Solutions to Fick’s equation were found for various initial and boundary conditions. These included a constant initial concentration over an entire membrane (with c = c0 at t = 0), a constant concentration (with c = c1 at x = 0) and a time-dependent concentration at x = L (with C = b0 + b1t + b2exp[-b3t] - (b2/4)exp[-4b3t]), where L was the thickness of the membrane. The mass of H which permeated through the membrane was determined and theoretical lines were fitted to experimental plots of the H pressure, in the system volume, as a function of time. Stationary flows and diffusion coefficients (dependent or independent of stress) were determined for a Pd81Pt19 membrane, with initial H atomic ratios of 0.015, during the absorption and desorption of H at 288.4K.

Diffusion Coefficients of Hydrogen in a Pd81Pt19 Membrane with Time-Dependent Boundary Conditions. D.Dudek: Journal of Alloys and Compounds, 2001, 329[1-2], 1-7