Crystal structure of a natural potassium-barium hexatitanate isostructural with K₂Ti₆O₁₃

Abstract

The crystal structure of a mineral with the stoichiometry (K_0.58Ba_0.36)₂(Ti_0.93Fe^III_0.06)₆O₁₃ has been determined by X-ray diffraction and refined by full-matrix least squares to a residual of 0.076 for 1688 ?observed? reflections. Crystals are monoclinic, C2/m, a = 15.453(2), b = 3.8368(7), c = 9.123(2) Ǻ,β = 99.25(1)°, Z = 2, and are isostructural with the (Na,K,Rb)₂Ti₆O₁₃ family. High-resolution electron microscopy has confirmed that the Ba and Fe^III species (the latter in a high-spin state) are randomly substituted for K and Ti respectively.