Dissociative water vapour absorption in BaZr0.85Y0.15O2.925/H2O: pressure-composition isotherms in terms of Fermi-Dirac statistics

Thin films of proton-conducting BaZr0.85Y0.15O2.925 perovskite-type ceramic s, prepared in a sol-gel process by multiple dip-coating on silicon single crystal wafers, and powder samples, prepared by the conventional carbonate route, were charged with hydrogen by dissociative water absorption at defin ite values of water vapour pressures and temperatures. The absolute content of the absorbed hydrogen was determined ex situ at room temperature using the N-15 nuclear resonance reaction analysis. From the resulting water vapo ur pressure-hydrogen composition isotherms the absorption enthalpies and en tropy were calculated, using our two site model, based on Fermi-Dirac stati stics.