点欠陥

point defect

[目次：結晶等(結晶構造／材料試料)]

原子サイズの欠陥のこと。特に、格子点に原子がいない場合を(原子）空孔（vacancy）という。格子点でないところに原子が入り込んだ場合を格子間原子（interstitial）という。空孔は熱平衡状態で存在し、原子の拡散に重要な役割を果たす。格子間原子は不純物原子であることもあるが、高エネルギー粒子を結晶に照射すると格子点の原子が弾き飛ばされてできる。後者の場合、格子間原子は動きやすいので、空孔と再結合して消えることが起こりやすい。

"Point defect" is defined as atomic-size defect. In particular, when no atom exists at a lattice point, this defect is called "vacancy type point defect." On the other hand, when an atom is introduced into a position other than a lattice point, the defect is termed "interstitial type point defect." Vacancies can exist in a crystal at the thermal equilibrium state and play an important role for diffusion of atoms. Interstitial atoms are normally impurity atoms, but they can be the same atoms of the crystal when the atoms at the lattice points are ejected by irradiating the crystal with high-energy particles. In the latter case, since the interstitial atoms are easy to move, the atoms are likely to disappear by recombination with vacancies.