Features of copper bromide nanocrystals formation in fluorophosphate glass

Formation of CuBr nanocrystals in fluorophosphate glass is investigated for the first time. The features of the nanocrystals nucleation and growth during isothermal treatment of the glass are analyzed based on spectral studies results. The mean size of the CuBr nanocrystals formed via thermo-induced crystallization varies within 7-10 nm. The nanocrystals size of 9 nm is revealed to be critical, below which the CuBr nanocrystals possess cubic structure, and above which the structure of the nanocrystals becomes hexagonal. While during spontaneous nanocrystals nucleation from the glass melt, without additional thermal inducing, the CuBr crystal structure remains cubic regardless of the size. A preliminary explanation of the effects revealed is proposed, assuming the principal role of internal pressure in drops of a copper halide liquid in a glass matrix.