Glasses with PBS and/or PBSE crystals

摘要

This invention is directed to the production of glass bodies containing crystallites of PbS and/or PbSe. The crystallite-containing bodies are formed by the thermal crystallization in situ of glass bodies having compositions essentially free from CdO and consisting essentially, expressed in terms of weight percent on the oxide basis except for fluorine, sulfur, and selenium which are expressed in terms of weight percent on the elemental basis, ofPP ______________________________________ PPSiO.sub.2 PP 58-65 RO 0-15 PPNa.sub.2 O P P 10-15 F 1-3.5 PPZnO 5-17 S 0-3 PPAl. sub.2 O.sub.3 PP 0.5-5 Se 0-3 PPPbO 3-6 S + Se 1-3 PP______________________________________ PPPPwherein RO consists of at least one alkaline earth metal oxide in the indicated proportions selected from the group consisting of 0-5% BeO, 0-5% MgO, 0-15% CaO, 0-10% SrO, and 0-10% BaO.