Stresses induced by hydrogen absorption and desorption in Pd nanofilms

The stresses induced by hydrogen absorption in Pd nanofilms were studied by the electrochemical quartz crystal microbalance (EQCM) and bending beam me thods. In the EQCM method, hydrogen was charged electrolytically into a Pd nanofilm that was coated on an AT- or ET-cut quartz crystal. For Pd films i n a thickness of 120-nm on the AT-cut and 158-nm on the BT-cut quartz cryst al, compressive stresses of 1.07x10(3) MPa and 1.70X10(3) MPa, respectively , were measured. With the bending beam technique, the bending curvature of the Si substrate during gas-phase hydrogenation was monitored. The maximum compressive stress induced in a 50-nm Pd film on the Si substrate during hy drogenation at 0.2 MPa of hydrogen gas was 944 MPa. When hydrogen was desor bed from the film, a tensile stress of 708 MPa in the film was observed. Wh en the thickness of the Pd Nm was increased to 130 nm, peeling of the Pd fi lm from the substrate occurred. (C) 2001 Elsevier Science B.V. All rights r eserved.