CHEMICAL AND STERIC CONSTRAINTS IN INORGANIC SOLIDS
CHEMICAL AND STERIC CONSTRAINTS IN INORGANIC SOLIDS
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DOI：
10.1107/s0108768192002453
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发表时间：
1992-10-01
期刊：
影响因子：
--
通讯作者：
BROWN, ID
中科院分区：
文献类型：
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作者：
BROWN, ID
观察到的许多无机固体的结构是化学键合和三维几何形状之间相互冲突的要求的折衷结果。理想的化学结构和键的几何形状可以预测使用键价模型，这是在一些细节。当理想结构被映射到三维空间中时，对这种几何形状施加的约束在许多情况下要求理想键长是应变的。特别是在含有中等强度键的化合物（例如二价和三价阳离子的氧化物和卤化物）中，这种应变的松弛可能导致非化学计量、不寻常氧化态的稳定、键合环境的扭曲和对称性的降低。由此产生的丰富的晶体化学往往与重要的物理性质，如铁电性和超导性。给出的例子表明，这些属性可以，至少在某些情况下，直接从化学式通过考虑生成符合化学和空间约束的结构的问题。
The structures observed for many inorganic solids are the result of a compromise between the conflicting requirements of chemical bonding and three-dimensional geometry. The ideal chemical structure and bond geometry can be predicted using the bond-valence model which is developed in some detail. The constraints imposed on this geometry when the ideal structure is mapped into three-dimensional space require, in many cases, that ideal bond lengths be strained. Particularly in compounds containing bonds of intermediate strength (e.g. the oxides and halides of di- and trivalent cations), the relaxation of this strain can result in non-stoichiometry, stabilization of unusual oxidation states, distortion of bonding environments and lowering of symmetry. The resulting rich crystal chemistry is often associated with important physical properties such as ferroelectricity and superconductivity. Examples are given which show that these properties can, at least in some cases, be derived directly from the chemical formula by considering the problems of generating a structure that conforms to both the chemical and the spatial constraints.