Silicatoniobate de Potassium, K3Nb3O6Si2O7

Single crystals of tripotassium niobium oxide silicate, K 3 Nb 3 O 6 Si 2 O 7 , have been obtained by slow cooling from a melt. This compound crystallizes in the hexagonal system with space group P62c. The framework, built up from Si 2 O 7 ditetrahedra and a group of three corner-linked NbO 6 octahedra, is isotypic with that of Ba 3 Nb 6 O 12 (Si 2 O 7 ) 2 . The filling of tunnels by K + (or Ba 2+ ) cations determines the space group to be P62c (or P62m)