Accession Number : AD0282758

Title :   THERMODYNAMIC PROPERTIES OF ALUMINUM NEAR ITS SUPERCONDUCTING CRITICAL TEMPERATURE

Corporate Author : ILLINOIS UNIV URBANA

Personal Author(s) : HOPKINS,DON CARLOS

Report Date : 12 JAN 1962

Pagination or Media Count : 1

Abstract : The specific heat, latent heat and critical field of a single crystalline sphere of 99.995% pure Al have been measured simultaneously between 1.06 and 1.19 K. These quantities are thermodynamically related, but the evidence indicated a discrepancy between the critical field and specific heat much larger than the experimental uncertainty. However, the independently measured thermodynamic properties were found to be much more consistent than previously observed. The specific heat and critical field measurements were consistent with each other within experimental error, but the latent heat deviated by a small but experimentally significant amount from consistency with the other two measured quantities. The detailed shape of the specific heat curve near T sub c was also measured in a magnetic field less than 10 to the -3 power gauss with temperature intervals as fine as 18 x 10 to the -6 power K. Temperature changes as small as 5 x 10 to the -6 power K were detectable with power dissipation of .002 ergs/sec and time constant of 2.5 sec. The transition occurs at 1.180 ! .001 K with a smooth change in specific heat of 2.21 mjoule/mole degree which is complete in about 2 x 10 to the -3 power K. The width and shape of the transition were compared with a calculation based on temperature fluctuations. (Author)

Descriptors :   *ALUMINUM, LOW TEMPERATURE RESEARCH, MAGNETIC FIELDS, MATHEMATICAL ANALYSIS, MEASUREMENT, METAL CRYSTALS, PHASE STUDIES, SINGLE CRYSTALS, SPHERES, SUPERCONDUCTORS, TEST EQUIPMENT, TEST METHODS, TESTS, THEORY

Distribution Statement : APPROVED FOR PUBLIC RELEASE