Measurements were made of self-diffusion coefficients in ceramic samples of solid solutions by using suitable radio-tracers (table 195). It was found that, as the Ti content of the solid solution increased, the self-diffusion coefficients of 44Ti increased, and that the Ti diffusivity was greater than the Sr diffusivity for all of the compositions within the homogeneity range. This was attributed to the appreciable difference between the ionic radii of Ti (0.0605nm for a coordination number of 6) and Sr (0.118nm for a coordination number of 6 and 0.144nm for a coordination number of 12). This difference was suggested to be responsible for a distortion of the crystal structure of Sr6Nb2O11; thus producing new paths for both the short-circuit and intercrystalline diffusion of Sr ions. A comparison of Ti and Nb mobilities suggested that Nb was fixed more securely within the NbO6 octahedron, than was Ti, because of a strong polarization of the neighboring O atoms. The Nb therefore had a noticeably smaller self-diffusion coefficient.

A.L.Podkorytov, M.I.Pantyukhina, V.M.Zhukovskii, N.A.Simaranova, N.V.Sherstneva, G.I.Dontsov: Neorganicheskie Materialy, 1995, 31[8], 1097-9 (Inorganic Materials, 1995, 31[8], 1007-9)