Homogeneous nucleation in phase separation of solid 3He– 4He mixtures

Abstract

NMR and pressure have been measured during phase separation in solid 3 He – 4 He mixtures. Spin echoes were used to observe bounded diffusion and to estimate the diffusion coefficient, size and nuclei concentration in the 3 He -enriched phase. The characteristic phase separation time constant of the mixture was found from pressure measurements. The results argue convincingly for homogeneous nucleation. The surface tension of the nuclei is found independently from NMR and from pressure measurements; the two determinations agree well and yield a surface tension coefficient of 4.9×10 −6 J m −2 .