The potassium niobyl cyclotetrasilicate K2(NbO)2Si4O12

The single-phase compound K2(NbO)2Si4O12 was prepared by solid-state reaction. It crystallizes in the tetragonal system, space group P4bm with a = 8.7404(8)Å and c = 8.136(1)Å, Z = 2. The structure was determined from 484 reflections collected with a Nonius CAD4 diffractometer with MoKα radiation. The final R index and weighted Rw index are 0.021 and 0.022, respectively. This framework structure is built up from chains of corner-shared NbO6 octahedra running parallel to the four-fold axes and linked together by four-membered Si4O12 single rings. This structure is very similar to that of K4(ScOH)2 Si4O12.