The structures of 1-dimensional ionic conductors Kx(Ga1-yAly)2+xTi2-xO7 (x approximately 0.14, y approximately 0.10, 0.23, 0.39) were refined by single-crystal X-ray diffraction. A 1-dimensional tunnel-like space with a large cross section was formed by the linkage of coordination polyhedra of the metal and O ions; K ions were distributed in the tunnel. Significant differences were seen in structures with different Al content; these differences could be explained by considerations of crystal chemistry. The probability density functions (PDFs) of the K ion were obtained using up to fourth-order terms of the atomic displacement parameters. The joint PDFs for the K ion had clarified that a K conduction path deviates slightly from the central axis of the tunnel in all the samples. In contrast with the usual one-dimensional ionic conductors, no distinct bottleneck effect was observed from the joint-PDFs and one-particle potentials.

X-ray Diffraction Study for One-Dimensional Ionic Conductors Kx(Ga1-yAly)2+xTi2-xO7 (x = 0.14, y = 0.10, 0.23, 0.39). Y.Michiue, S.Yoshikado: Acta Crystallographica B, 2005, 61[6], 608-15