Preparation and crystal structure of the new quaternary europium-polysulfide KCuEu2S6

The new quaternary europium polysulfide KCuEu2S6 was obtained using the reactive flux method at an intermediate temperature of 380 degrees C by reacting K2S3 with elemental Cu, EuS and an excess of sulfur. The Eu3+ ions exhibit a bicapped trigonal prismatic coordination and the Cu+ ions are in a tetrahedral environment. The crystal structure is characterized by anionic layers of interconnected Eu and Cu polyhedra with K+ ions residing between the anionic sheets [Cu-Eu2S6](n-)(n). The Cu+ ions occupy one half of the tetrahedral sites in an ordered fashion.