Temperature dependence of the quadrupole interaction forRh100,Cd111, andTa181in Be

The temperature dependence of the electric field gradients at ${}_{}{}^{100}{}_{}{}^{}\mathrm{Rh}$, ${}_{}{}^{111}{}_{}{}^{}\mathrm{Cd}$, and ${}_{}{}^{181}{}_{}{}^{}\mathrm{Ta}$ impurities in Be have been measured by time-differential perturbed-angular-correlation methods. The observed temperature dependences are quite different. The interaction frequencies decrease for ${}_{}{}^{100}{}_{}{}^{}\mathrm{Rh}$ and ${}_{}{}^{111}{}_{}{}^{}\mathrm{Cd}$ with rising temperature, but increase for ${}_{}{}^{181}{}_{}{}^{}\mathrm{Ta}$, which is quite unusual. The probes were produced by ion implantation of the activities ${}_{}{}^{100}{}_{}{}^{}\mathrm{Pd}$, ${}_{}{}^{111}{}_{}{}^{}\mathrm{In}$, and ${}_{}{}^{181}{}_{}{}^{}\mathrm{Hf}$. Channeling experiments showed that Pd implanted into Be occupies substitutional sites. The results are compared with presently discussed models.