PREPARATION AND PROPERTIES OF PHOSPHATE-GLASSES AND GLASS-CERAMICS CONTAINING LARGE AMOUNTS OF TITANIUM .4.

Phosphate glasses containing very large amounts of TiO2 have been prep ared in the compositions of (3Na2O.67TiO2.30P2O5)+5SiO2(mol%) (Glass-1 ) and (3Na2O.72TiO2.25P2O5)+5SiO2(mol%) (Glass-2). The thermal expansi on coefficient (alpha) from 30 to 600-degrees-C were 7.7 x 10(-6)degre es-C-1 and 6.9 x 10(-6)degrees-C-1, respectively. The glass-ceramics p repared by heating Glass-1 at temperatures in 50-degrees-C intervals f rom 800 to 1000-degrees-C for 30h had alpha = 0.7-2.2 x 10(-6)degrees- C-1 and glass-ceramics prepared by heating Glass-2 at various temperat ures from 900 to 1100-degrees-C for 30h had alpha = 1.6-8.4 x 10(-7)de grees-C-1 in the same temperature range. The bending strengths of the glass-ceramics from Glass-1 were larger than those from Glass-2. The l ow thermal expansions of these glass-ceramics were attributed to NaTi2 (PO4)3-like phase, TiO2 and (TiO)2P2O7 produced by crystallization, an d the bending strengths were greatly influenced by the crystalline pha ses. The NaTi2 (PO4) 3-like phase seems to be a solid solution of NaTi 2 (PO4)3 and Si4+, Na1+xTi2P3-xSixO12, as judged from the differences between the lattice parameters of this phase and those of NaTi2 (PO4)3 .