Structure and proton mobility in the defect pyrochlore (H 2O) xH 2Ta 2O 6

• Published in: Solid state communications Vol. 59; no. 8; pp. 569 - 573
• Main Authors: Dickens, P.G., Weller, M.T.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 1986
• ISSN: 0038-1098; 1879-2766
• DOI: 10.1016/0038-1098(86)90061-X

The structure of the defect pyrochlore (D 2O) 0.38D 2Ta 2O 6 has been determined by powder neutron diffraction. The deuteroxyl deuterons randomly occupy sites ∼ 1.04 Å from the framework oxygens. The water molecules are situated on sites at the centre of the defect pyrochlore cavity, 8 b position of Fd3 m, and the O W-D W bonds lengths are 0.97 Å. A pulsed solid state N.M.R. study of (H 2O) 0.42H 2Ta 2O 6 has shown that this material is a reasonable proton conductor with a room temperature diffusion co-efficient of ∼ 10 -9 cm 2 s -1.