Glass transformation effect of liquation glasses from the SiO 2-B 2 O 3-P 2 O 5-K 2 O-MgO-CaO system was studied by DSC, SEM-EDS and 31 P, 29 Si and 11 B MAS NMR spectroscopy methods. The relation between the B 2 O 3 content in the analysed glasses and phase separation phenomenon, structure and glass transition effects was discussed. It was shown that increasing content of B 2 O 3 causes the formation of P-O-B III , P-O-B IV and Si-O-B III and Si-O-B IV bonds which results in the appearance of liquation in analysed glasses. Simultaneously, double glass transition effect was observed with gradual decrease of T g and E a values. The observed relations were explained using crystalochemical parameters (i G , L) of chemical bonds present in the structure of analysed glasses.
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.
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