Hall coefficients of Al-Zn solid solution alloys

The Hall coefficient R H and the electrical resistivity p of high-purity aluminium and aluminium-base zinc solid solution alloys have been measured as a function of composition at 4·2 and 77°K. At both temperatures, RH changes from negative to positive values with increasing zinc contents. The critical points at which R H is zero are 5·2 at. % Zn at 4·2°K and 7·5 at. % Zn at 77°K, respectively. A rigid two-band model has been employed to account quantitatively for the behaviour of R H and p simultaneously. The relaxation times due to both the thermal scattering and the solute atom scattering have been numerically analysed by using experimental data. The impurity relaxation times are shown to obey the Nordheim concentration rule fairly closely. The effective mass ratio m e/m n of the electrons in the third Brillouin zone to the holes in the second zone is estimated to be 0·44.