Anomalous elastic and inelastic properties of the Co$_{x}$(CaF$_{2}$)$_{100-x}$ nanogranular composites

Elastic $(G)$ and inelastic $(Q^{-1})$ properties of the Co$_{x}$(CaF$_{2}$)$_{100-x}$ ($x$ = 41–84 at %) nanocomposites fabricated with the aid of ion-beam sputtering are studied in a temperature interval of 170–750 K. Maximum internal friction related to hopping of Co atoms inside metal granules is revealed at a temperature of 227 K. It is shown that the maxima increase with increasing concentration of metal phase. A noticeable increase in dependence $Q^{-1}(T)$ at a temperature of greater than 675 K is caused by diffusion of vacancies in the Co granules under geometrical confinements.