Electrical resistivity and optical absorption in EuLiH3 and SrLiH3*

The electrical and optical properties of single crystals of SrLiH2 and EuLiH3 were investigated. Electrical resistivity measurements were carried out in the temperature range from 0 to 400°C using the van der Pauw technique. The room temperature resistivity values were 107 ohm-cm for both materials. The thermal activation energies observed were attributed to impurity effects. Optical transmission and diffuse reflectance measurements were made over the spectral range from 0·6 to 5·5 eV. Evidence was found for both impurity and intrinsic absorptions. For SrLiH3 a single intrinsic absorption was found at about 4·0 eV. Three intrinsic absorptions were found for EuLiH3 at 2·0, 4·0 and 5·2 eV. The common absorption at 4·0 eV is attributed to the valence band, which is largely H− in character, to conduction band transition. The two additional absorptions for EuLiH3 are assigned to transitions between localized 4f levels located within the band gap and 5d bands in analogy with results for other divalent europium compounds.