Doping of sapphire single crystals with 111In and 111mCd detected by perturbed angular correlation

The electric hyperfine interaction of ion beam implanted In-111 and Cd-111m probe atoms in sapphire (Al2O3) single crystals has been investigated using perturbed angular correlation spectroscopy. For both probe atoms the same distinctive electric field gradient was found, indicating that nearly all the implanted probe atoms form a stable substitutional configuration in the temperature range between 77 K and 873 K on the aluminum sublattice. A comparative study between In-111 and Cd-111m-measurements points to a dynamic interaction initiated by the electron-capture of In-111(EC)Cd-111 similar to In2O3 and La2O3. Size and orientation of the EFG are discussed in comparison to experimental results in Cr2O3 single crystals.