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We report on the synthesis, sintering, and crystallization behaviors of a glass with a composition corresponding to 90 mol % CaMgSi2O6-10 mol % NaFeSi2O6. The investigated glass composition crystallized superficially immediately after casting of the melt and needs a high cooling rate (rapid quenching) in order to produce an amorphous glass. Differential thermal analysis and hot-stage microscopy were employed to investigate the glass forming ability, sintering behavior, relative nucleation rate, and crystallization behavior of the glass composition. The crystalline phase assemblage in the glass-ceramics was studied under nonisothermal heating conditions in the temperature range of 850–950 °C in both air and N2 atmosphere. X-ray diffraction studies adjoined with the Rietveld–reference intensity ratio method were employed to quantify the amount of crystalline phases, while electron microscopy was used to shed some light on the microstructure of the resultant glass-ceramics. Well sintered glass-ceramics with diopside as the primary crystalline phase were obtained where the amount of diopside varied with the heating conditions. [ABSTRACT FROM AUTHOR]

Abstract: The aim of the present study is to investigate the apatite formation process from glasses in the fluorapatite–diopside–anorthite–albite system. The effects of partial and total replacement of anorthite fraction by albite in the ternary composition 26 Ca5(PO4)3F−44 CaAl2Si2O8−30 CaMgSi2O6 (wt.%) on the properties of glasses and glass-ceramics were evaluated. The scanning electron microscopy (SEM) examination of glasses revealed the precipitation of a nanosize droplet phase in the glassy matrices suggesting the occurrence of amorphous phase separation in all annealed glasses. An overall trend towards polymerization of the glass network with increasing albite content was demonstrated by employing MAS-NMR and FTIR spectroscopy. X-ray diffraction (XRD) and differential thermal analysis (DTA) were used to assess the effect of albite content on the devitrification process and formation of fluorapatite crystalline phase (Ca5(PO4)3F). [Copyright &y& Elsevier]

Abstract: Oxyfluoride glasses in the system CaO–MgO–BaO–SiO2–Al2O3–La2O3–CaF2 were obtained by adding CaF2 (3–8wt%) to a parent diopside based glass composition, Ca0.8Ba0.1MgAl0.1La0.1Si1.9O6. The characterization of the glasses has been made by density, dilatometry and FTIR measurements. Non-isothermal crystallization kinetic studies in conjunction with XRD and SEM have been employed in order to investigate the effects of fluoride ion additions on crystallization behaviour and mechanism of glasses. [Copyright &y& Elsevier]