【作者】 于大秋；

【导师】 薛冬峰；

【作者基本信息】 大连理工大学 ， 化学工艺， 2008， 博士

【摘要】 随着功能材料研究的不断发展,人们越来越关注决定材料性能的内在因素。化学键方法是一种研究晶体结构与性能关系的重要手段,在功能材料的结构评价和性能预测以及新型材料的设计中具有广泛的应用价值。论文从晶体的微观特征入手,将化学键方法应用于硼酸盐晶体和氢键性质的研究当中。硼酸盐晶体具有优良的非线性光学（NLO）性质,这与其种类繁多的聚阴离子基团结构密切相关,化学键参数d₀能够反映中心阳离子在不同晶体结构框架中化学键合行为的微观差异,基于此观点,论文较系统地计算了758个硼酸盐晶体结构中B-O键的参数d₀。结果表明,基本结构单元（FBBs）的详细构型、含水与否以及卤素离子或其它阴离子基团的存在都会影响d₀值。于是针对不同类型的FBBs,分别推荐了合适的d₀参数。由于参数d₀与硼酸盐晶体的最大NLO张量系数之间具有协同的变化趋势,因此可以作为判断和预测硼酸盐NLO性质乃至设计新型硼酸盐晶体的有用参数。含水硼酸盐结构中存在着大量的氢键,对晶体的NLO性质具有重要的贡献。为了揭示氢键对材料性能的影响,充分发挥其作为功能键的作用,论文研究了含水硼酸盐晶体中的二中心O-H…O氢键。基于较强的O-H和较弱的H…O键是两种不同类型的键,具有不同的化学键参数d₀这一基本思想,从氢键的静电作用和几何构型出发,以两种不同的方法（即库仑定律和黄金比率）,计算了O-H和H…O键的参数d₀,得到了参数d₀与相应键长的线性拟合函数,并用以调控晶体结构的堆积方式和改善晶体的电光性质,提出了该函数在含氢键的硼酸盐晶体设计中的应用模式。论文进一步将氢键的研究拓展到各种无机晶体的多中心O-H…O体系,构建了真实键合环境下氢键体系的势能函数。分别拟合了反映不同键长敏感性的多项式函数,用于计算O-H和H…O的键价,并通过评价中心氢原子、质子给予体和接受体氧原子的键价和,证实了函数的合理性。同时,细致分析了O-H和H…O键的相互作用能,也考察了力常数和振动频率与几何参数之间的关系。这种基于能量的氢键分析方法能够很容易地推广到其它同核体系,有望应用于异核体系的研究中。论文通过对复杂O-H…O作用的简化,计算了氢键的键价,阐述了氢键体系的微观特征,从能量角度定量地分析和认识了晶体中的氢键作用,也为如何有效运用氢键进行功能材料的设计提供了指导。更多还原

【Abstract】 With the increasing development in the study of functional materials,more and more attentions are paid on the internal factors that determine materials properties.The chemical bond method provides an important tool for studying the relationship between the crystal structure and properties,which is widely applied to the structural evaluation and property prediction of functional materials,and even offers some valuable information for further materials design.On the basis of the microscopic characteristics of crystals,this thesis exploringly applies the chemical bond method to the study of borates and hydrogen bonds.Borates possess excellent nonlinear optical（NLO） properties,which are strongly related to their various structural configurations.The discrepancy of the chemical bonding parameters d₀ should not be ignored when investigating the microscopic structures of borate crystals, which reflects the chemical bonding behaviors of central cations in the crystallographic framework.Therefore,the parameters d₀ of B-O bonds were systematically calculated in the 758 investigated oxoborates.By considering the factors that influence the d₀ parameters, including the detailed configurations of borate fundamental building blocks（FBBs）, anhydrous or hydrous,the interstitial halogen anions and the substitution of other anionic groups,more precise d₀ data were recommended for various kinds of FBBs.On the basis of the cooperative trend between the d₀ parameter of various FBBs and the calculated largest NLO tensor coefficient of different borates,d₀ values for the unique configuration of FBBs may serve as a useful parameter for pre-investigating the NLO properties of borates,and even for designing novel borate crystals.Hydrogen bonds widely exist in hydrated borates,and often have dominant NLO contributions to the total nonlinearity of crystals.Two-center O-H…O hydrogen bonds in hydrated borates were investigated,in order to reveal their effect on materials properties and further effectively utilize them as functional bonds.With the notion that the stronger O-H and the weaker H…O bonds are two different types of bonds and should have different chemical bonding parameters d₀,two different approaches,respectively basing on the electrostatic interaction（Coulomb’s law） and geometric configuration（Golden ratio）,were used to calculate d₀ values.The linear correlation between the parameter d₀ and the corresponding bond length was found,which can be employed in the structural design of borate crystals with hydrogen bonds by tuning the structural packing or modifying the electric and optical properties.With deeper studying of general systems beyond the limit of borates,the potential energy function that reflects the actual bonding environment was successfully constructed for a variety of homonuclear O-H…O hydrogen bonds in inorganic solids,including two-center, three-center and multicenter types.Two polynomial functions exhibiting different length sensitivities were respectively proposed for the bond valence calculation of O-H and H…O bonds,the validity of which was proved by evaluating the bond valence sums around not only the central H atoms but also the proton donor and acceptor O atoms in O-H…O systems.The interaction energies of O-H and H…O bonds were analyzed in detail,and the geometric parameters were also connected to the force constants and stretching frequencies of hydrogen bonds.This analysis method from the energy viewpoint can be readily extended to other systems of homonuclear hydrogen bonds,and may be hopefully applied in heteronuclear systems.Due to the simplification of complicated O-H…O interactions,the bond valences were calculated and then the microscopic interactions were studied in hydrogen bond systems. Therefore,this work may shed light on understanding the underlying nature of hydrogen bonds in the actual crystals on the basis of the quantitative analysis of energy,which may also give people some exciting advances to reasonably analyze and employ O-H…O hydrogen bonds in inorganic solids.更多还原