Accession Number:

AD0633102

Title:

ULTRASONIC ATTENUATION IN SODIUM AT LOW TEMPERATURES.

Descriptive Note:

Technical rept.,

Corporate Author:

CALIFORNIA UNIV LOS ANGELES DEPT OF PHYSICS

Personal Author(s):

Report Date:

1964-08-01

Pagination or Media Count:

133.0

Abstract:

The ultrasonic attenuation in a wire sample of sodium was measured by pulse-echo and resonant techniques over a temperature range of 2 -77K at frequencies of 200-300 kc in order to investigate the effects of the martensitic transformation and the electron-lattice interaction. The onset of the transformation into the h.c.p. structure was indicated by an increase in the attenuation which then decreased as absolute zero was approached. The attenuation displayed a large temperature hysteresis, reverting irreversibly into the high temperature phase, b.c.c. at about 52K. Qualitative agreement with theory was found for the electron-lattice interaction. A metastable state of sodium was formed during extrusion of the sodium wire at liquid nitrogen temperatures which consisted of body-centered cubic and hexagonal close-packed structures as evidenced by ultrasonic velocity, specific heat and x-ray diffraction experiments. The reversion temperature for the metastable state was about 116K at which point it reverted into the b.c.c. structure usually seen at this temperature. Author

Subject Categories:

  • Solid State Physics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE