Electron-phonon scattering in HgBr2 and IBr graphite intercalation compounds

The Hall coefficient and the dc resistivity in the basal plane and along the c axis of stage-2 IBr and stage-3 HgBr2 graphite intercalation compounds (GICs) were measured between 4.2 and 370 K. The resistivity of the IBr GIC indicates a metallic-like behaviour and a structural phase transition at 175 K. The Hall coefficient above 300 K of the HgBr2 GIC indicates deintercalation from an irreversible reduction of the carrier concentration. A study of the temperature dependence of the resistivity and Hall coefficient of the stage-2 IBr GIC above room temperature shows that the electron-out-of-plane phonon scattering plays a major role in this compound. The Hall coefficients are temperature independent below room temperature. The one-carrier model gives a value of 8.1 × 1026 m-3 for the IBr and a value of 7.9 × 1026 m-3 for the HgBr2 GIC for the carrier concentrations.