THE HARDENING OF ALKALI-HALIDE CRYSTALS BY POINT DEFECTS

Journal Article · Fri Mar 01 04:00:00 EST 1963 · J. Phys. Soc. Japan

OSTI ID:4655874

Johnston, W G; Nadeau, J S; Fleischer, R L

The hardening of alkali-halide crystals by divalent impurities and by radiation-produced defects was studied in the temperature range of 20.5 to 300 deg K. The amount of hardening produced by small concentrations of divalent metal impurities, and the temperature dependence of the hardening depended sensitively on the state of dispersion of the impurities. At 20.5 deg K the greatest hardening was produced by divalent ion-vacancy pairs. At 300 deg K the greatest hardening was produced by impurity clusters in extremely slowly cooled crystals. From mechanical tests and optical studies of irradiated crystals it was deduced that the severe hardening produced at room temperature by x rays and gamma rays is due to the interstitial halogen ions that are formed when F-center vacancies are created. The V/sub K/-center (self-trapped hole) that is produced during irradiation at 77 deg K is also very effective in hardening LiF. The behavior of alkali halide crystals is compared with that of other materials in which severe hardening is produced by small concentrations of defects. The principal correlation is that all defects which produce severe hardening have non- symmetrical strain fields associated with them. The manner in which the non- symmetrical, or tetragonal strain can produce the great hardening is discussed. (auth)

• Research Organization: General Electric Research Lab., Schenectady, N.Y.
• NSA Number: NSA-17-035766
• OSTI ID: 4655874
• Journal Information: J. Phys. Soc. Japan, Journal Name: J. Phys. Soc. Japan Vol. Vol: 18: Suppl. I
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ALKALI METALS
CHEMISTRY
CONFIGURATION
CRYSTALS
DEFECTS
GAMMA RADIATION
HALIDES
HARDNESS
IMPURITIES
METALS
RADIATION EFFECTS
X RADIATION