B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 47 Lenin Ave., Kharkov 61103, Ukraine
Received November 24, 2006, revised January 5, 2007
Precise measurements of the temperature dependence of pressure were carried out on high quality crystals of 4He and 3He-4He solutions grown under constant volume conditions. The phonon and vacancy contributions to pressure were estimated within Debye`s model of phonons and the model of wide band vacancions. The other available thermodynamic data were analyzed for pure solid helium isotopes and their solutions using this approch. The Debye temperatures and vacancy activation energies have been obtained and the universal molar volume dependence of these parameters has been found for 3He, 4He and 3He-4He solutions. The corresponding Grüneisen parameters have been obtained, which appear to be independent of the molar volume.
PACS: 67.80.-s Solid helium and related quantum crystals; PACS: 67.57.Bc Thermodynamic properties; PACS: 67.80.Cx Structure, lattice dynamics, and sound propagation.