Bulk electro- and thermotransport in Al

The electro- and thermotransport properties of Al have been very well investigated for short circuit paths while the bulk transport is controversial. In particular there is a work of Matlock and Stark [1] where the thermotransport in single crystals has a great positive heat of transport Q* and a small negative value in polycrystals. To clarify the situation we have reinvestigated the elctro- and thermotransport of Al. We found an electrotransport directed to the anode with a temperature dependent effective charge number z* between -4.5 and -3.3, rising from 410 to 610C, and an activation energy of 1.14eV for an average constant z* For the residual resistivity of the activated complex we get 0.5 mu Omega cm/at%. The thermotransport is directed to the cold end with a very small heat of transport (Q*=0.07eV) and an activation energy of 1.25eV. Within the limits of error the activation energies of electro- and thermotransport agree with the activation energy for selfdiffusion Q(d)=1.28eV. Hence we assume that the jump mechanisms for diffusion and transport are the same. Since our large-grained polycrystalline material behaved like a single crystal our results have to be compared with the single crystal data of Stark et al.[1,3]. Both results have the same positive sign but our value (0.07eV) is by a factor of 7 smaller than that of Stark et a1.(Q*=0.48eV).