ISOTOPIC PHASE-SEPARATION AND DIFFUSION-P ROCESSES IN SOLID HE-3-HE-4MIXTURES

The kinetics of He-3 bcc phase growth during phase separation of hcp H e-3-He-4 mixtures with the initial He-3 concentration of 3.18% under p ressure of 3.7 MPa has been studied using the low frequency pulse NMR technique. The characteristic time tau of mixture decay during its ste p-like cooling into the metastable region has been measured. The value of tau is shown to monotonically decrease with lowering temperature a nd the attendant decrease in the equilibrium concentration of He-3 in the hcp phase. Possible reasons of the effect, in particular the role of a mass quantum diffusion, are discussed.