Recent topics on lattice defects

Recent topics on lattice defects are reviewed. Positron annihilation has been used for the determination of the Fermi surface of alloys. Study of lattice defects is also possible with the phenomena of positron annihilation, since the probability of pair annihilation of electron and positron trapped at vacancy is small. Study of radiation damage can be made with super high voltage electron microscopes. Precise discussion on the kinematics of recovery of the point defects due to radiation has become to be made. The anisotropy of ejection energy will be determinable. Dynamic theory of dislocations has been developed. A theory for phonon scattering by vibrating dislocations was compared with experiment. The uniform motion of dislocations in crystal, and the interaction of dislocations and conductive electrons have been studied. Behavior of the lattice defects in quantum solid was investigated. The vacancy in it is named as defection, and the state is designated by quasimomentum K. Dislocations in solid helium was studied. The theory of dislocations of liquid and noncrystalline substances in also introduced. (Kato, T.)