Nanoclusters of 4He atoms.around vacancies in solid mixtures of 4He in 3He

The precision measurements of pressure in solid 4He-3He solutions were performed with cycling temperature within the phase separation region. As a result of the cycling, the pressure difference AP at the lowest (2 ~ 100 mK) and the highest (2~ 200 mK) temperatures is found to decrease 3 times and then to get stable DeltaP and the absolute pressure come back to their initial values only after heating of the sample up to a temperature considerably higher than the separation temperature. The results obtained are interpreted within the framework of the hypothesis that pure 4He clusters are formed around quasi-equilibrium vacancies under such conditions. The properties of these clusters are calculated thermodynamically. The calculation allows us to explain quantitatively the features observed. The cluster concentration found from the comparison with the experimental results is 8.105, and their radius is equal to 3 or 4 interatomic distances at low temperatures. The characteristic time to achieve the stationary state under these conditions is obtained. It is assumed that this time is conditioned by the processes at the cluster boundary.