Deuterium Sites in the Defect Pyrochlore DTaWO sub 6 : Location from Neutron Power-Diffraction Data

摘要

Time-of-flight Rietveld refinement and Fourier synthesis of high-resolution powder diffraction data from DTaWO sub 6 led to the location of deuterium in partially occupied 48f sites of Fd3m (origin at 3m) as distances of 1.024(9) A at 300 exp 0 K and 1.021(10) A at 12 exp 0 K from each oxygen position. The deuterium sites form spirals in the interconnecting open channels parallel to (110) directions with distances between nearest neighbors of 2.653(2) A at 300 exp 0 K and 2.652(2) A at 12 exp 0 K. These results are consistent with both classical hopping and tunneling models of deuteron transport in this system. (ERA citation 07:011437)