Glasses and glass-ceramics in the SrO–TiO2–Al2O3–SiO2–B2O3 system and the effect of P2O5 additions

The glass formation abilities of various compositions in SrO–TiO2–Al2O3–SiO2, SrO–TiO2–B2O3–SiO2, SrO–TiO2–Al2O3–B2O3, and SrO–TiO2–Al2O3–SiO2–B2O3 systems were studied.Many new compositions were found to be suitable for the casting of crack-free, optically clear glasses of different color and with glass transition temperatures ranging from 595 to 775 C. The crystallization behavior, structure, and thermal expansion behavior of selected glasses were analyzed by DTA, XRD, dilatometry, and heat treatment. The effect of P2O5 on the glass structure and crystallization behavior was also studied. P2O5 played a dual role depending on composition. In some glasses it acted as a nucleating agent while in others it suppressed crystallization. Heat treatment of borate and borosilicate glasses transformed them into glass-ceramics while comparable SrO–TiO2– Al2O3–SiO2 glasses showed a lower tendency to crystallize and form glass-ceramics under the same conditions.