Abstract
We present band-structure calculations of , an intercalation compound in which the Sn atoms have a very uncommon linear coordination by two S atoms and an unusual formal valency . The Sn 5 and 5 states show strong metal-metal bonding in the intercalant planes and the Fermi level is crossed by a very wide band composed of these Sn 5 states. Angle-resolved photoelectron spectra are in agreement with the calculated band structure. is metallic as is reflected in the measured transport properties (resistivity, Hall effect, thermoelectric power). Low-temperature specific-heat measurements show an anomaly due to superconductivity below 2.8 K. The Sn 4d core levels, measured with photoelectron spectroscopy, show a splitting of 1 eV, indicating the presence of two different types of Sn atoms. This could be due to a valence disproportionation →+ and rapid valence fluctuations between and .
- Received 1 September 1989
DOI:https://doi.org/10.1103/PhysRevB.40.12111
©1989 American Physical Society