Formation of two distributions of nanoparticles of a new phase in a solid solution

Processes of the formation of the double distribution of CuCl nanoparticles in glass in two-stage annealing have been analyzed. The distribution of CuCl nanoparticles with the average radius $R_1 = 14$ and $18$ nm appears in $20$ and $40$ min at temperature $T_1 = 700\,^\circ\mathrm{C}$ in samples 1 and 2, respectively. By this time, the formation of new clusters ends, and only the growth of previously formed clusters occurs (the second stage of nucleation). Then, the formation of the CuCl phase continues at $T_2 = 500\,^\circ\mathrm{C}$. A decrease in the temperature is accompanied by a decrease in the critical radius of particles of a new phase. For this reason, the formation and growth of new CuCl nuclei begin again and the second distribution with a mean radius of $1$ nm or larger is formed. As a result, double distributions of CuCl nanoparticles with significantly different mean radii are formed in samples 1 and 2. The concentration and mean radius of CuCl particles in distributions have been determined from the optical absorption spectra of CuCl nanocrystals at $80$ K in the wavelength range of $300$–$500$ nm.