Characterization and electrical transport properties of the misfit layer compounds (BiSe)1.10NbSe2 and (BiSe)1.09TaSe2

Compounds (BiSe)1.10NbSe2 and (BiSe)1.09TaSe2 were prepared by high-temperature reaction of the elements. Crystals were grown by vapor transport. The misfit layer compounds are built of alternate sandwiches NbSe2 (TaSe2) with Nb (Ta) in trigonal prisms of Se and interface modulated double layers of BiSe; 13 of the Bi atoms are at distances of 3.19 Å across the interface. Electrical transport properties (resistivity, Hall effect and Seebeck effect) are in agreement with conduction by light holes and heavy electrons in the 4dz2 band of NbSe2 (5dz2 band of TaSe2). There is no significant electron donation from BiSe to NbSe2 (TaSe2); three 6p electrons per Bi being used for Bi-Se and Bi-Bi bonds.