DISLOCATION RESISTIVITY IN CU - DEPENDENCE OF THE DEVIATIONS FROM MATTHIESSENS-RULE ON TEMPERATURE, DISLOCATION DENSITY AND IMPURITY CONTENT

Measurements of dislocation resistivity and the deviations from Matthi essen's rule (DMRS) are reported for polycrystalline Cu samples with v arious dislocation densities, impurities and phonons. Since this DMR c an reach the same order of magnitude as the dislocation resistivity it self, its quantification is essential in using the electrical resistiv ity for dislocation density measurement. In the framework of the class ical two-group model, a formula for the DMR is derived for the three i ndependent scatterers. The fits by this formula are satisfactory provi ded that isotropic phonon scattering is chosen for samples with high d islocation densities. White samples with a high purity (residual resis tivity ratio (RRR) greater than or equal to 300) show dislocation scat tering anisotropies A(dis) similar or equal to 0.1 irrespective of dis location density, the more impure material (purity 99.99%) (RRR = 130) exhibits a significant decrease in A(dis) at tow dislocation densitie s, indicating some contribution of enhanced strain fields in the dislo cation structure. This leads to an enhanced DMR contribution in this m aterial and makes the determination of tile dislocation density N by t he electrical resistivity method less reliable. Nevertheless, in the w hole purity range considered, the electrical resistivity yields at lea st the same measuring resolution as TEM of about Delta N similar or eq ual to 1 x 10(9) cm(-2), but a better performance for high dislocation densities up to the order of 10(14) cm(-2).