Formation and densification of Pb 0.1Ca 0.9La 2S 4 powders by sulfidization of modified metal alkoxides

Abstract

The highly sinterable submicron CaLa 2S 4, (CLS) powders with high La/Ca ratios were prepared by sulfidizing calcium and lanthanum alkoxides under CS 2 for 8 h and then a pure H 2S atmosphere for 2 h at 500–800°C. It is for application in infrared transmitting window material of 8–14 μm wavelength. In the range of La/Ca ratios from 10 to 15, the phase obtained are LaS 2 intermediate phase at low temperature (500°C), a β-La 2S 3 minor phase at 700°C, and a pure Th 3 P 4 phase after 800°C treatment. The Pb x Ca 1− x La 2S 4 (PCLS) sulfide particle sizes formed are in the range 0.2–5 μm. After HIPing and annealing in an H 2S atmosphere at 1350°C, the Pb 0.1Ca 0.9La 2S 4 pellet has 60% IR transmittance in the 14 μm region for the specimen with a thickness of 0.86 mm. The IR transmittance at 11 μm region for pellet of Pb 0.1Ca 0.9La 2S 4 with 1.6 wt% chlorine residue is 55%, while the IR transmittance at 11 μm region of it with 0.2 wt% chlorine residue is 43%.