Anew series of (Y2-yLiy)Ti2O7-y having an ordered pyrochlore phase was prepared by a solid state reaction method with a solid solution range of 0.05 y 0.10. Unit cell parameters obtained by the Rietveld refinement method shows that the a-axis decreases linearly with increasing the amount of Li ion addition,indicating the successful incorporation of the Li ion into unit cell. The average x-fractional coordinate of the O(1) site depends on the ionic radius ratio of r(A3+)/r(Ti4+) in theA2Ti2O7 with a pyrochlore phase. The Ti K-edge XANES spectra of the (Y2-yLiy)Ti2O7-y show that the valence of the Ti ions is slightly less than 4 so that Ti is in the mixed valence state. Average particle size increases with increasing the amount of extra Li ion addition, which acts as a flux to lower the melting point of the materials.
Journal of the Chinese Chemical Society=中國化學會會誌 56(6), pp.1112-1117