ELECTRONIC-STRUCTURE AND TRANSPORT-PROPERTIES OF BA6CU12FE13S27

The electrical properties and bonding in Ba6Cu12S13S27 are analyzed wi th the extended Huckel tight-binding method. Because the Fermi level c rosses several bands, metallic properties could be expected for this m aterial. The electrical conductivity measurements as well as diffuse r eflectance spectrum show that Ba6Cu12S13S27 is a semiconductor with a band gap of 2.49 eV. The discrepancy between the theoretical and exper imental electrical properties is attributed to a random distribution o f the Cu and Fe atoms in the structure. (C) 1997 Elsevier Science Ltd.