STRUCTURE OF K1.0TI8O16 AND K0.0TI8O16

Potassium titanium bronze K1.0Ti8O16 and its chemically oxidized 'exuviae' oxide K0.0Ti8O16 crystallize in a tetragonal system, I4/m, with the hollandite-type one-dimensional tunnel structure. For K1.0Ti8O16, M(r) = 678.13, a = 10.1776 (5), c = 2.9614 (2) angstrom, V = 306.75 (3) angstrom3, Z = 1, D(x) = 3.67 Mg m-3, lambda(Mo Kalpha) = 0.71069 angstrom, mu = 5.55 mm-1, F(000) = 323, T = 298 K, R = 0.048 for 947 unique observations. For K0.0Ti8O16, M(r) = 639.03, a = 10. 164 (2), c = 2.9631 (7) angstrom, V = 306.1 (1) angstrom3, Z = 1, D(x) = 3.4 Mgm-3, mu = 5.21 mm -1, F(000) = 304, R = 0.020 for 1084 independent reflections. The structural modification caused by K deintercalation via oxidation of the host framework is followed using the present data as well as those from two previous studies of the bronze with different degrees of oxidation. One of the most distinct changes is the expansion of the tunnel diameter upon K removal.