Formation and densification of Pb0.1Ca0.9La2S4 powders by sulfidization ofmodified metal alkoxides

The highly sinterable submicron CaLa2S4, (CLS) powders with high La/Ca rati os were prepared by sulfidizing calcium and lanthanum alkoxides under CS2 f or 8 h and then a pure H2S atmosphere for 2 h at 500-800 degrees C. It is f or application in infrared transmitting window material of 8-14 mu m wavele ngth. In the range of La/Ca ratios from 10 to 15, the phase obtained are La S2 intermediate phase at low temperature (500 degrees C), a beta-La2S3 mino r phase at 700 degrees C, and a pure Th3P4 phase after 800 degrees C treatm ent. The PbxCa1-xLa2S4 (PCLS) sulfide particle sizes formed are in the rang e 0.2-5 mu m. After HIPing and annealing in an H2S atmosphere at 1350 degre es C, the Pb0.1Ca0.9La2S4 pellet has 60% IR transmittance in the 14 mu m re gion for the specimen with a thickness of 0.86 mm. The IR transmittance at 11 mu m region for pellet of Pb0.1Ca0.9La2S4 with 1.6 wt% chlorine residue is 55%, while the IR transmittance at 11 mu m region of it with 0.2 wt% chl orine residue is 43%. (C) 1999 Elsevier Science Limited and Techna S.r.l. A ll rights reserved.