Hydrogen permeability of SrCe1−xMxO3−δ (x=0.05, M=Eu, Sm)

The hydrogen permeability of SrCe0.95Eu0.05O3−δ and SrCe0.95Sm0.05O3−δ was studied as a function of temperature, hydrogen partial pressure (PH2) gradient, and water vapor partial pressure (PH2O) gradient. Under a 100% dry hydrogen condition at 1123 K, the hydrogen permeation rates of dense membranes (1.72 mm thick) are ≈3.19×10−9 mol/cm2 s for SrCe0.95Eu0.05O3−δ and 2.33×10−9 mol/cm2 s for SrCe0.95Sm0.05O3−δ. Under wet hydrogen conditions at 1123 K, the hydrogen permeation rates are ≈2.89×10−9 and 1.21×10−9 mol/cm2 s, respectively, for the same materials. The dopant dependence of hydrogen permeability is explained in terms of the ionization potential of the dopant. Electronic conductivity was calculated from hydrogen permeation fluxes; activation energies for electron conduction under both dry and wet conditions were also calculated. The PH2O dependence of electronic conductivity and hydrogen permeability is discussed.