The diffusion of these elements into monocrystalline and polycrystalline samples was studied. It was found that the volume diffusion coefficients of Ga ions in single crystals were larger than those of Sc or Yb. On the other hand, the diffusion coefficients of Sc and Yb had almost the same value. The cation diffusion exhibited an extrinsic behavior. The cation ratio, Y/Al, affected the diffusivity of Sc and Yb. It was noted that Y-rich material had a smaller concentration of Y vacancies than that with a stoichiometric composition. The Sc and Yb diffused preferentially along grain boundaries.

Diffusion of Scandium, Gallium and Ytterbium Ions into Single- and Poly-Crystalline Yttrium Aluminium Garnet. H.Haneda, Y.Miyazawa, I.Sakaguchi, H.Nozawa, T.Yanagitani, M.J.Melendo: Journal of the Ceramic Society of Japan, 2001, 109[2], 114-21