Formation and densification of CaLa2S4 powders by sulfidization of metal alkoxides

A powder synthesis method was developed for preparing a highly sinterable submicrometer-sized sulfide from calcium and lanthanum alkoxides. Simultaneous sulfidization of these metal alkoxides at 400 to 750 °C in a pure H2S atmosphere produced stoichiometric CaLa2S4 powders with particle sizes in the range 0.9–1.4 μm. Some contaminants (chlorine, carbon, magnesium, silicon and aluminum) from the raw materials and furnace were found. Powders were sintered to give a high density and fine grain size. The specimens were translucent with uniform structure. The experimental results suggested that less rigorous consolidation with highly homogeneous precursor materials and fine particle sizes were required for translucent sulfide densification.