THE FORMATION OF INTERSTITIALS AND VACANCIES IN ALKALI HALIDES

Journal Article · Sun Jan 01 04:00:00 EST 1961 · Discussions Faraday Soc.

DOI:https://doi.org/10.1039/df9613100151· OSTI ID:4796248

Smoluchowski, R; Wiegand, D A

Alkali halide crystals were x-irradiated under a variety of conditions and the volume expansion and optical absorption studied. At low temperatures both LiF and NaCl were found to expand on irradiation. However, on warming to room temperature, at least two stages of annealing are observed for LiF, while none were found for NaCl. LiF also differs appreciably from KCl and NaCl in the dependence ot F-centre formation at room temperature on intensity of irradiation and sensitivity to plastic deformation. It can be deduced from these results that similar defects may not be generated in all alkali halides in significant densities by x irradtation and that more than one mechanism of defect generation may be important. A possible mechanism of defect generation is considered in which halogen vacancy-interstitial pairs are produced hy multiple ionization. The collision of, for example, a Cl/sup +/ with a Cl/sup -/ leads to the formation of a Cl/sup +/ Cl/sup -/ molecule. By a de-excitation exchange, the electronic energy of this state is converted into several ev of repulsive kinetic energy. This kinetic energy is sufficient to form, possibly with the help of focused collisions, a halogen vacancy and an interstitial separated by many lattice parameters. The efficiency of multiple ionization by Auger effect is estimated for KCl and found to be consistent with the reported F-centre formation rate at low temperatures. (auth)

• Research Organization: Princeton Univ., N.J.
• NSA Number: NSA-16-013658
• OSTI ID: 4796248
• Journal Information: Discussions Faraday Soc., Journal Name: Discussions Faraday Soc. Vol. Vol: No. 31
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ABSORPTION
ALKALI METALS
ANNEALING
AUGER EFFECT
CHLORINE
COLLISIONS
CRYSTALS
DEFECTS
DEFORMATION
EFFICIENCY
ELECTRONS
ENERGY
EXCITATION
EXPANSION
FRANCE
HALIDES
HALOGENS
HEATING
INTERACTIONS
INTERSTITIALS
IONIZATION
IONS
IRRADIATION
LATTICES
LIGHT
LITHIUM FLUORIDES
LOW TEMPERATURE
METALS, CERAMICS, AND OTHER MATERIALS
MOLECULES
POTASSIUM CHLORIDES
RADIATION EFFECTS
SENSITIVITY
SODIUM CHLORIDES
VACANCIES
X RADIATION