【作者】 王文芮孜；

【导师】 李如康；

【作者基本信息】 中国科学院研究生院（理化技术研究所） ， 凝聚态物理， 2009， 硕士

【摘要】 在过去的五十年,硼酸盐体系的研究工作取得了长足进展,发现并且合成了许多化合物,其中一些具有非中心对称结构的化合物经过筛选,成功应用于现代科技的方方面面,硼酸盐的非线性光学晶体就是其中一类。其中,水合硼酸盐,例如:五硼酸钾KB₅O₈·4H₂O是人们最早发现的真空紫外倍频晶体,通过相位匹配,可以获得波长为216.8nm的紫外光;正交相一水六硼酸二钙2CaO·3B₂O₃·H₂O是一种潜在的的非线性光学材料。[IO₃]-具有一孤对电子,当形成不具有中心对称结构的晶体时,常具有较强的热电、压电、非线性光学效应。以[IO₃]-基团为结构单元堆积而成的金属碘酸盐,部分碘酸盐的[IO₃]-基团在晶体结构中取向一致地排列,导致碘酸盐晶体材料具有较大的非线性光学系数。水热法和溶液法用于制备了许多新型的无机化合物。本论文工作正是采用这两种晶体生长方法具体研究了Sr₂B₁₁O₁₆（OH）₅ H₂O和NaIO₃·H₂O单晶的生长,以及Ga（IO₃）₃化合物的新的合成方法。粉末倍频测试证明这些化合物都具有倍频效应,因此它们都是潜在的非线性光学材料。差热和热重用于测试Sr₂B₁₁O₁₆（OH）₅ H₂O晶体的热稳定性。我们得到的晶体包含的结晶水数目与早前报道的天然的Sr₂B₁₁O₁₆（OH）₅ H₂O矿物的结晶水数目不一致。基于Sr₂B₁₁O₁₆（OH）₅ H₂O的晶体结构,在[B₅O₈（OH）]₂-基团堆积的聚阴离子层与层之间,推测还可以容纳其他水分子。我们提出Sr₂B₁₁O₁₆（OH）₅ nH₂O分子式,在本论文中得到的晶体的结晶水数目n值为2.26。更多还原

【Abstract】 The last 50 years great advances have been seen in the field of borates. A large number of compounds have been discovered and synthesized. Some of these compounds have non-centrosymmetric structures, which have been applied successfully as nonlinear optical crystals. Among them, hydrated borates: i.e. Potassium Pentaborate (KB5O8·4H2O) is the pioneer vacuum ultraviolet frequency-doubling crystal which is possible to produce phase-matched second-harmonic generation (SHG) at wavelengths as short as 216.8nm. Orthorhombic Calcium Triborate Hydrate (2CaO·3B2O3·H2O) has been proposed as a potential nonlinear optical material.Metal iodates contain isolated [IO3]- groups which has a lone pair to form non-centrosymmetric structure. Metal iodates have been shown to exhibit pyroelectric, piezoelectric, and second-harmonic generation properties. The [IO3]- groups in some metal iodates orient perfectly parallel, which leads to large nonlinear optical coefficients.Hydrothermal synthetic methods and Solution evaporation methods are commonly adopted in producing hydrated inorganic compounds. In this paper Sr2B11O16(OH)5 H2O and NaIO3·H2O single crystals have been prepared by these two crystal growth methods. And Ga(IO3)3 has been synthesized by a precursor route. Powder SHG test confirmed the nonlinear optical property of the three compounds.Thermal stability of crystalline Sr2B11O16(OH)5 H2O has been determined by differential thermal analysis (DTA) and thermogravimetry (TG). It shows that our hydrated crystal contains 2.26 water molecules, which does not agree with the natural mineral reported previously. Based upon its crystal structure, which is built by [B5O8(OH)]2- polyanions forming two infinite sheets interlinked by Sr cations, we speculate that the structure can host another water molecule in the voids. So the best molecular formula to describe our crystal may be put forward as Sr2B11O16(OH)5 nH2O, with n = 2.26.更多还原