MATTHIESSENS RULE AND ELECTRICAL RESISTIVITY OF IRON-SILICON SOLID SOLUTIONS

The electrical resistivities of iron-silicon solid solutions (0.97-7.7 a/o silicon) were measured between 4.2° and 310°K. Above 30°K the data were analyzed for deviations from Matthiessen's rule. Initially, abnormal negative deviations were observed, however, these anomalies could be ascribed to systematic changes with silicon content in the ideal resistivity. The ideal resistivity of the alloys was identical to that of pure iron when scaled in magnitude by a concentration-dependent parameter and when the temperature was scaled by a characteristic resistivity temperature. This characteristic temperature varied with silicon concentration in the same manner as the ferromagnetic Curie temperature and in marked contrast to the lattice Debye temperature. This similarity in dependence on silicon content suggests the resistivity is more critically dependent on the magnetic properties of the host metal than on its lattice dynamics. After the appropriate corrections to the ideal resistivity were made, the deviations from Matthiessen's rule were concentration independent as expected from some theories for high solute resistivity alloys. The corrected deviations were compatible with explanations involving anisotropies with respect to electron wave vector in the scattering processes and to a lesser extent with spin mixing theories involving anisotropies with respect to spin. © 1969.