Cyclic thermal conductivity changes of Pd-catalyzed Ni-Mg alloy films by gasochromic hydro- and dehydrogenations

To investigate the thermal-switching properties of Pd-catalyzed Ni-Mg alloy films, we conducted in situ analyses of the films' electrical, optical, and thermal properties through hydrogen gasochromic reactions. These reactions allow the films to reversibly switch between metallic (dehydride) and semiconductor (hydride) phases. The thermal conductivities of the metallic and semiconductor states were found to be 14 and 1.0 W m-1 K-1, respectively. By applying the Wiedemann-Franz law, we attributed the significant decrease in thermal conductivity during hydrogenation to the reduction in free electrons.