Accession Number : AD0614520

Title :   THE SPECIFIC HEATS BELOW 320K OF POTASSIUM, RUBIDIUM AND CAESIUM,

Corporate Author : NATIONAL RESEARCH COUNCIL OF CANADA OTTAWA (ONTARIO) DIV OF PURE PHYSICS

Personal Author(s) : Filby,J. D. ; Martin,Douglas L.

Report Date : 28 MAY 1964

Pagination or Media Count : 25

Abstract : The specific heat of potassium was measured in the range 0.4 to 26K and the specific heats of rubidium and caesium in the range 0.4 to 320K. Previously reported specific heat anomalies in the range 100 to 300K were not confirmed. A slow release of energy dependent on thermal history, was observed from rubidium and caesium in the region of 4K and may correspond to the annealing out of defects introduced by plastic strain on cooling. Positive anharmonic contributions to the specific heat are evident at high temperatures and an additional contribution to the specific heat becomes apparent from about 50K below the melting point and may be identified with the thermal generation of lattice vacancies. The melting point of pure rubidium is estimated as 312.65=0.01K and the latent heat of fusion as 524.3=1.0 cal/gatom. For caesium the melting point is 301.55+0.01K and, with some assumptions, the latent heat is 498.9=0.5 cal/gatom. For both metals the specific heat of the liquid decreases with increasing temperature. (Author)

Descriptors :   (*POTASSIUM, SPECIFIC HEAT), (*RUBIDIUM, SPECIFIC HEAT), (*CESIUM, SPECIFIC HEAT), CRYOGENICS, LOW TEMPERATURE, MEASUREMENT, MELTING

Distribution Statement : APPROVED FOR PUBLIC RELEASE