Phase separation in the glasses of the (8–x)Na2O · xFe2O3 · 22B2O3 · 70SiO2 system

Аннотация

Glasses with the (8–x)Na₂O · xFe₂O₃ ∙ 22B₂O₃ ∙ 70SiO₂ compositions, where the Fe₂O₃ content varies from 2 to 6 mol %, which were heat-treated at the temperatures of 550 and 700°С for 144 and 2 h, respectively, have been studied by dilatometry, electron microscopy, and X-ray powder diffractometry. It has been shown that, with an increase in the total concentration of Fe₂O₃ in the glass, there is a trend to the transition from an interconnected to a droplet-matrix phase-separated structure. The crystal line phases of Fe₃O₄, FeSiO₃, and β-Fe₂O₃ are formed depending on composition, while the latter is observed only in the glass with the equivalent contents of Na₂O and Fe₂O₃. There is a minimum on the glass transition temperature dependence of the composition at equimolar (4 mol %) contents of Na₂O and Fe₂O₃.