Adsorption and diffusion of a silver atom and its cation on α-SiO2 (0 0 1): Comparison of a pure surface with a surface containing an Al defect

By employing DFT approaches we studied the adsorption of a single Ag atom and its cation on different sites of a pure α-quartz (0 0 1) surface and on an α-quartz (0 0 1) surface containing an Al defect. The energetically different adsorption sites of Ag and Ag+ were revealed and the profiles of diffusion were calculated. Diffusion of an Ag atom through the pure α-quartz surface is predicted to have a much lower barrier than an Ag cation. However in case of diffusion through the α-quartz surface with an Al defect the barriers are almost the same for both cation and neutral Ag.