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化合物Sr3B6O11F2、Pb8M(BO3)6 (M = Zn, Cd)的合成、结构和性能研究
黄振军
学位类型硕士
导师潘世烈
2013-05-28
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
关键词氟硼酸锶 非线性光学晶体 硼酸盐 晶体生长
其他摘要

本论文在SrO-SrF2-H3BO3PbO-MO-H3BO3(M = Zn, Cd)体系中探索获得了三种化合物:Sr3B6O11F2Pb8M(BO3)6(M = Zn, Cd)。其中,Sr3B6O11F2具有极性结构。对这三种化合物的固相合成、晶体结构、晶体生长、物化性能以及电子结构等进行了研究。

1.采用高温溶液法生长出Sr3B6O11F2,该晶体为单斜晶系,空间群为P21(No. 4),晶胞参数为:a= 6.3847(6) Åb= 8.2493(9) Åc= 9.3867(9) Åβ= 101.680(5) °V = 483.21(8)Å3Z = 2Sr3B6O11F2晶体结构是由一个共价键网络与一个离子键网络相互穿插组成的。共价键网络是由B6O14基团组成,离子键网络是由Sr3F基团组成。非线性光学测试表明Sr3B6O11F2的粉末倍频效应约为2.5KH2PO4(KDP),偶极矩计算表明倍频效应的主要贡献是BO3基团与SrOnF2(n = 7, 8)多面体在b方向的极性叠加。紫外-可见-近红外漫反射光谱显示,其紫外截止边低于190 nm。通过第一性原理计算,Sr3B6O11F2为直接带隙化合物,能隙为5.53 eV,主要影响来自于O-2pB-2pSr-5s轨道。在可见光区的双折射率约为0.0434-0.0403,非线性光学系数为d21 = 1.084 pm/Vd22 = -1.174 pm/Vd36 = -0.538 pm/V

2.采用高温溶液法生长出Pb8Cd(BO3)6晶体,该晶体为三方晶系,空间群为R3̅ (No. 148)a= 9.5584(16) Å, c= 18.670(3)ÅV1477.2(4) Å3Z= 3Pb8Cd(BO3)6晶体结构具有一个二维的∞[Pb8B6O18]2-阴离子层,该层是由BO3PbO46基团组成,层与层之间通过Cd2+连接形成三维框架。实验证实Pb8Cd(BO3)6为同成分熔融化合物,紫外-可见近红外漫反射光谱显示,其紫外截止边为260nm。通过第一性原理计算,Pb8Cd(BO3)6为间接带隙化合物,能隙为3.13 eV,主要影响来自于O-2pPb-6p轨道。

3.采用高温溶液法生长出Pb8Zn(BO3)6晶体,Pb8Zn(BO晶体结构:三方晶系,空间群为R3̅ (No. 148)a= 9.505(6) Åc= 18.162(9)ÅV1421.0(2)Å3Z= 3。该晶体与Pb8Cd(BO3)6具有相似的晶体结构,不同处为层与层之间的连接离子。通过第一性原理计算,Pb8Zn(BO3)6为间接带隙化合物,能隙为3.06 eV,主要影响来自于O-2pPb-6p轨道。

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Three new compounds Sr3B6O11F2, Pb8Cd(BO3)6 and Pb8Zn(BO3)6 have been obtained in SrO-SrF-H3BO3 and PbO-MO-H3BO3 (M = Cd, Zn) systems, respectively. Therein, Sr3B6O11F2 crystallizes in polar space group. In this dissertation, the synthesis, crystal structure, crystal growth and properties of the above compounds were investigated. 1. Single crystal of Sr3B6O11F2 was grown by high temperature solution method. Sr3B6O11F2 crystallizes in monoclinic space group P21 (No. 4) with lattice constants a = 6.3847(6) ?, b = 8.2493(9) ?,c = 9.3867(9) ?, β = 101.680(5) °, V = 483.21(8) ?3 and Z = 2. The structure of Sr3B6O11F2 can be described as two interpenetrating networks, which are composed of B6O14 and Sr3F groups, respectively. On the basis of the power SHG measurement, Sr3B6O11F2 belongs to the phase-matching class with a SHG response of approximately 2.5 times that of KH2PO4 (KDP), which comes from the cooperative effect of BO3 groups and SrOnF2 (n = 7, 8) polyhedra. The UV cutoff wavelength edge is below 190 nm. The electronic band structure and optical properties have been studied by ab initio calculations. The band structure and densities of states (DOS) calculation conclude an direct energy gap 5.527 eV, and the band structure is determined by O-2p, B-2p and and Sr-5s orbitals. The birefringence of Sr3B6O11F2 is about 0.0434 – 0.0403 in the visible region, the calculated SHG coefficients are d21 = 1.084 pm/V, d22 = -1.174 pm/V and d36 = -0.538 pm/V, respectively. 2. Single crystal of Pb8Cd(BO3)6 was successfully synthesized by high temperature solution method and their structure was determined by single-crystal X-ray diffraction method. The compound crystallizes in the trigonal space group R with unit-cell parameters a = 9.5584(16) ?, c = 18.670(3) ?, V = 1477.2(6) ?3 and Z = 3. The crystal structure represents a new two-dimensional (2D) ∞[Pb8B6O18]2- layer, which is composed of BO3 and PbOx (x = 4, 6) polyhedra. The layers are further bridged by the Cd2+ ions, giving rise to a three-dimensional (3D) framework. Thermal analysis proves that Pb8Cd(BO3)6 melts congruently, UV-Vis-NIR diffuse reflectance spectra show that UV absorption edge is at about 260 nm, and band structure calculations conclude an indirect energy gap 3.13 eV, the band structure is determined by O-2p and Pb-5p orbitals. 3. Single crystals of Pb8Zn(BO3)6 was successfully synthesized by high temperature solution method and their structure was determined by single-crystal X-ray diffraction method. The compound crystallizes in the trigonal space group R with unit-cell parameters a = 9.505(6) ?, c = 18.162(9) ?, V = 1421(2) ?3, Z = 3. Pb8Zn(BO3)6 and Pb8Cd(BO3)6 have similar 3D framework, except the bridge atoms. The band structure calculations conclude an indirect energy gap 3.06 eV, the band structure is determined by O-2p and Pb-5p orbitals. KEY WORDS: Sr3B6O11F2; nonlinear optical crystal; borate; crystal growth

文献类型学位论文
条目标识符http://ir.xjipc.cas.cn/handle/365002/2511
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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黄振军. 化合物Sr3B6O11F2、Pb8M(BO3)6 (M = Zn, Cd)的合成、结构和性能研究[D]. 北京. 中国科学院大学,2013.
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