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Semiconducting properties and band structure of polycrystalline Bi/sub 4/Mo/sub 20/O/sub 62/ compounds

Journal Article · · J. Polym. Sci.; (United States)
OSTI ID:6487757

Transport coefficient measurements (electrical conductivity, thermoelectric power and Hall effect) have been performed on compacted bars of Bi/sub 4/Mo/sub 20/O/sub 62/ in polycrystalline form over the temperature range (130-500 K). Experimental results are discussed in comparison to those obtained recently on Sb/sub 4/Mo/sub 20/O/sub 62/. They are interpreted on the basis of the same p-type semiconductor model with two inverted deep levels near the midgap. Conduction mechanisms are governed by acoustical-phonon scattering of the carriers. The top of the valence band is assumed to be formed from the d /sub xy/ orbitals of some of the Mo atoms leading to narrow bonding bands, while the donor and acceptor levels may be formed from the nonbonding d /sub xy/ orbitals of some of the Mo atoms of the distorted octahedron framework. EPR measurements are discussed on the basis of this model and in comparison to the EPR results for Sb/sub 4/MO/sub 20/O/sub 62/. It is assumed that more than one narrow energy level (localized d states located below the valence band) contributes to the area of the line. The XPS spectrum obtained on Bi/sub 4/Mo/sub 20/O/sub 62/ is also discussed.

Research Organization:
Laboratoire de Physique des Materiaux et Composants de l'Electronique, Nantes
OSTI ID:
6487757
Journal Information:
J. Polym. Sci.; (United States), Journal Name: J. Polym. Sci.; (United States) Vol. 46:6; ISSN JPSCA
Country of Publication:
United States
Language:
English