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碱金属/碱土金属复合硼酸盐和稀土硼酸盐的合成、结构及性质研究
马茹茹
Subtype硕士
Thesis Advisor杨云
2018-05-24
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline材料物理与化学
Keyword截止边 晶体结构 孤立bo3 碱金属/碱土金属 稀土硼酸盐
Abstract

光电功能晶体材料因为其在光电子和激光领域应用广泛,而成为材料科学的一个重要的分支和研究热点,因此,人们对光电功能晶体材料的需求也越来越迫切,也对其性能提出了更高的要求。本文主要以探索紫外或深紫外光学晶体材料为主要目标,采用高温熔液法,合成了系列化合物。主要的合成策略如下:(1)在阴离子选择上,根据P. Becker理论和阴离子基团理论,调控阳离子和B之间的比例,来获得含孤立的BO3基团的化合物;(2)在阳离子的选择上,引入没有核外d-d或f-f电子跃迁的碱金属,碱土金属以及稀土离子,目的是使其在紫外或深紫外有较宽的透过波段。主要研究内容如下:(I) 一系列含孤立BO3基团的稀土硼酸盐。1. 复合碱金属含La硼酸盐LiCs2La(BO3)2和Li3K9La3(BO3)7,具有三维的开放性骨架和较短紫外的截止边。LiCs2La(BO3)2和Li3K9La3(BO3)7是通过高温熔液法合成的,这两个化合物分别结晶于正交晶系,Pbcm空间群和单斜晶系,P2/c空间群。这两个化合物都具有由阳离子多面体和孤立BO3基团组成的三维开放性框架,Cs离子和K离子填充在结构框架中的孔道中。通过自发成核结晶的方法生长了毫米级的单晶,晶体尺寸分别为2.0 × 1.0 × 1.0 mm3 (LiCs2La(BO3)2)和2.5 × 2.0 × 1.0 mm3 (Li3K9La3(BO3)7)。紫外-可见-近红外漫反射测试表明LiCs2La(BO3)2和Li3K9La3(BO3)7的紫外截止边分别为 < 190 nm和 < 200 nm。热学性质测试表明该两个化合物都为非同成分熔融化合物。通过第一性原理计算方法计算LiCs2La(BO3)2化合物的双折射率为0.036@1064 nm。2. 含Sc氧合硼酸盐ScMO(BO3) (M = Ca和Cd),具有新颖的八面体共边连接的基本构筑单元和较短的紫外截止边。ScMO(BO3) (M = Ca和Cd)是通过高温熔液法合成的,都结晶于正交晶系,Pnma空间群。该结构具有三维的阳离子框架和平行排列的BO3基元。阳离子框架的基本组成单元是由两个[Ca(1)O4]6?链和两个[Sc(1)O4]5?链组成。ScMO(BO3) (M = Ca和Cd)的紫外截止边分别为230和249 nm。热学性质测试表明该两个化合物都为非同成分熔融化合物。第一性原理计算表明,Sc-3d和O-2p轨道之间相互作用形成的(d-p)π键对带隙的有一定的影响,进一步理解了微观电子构型和宏观光学性质之间的关系。(II) 碱金属碱土金属复合硼酸盐。在Li2O-M2O-SrO-B2O3四元体系中通过高温熔液法得到了三个碱金属碱土金属复合硼酸盐,Li2KSr6(BO3)5,Li2Rb7Sr24B19O57和Li2Rb2SrB18O30。(i) Li2KSr6(BO3)5结晶于正交晶系,Pnma空间群。Li2KSr6(BO3)5的B-O基团是孤立的BO3基团。该结构中有[Li2O7]12-链和[KB(4)O11]18-链,Sr-O多面体形成一个三维的阳离子框架;(ii) Li2Rb7Sr24B19O57结晶于三方晶系。该化合物的B-O阴离子基团都是孤立的BO3;(iii) 在Li2Rb2SrB18O30结构中,基本构筑单元[B9O19]11?通过共享氧原子形成三维的开放性骨架,B孔道为空的,A孔道和C孔道分别由Rb原子和Sr原子占据。Rb-O多面体形成链状结构,LiO5和RbO11多面体连接相邻的链,并结合Sr-O 3D框架,形成Li-Rb-Sr-O阳离子层状结构。Li2Rb7Sr24B19O57和Li2Rb2SrB18O30的紫外截止边小于200 nm。热学性质测试表明该两个化合物都为非同成分熔融化合物。理论计算Li2KSr6(BO3)5的带隙为4.05 eV,双折射率0.034@1064 nm。Li2Rb2SrB18O30的理论带隙为5.68 eV。

Other Abstract

Optoelectronic functional crystal materials have become an important branch and research hotspot of materials science because of their wide application in optoelectronics and lasers. Therefore, people's demand for optoelectronic functional crystal materials has become more urgent and made higher requirements on their performance. The main purpose of this thesis is to explore the ultraviolet (UV) or deep ultraviolet (deep-UV) optical crystal materials and a series of compounds have been synthesized using the high-temperature solution method. The main synthetic strategies are as follows: (1) on the choice of anionic groups, according to the P. Becker theory and the anionic group theory, adjust the ratio of A/B (A= cationic) to obtain compounds containing isolated BO3 units. (2) on the choice of cationic groups, introduce the alkali metal, alkaline earth metal and rare-earth cations without d–d or f–f electron transitions to wide the transmittance in the UV or deep-UV region. The main research contents are as follows:(I) A series of rare-earth borates containing isolated BO3 units. 1. Mixed alkali metal lanthanum borates, LiCs2La(BO3)2 and Li3K9La3(BO3)7, with three-dimensional open frameworks and short cut-off edges.LiCs2La(BO3)2 and Li3K9La3(BO3)7 are synthesized by the high-temperature solution method. They crystallize in the orthorhombic space group Pbcm and the monoclinic space group P2/c, respectively. The structures of LiCs2La(BO3)2 and Li3K9La3(BO3)7 have three-dimensional (3D) open framework surrounded by cation polyhedra and isolated BO3 units and the Cs and K atoms reside in the channels. Millimeter-sized crystals of LiCs2La(BO3)2 and Li3K9La3(BO3)7 with sizes of 2.0 × 1.0 × 1.0 and 2.5 × 2.0 ×1.0 mm3 have been obtained through a spontaneous nucleation method. The UV-Vis-NIR diffuse reflectance spectra indicate that LiCs2La(BO3)2 and Li3K9La3(BO3)7 have short cut-off edges, < 190 nm and < 200 nm, respectively. Thermal behavior results that title compounds melt incongruently. First-principle theoretical studies were carried out to evaluate the birefringence of LiCs2La(BO3)2, 0.036@1064 nm. 2. Sc-based oxyborates ScMO(BO3) (M = Ca and Cd) featuring interesting edge-sharing basic building unit (BBU) and UV cut-off edges.ScMO(BO3) (M = Ca and Cd) are synthesized by the high-temperature solution method and crystallize in the orthorhombic space group Pnma. ScMO(BO3) (M = Ca and Cd) has a three-dimensional (3D) cationic framework and parallel arranged BO3 triangles. Basic building unit (BBU) of cationic framework is constructed by two [Ca(1)O4]6? chains and two [Sc(1)O4]5? chains. The cut-off edges of ScMO(BO3) (M = Ca and Cd) are 230 and 249 nm, respectively. Thermal behavior results that title compounds melt incongruently. The first-principle theoretical studies indicate that the (d–p)π conjugation interaction between Sc-3d and O-2p orbitals plays a major role in the band gaps, which gives further insights into the relationship between the microscopic electron configuration and optical properties.(II) Mixed alkali metal and alkaline earth metal borates.In the Li2O–M2O (M=K and Rb)–SrO–B2O3 systems, we synthesized three mixed alkali metal and alkaline earth metal borates through high-temperature solution method, Li2KSr6(BO3)5, Li2Rb7Sr24B19O57 and Li2Rb2SrB18O30. (i) Li2KSr6(BO3)5 crystallizes in the orthorhombic space group Pnma. The anionic groups of Li2KSr6(BO3)5 are isolated BO3 triangles. The structure of title compound has [Li2O7]12-chain and [KB(4)O11]18-chain, Sr-O polyhedra constitute 3D cationic framework; (ii) Li2Rb7Sr24B19O57 crystallizes in the trigonal space group. The anionic groups of Li2KSr6(BO3)5 are isolated BO3 triangles; (iii) in the structure of Li2Rb2SrB18O30, the fundamental building blocks [B9O19]11? form 3D open-framework. Type B channel is empty, while types A and C channels are filled with the Rb and Sr atoms. Rb-O polyhedra constitute a 1D chain, and then each chain connects with the neighboring LiO5 and RbO11 polyhedra to form a Li-Rb-Sr-O infinite layer. The cut-off edges of Li2Rb7Sr24B19O57 and Li2Rb2SrB18O30 are below 200 nm, respectively. Thermal behavior results that title compounds melt incongruently. Li2KSr6(BO3)5 possesses calculated band gap 4.05 eV and the birefringence, 0.034@1064 nm. Li2Rb2SrB18O30 has calculated band gap 5.68 eV

Document Type学位论文
Identifierhttp://ir.xjipc.cas.cn/handle/365002/5462
Collection材料物理与化学研究室
Recommended Citation
GB/T 7714
马茹茹. 碱金属/碱土金属复合硼酸盐和稀土硼酸盐的合成、结构及性质研究[D]. 北京. 中国科学院大学,2018.
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