Temperature dependence of the electric field gradient generated by nearest-neighbor impurity atoms in cubic Ag metal

Abstract

The electric quadrupole interactions produced by near-neighbor (nn) and distant-neighbor impurity atoms of Cu, Au, Zn, In, Ga, Al, Sn, and Sb in a cubic Ag lattice are measured as a function of the temperature by the time differential perturbed angular correlation method. The results show that both the high-frequency interaction vhQ-generated by nn impurities-and the low-frequency interaction v1Q- generated by distant impurities-follow the relation vQ(T) = vQ(O) (I -a T 312). From the present measurements it can be concluded that both coefficients, ∝h and ∝1 are strongly dependent on the mass M of the impurity. For the case of Al, Ga, and In impurities with the same charge difference ∆Z = 2 between host and impurity, both ∝h and ∝1 scale as M-n with n = 0.37 ±0.04 and n = 0.9 ±0.4, respectively. lt is shown that for a Sn impurity the unnormalized slope ∝h ·vhQ(O) is independent of the concentration in the range 1.5-3 at. %. A strong dependence of ∝h and ∝1 on ∆Z, the charge difference between host and impurity, is also observed; however, the results do not follow a simple relation.