Protonic Mobility of Neodymium Tungstate

This work aims at studying protonic transport of mixed proton-electron-conducting Nd5.5WO11.25-delta oxide synthesized by a citrate method as material for hydrogen separation membranes. Structure of samples was characterized by X-ray diffraction ( XRD), and protonic mobility was studied using temperature-programmed desorption of H2O and isotope heteroexchange of the bulk protons with D2O as well as mass relaxation after an abrupt change of H2O partial pressure. The temperature range of Nd5.5WO11.25-delta efficient operation is 300-400 degrees C, where H+ tracer diffusion and chemical diffusion coefficients are similar to 1 x 10(-11) and similar to 2 x 10(-5) cm(2)/s, respectively, being comparable to or even better than those for similar systems. Hence, Nd5.5WO11.25-delta is a promising material for the design of hydrogen separation membranes.