【作者】 丁钟生；

【导师】 李克艳； 薛冬峰；

【作者基本信息】 大连理工大学 ， 功能材料化学与化工， 2011， 硕士

【摘要】 材料是在一定条件下原子的自组装形成的,因此材料的性质是由原子之间的相互作用决定的。电负性是描述原子性质的一个重要参数,它表示“分子中的原子将电子吸引向自身的能力”。材料、物理、化学学科的融合,使得电负性能够成为建立材料微观结构和宏观性质之间定量关系的一种工具。超硬材料由于重要的工业用途而备受人们关注,具有较高硬度的物质一般都具有较大的体积模量,因此研究晶体的体积模量对于超硬材料的研究有着重要的意义。本论文从电负性的观点出发,研究了无机晶体材料的体积模量。晶体的体积模量反映了晶体对外界均一性压缩的抵抗能力,本质上由化学键对外界压缩的抵抗能力决定。基于电负性,我们确立了两个参数来描述化学键抵抗外界压缩的能力—键模量和有效离子性,建立了计算简单晶体体积模量的模型。我们发现对于阳离子具有较高价态的物质,晶体的体积模量主要由键模量决定；对于阳离子显示较低价态的物质,晶体的体积模量是由键模量和有效离子性共同决定。简单ANB8-N型晶体、氧化物和氮化物晶体的体积模量计算值和实验值吻合的很好。考虑到复杂晶体和合金本质上是由多种不同类型的键组成的,把计算简单晶体体积模量的模型扩展到复杂晶体和合金领域。根据复杂晶体中化学键间的键强差不同,我们提出了计算复杂晶体体积模量的方法。对于键强差较小的物质,晶体的体积模量是由化学键对外界压缩的平均抵抗能力决定的；对于键强差较大的物质,晶体的体积模量是由较弱化学键对外界压缩的抵抗能力决定的。黄铜矿晶体、含氧尖晶石和含氮尖晶石、不同晶体结构的ABO4型化合物的体积模量计算结果与实验值吻合,证实了我们计算晶体材料体积模量模型的有效性。另外,根据该模型我们还预测了一些低压缩性的晶体。更多还原

【Abstract】 The macroscopic properties are determined by the actions between atoms because materials are formed through the self-assembly of atoms in certain conditions. Electronegativity (EN) is an important parameter to scale atomic property, which was defined as "the power of an atom in a molecule to attract electrons to itself". EN is a useful tool to establish the relations between the microscopic structure and the macroscopic properties due to the combination of the subjects of material, physics, and chemistry. On the other hand, much attention is focused on superhard materials due to their importance in industry. It is of significance to investigate the bulk modulus of crystals due to the fact that superhard materials often possess large bulk modulus. The purpose of this thesis is to investigate the bulk modulus of inorganic crystals from the viewpoint of EN.The bulk modulus of crystals reflects the resisting ability of crystals to uniform compression, which is essentially determined by the resisting ability of chemical bonds to compression. Two key parameters, bond modulus and effective ionicity, are used to describe the resisting ability of chemical bonds to compression on the basis of EN. Further, we proposed a model to calculate the bulk moduli of simple crystals. We found that the bulk modulus of crystals is mainly determined by bond modulus for compounds of high cationic valences while that is determined by both of bond modulus and effective ionicity for compounds of low cationic valences. The calculated bulk moduli of ANB8-N crystals, oxides and nitrides agree well with the experimental values.The model of calculating the bulk moduli of simple crystals is extended to estimate the bulk moduli of complex crystals and alloys, which are composed of different types of chemical bonds. We proposed the calculation procedures of the bulk moduli of complex compounds on the basis of bond strength difference between different bonds. For compounds of small bond strength difference, the bulk modulus is determined by the average resisting ability of chemical bonds to compression while for that of large bond strength difference, the bulk modulus is determined by the resisting ability of weaker bonds to compression. The consistency between the calculated bulk moduli and the experimental data of chalcopyrites, spinels, and ABO4 compounds confirms this model. Based on this model, we also predicted some low compressibility crystals.更多还原