Explanation

The normal arrangement of atoms in some areas of the crystal is broken, which is shown by the loss of some normal adjacent relations of some atoms. According to the difference in geometric morphology, crystal defect are generally divided into three categories: ① point defects, atomic scale lattice defects, such as vacancy, interstitial atoms and impurity atoms in crystal. It also includes very small complexes composed of these fundamental point defects, such as vacancy, vacancy solute component complexes; ② Line defect. It is characterized by very small scale in both directions. It is also called one-dimensional defect, such as dislocation in crystal; ③ Surface defects, characterized by small scales in only one direction, are also known as two-dimensional defects.

Classification