₂两种硼酸锌镉化合物的学术争议。CdZn₂B₂O₆粉末非线性效应为KDP微晶的2.6倍,物理化学性质稳定,是有潜在应用前途的非线性光学晶体。最后,从改变CdO-ZnO-B₂O₃体系中CdO或者ZnO入手,进行新型硼酸盐晶体的探索研究。考察了九个体系中的四十余种不同计量比的样品,生长出了Ba_2.80Zn_0.20B₆O₁₂、CdZn₂KB₂O₆F硼酸盐新晶体,进行了结构解析和性能的研究。纠正和补充了文献中有关Ba₂ZnB₆O₁₂晶体的XRD和结构等报道。同时,分别采用SrB₂O₄、Bi₄B₂O₉、CdB₂O₄和BaB₂O₄助熔剂,进行了ZnO单晶的生长研究。此外,本论文还对CsLiB₆O₁₀晶体进行了化学侵蚀及开裂机理的研究。更多还原

【Abstract】 Owing to expanding the frequency range of solid laser sources, the inorganic nonlinear optical （NLO） borate crystals have been widely used in optical communication, laser medicine and signal processing. Numerous investigations have been undertaken on new NLO crystals, which are characterized by a large NLO coefficient, a broad optical transparency range, a high damage threshold and high optical quality. In present dissertation, the aim is to find some new NLO borate crystals.Firstly, the growth and properties of Cd₃Zn₃B₄O₁₂ crystal have been studied in detail. Cd₃Zn₃B₄O₁₂ polycrystals were synthesized by solid-state and wet chemical reaction method successfully, and the latter is the more effective way to prepare single-phase compound. Cd₃Zn₃B₄O₁₂ single crystals have been grown by the flux method. Twenty-four fluxes and sixty samples have been used for the crystal growth. The experiment results show that Cd₃Zn₃B₄O₁₂ crystals with millimeter grade were grown from the self-flux B₂O₃ （Cd:Zn:B=1:1:1.5）; and larger crystals were obtained from the PbO-0.85PbF2 fluxes easily. The grown crystals were characterized by Differential Scanning Calorimetry and Thermogravimetric （DSC/TG）, Infrared and Raman analysis, NLO effect and chemical stability. The analytical results indicate that Cd₃Zn₃B₄O₁₂ crystal exhibits an excellent NLO effect, and is very stable in neutral solution and not hygroscopic in air at room temperature.Secondly, crystal growth in other different ratio compounds has been investigated in the CdO-ZnO-B₂O₃ system. The experimental results show that the wet chemical method is a better way than the solid-state reaction method to prepare pure cadmium dizinc diborate compound. The CdZn₂B₂O₆ single crystals have been grown by the Kyropoulos method and the vertical Bridgman method for the first time. The properties of the CdZn₂B₂O₆ are similar to these of Cd₃Zn₃B₄O₁₂, including the crystal structure, XRD, Infrared and Raman analysis. The Cd²⁺ and Zn²⁺ cations in the two compounds share the same site in the unit cell and the distribution is disordered, thus the occupancy positions differences of the Cd2+ or Zn2+ cations result in different ratios of Cd and Zn in the crystals. The Cd and Zn ratios of CdZn₂B₂O₆ and Cd₃Zn₃B₄O₁₂ crystals were assigned to be 1:2 and 1:1, based on the result of the Ionic Coupled Plasma Atom Emission Spectrometer （ICP-AES） analysis. The theoretic analysis and experimental results denote the existence of the two crystals, and provide a satisfying explanation on the similar properties. The powder NLO coefficient of the CdZn₂B₂O₆ crystal is 2.6 times as large as that of KH₂PO₄ （KDP） crystal, and this stable crystal is a promising material for NLO applications in ultraviolet-transparent range.Lastly, starting with the change of CdO or ZnO in the CdO-ZnO-B₂O₃ system, new NLO borate crystals have been researched using high-temperature solid-phase and wet chemical reactions, crystal growth and powder NLO effect methods. Over forty samples in nine systems have been studied, such as BaO-ZnO-B₂O₃, SrO-ZnO-B₂O₃, CaO-ZnO-B₂O₃, MgO-ZnO-B₂O₃, Yb₂O₃-ZnO-B₂O₃, La₂O₃-ZnO-B₂O₃, Gd2O3-ZnO-B₂O₃, CdO-SrO-B₂O₃ and so on. The growth and properties of Ba_2.80Zn_0.20B₆O₁₂ and CdZn₂KB₂O₆F new borate crystals have been investigated. The XRD and crystal structure of Ba₂ZnB₆O₁₂ crystal have been corrected, and the analysis of differential thermal, Infrared and Raman have been supplemented. At the same time, ZnO single crystal has been grown from the SrB₂O₄, Bi4B2O9, CdB2O4 and BaB₂O₄ fluxes respectively.In addition, the etching patterns on different surfaces of CsLiB₆O₁₀ （CLBO） crystal and its cracking mechanism have been investigated. The cracking evolution of CLBO crystal immerged in pure water was exhibited and discussed finally.更多还原