Heat capacity of hafnium mononitride from temperatures of 5 to 350 K: An estimation procedure

Abstract

Measurements of the heat capacity by quasi-adiabatic, intermittent energy increments from 5 to 350 K show small high heat-capacity anomalies near 7 and 10 K which are attributed to superconducting transitions seen by magnetic measurements on the same carefully synthesized and well-characterized sample of (Hf 0.934 Zr 0.057 )(N 0.97 ). Although no previous heat capacity measurements over the cryogenic region are known, the estimated 298.15 K standard entropy values ( S/R ) vary in the literature from about 200 per cent higher to 5 per cent lower than our measured value of (5.28±0.01)R −1 when the formula is represented as above. A simple scheme to represent and predict values based on both molar volumes and atomic masses for related materials is presented which seems more reliable on a limited sample than do others despite the intrusion of lanthanide contraction.