Evidence of Homogeneous Nucleation at Phase Separation in Solid Mixtures of ⁴He in ³He

Abstract

A generalized relation for the characteristic time constants of mixture separation was found in the framework of the homogeneous nucleation theory. It allows us to describe the data on the separation kinetics at various concentrations c, molar volumes, and supercooling levels. Using precise pressure measurements, the separation time constants were obtained for 5 samples with the ⁴He concentration of 2.2–3.34% in the pressure range 31.5–38.6 bar. The data obtained for all the samples are in good agreement with the generalized relation if the impurity diffusion coefficient is proportional to c ^−4/3. The value of surface tension on the inclusion boundary was estimated from comparison between experiment and theory. It is in adequate agreement with the data obtained in other experiments. The obtained resugts are considered as evidence of homogeneous nucleation at phase separation of solid³He-⁴He mixtures.