AKS doped tungsten wires-investigated by electrical measurements II. Impurities in tungsten

The Al, K, Si doped tungsten wires contain several minor impurities (in the ppm range), which are usually measured by chemical analysis. The excess electrical resistivity measures only those impurities, which are present in solute form. However, this property enables the resistivity to follow solution-dissolution processes, and solute interactions with lattice defects. Combining the resistivity measurements e.g. by thermoelectric power, it helps separating several kinds of solute impurities from each other. Processes like segregation-desegregation (Fe, Co), oxidation-reduction (At, Si), and the development of the stationary evaporation profile, can be studied as well. (C) 2002 Elsevier Science Ltd. All rights reserved.