文档介绍：课件下载: 课件下载 ./~zhaojin/ 晶格 The crystal lattice: Bravais lattice (3D) A Bravias lattice is a lattice of points, defined by This reflects the translational symmetry of the lattice 反映了晶格的平移对称性 Primitive cell 原胞?一个晶格的周期重复单元称作点阵的晶胞( unit cell) ,最小周期重复单元称作原胞( Primitive cell ) ?以点阵基矢构成平移矢量, 可以把原胞复制填满整个空间。以点阵基矢构成平移矢量, 可以把原胞复制填满整个空间。|a 1 | 、|a 2 | 、|a 3 | 被称为晶格常数( lattice constant) How to form acrystal ? ?We could think: all that remains to do is to put atoms on the lattice points of the Bravais lattice. 向晶格点阵上堆积原子向晶格点阵上堆积原子?But: not all crystals can be described by aBravais lattice (ionic, molecular, not even some crystals containing only one species of atoms.) 并不是所有的晶体都能够被晶格点阵简单描述,有时一种晶体包含有不同类型的原子。?BUT: all crystals can be described by bination of aBravais lattice and a basis This basis iswhat one “ puts on the lattice points ”所有的晶体都可以被 basis . This basis iswhat one puts on the lattice points . 所有的晶体都可以被描述为: 晶格点阵+ 基元,基元就是往点阵上堆积的东西晶面与晶向