Crystal growth of F‐phlogopite from glasses of the SiO2–Al2O3–MgO–K2O–F system

A study on the devitrification of fluorophyllosilicate glass precursors is presented. The research has been focused on the early stages of the crystallization process and shows the variation in the crystallization mechanism with increasing the fluorine content. The devitrification process has been studied by means of differential scanning calorimetry (DSC) and field‐emission scanning electron microscopy (FESEM). These complementary techniques established that both surface (heterogeneous nucleation) and volume (internal homogeneous nucleation) mechanisms are present in the crystallization process of fluorophlogopite‐based glasses, the latter being predominant. By increasing the percentage of fluorine in the parent glass, a variation in the location of the first crystals developed from the internal volume of the glass toward the external surface was observed. Such an alteration in the crystallization mechanism was also checked by examining the microstructure of crystallized samples prepared under short‐time treatments.R. Casasola and J.M. Pérez express their gratitude to the Spanish National Research Council (CSIC) for their contract through the JAE Program (JAEPre‐08‐00456 and JAEDoc‐08‐00362, respectively), which is co‐financed by the European Social Fund. The financial support through the projects MAT 2006‐05977 and MAT2013‐40477‐P is also recognized.Peer reviewe