The electric-field gradient (EFG) at ${}^{111}\mathrm{Cd}$ nuclei dilutely substituting an $A$ cation site in delafossites $A^{+1\mathrm{}}{B}^{+3\mathrm{}}{\mathrm{O}}_2$ has been measured using a perturbed-angular-correlation technique. The radioactive isotope ${}^{111}\mathrm{Ag}({\beta }^{-}{)}^{111}\mathrm{Cd}$ was used as the hyperfine probe and introduced into the samples by thermal diffusion. The EFG’s measured using a ${}^{111}{\overrightarrow{\mathrm{Ag}\mathrm{}}}^{111}\mathrm{Cd}$ probe are compared with those measured using the ${}^{111}{\overrightarrow{\mathrm{In}}}^{111}\mathrm{Cd}$ probe and with the calculated values using the point-charge model including the local distortion introduced by the probe. The results are also discussed in terms of a previously observed correlation between the electric-field gradient and the cation-oxygen bond length in these delafossites and other binary oxides.

• Received 10 February 1998

DOI:https://doi.org/10.1103/PhysRevB.58.2563