Heterogeneous nucleation of alkaline earth feldspars in glasses

Though suitable conditions of structural geometry favouring epitaxy were demonstrated, yet it was observed that epitaxy was not a dominant and, possibly, not even an important factor in the nucleation processes studied. Indeed, the mere presence of close structural geometrical fit between the catalyst and the nucleus does not necessarily lead to epitaxy. Other factors such as the concentration of the nucleating agent in the glass and variations in the chemical composition of the glass, and their effects on the nucleation are discussed. Also the effect of the feldspar structure on the kinetic barrier for its nucleation, and several specific liquid phase separation phenomena, are evaluated.