Vol. 49, Issue 3, pp. 437-444

Vol. 49 Issue 3 pp. 437-444

The phase separation phenomenon in the Na2O–B2O3–SiO2–Fe2O3 glass-forming system and its application for producing porous glasses

Marina Konon, Tatyana Antropova, Irina Polyakova, Irina Anfimova, Lidiya Dikaya, Ekaterina Semenova, Ludmila Kurilenko

Keywords

Na2O–B2O3–SiO2–Fe2O3 glass-forming system, phase separation, crystallization, phase separation diagram, chemical durability, magnetite, leaching, porous glass

Abstract

Glasses in the Na2O–B2O3–SiO2–Fe2O3 system with a constant SiO2 content 70 mol% were synthesized using conventional melting in platinum crucibles in SiC-furnace in air. After synthesis and annealing, glasses were heat treated at 550°C for 96–144 hrs to promote phase separation. A tentative region of phase separation for this temperature was outlined. X-ray powder diffractometry results showed three iron-containing phases (Fe3O4, FeSiO3 and β-Fe2O3) forming in the investigated glasses with magnetite being the main phase as it is observed in most of the glasses. Chemical durability studies showed that compositions of phase-separated glasses suitable for synthesis of porous glasses, both iron-free and iron-containing lie in between 4 and 8 mol% of Na2O. Bulk samples of porous glasses were obtained within the chosen region having the following parameters: specific surface area 40–185 m2/g, porosity 30%–45%, pore diameter 3–14 nm. The parameters of porous structure of iron-containing porous glasses are of the same order of magnitude as the porous glass used for the multiferroic nanocomposite synthesis.

Vol. 49
Issue 3
Article No: 06
pp. 437-444

0.29 MB
OPTICA APPLICATA - a quarterly of the Wrocław University of Science and Technology, Faculty of Fundamental Problems of Technology