Vitrification in the system of K2O-BaO-B2O3-Al2O3-TiO2 containing (mol%): K2O (0 to 28), BaO (0 to 28), B2O3 (5 to 24), Al2O3 (7 to 25) and TiO2 (33 to 60) was investigated by fusion at 1450°C for 2 h. The fields of vitrification were analyzed with different forms of diagrams. It is shown that stable glasses can be produced with batchs containing 62 to 75 mol% of glass-formers ([TiO2]+[B2O3]+[Al2O3]) including (TiO2) up to 48 mol% and (R2O3)>20 mol%. For those compositions with (TiO2)=35 to 47 mol%, the molar ratio of (Al2O3) / (B2O3) can be varied in the range of 1 to 2.5. The structure of obtained glasses was characterized by scanning electron microscope (SEM) and infrared (IR); the investigated glasses contained one or two vitreous phases depending on their chemical composition. One-phase glasses can be obtained with compositions of (Al2O3) / (B2O3)≥1.75. The vitreous phase of one-phase glasses and the main glassy phase of two-phase glasses are formed by octahedra of TiO6/2 and AlO6/2 as well as (B3O6)3- rings; the droplets of the second vitreous (borate) phase was formed by BO3/2, TiO4/2 and BO4/2-, AlO4/2- groups combined with Ba2+ and K+ cations.
Key words: Vitrification, borate, titanate, two-phase glasses.
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