Investigations on the crystal-structure and non-ambient behaviour of K2Ca2Si8O19 ‐ a new potassium calcium silicate

K2Ca2Si8O19, a previously unknown crystalline compound of the ternary oxide system K2O-CaO-SiO2, was synthesized in the course of solid state reactions at 900 °C. Its crystal structure was solved from single-crystal structure data. Being built up of silicate double-layers and double-chains of [CaO6]-octahedra K2Ca2Si8O19 is structurally related to minerals like rhodesite or stilpnomelane.198