Sulfuration of yttrium oxide in a flux of sodium carbonate and sulfur: Reinvestigation

Abstract

Reactions of yttrium oxide with sodium carbonate-sulfur flux are reinvestigated by IR spectroscopy, gas evolution analysis, XRD, and elemental analysis. Initially, the terminal bond of the polymeric sulfur is attacked by sodium carbonate to form sodium polysulfide with the evolution of CO2 and COS. Yttrium oxide reacts with CO2 forming yttrium oxycarbonate, which consecutively reacts with sulfur supplied by sodium polysulfide at high temperatures to give yttrium oxysulfide. The reaction of yttrium oxide with CO2 is a solid-gas reaction producing a porous layer. Thus the reaction rate is independent of the original particle size of yttrium oxide.