Abstract: A series of new glasses in the PbBr₂-PbCl₂-PbF₂-PbO-P₂O₅ system were prepared and some properties of the glasses in the PbBr₂-PbCl₂-PbF₂-PbO-P₂O₅ system were studied.
Their composition dependence of glass transition temperature(T_g), thermal expansion coefficient and water durability was reported. Glasses in the
PbBr₂-PbCl₂-P₂O₅ ternary system have relative low glass transition temperature(>146℃). When PbO and/or PbF₂ are introduced into the ternary system, the glass transition temperature increases considerably. Glasses containing PbO have higher transition
temperature than those containing PbF₂. The glasses in this system have relative high thermal expansion coefficient(25×10^-6/℃). Most of the glasses exhibit good water durability,
and the dissolution rate in deionised water at 25℃ is in the order of 10^-4～10^-5mm/day. The introduction of PbO and/or PbF₂
into the glasses does not change their water durability much. With the increase of P₂O₅, the water durability of the glass becomes bad obviously.

Key words: phosphate glasses, thermal properties, water durability