Stages of Homogeneous Nucleation in Solid Isotopic Helium Mixtures

TL;DR

This study investigates the homogeneous nucleation process in solid helium isotopic mixtures through pressure and NMR measurements, identifying all three stages and confirming the coarsening mechanism aligns with Lifshitz-Slezov theory.

Contribution

It provides experimental evidence of all three stages of homogeneous nucleation in solid helium mixtures and confirms the coarsening mechanism matches theoretical predictions.

Findings

Identification of all three nucleation stages

Confirmation of the Lifshitz-Slezov coarsening exponent

Pressure and NMR measurements effectively track phase separation

Abstract

We have made pressure and NMR measurements during the evolution of phase separation in solid helium isotopic mixtures. Our observations indicate clearly all three stages of the homogeneous nucleation - growth process: 1) creation of nucleation sites; 2) growth of the new-phase component at these nucleation sites; and 3) coarsening: the dissolution of sub-critical droplets with the consequent further late-stage growth of the super-critical droplets. The time exponent for the coarsening, a = 1/3, is consistent with the conserved order parameter Lifshitz-Slezov evaporation-condensation mechanism.