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镉/铅硼酸盐中阳离子对光学效应影响的DFT研究
井群
学位类型博士
导师杨志华
2015-05-20
学位授予单位中国科学院大学
学位授予地点北京
学位专业微电子学与固体电子学
关键词阳离子贡献 第一原理方法 光学性质 电子结构
摘要

非线性光学晶体是全固态激光器实现激光频率转换的关键材料,在半导体工业、精密机械加工、信息存储与传输、科学研究等领域有重要的应用。为满足国民经济发展需求,亟需发展具有较大倍频效应和适中双折射率的新型非线性光学材料。在碱金属/碱土金属硼酸盐中引入不对称电荷密度分布基元(如含d10电子、孤对电子的阳离子基元等)成为获得非线性光学材料的有效途径。为有效设计出满足需求的新型硼酸盐材料,需要明确:(1)材料结构如何影响光学性能?(2)为什么引入含d10电子、孤对电子阳离子能导致材料线性及非线性光学效应出现明显差别?(3)含d10电子、孤对电子阳离子对光学各向异性性质影响机制是什么?针对以上问题,作者利用第一原理方法计算一系列镉硼酸盐、铅硼酸盐以及与之同构的碱金属/碱土金属硼酸盐的电子结构和光学性质,并利用倍频密度分析工具和实空间原子切割工具分析材料中离子或者离子基团的贡献,获得如下研究结果:1、基于密度泛函理论(DFT)平面波赝势算法,发展了一种计算单斜晶系双折射率的方法,克服了由于单斜晶系晶体轴与光学主轴不重合而难计算材料双折射率的问题。2、利用第一原理方法研究了一类包含孤立BO3基团的类磷灰石结构材料(KSr4(BO3)3, Ca5(BO3)3F, 及Cd5(BO3)3F)的电子结构及光学性质,并利用倍频密度分析工具及实空间原子切割工具研究了BO3基团的贡献。研究结果表明,这类类磷灰石结构材料的倍频效应主要取决于具有共轭π轨道的BO3基团以及BO3基团的排列方式。3、利用第一原理方法及实空间原子切割方法研究了镉/铅硼酸盐中含d10电子、孤对电子阳离子对线性、非线性光学性质的贡献。研究结果表明:Cd-O之间的共价相互作用是Cd5(BO3)3F的倍频效应为Ca5(BO3)3两倍的主要原因;Pb2B5O9Cl与M2B5O9Cl (M=Sr, Ba)相比具有较大的双折射率以及倍频效应, 主要归因于Pb(II)-O的共价相互作用强于M-O (M=Sr, Ba)。4、使用第一原理方法初步研究了一系列铅硼酸盐材料中铅孤对电子的立体化学活性强弱对光学效应影响的机理。计算了包括PbBa2(B3O6)2、Pb2BO3F、Pb2B5O9Cl以及PbB4O7等铅硼酸盐的光学性质(双折射率等),并利用实空间原子切割方法分析了不同离子及离子基团的贡献。研究结果表明:(1)、Pb(II)阳离子对材料双折射率的贡献和Pb(II)孤对电子的立构活性程度有关,Pb(II) 孤对电子的立构活性越大,Pb(II)阳离子对材料双折射率的贡献越大;(2)、Pb(II)阳离子的立构活性程度和与Pb(II)阳离子配位的O原子有关。5、基于Pb(II)阳离子以及BO基团的电子结构,以及二者的连接方式,利用第一原理方法研究了Pb2Ba3(BO3)3Cl材料具有较大倍频效应增益的内在机理。研究结果表明,Pb(II)阳离子和BO基团共边连接方式有利于获得具有较大倍频效应增益的铅硼酸盐;具有孤立BO3基团的铅硼酸盐是潜在的、可以获得较大倍频效应增益的铅硼酸盐材料。

其他摘要
As key device using for frequency conversion, ultraviolet/deep-ultraviolet (UV/DUV) nonlinear optical (NLO) materials play an important role in semiconductor industry, precision machining, information storage and transmission, and scientific research and development (R&D). To meet the demand of the rapid development of the national economy, scientists must speed up the design and syntheses of novel NLO materials with relative large SHG response and suitable birefringence. A general strategy is to combine boron-oxygen groups with asymmetric electron density distribution cations, such as cations containing d10 valence electrons, and lone-pair metal cations. In order to successful design and syntheses, some questions should be answered firstly: (1) how can the structures affect their optical properties; (2) why obvious different linear and nonlinear optical properties can be found in cadmium borates, and lead borates; (3) how can the cations containing d10 electrons and lone-pairs affect the anisotropic optical properties? In order to answer these questions, the author has calculated the electronic structures and optical properties of cadmium borates and lead borates along with alkaline/alkalilne-earth borates using the first-principles method, SHG-density method, and real-space atom-cutting method. The results show that: 1, It is very difficult to calculate the refractive indices and birefringence of monoclinic crystals because the dielectric axes are not superposed on the crystallographic axes. In this thesis, a new method has been developed to calculate birefringence of monoclinic crystals using the dielectronic constant tensors obtained by density functional theory (DFT) method.. 2, The electronic structures and optical properties of a family of apatitle-like materials with isolated BO3 groups(KSr4(BO3)3, Ca5(BO3)3F, and Cd5(BO3)3F) have been investigated using first-principles method. The results show that the SHG responses are mainly attributed to BO3 groups with π conjugated configuration and their alignment framework. 3,The contribution of cadmium cations, and lead cations have been investigated using first-principles method and real-space atom-cutting method. The results show that the strong covalent interactions between the boron-oxygen groups and the cadmium atoms contribute the enhancement of SHG responses; the birefringence and SHG response are enhanced when the alkaline-earth cations were substituted by lead, and the enhanced birefringence and SHG response have relation to the interaction between the oxygen and lead atoms . 4, The mechnish of the intensity of the stereochemical activity of lead cations induced birefringence have been investigated. The birefringence of a series of lead borates (PbBa2(B3O6)2、Pb2BO3F、Pb2B5O9Cl and PbB4O7) using first-principles and real-space atom-cutting methods. The results show that (1), the contribution to birefringence of lead cations has relation with the intensity of the stereochemical activity of lead cations, the larger the intensity of the stereochemical activity are, the more contribution to birefringence the lead cations give; (2), the degree of the stereochemical activity of lead cations has relation with the oxygen atoms the lead cations interconnected with.
文献类型学位论文
条目标识符http://ir.xjipc.cas.cn/handle/365002/4231
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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井群. 镉/铅硼酸盐中阳离子对光学效应影响的DFT研究[D]. 北京. 中国科学院大学,2015.
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