Abstract
Glasses and devitrificates from the SiO2–B2O3–P2O5–K2O–CaO–MgO system with constant contents of SiO2 and P2O5 network formers, modified by the addition of B2O3, were analyzed. All materials were synthesized by the traditional melt-quenching technique. The glass stability (GS) parameters (Krg, ∆T, KW, KH) were determined. The effect of the addition of B2O3 on the GS, liquation phenomenon, crystallization process, and the type of crystallizing phases were examined using SEM-EDS, DSC, XRD, and Raman spectroscopy imaging methods. It was observed that the addition of B2O3 increased the tendency of the glass to crystallize. Both phosphates (e.g., Ca9MgK(PO4)7, Mg3Ca3(PO4)4), and silicates (e.g., K2Mg5(Si12O30), CaMg(Si2O6), MgSiO3) crystallized in the studied system. The Raman spectrum for the orthophosphate Mg3Ca3(PO4)4 stanfieldite type was obtained. Boron ions were introduced into the structures of crystalline compounds at high crystallization temperatures. The type of crystallizing phases was found to be related to the phenomenon of liquation, and the order of their occurrence was dependent on the Gibbs free enthalpy.
Highlights
Glasses containing B2 O3 in their composition may demonstrate the phenomenon of phase separation
The main objective of this work was to study the influences of various B2 O3 contents on the structure and crystallization processes of multicomponent glasses from the SiO2 –B2 O3
Complex multistage crystallization processes induced by the thermal treatment were characterized by SEM-EDS, DSC, XRD, and Raman spectroscopy mapping
Summary
When a liquid is cooled below its melting point, crystal nucleation can occur homogeneously or heterogeneously in the body of the liquid or on the surface. A typical glass-forming silicate melt is unique among solutions due to its ability to dissolve most chemical elements. Such a melt is, a solution of oxides present in a thermodynamic equilibrium. A solution of oxides present in a thermodynamic equilibrium Another unusual property of a glass-forming melt is its enormous change in viscosity with temperature. The viscosity of the material increases with cooling, but at certain temperatures, the mobility of molecules may still be great enough for a crystalline phase to form [2]
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