RADIATION EXPANSION AND THERMAL EXPANSION IN X-RAYED ROCKSALT

Technical Report · Tue Nov 01 04:00:00 EST 1960

OSTI ID:4114189

Merriam, M F

The volume expansion of NaCl heavily irradiated at room temperature with penetrating x rays was studied with a photoelastic technique. In the course of the study a new effect was found: the coefficient of thermal expansion of NaCl is increased by irradiation. The magnitude of the fractional increase in expansion coefficient is about fourteen times the concentration of radiation induced defects, as measured by the volume expansion. Typically, this increase is a fraction of 1 per cent. Its algebraic sign and approximate magnitude is predicted on general thermodynamic grounds. The increase in expansion coefficient seems to be correlated only with the total concentration of point lattice defects, and is rather insensitive to their electronic state or spatial distribution. The growth and annealing of the volume expansion have been measured, and correlated with the growth and annealing of the optical absorption. The volume expansion increases linearly with time for short irradiation times at a rate consistent with that implied by the F center growth curve on the basis of Mitchell's interpretation. The annealing of the volume expansion and optical absorption is in general agreement with the earlier results of Kobayashi. Interpretation of the annealing data is difficult if the Varley mechanism of vacancy generation is assumed. There is some evidence that the initial annealing of the volume expansion is limited by diffusion of negative ion vacancies. An interesting surface feature, apparently connected with the radiation, was observed on several samples. (auth)

• Research Organization: Carnegie Inst. of Tech., Pittsburgh
• NSA Number: NSA-15-007853
• OSTI ID: 4114189
• Report Number(s): TID-11502
• Country of Publication: United States
• Language: English

Related Subjects

ABSORPTION
ANNEALING
CRYSTALS
DEFECTS
EXPANSION
F CENTERS
HEATING
IONS
IRRADIATION
LATTICES
LIGHT
METALS, CERAMICS, AND OTHER MATERIALS
MOTION
QUANTITY RATIO
RADIATION EFFECTS
ROCKS
SALTS
SODIUM CHLORIDES
THERMODYNAMICS
VACANCIES
X RADIATION