Multi-Layered Ni64Zr36/M/Ni64Zr36 (M=V, Nb) Thin Films for Hydrogen Purification

Abstract For hydrogen purification at low temperature, multi-layered hydrogen-permeable thin films with amorphous Ni64Zr36/M/Ni64Zr36 (M=V, Nb) structure were developed and the microstructure and hydrogen permeation performance were examined. The multi-layered thin films were deposited through DC-magnetron sputtering using Ni64Zr36 and V/Nb targets. The overall thickness was adjusted to 2 μm, and that of the internal V or Nb layer was varied between 0.5 and 1.6 μm. The hydrogen permeability was measured in the range of 373 ∼ 573K. All the multi-layered thin films showed negative activation energy for hydrogen permeation indicating an increasing permeability with a decreasing temperature. The calculated negative activation energy, - 0.43 ∼ - 0.60 kJ/mol for Ni64Zr36/V/Ni64Zr36 thin films and - 1.19 ∼ - 3.90 kJ/mol for Ni64Zr36/Nb/Ni64Zr36 thin films, and the increased hydrogen permeation at low temperature region is obviously due to the V or Nb mid-layer. The observed hydrogen permeability of the prepared thin films was higher than the reported value of amorphous Ni64Zr36 alloy membrane at 573K and reached the permeability of Pd at 373K.