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金属硼酸盐、磷酸盐及硼酸磷酸盐新化合物的合成、结构及性能研究
黄生世
学位类型硕士
导师潘世烈
2015-05-20
学位授予单位中国科学院大学
学位授予地点北京
学位专业材料工程
关键词硼酸盐 磷酸盐 硼酸磷酸盐 晶体结构 性能测试
摘要

近年来,对含有B-O、P-O基团化合物的研究成为一个热点。这不仅是因为这些化合物具有丰富的结构化学,也因为它们常具有一系列优异的光学性能。例如,在B-O、P-O基团中,由于原子电负性相差较大,键长较短,从而使其有利于紫外光波的透过;这些化合物具有相对稳定的物理化学性能;这些化合物的带量能隙较大,从而使得其激光损伤阈值较高。本论文设计、合成出了五种含有B-O、P-O基团的化合物:Na2K2Ba(B9O15)2、APbPO4 (A = K, Rb, Cs)和LiPb4(BO3)(PO4)2,并对这些化合物的晶体结构、固相合成、性能表征及电子结构等进行了研究。1.以K2CO3和PbCl2为助熔剂,采用高温熔液法,第一次合成出了富硼的复合碱金属碱土金属四元硼酸盐化合物Na2K2Ba(B9O15)2。它结晶于单斜晶系P21/c(No. 14)空间群,晶胞参数为a = 8.493(8) Å,b = 8.540(9) Å,c = 17.102(16) Å,β = 90.453(11)°,Z = 2,V = 1240(2) Å3。晶体结构中,三个[B3O7]5-基团通过共享氧原子形成[B9O19]11-基团,[B9O19]11-基团再通过共享端基氧原子进一步连接,形成三维的[B9O15]3-框架结构,金属原子填充在空隙中。粉末XRD测试和差热热重测试表明,该化合物为非一致熔融化合物。加入助熔剂是生长该晶体的必要手段。计算结果表明,该化合物的光学性能主要决定于硼氧基团。2.采用高温熔液法,合成出了APbPO4(A表示碱金属原子)体系中的三个化合物APbPO4 (A = K, Rb, Cs)。这三种化合物结晶在同一个空间群Pnma(No. 62),但是它们的结构却并不全部同构。APbPO4 (A = K, Rb)同构,以RbPbPO4为例,它是通过[Pb1|Rb1O4]∞链与孤立的PO4四面体组成三维框架结构,Pb2|Rb2原子填在空隙中。而CsPbPO4的三维框架是由另一种[PbO4]∞链与孤立的PO4四面体组成,Cs原子填充在孔道中。UV-Vis-NIR漫反射光谱测试表明,这三个化合物的光学透止边分别在250,254,242 nm以下。3.通过统计分析和实验发现,化合物中[M/(B+P)]的比值对阴离子构型有很大影响,调控这个比值是合成新型硼酸磷酸盐化合物的有效方法。在Li2O-PbO-B2O3-P2O5体系中,通过调控[M/(B+P)]的比值,合成出了该体系第一个硼酸磷酸化合物LiPb4(BO3)(PO4)2。它结晶在Pbca(No. 61)空间群,晶胞参数为a = 12.613(13) Å,b = 6.551(7) Å,c = 25.36(3) Å,Z = 8,V = 2095(4) Å3。它的三维结构是由波浪状的二维[B2Pb8O18]∞层与[LiP2O8]∞链连接而成,其中BO3和PO4基团在结构中都是孤立存在的。计算结果表明,该化合物是一个直接带隙化合物。在波长在1064-350 nm范围内,它的双折射率在0.040~0.090之间。

其他摘要

The exploration of new borate and phosphate compounds has been a hot topic in recent years owing to their rich structural chemistry and a series of excellent optical performance. For example, it is benificial for these compounds to have a wide transparency range because of the large electronegativity of the atoms in B-O and P-O groups and the short bond length of B-O and P-O groups. These compounds have relatively stable physical and chemical properties. Because of the larger optical band gap of these compounds, they usually have larger optical damage threshold. Five compounds, Na2K2Ba(B9O15)2, APbPO4 (A = K, Rb, Cs), and LiPb4(BO3)(PO4)2, have been obtained in borate, phosphate, borate-phosphate systems, respectively. In this thesis, the crystal structures, syntheses, performance measurements and the electronic structures of the above compounds were investigated. 1. A new mixed-alkali- and alkaline-earth-metal quaternary borate, Na2K2Ba(B9O15)2, has been synthesized by spontaneous crystallization use K2CO3 and PbCl2 as flux. Na2K2Ba(B9O15)2 crystallizes in the monoclinic system, P21/c (No. 14) space group with a = 8.493(8) ?, b = 8.540(9) ?, c = 17.102(16) ?, β = 90.453(11)°, V = 1240(2) ?3, and Z = 2. In the structure, three [B3O7]5- groups form a [B9O19]11- group by sharing oxygen atoms, and the [B9O19]11- groups are further condensed into a 3D [B9O15]3- framework with the metal atoms filled in the pore space. The powder XRD pattern and the TG/DSC curves unambiguously demonstrates that Na2K2Ba(B9O15)2 is an incongruently melting compound. Therefore, the flux method is necessary for the purpose of its crystal growth. The calculated result shows that the optical properties of the compounds mainly depends on boron oxygen groups. 2. Three alkali metal lead orthophosphates, APbPO4 (A = K, Rb, Cs), have been synthesized by spontaneous crystallization. They crystallize in the same space group Pnma (No. 62), but they are not all isostructural. APbPO4 (A = K, Rb) are isostructural, and the three-dimensional (3D) structure of RbPbPO4 (representative) consists of [Pb1|Rb1O4]∞ chains connected by isolated PO4 tetrahedra, with the Pb2|Rb2 atoms filling in the pore space. The 3D structure of CsPbPO4 consists of another kind of [PbO4]∞ chains connected with isolated PO4 tetrahedra, and the Cs atoms reside in the channel. The UV-Vis-NIR diffuse reflectance spectra exhibit that the cut off edges of three compounds are below 250, 254 and 242 nm, respectively. 3. Analysis results show that through regulating the ratio of [M/(B+P)] is also an effective strategy to synthesize new borate-phosphates. And the first lithium lead borate-phosphate, LiPb4(BO3)(PO4)2, has been synthesized by regulating this ratio. It crystallizes in the orthorhombic space group Pbca (No. 61) with a = 12.613(13) ?, b = 6.551(7) ?, c = 25.36(3) ?, V = 2095(4) ?3, and Z = 8. It possesses a 3D structure with a corrugated 2D layer of [B2Pb8O18]∞ that is further connected by a [LiP2O8]∞ chain, both BO3 and PO4 were isolated. The calculated result of electronic structure and optical properties shows that LiPb4(BO3)(PO4)2 is a direct bandgap semiconductor with a relative large birefringence about 0.040~0.090 with the wavelength from 1064 to 350 nm.

文献类型学位论文
条目标识符http://ir.xjipc.cas.cn/handle/365002/4238
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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黄生世. 金属硼酸盐、磷酸盐及硼酸磷酸盐新化合物的合成、结构及性能研究[D]. 北京. 中国科学院大学,2015.
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