Interband transitions, IR-active phonons, and plasma vibrations of some metal hexaborides

摘要: The high IR reflectivity of monocrystalline metallic metal hexaborides is superimposed by weak phonon spectra. symmetry selection rules are lifted, probably because structural defects. From the plasmon-phonon polariton frequencies in LaB 6 compared with those semiconducting EuB and YbB , softening hardening specific F 1u modes free carriers determined. plasma edges some parameters electronic transport derived. electron concentration increases proportional to C content, whose donor properties found be comparable hydrogen-like impurities. existence energy gaps proves that these compounds semiconductors.