Color Centers and the Flow Stress of LiF Single Crystals

Journal Article · Mon Jan 01 04:00:00 EST 1962 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.1702432· OSTI ID:4740611

Nadeau, John S.

Lithium fluoride crystals were exposed to cobalt-60 gamma radiation at 300 and 78 deg K. Changes of the flow stress and of the optical absorption were measured in an effort to relate the hardening to identifiable color centers. In crystals irradiated at 300 deg K there was found to be a correlation between the flow stress and the concentration of F centers. The magnitude of the hardening, however, suggested that the correlation was caused by interstitial defects. Comparison of the hardening produced by additive coloring with that produced by irradiation indicated that the hardening defects were interstitial fluorines. This direct relation between intersti tials and F centers was related to the mechanism for F-center production in the bulk crystal. Some limited experiments with NaCl and KCl showed qualitatively the same behavior. Irradiation of LiF at 78 deg K produced stable trapped-hole centers, and pulse-annealing experiments showed that the V/sub k/ center (self-trapped hole) contributed to the hardness at low temperatures. A sharp decrease of flow stress was observed at about 110 deg K where paramagnetic resonance experiments and optical measurements indicated disappearance of the V/sub k/ center.

• Research Organization: General Electric Research Lab., Schenectady, N.Y.
• Sponsoring Organization: USDOE
• NSA Number: NSA-17-005000
• OSTI ID: 4740611
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 12 Vol. 33; ISSN JAPIAU; ISSN 0021-8979
• Publisher: American Institute of Physics (AIP)
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANNEALING
COLOR
COLOR CENTERS
DEFECTS
DEFORMATION
FLOW STRESS
FLUORINE
HARDNESS
INTERSTITIALS
IRRADIATION
LATTICES
LIGHT
LITHIUM FLUORIDES
MAGNETIC RESONANCE
MEASURED VALUES
MONOCRYSTALS
POTASSIUM CHLORIDES
SODIUM CHLORIDES
STRESSES
VACANCIES