Electric-field gradients in Sm2O3, Gd2O3, and Ho2O3 measured with perturbed-angular-correlation spectroscopy.

Abstract

The time-differential perturbed-angular-correlation (PAC) method with ion-implanted $^{111}\mathrm{In}$ tracers was employed to study the hyperfine interactions of $^{111}\mathrm{Cd}$ nuclei in the rare-earth sesquioxides ${\mathrm{Sm}}_{2}$${\mathrm{O}}_{3}$, ${\mathrm{Gd}}_{2}$${\mathrm{O}}_{3}$, and ${\mathrm{Ho}}_{2}$${\mathrm{O}}_{3}$. Up to five electrical quadrupole interactions appeared in each oxide, two of which we attribute to the electric-field gradients (efg) acting on $^{111}\mathrm{Cd}$ on the substitutional lattice sites in the cubic bixbyite phase; in ${\mathrm{Gd}}_{2}$${\mathrm{O}}_{3}$ and ${\mathrm{Sm}}_{2}$${\mathrm{O}}_{3}$ small fractions can also be related to the B phase. The scaling of the efg in the C phase is discussed in connection with previous findings in other ${\mathrm{M}}_{2}$${\mathrm{O}}_{3}$ sesquioxides. A slight linear increase of the quadrupole coupling constants ${\ensuremath{\nu}}_{\mathit{Q}}$ for increasing temperature was found.