Processing techniques have been developed for the fabrication of optically transparent, theoretically dense CaLa2S4 - La2S3 ceramics with a potential application as windows for the mid-infrared. Extreme care is needed to avoid oxygen. Best results were obtained by pre-sintering in an H2S/H-2 atmosphere followed by hot-isostatic pressing. Microstructures, hardness measurements, and infrared absorption spectra serve to characterize the various processing procedures.
			
									
				Keywords:  IR windows; Hot pressing; Phase equilibria; Thorium phosphide structures