Fabrication of Ce_(0.8)Gd_(0.2)O_(2-δ) thin-film oxygen transport membranes by reactive magnetron sputtering

摘要

Oxygen transport membranes consisting of mixed ionic electronic conductors have attracted great interest for the efficient separation of oxygen from air or for application in membrane reactors. In the latter case, Ce_(0.8)Gd_(0.2)O_(2-δ) (CGO) is an interesting material due to its high stability and ambipolar conductivity in accordant conditions. CGO thin-film membranes (0.8-1.1 urn in thickness) were deposited by DC reactive magnetron sputtering on porous substrates made from α-Al_2O_3 and yttria-stabilized zirconia (8YSZ). Deposited films were characterized by electron microscopy, X-ray diffraction, and He leakage. Different deposition behavior was observed depending on the substrates' properties and bias assistance. A four-zone model was derived for 8YSZ substrates revealing proper parameters with regard to the sintering temperature of the substrate and bias power applied during sputtering in order to achieve intact coatings. The minimum He leak rates of CGO thin film membranes reached the range of 10~(-4)hPa·dm~3·cm~(-2)·s~(-1).