Formation of silicon nanoclusters upon disproportionation of silicon monoxide

In this work, the processes of disproportionation of solid-phase silicon monoxide, accompanied by the formation of nanocrystalline silicon precipitates in the medium of amorphous SiO$_x$ suboxide (initial composition SiO$_{0.9}$), have been studied. Based on the data of X-ray diffraction analysis and transmission electron microscopy, the dynamics of changes in the amount, concentration and size of phase precipitates of silicon with an increase in the temperature of isochronous annealing from 800$ ^{\circ}$C to 1200$^{\circ}$C is traced. It was found that with a monotonic increase in the total mass of the precipitated silicon, the number of its crystallization centers per unit volume nonmonotonically depends on temperature. The activation energy of diffusion of silicon atoms in the SiO$_x$ matrix was determined to be $E_{a1}$ = 1.64 eV, and the activation energy of their transfer from the formed precipitates to the growth medium of SiO$_x$ was $E_{a2}$ = 2.38 eV. Anisotropic deformation of silicon crystallites precipitated during the disproportionation of SiO has been revealed for the first time. This phenomenon is associated with the difference in the specific volumes of the separated phases and the anisotropy of the growth rate of silicon precipitates formed in a solid amorphous medium.