Basic knowledge of Crystallography Space lattice and unit cell

The Concept of Crystals

Crystallography is a natural science with crystals as its research object. The continuous development of science and technology has gradually deepened people's understanding of crystals. Crystals are particles (atoms, molecules, or ions) with periodic

A solid arranged in a regular manner in three-dimensional space through sexual repetition, or a crystal is a solid with a lattice structure.

Spatial lattice and crystal cell

In the crystal structure, such points will be found, occupying the same position and having the same environment in the crystal structure, called equivalent points. According to the definition of crystal, it can be seen from the crystal junction

The series of equivalent points found in the structure must be periodically repeated in three-dimensional space. The geometric points arranged periodically in three-dimensional space are called a spatial lattice, and the geometric points or equivalent points in the spatial lattice are called matrix or nodes. Therefore, corresponding to each crystal structure, a corresponding spatial lattice can be created, and the arrangement of nodes in the lattice reflects the repetitive pattern of particle arrangement on the corresponding nodes. Different crystals can have different structures, and the corresponding spatial lattice can also be different, but their differences only lie in the direction and spacing of the nodes that generate repetition.

A spatial lattice is actually a geometric figure abstracted from a crystal structure. The so-called abstraction is to remove non essential secondary things and extract essential things that can reflect the commonality of matter. In the NaCl crystal structure, removing cI or Na+leaves behind massless geometric points. The process of connecting these geometric points into spatial lattice construction is an abstract process. The nodes in a spatial lattice are only geometric points, not specific particles (ions or atoms). A spatial lattice is an infinite geometric figure, while for actual crystals, the particles that make up the interior of the crystal are atoms or ions with actual content. Therefore, the regularity of the spatial distribution of particles in the spatial lattice characterizes the regularity of the specific particle arrangement in the crystal lattice structure.

In order to explain the rules and characteristics of the lattice arrangement, a representative basic unit (the smallest Parallelepiped) can be taken from the lattice as the constituent unit of the lattice, called the unit cell. The three-dimensional repeated stacking of crystal cells forms a spatial lattice. Research has shown that crystals can only form a limited number of spatial lattice structures in space, namely fourteen types of Bravi lattice structures. Zirconia ceramic

Website: https://www.zhengtaifeng.com/