Sulfure d'ytterbium, de calcium et de potassium, CaK0,5Yb1,833S4

The Yb and Ca atoms have slightly distorted octahedral environments and the K atom has regular sixfold prismatic coordination. The sites are completely (Yb, Ca) or partially (Yb, K) occupied. The compound crystallizes with a layer structure; each layer is made up of [CaS6] or [YbS6] octahedra and is perpendicular to the c axis. Groups made up of three layers, [Yb(1)S6], [CaS6] and [Yb(2)S6], are held together by K atoms.