Optical properties of Pr thin film and nanoparticle layers during hydrogen loading and deloading

Abstract

Changes in the optical properties of Pd capped Pr thin film and nanoparticle layers prepared by vacuum evaporation and inert gas evaporation techniques, respectively, have been studied as a function of time during hydrogen loading and deloading. These samples were characterized by transmission electron microscopy, atomic force microscopy, x-ray diffraction, and spectrophotometery techniques. Absorption spectra of Pr thin film and nanoparticles samples in metal, and hydrogen loaded and deloaded states have been reported. It is observed that filling of octahedral sites in the dihydride phase results in changes in absorption coefficient values at 1.5–2.0 eV and H content in the trihydride phase causes shift of the absorption edge. Enhanced surface area, loose topography, a larger number of interparticle boundaries due to small sizes, relatively loose adhesion to the substrate, and smaller structural changes in nanoparticle layers result in larger and faster changes in the optical properties during loading in comparison to thin film