Pippard relations for cubic gauche nitrogen

The Pippard relations (C P vs. a P and a P vs. k T ) are examined at various temperatures up to 1200 K at zero pressure (P = 0) for the cubic gauche nitrogen. The specific heat (C P ) is related to the thermal expansion ( a P ) and the a P is also related to the isothermal compressibility ( k T ) as the Pippard relations for this solid structure. For those relations, experimental data are used from the literature. It is found that the variation of the C P with the a P and a P with the k T is linear. Using the linear relations dP/dT is predicted, which can be compared with the experimental measurements in the P – T phase diagram of cubic gauche nitrogen.