The heat capacity and derived thermophysical properties of the highTCsuperconductor YBa2Cu3O7minus;dgr;from 5.3 to 350 K

摘要

The heat capacity of the perovskite highhyphen;TCsuperconductor YBa2Cu3O7minus;dgr;was measured from 5.3 to 350 K in an adiabatic calorimetric cryostat. A break in the heathyphen;capacity curve, associated with the critical temperature for superconductivity was observed between 90.09 and 92.59 K. The transition temperature was identified as 91.44 K, and Dgr;Cp,mwas calculated to be 0.559Rat that temperature. The lattice heat capacity was evaluated by means of the recently developed Komada/Westrum phonon distribution model and the apparent characteristic temperature THgr;KWwas calculated to be 107.7 K. The excess electronic heat capacity for the superconducting phase was evaluated and the energy gap was identified as 234.Rthinsp;K. Excess contribution, resulting from magnetic impurities, was noted below 20 K. Thermodynamic properties at selected temperatures are presented.