Abstract
Eight kinds of Na2O-TiO2-P2O5 glasses with P2O5 content, of 30 to 40 mol% were prepared. In the series of glasses with the same P2O5 content, the density and the glass tran-sition temperature increased linearly with an increase of TiO2 content, whereas the ther-mal expansion coefficient decreased. The same behavior in properties was also recognized in the series with Na2O/P2O5= 1. These results indicated that TiO2 is very effective for strengthening of glass structure. From the glasses with TiO2 content of 30 mol% or more, NaTi (PO4) 3 (NTP) was produced as the main phase by crystallization. The crystallized samples prepared from 40Na20 30TiO2 30P2O5 and 30Na2O 40TiO2 30P2O5 glasses at various temperatures showed thermal expansion coefficients of - 0.2 to 4.0 × 10-6°C-1. The low thermal expansion values of these crystallized glasses are due to the formation of NTP.
