Preparation and properties of MoO₃-V₂O₅ -P₂O₅-Fe₂O₃ glasses

Glasses in the MoO₃-V₂O₅ -P₂O₅-Fe₂O₃ quaternary system were prepared as potential replacements to lead-based frits for low temperature sealing applications. The glass forming regions were explored and the glass forming ability, thermal expansion, and water durability were investigated. Results show that MoO₃-V₂O₅ -P₂O₅ ternary system has strong glass forming ability, which extended down to 10 mol% P₂O₅. The glass forming region in the MoO₃-V₂O₅ -P₂O₅-Fe₂O₃ quaternary system becomes relatively wider while the stabilities of the glasses against crystallization are still strong with 10 mol% Fe₂O₃. With the increasing content of Fe₂O₃ the glass forming region becomes smaller. The glass forming ability in this quaternary system is most strong as the ratio of MoO₃/V₂O₅ equals to 1.5. The thermal expansion coefficient can be increased and the water durability improved by adding Fe₂O₃ content into the MoO₃-V₂O₅ -P₂O₅ ternary system. Trivalence iron ions can enter into phosphate chain and form Fe-O-P bond in place of P = O double bond, hereby increase the water durability of glasses. Many glass compositions in the system of MoO₃-V₂O₅ -P₂O₅-Fe₂O₃ have a thermal expansion coefficient of 60-110 × 10^-7/°C and a dissolution rate in deionized water at 90°C of 8.0 × 10^-9 g·cm^-2·min^-1, which will be a good alternative to lead-based sealing frits.