J. Phys. Colloques
Volume 46, Numéro C10, Décembre 1985Eighth International Conference on Internal Friction and Ultrasonic Attenuation in Solids
|Page(s)||C10-87 - C10-90|
J. Phys. Colloques 46 (1985) C10-87-C10-90
LOW TEMPERATURE ULTRASONIC RELAXATION IN A DILUTE Ta-H ALLOYK.R. MASCHHOFF and A.V. GRANATO
Physics Department and Materials Research Laboratory, University of Illinois, 104 S. Goodwin, Urbana, IL 61801, U.S.A.
The ultrasonic attenuation of tantalum containing approximately 500 atomic ppm of hydrogen has been measured as a function of temperature below 5 K at frequencies between 10 and 55 MHz. In addition to hydrogen, the tantalum contains approximately 120 atomic ppm of carbon and 100 atomic ppm of oxygen interstitials. A peak in the attenuation in the C11 mode was found below 2 K. The peak is caused by the relaxation of hydrogen trapped near the carbon and/or oxygen impurities. No peak was seen in the C44 mode in the same temperature range. Similar relaxation processes have previously been observed in dilute Nb-O-H alloys, but the peak temperatures observed in those systems are higher than those observed in Ta.