Structural aspects of insertion reactions of the pyrochlore, KNbWO(6).

Structures of a set of pyrochlore related structures KNbWO (6), K(1.88)NbWO(6), and KNbWO(6).0.69D(2)0 have been determined by neutron powder profile analysis. This structural framework is capable of insertion reactions with Na, K, and Rb. These compounds are all cubic in space group Fd3m. The K ions are on special positions in K(1.88)NbW0(6) and each K is coordinated by six equidistant oxygens arranged about it in a non-planar chair configuration. In KNbW0(6) the K is in a more complex geometry having 12 oxygens within 3.7A. The D(2)0 molecules are coordinated to each K in KNbW0(6) at distances of 2.35 and 2.85Angstroms, somewhat shorter than unconstrained hydrates.