The term “halide glass” refers to glasses in which the anions are from elements in Group VIIA of the periodic table, namely, F, Cl, Br and I, as opposed, for example, to “oxide glasses,” such as silicates, borates, phosphates, etc. Two known single component halide melts are glassforming, BeF2 and ZnCl2, but the majority of halide glasses are multicomponent. Practical interest in halide glasses has been generated almost entirely by their optical properties, which cannot be duplicated in a more conventional oxide glass. Barriers to the practical deployment of halide glasses have their origin in materials properties in which they can be markedly inferior to oxide glasses, e.g., mechanical strength, resistance of the melt to crystallization, chemical durability, etc.

In the past decade there has been considerable and accelerating research activity in the area of halide glass science and engineering. Halide glass research up to 1980 has been reviewed by Baldwin et al. and oxide and halide glasses for laser applications have been compared by Weber. Four international symposia on halide glass science and engineering have been held in the period 1982–1987, the proceedings of the last two of which have been or will be shortly published. The proceedings of a 1986 NATO-sponsored meeting on halide glasses have also been published in book form.