Temperature dependent interaction of hydrogen with PdAg nanocomposite thin films revealed by in-situ synchrotron XRD

Abstract

PdAg nanocomposite alloy thin films were synthesized using a DC magnetron sputtering process to study the structural changes that occur in the alloy film during the process of hydrogenation and dehydrogenation at different temperatures. The atomic composition of the nano-composite film is 88 at % Pd and 12% at Ag, as determined by the EDAX analysis. In-situ synchrotron X-ray diffraction (XRD) has been used to monitor the subtle structural changes that occurred throughout the hydrogenation and dehydrogenation cycles at an interval of 10 s. This aspect has not been addressed so far. In-situ XRD studies reveal that the XRD peak shifts towards a lower angle due to the lattice expansion in the alloy due to hydrogenation. The change in peak shift is found to be different for different temperatures. The present study also shows no hysteresis during the hydrogen absorption and desorption processes. In addition, the results show that (i) the phase segregation has been observed at 250 °C, (ii) the peak shift during the hydrogenation process at higher temperatures is not significant, whereas the peak shift throughout the process is more rapid and pronounced at ambient temperature.