Hydrogen concentration dependence on thermal and electrical conductivities of metal-hydride composite materials

Thermal conductivities of uranium-ziruconium hydrides (45 wt%U-ZrHx : x=1.60 and 1.90) have been calculated at temperature up to 773 K by taking into account the thermal diffusivity, measured using a laser-flash method, the specific heat and the density. The thermal conductivity increased with increasing the content of hydrogen retained in ZrHx. Moreover, the electronic and phonon heat conductions have been estimated from Wiedemann-Franz rule and electrical conductivity, obtained using a four-contact DC method. The increment of the conductivity is attributed to the phonon as well as electron scatterings due to hydrogen vacancy in the hydrides. The contribution by the phonons was greater than that by the electrons at temperatures below 500 K, while both electrons and phonons play an important role in the thermal conductivity above 500 K.