Impact of MgO-ZnO substitution on nucleation of aluminosilicate glasses

Abstract

The nucleation mechanisms is of technically interest and important in glass-ceramics production. Here we investigate the nucleation behaviors of NiO-doped MgO-Al₂O₃-SiO₂ and ZnO-Al₂O₃-SiO₂ glasses. It is found that crystallization tends to takes place on the surface and the interior of glasses for the former and the latter, respectively. The origin of different nucleation behavior is studied by comparing aluminum coordination, configurational entropy and rheological properties of the glasses. The substitution of MgO by ZnO leads to increase of tetrahedral aluminum concentration, and decrease of configurational entropy above glass transition temperature, in particular, the latter is closely related to volume nucleation. In addition, the qualitative comparison of thermodynamic and kinetic barriers of steady-state nucleation rate of two glasses indicates that ZnO-bearing aluminosilicate glass possesses higher diffusivity and lower critical nucleus size, which favoring volume nucleation.