Synthesis and characterizations of LaM2Ḿ3S6-y(M: Mg, Ca, Sr, Ba; Ḿ:Cu, Fe), La2SrS4 and La2CaS 4

Abstract

YN2M^3S6-y, (M= Ca, Sr, Ba, Mg and M= Cu, Fe) type of compounds were synthesized and the effect of rare earth elements on these type of compounds was investigated. By replacing Y with La, LaBa 2Cu3S6-y compound was synthesized based on solid-gas reaction and the obtained samples were characterized by XRD, IR and EDX methods. Crystal structure of LaBa2Cu3S6-y was orthorhombic and refined unit cell parameters were a =10.16(1), b=12.72(2) and c=13.54(0)Å. This compound showed a semiconducting behavior in the range 78-300°K. After the replacement of La element with Gd and Dy, as result of the sulfidizing process for both rare earths, GdO2S and DyO2S compounds were observed in the X-ray pattern of the products. When Ba is replaced with Sr and Ca, the La2SrS4 and La2CaS4 products were obtained. These two compounds were synthesized first time by solid-gas sulfidizing reaction method. The La 2CaS4 ceramic has become a novel optical window material lately for 8-14 μm IR range.