A linear variation of the thermal expansivity with the isothermal compressibility for ammonia solid III near the melting point

The thermal expansivity alpha (p) is related to isothermal compressibility kappa (T) at various pressures for constant temperatures of 254.6, 274 and 297.5 K close to the melting pressure in ammonia solid III. By analyzing the experimental data for kappa (T) according to a power-law formula, a linear variation of alpha (p) with the kappa (T) is established here close to the solid-liquid transition in ammonia. Anomalous behavior of thermal expansivity alpha (p) and the isothermal compressibility kappa (T) near the melting pressure is indicative of the lambda-type transition in ammonia solid III