THIN-FILMS OF PD/NI ALLOYS FOR DETECTION OF HIGH HYDROGEN CONCENTRATIONS

Thin alloy films of Pd and Ni (8% < Ni < 20% in at. %) formed by dual-electron-beam evaporation techniques have been found to give durable and quickly reversible detectors of high H-2 concentrations (pH2 0.1%-100%, 0.7-700 Torr) near 1 atm and 300 K, including accurate determinations of pH2 around the lower explosive limit of 4% in air. The addition of Ni suppresses the alpha to beta-phase transition found in pure Pd under these conditions. The measurement of resistivity changes in the thin films along with flatband shifts of metal-oxide-semiconductor capacitors on the same Si wafer gives accurate values of pH-2 over more than six decades.