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稀土硼酸盐和氟钛酸盐的合成,结构及光学性质研究
徐冬冬
学位类型硕士
导师潘世烈
2017-05-31
学位授予单位中国科学院大学
学位授予地点北京
学位专业材料物理与化学
关键词截止边 紫外 蓝移 过渡金属氟化物 稀土硼酸盐
摘要

光电功能晶体材料在工业、军事、医疗、科研等领域具有不可替代的作用,是材料科学与工程领域研究的热点。众所周知,光电功能晶体材料的光学应用范围与晶体的截止边紧密相关。对于短波紫外或深紫外的非线性光学晶体材料而言,紫外截止边要求低于266 nm甚至低于200 nm。针对这一点,本文提出了新的设计策略,探索了新的体系,来合成截止边在短波紫外甚至深紫外区的新化合物。合理的设计策略有效地使化合物的截止边蓝移,甚至低于190 nm。主要内容如下:(I) 一种复合阴离子基团的过渡金属氟化物。著名的非线性光学晶体KTP(KTiOPO4)晶体的截止边为350 nm,限制了其在紫外光区的应用。针对截止边这一点,本文提出了将在在紫外波段存在光学吸收的Ti-O键用Ti-F键取代的设计策略。基于该思路的指导,利用水热法首次合成了含[MF6](M为过渡金属离子)基团的复合阴离子基团过渡金属氟化物,Na3NH4(TiF6)(SO4)?H2O (NTS)。透过光谱表明,其紫外截止边为242 nm。NTS的结构特点是具有由四种结构基元(i.e., [NH4], [TiF6], [SO4], H2O)通过四种氢键(i.e., N–H···O, N–H···F, O–H···O, O–H···F)相连组成的层。通过调节水热条件生长了尺寸为5.0×2.5× 1.0 mm3的透明单晶。(II) 系列稀土硼酸盐。1. 将没有d-d和f-f电子跃迁的碱金属离子和稀土离子La3+同时复合到硼酸盐体系中,合成了三种具有较短紫外截止边的碱金属复合镧硼酸盐。这三种化合物均是通过高温熔液法合成的。其中,化合物LiRb2LaB2O6与著名的多孔材料MOF-5(分子式为Zn4O(BDC)3,BDC = 1,4-benzenedicarboxylate)具有类似的拓扑结构。此外,该化合物具有较低的紫外截止边(< 190 nm)和适中的双折射率(实验值 0.040@589.3 nm, 计算值 0.038@589.3 nm)。LiRb2LaB2O6还表现出较好的热学稳定性和水稳性,是一种新的具有MOF-5拓扑结构和短的紫外截止边的稀土硼酸盐。2. 其他三种稀土硼酸盐。除了基于镧的稀土硼酸盐外,本文还探索了钪硼酸盐和镥硼酸盐体系。其中,ScCaO(BO3)和ScCdO(BO3)是两种同构的非一致熔融化合物,三维结构由共平面的[BO3]基团和[ScO6]、[CaO6]/[CdO6]八面体基团构成。漫反射光谱表明,其紫外截止边分别为230 nm,249 nm。这两种化合物还表现出高的热稳定性。

其他摘要

Photoelectric functional crystal materials are the focus of research in the fields of materials science and engineering due to the irreplaceable role played in industry, military, medical treatment, scientific research and other fields. As we all know, the optical application range of functional crystal materials is closely related to the cut-off dege. For short-wave ultraviolet (SWUV) or deep-ultraviolet (DUV) nonlinear optical (NLO) crystals, the cut-off dege at ultraviolet side should be lower than 266 nm,and even lower than 200 nm. In order to meet this requirement, we proposed new design strategies and explored new systems to synthesize a series of compounds which are transparent in SWUV or DUV region. The main results are concluded as follows:(I) One mixed-anion transition metal (TM) fluoride with [TiF6] anion groups.The cut-off edge of famous NLO material KTP is 350 nm, which limits its optical application in UV region. In response to this, we put forword a new strategy for the blue shift of cut-off edge, i.e. utilizing the Ti-F bonds to replace the Ti-O bonds which contribute to the optical absorption in UV side. Based on this idea, the first mixed-anion transition metal (TM) fluoride with a [MF6] (M = TM cations) anion group, Na3NH4(TiF6)(SO4)?H2O (NTS), was synthesized by a facile hydrothermal method. Transmittance spectrum of NTS crystal indicates that its UV cut-off edge is 242 nm. The structure of NTS features hydrogenbonded layers constructed by four kinds of building blocks, i.e., [NH4], [TiF6], [SO4], H2O, and four categories of hydrogen bonds, i.e., N–H···O, N–H···F, O–H···O and O–H···F. A transparent crystal with a size up to 5.0×2.5× 1.0 mm3 has been grown just by controlling the hydrothermal conditions.(II) A series of rare-earth borates.1. Three alkali metal mixed lanthanum borates with short UV cut-off edge were synthesized using a high-temperature solution method by combining the alkali metal ions and the rare-earth ions La3+ without d-d and f-f electron transitions into the borate system. Interestingly, LiRb2LaB2O6 shares a similar topological structure with the famous porous material MOF-5, which is formed from Zn4O(BDC)3 (BDC = 1,4-benzenedicarboxylate). Moreover, it possesses a short cut-off edge (< 190 nm) and moderate birefringence (exp. 0.040@589.3 nm, cal. 0.038@589.3 nm). LiRb2LaB2O6 also exhibits good thermal and water stability. In a word, LiRb2LaB2O6 is a new rare-earth borate with a MOF-5-like topological structure and a short UV cut-off edge.2. Other three rare-earth borates.In addition to lanthanum based rare-earth borates, this thesis also explored the scandium based and lutetium based borates. Among of them, ScCaO(BO3) and ScCdO(BO3) are two isostructural compounds exhibiting the incongruent melting characteristic, and the three-dimensional structures are composed of coplanar [BO3] groups and [ScO6] and [CaO6]/[CdO6] octahedral groups. Diffuse reflection spectra indicate that their UV cut-off edges are 230 nm and 249 nm, respectively. These two compounds also exhibit high thermal stability.

文献类型学位论文
条目标识符http://ir.xjipc.cas.cn/handle/365002/4966
专题材料物理与化学研究室
作者单位中国科学院新疆理化技术研究所
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徐冬冬. 稀土硼酸盐和氟钛酸盐的合成,结构及光学性质研究[D]. 北京. 中国科学院大学,2017.
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