Hydrogen Solubility of Magnetron Co-Sputtered FCC and BCC PdCuAu Thin Films

Abstract

Palladium–copper–gold (PdCuAu) ternary alloy membranes are promising alternatives to pure palladium for the purpose of hydrogen separation processes. In the current work, PdCuAu ternary alloys were prepared by magnetron cosputtering deposition. All as-deposited samples showed face-centered cubic (fcc) structure in the composition range of study: 30 ≤ [Pd] ≤ 100, 0 ≤ [Cu] ≤ 66, and 0 ≤ [Au] ≤ 6 (in at%). The body-centered cubic (bcc) phase was prepared from the fcc samples by annealing for 4 h at 400 °C under Ar and was identified in alloys with Pd content between 40 and 46 at%. The hydrogen solubility was evaluated for both fcc and bcc phases using an electrochemical method and an electrochemical in situ X-ray diffraction method, respectively. The alloys’ hydrogen solubility increases with the lattice parameter and palladium content, and decreases with crystallite size and phase transition to bcc. In the same range of composition, the hydrogen solubility of the fcc and bcc phases vary in the same way with...