Low Temperature Physics: 32, 1072 (2006); https://doi.org/10.1063/1.2389014 (4 pages)
Физика Низких Температур: Том 32, Выпуск 11 (Ноябрь 2006), c. 1408-1413    ( к оглавлению , назад )

Lattice distortion of quantum cryocrystals under pressure

S.M. Tretyak, T.N. Antsygina, and Yu.A. Freiman

B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine, 47 Lenin Ave., Kharkov 61103, Ukraine
E-mail: freiman@ilt.kharkov.ua

Received July 19, 2006

Аннотация

The hcp lattice distortion parameter d, the deviation of c/a ratio from the ideal hcp value √8̅/̅3̅ , have been calculated for solid He under pressure taking into account two- and three-body interatomic forces. The resulting lattice distortion parameter is small and negative, that is the lattice is slightly flattened compared with the ideal hcp lattice. It monotonically increases in absolute value with pressure and reaches 10–3 for molar volume of ~ 2.5 cm3/mol. Such small distrotions are most likely outside of possibilities of x-ray or neutron experiments but can be detected by optical methods based on measurements of the birefringence. The data on d can be used as a probe of the many-body forces.

PACS:
64.60.Cn - Order-disorder transformations; statistical mechanics of model systems
67.80.-s - Solid helium and related quantum crystals
67.90.+z - Other topics in quantum fluids and solids; liquid and solid helium (restricted to new topics in section 67)
81.40.Vw - Pressure treatment (see also 62.50.+p High-pressure and shock-wave effects in solids and liquids)

Ключевые слова: quantum cryocrystals, rare gas solids, lattice distortion parameter.