Temperature and pressure dependence of molar volume in solid phases of ammonia near the melting point

Temperature and pressure dependencies of the molar volume are studied here along the transition curve between solid I and solid II phases near the melting point in ammonia. The molar volumes are calculated in the temperature range of 217 to 224  K and in the pressure range of 3 to 8 kbar with respect to the triple point (T_t = 217.34 K, P_t = 3.070 kbar) where the melting curves of solid I and solid II coincide with the transition curve in ammonia.