Thermopower and thermal conductivity have been measured between 2 and 300 K on Sb${\mathrm{Cl}}_5$ graphite intercalation compounds spanning the stages 2-10. In addition, a strong transverse magnetic field has been used to separate the electronic and lattice parts of the thermal conductivity. The thermopower of all compounds is positive and increases with stage index. An anomaly near 230 K is associated with the commensurate-incommensurate transition. The thermal conductivity at high temperatures increases with the stage index but is significantly smaller than the conductivity of pure graphite. However, below about 5 K, the thermal conductivity of the intercalated material is larger than that of graphite due to as much as an order-of-magnitude enhancement in their electronic thermal conductivity. The lattice thermal conductivity of the intercalation compounds is smaller than that of graphite but it shows a surprising stage and temperature dependence which suggests that the low-frequency lattice modes of intercalant provide a significant contribution, particularly at low temperatures.

• Received 29 April 1982

DOI:https://doi.org/10.1103/PhysRevB.26.3312