The Effect of Reactive Processing on Window Properties of NaCl

The effect of reactive atmosphere processing (RAP) on single crystals of sodium chloride is studied with respect to defect chemistry, substructure, mechanical properties and optical absorption at 10.6 micrometers. A variety of reactive atmospheres are compared, including carbon tetrachloride, and several Freon-based compounds. These atmospheres were used in both Bridgman and Czochralski grown crystals. Yield and rupture strengths were measured for these crystals using four-point bending methods. Typical stress-strain curves are presented. Crystals examined after yielding, using x-ray topography techniques, exhibited pronounced glide bands in the (1,0,1) planes in the (1,0,-1) directions as expected for materials of rock salt structure. Optical absorption measurements at 10.6 micrometers using calorimetric techniques and a 50 watt laser show some improvement in the absorption of reactive processed crystals over that of non RAP processed crystals. Pub. in Proceedings of the Annual Conference on Infrared Laser Window Materials (4th), 6th Session, Tucson, Ariz. 18-20 Nov 74, p559-571 1974.