Nikolay E. Dyumin

Vacancy formation volume in BCC 3He along the melting curve

Abstract The value of the vacancy formation volume is obtained near the melting curve in BCC solid 3He in the temperature range 0.5–2.7 K for molar volumes 19.32– 24.60 cm 3 / mol . The data are obtained both by measuring the temperature dependence of the self-diffusion coefficient in 3He crystals at various densities and by use of the NMR data obtained by H.A. Reich. The value of the vacancy formation volume is in disagreement with the values calculated from the standard thermodynamical relation.

Isobaric vacancy formation volume in bcc 3He

The value of vacancy volume formation are obtained in bcc crystall3He at the temperature 0.5-0.66 K, and at molar volume 24,20 - 24,72 cm3/mole range. This data are obtained by measuring the pressure dependence of self-diffusion coefficient. The volume of formation is in agreement with the values calculated from theory, under assuming of existing the wide-zone tunneling motion in bcc3He.

Diffusion flow of solid3He

The diffusion flow in bcc crystals of3He is measured for few molar volumes. The self-diffusion coefficient of3He is determined in the temperature range 0.45–0.75 K, along with the vacancy diffusion coefficient which is found to be temperature independent. The effects observed are due to tunneling motion of heat vacancies in the helium crystals investigated.

Self-diffusion in4He crystals

Abstract The self-diffusion coefficient Ds of an atom is measured in low-density bcc and hcp4He crystals at 1.3–1.7 K. It is shown that the experimental Ds can be described in the frames of the vacancy quantum diffusion. The energy gap and the energy band width of the vacancion have been determined.