The Electrochemically Formed Palladium-Deuterium System. II. In situ Neutron Diffraction Studies

Abstract

An in situ neutron diffraction study of the electrochemical formation of β-PdD_x in 1 M LiOD at room temperature is described. Electrolysis at relatively high overpotentials for over 200 h resulted in the formation of β-PdD_0.59 (a = 4.0422 Ǻ), with no evidence for the formation of a bulk phase with higher deuterium content or occupancy of the tetrahedral sites in the face-centred cubic lattice. The formation of a thin layer on the surface of the cathode with x > 0.59 could account for the observation of gas evolution once electrolysis is stopped. Evidence for hysteresis in the re-formation of palladium by oxidation of β-PdD_x is also presented.