Electric Field Gradients in Dilute Copper Alloys

The electric-quadrupole-tensor parameters of copper neighbors to the impurities Zn, Cd, Ag, and Au have been measured by studying the angular dependence of the second-order splitting of the $\frac{1}{2}\leftrightarrow -\frac{1}{2}$ nuclear-magnetic-resonance transitions in single crystals of copper metal. The parameters for the first neighbors were determined for all the impurities, and for the second neighbors to Cd, Ag, and Au. The results for the charged impurities complement the work of Jensen, Nevald, and Williams on Ge, In, Sn, and Sb in copper, and show a systematic change in the electric field gradient at nearest-neighbor sites as a function of impurity valence for which present theory is inadequate.