High-temperature creep resistance in polycrystalline Al2O3 with 0.1mol% oxides of YO1.5, ZrO2 or MgO was examined by uniaxial compression creep testing at 1250C. The creep resistance was highly improved by the doping of Y or Zr even in the dopant level of 0.1mol%, but was retarded by Mg doping. The dopant effect on the creep resistance could not be explained in terms of, for example, ionic radius of the dopant cation or eutectic point in Al2O3-oxide of dopant cation system. Each dopant cation was found to segregate in grain boundaries, and was likely to influence grain boundary diffusion in Al2O3. The ionic bonding and the covalent bonding of Al–O were lowered by the introduction of VO’’ or VAl’’’ but the values of the net charge in Al and O were increased by the cations doping. The change in the value of Net Charge was correlated well with the high-temperature creep resistance in Al2O3 with cation doping. It was suggested that the ionicity in Al and O was an important factor to determine high-temperature creep resistance in polycrystalline Al2O3.

Vacancy Effect of Dopant Cation on the High-Temperature Creep Resistance in Polycrystalline Al2O3. H.Yoshida, Y.Ikuhara, T.Sakuma: Materials Science and Engineering A, 2001, 319-321, 843-8