Electrical transport properties of A₄C₆₀ (A=Li, Na, and Rb) under pressure

Abstract

In search of structural phase transformations, the electrical resistances of the alkali metal-intercalated fullerene compounds Li₄C₆₀, Na₄C₆₀, and Rb₄C₆₀ have been measured as functions of temperature and pressure. The compounds have different lattice structures, and in the first two, the fullerene molecules form two-dimensional covalently bonded polymer lattices. No phase changes could be identified over the ranges 100–400 K and 0–2 GPa. All materials are semiconducting under the conditions studied, and we see no strong dependence of the band gaps on pressure.

Keywords:

• Li₄C₆₀
• Na₄C₆₀
• alkali metal fulleride
• high pressure
• resistivity
• conductivity

Acknowledgements

This work was financially supported by the Swedish Research Council. T. Wågberg and M.G. Yao gratefully acknowledge further support from the Wenner-Gren Foundations.