Accession Number : AD0611968

Title :   THE THERMAL EXPANSION OF COPPER AT LOW TEMPERATURES,

Corporate Author : COMMONWEALTH SCIENTIFIC AND INDUSTRIAL RESEARCH ORGANIZATION NEW SOUTH WALES (AUSTRALIA)

Personal Author(s) : Carr,R. H. ; McCammon,R. D. ; White,G. K.

Report Date : 05 DEC 1963

Pagination or Media Count : 13

Abstract : The thermal expansion of copper has been determined at temperatures down to 2 K by means of an electrical capacitance technique. By measuring three-terminal capacitances in a ratio-transformer bridge length changes smaller than 10 to the minus 9 power cm can be detected in the capacitor-expansion cell. The linear expansion coefficient is given for below 10 K. These terms, identified respectively as electronic (e) and lattice (l) in origin, lead to the following values of the Gruneisen parameter: gamma sub e = 0.63=0.06, gamma sub l = 1.72=0.03 (= gamma sub 0). Gamma sub e is compared with a theoretical free-electron value of 2/3, and the low temperature value of gamma sub e is compared with values of 1.75 to 1.77 calculated from elastic constants. At room temperature gamma (approximately = gamma sub infinity) is 2.00, so that gamma sub infinity-gamma sub 0 approximately = 0.28, which agrees well with the theoretical estimates of Barron for a close-packed cubic lattice. (Author)

Descriptors :   (*COPPER, THERMAL EXPANSION), (*CRYOGENICS, COPPER), (*THERMAL EXPANSION, CRYOGENICS), AUSTRALIA, MEASUREMENT, DIFFERENTIAL EQUATIONS, THERMODYNAMICS, CAPACITANCE BRIDGES

Distribution Statement : APPROVED FOR PUBLIC RELEASE