Vacancy-impurity nanoclusters in solid solutions 3He- 4He

Abstract

Structural effects streaming from the quantum nature of the vacancies in solid helium are considered. As known, the point defects in quantum crystals are delocallized and turn into quasiparticles – defectons (vacancions, impuritons etc). An important feature is that the bottom of the quasiparticle energy band lies lower compared to the activation energy of a localized defect – as a rule by a half band width. However, the delocalization requires good periodicity and identity of the atoms around the defect. This may result both in repulsion between a vacancy and impurities, and in attraction between them. This leads to different effects – removal of impurities, new type of vacancy-impurity nanoclusters, creation of nuclei of new phases,vacancy induced local phase transition, change in the phase separation line in solid solutions. Experimental results are analyzed.