The microscopic mechanism of O diffusion in yttria-stabilized material was investigated by means of a polyhedron analysis. It was shown that the probability of finding an O ion in a tetrahedron increased as the number of Y ions at the corners of a tetrahedron increased. This tendency became marked with increasing dopant concentration; a behavior which was consistent with the fact that the O coordination number for an Y ion was larger than that for a Zr ion. Detailed study of the O migration between tetrahedra, in the [100] direction, showed that such migration occurred preferentially between tetrahedra having a common Zr-Zr edge, and that Y ions restricted the diffusion paths of O ions. Restriction by the Y-Y edge caused a decrease in O diffusion with increasing dopant concentration.

F.Shimojo, H.Okazaki: Journal of the Physical Society of Japan, 1992, 61[11], 4106-18