PNNL

Abstract

Two-phase powders for making mixed conducting cermet hydrogen separation membranes have been co-synthesized using the glycine-nitrate combustion technique. The two components include a proton conducting barium cerate-based ceramic and nickel oxide, which is subsequently reduced to electron conducting nickel metal. The particle size of the resulting powder is on the order of 10 nm in size and the two phases are intimately mixed. Analysis of energy dispersive x-ray (EDX) spectra taken during transmission electron microscopy (TEM) suggests that the elements partition into the compositions for which they were intended. X-ray diffraction (XRD) confirms that the desired barium cerate and nickel oxide phases are formed exclusively during synthesis and calcination. The composition of the cermet was further refined by determining (1) the combination of Zr- and Nd-doping levels in the barium cerate phase that impart stability at elevated temperatures in a carbon dioxide atmosphere, and (2) the percolation threshold of Ni in the composite.