The Effects of Irradiation of 100 keV Electrons on Alkali Halide Crystals; The Point Defect Coagulates in NaCl and KCl Irradiated at Room Temperature

Abstract

Thin films of KCl and NaCl single crystals prepared by chemical polishing were examined by an electron microscope. During the observation, the thin films were damaged by electron beam used for the image formation. As a result of electron irradiation at room temperature, plate shaped defects parallel to one of the {100} planes and elongated in one of the ⟨100⟩ directions were formed in both kinds of crystals. The maximum dimension of them was about 1 μ in long axis 1000∼3000 Å in short axis and ∼100 Å in thickness. It is supposed that these plates correspond to the small alkali metal colloids which were considered to be the origin of X-band absorption in the optical measurement, because the behaviour of the plates during heat treatment between room temperature and 300°C showed good agreement with that of the colloids.