Density of solid krypton at melting and isochoric equation of state of solid krypton and solid argon

Lattice parameters for crystalline krypton along its melting line are reported with an estimated experimental uncertainty (r.m.s.) of 27 ppm. The X-ray data span the range of melting temperatures from 127.3 to 138.9 K. These data and similarly precise melting line lattice parameters for argon which have already been reported are used to obtain values for (∂P/∂T)v. These span the range of volumes ≧ 1 cm3/mol below the triple point volume, and most are ten times more precise than any values reported heretofore. They are in excellent agreement with existing isochoric equation of state data and yield new high precision values for X-ray compressibilities at high temperatures along the sublimation curves of argon and krypton. Values for the isochoric temperature derivative of the isothermal bulk modulus are also obtained.