We report the results of a neutron powder diffraction study of the La(0.62)Li(0.16)TiO3 perovskite that determined the diffusion path of lithium cations at room temperature. At 77 K, the Li cations are located at the 2c site (Wycoff notation of the Cmmm space group) on the (002) La deficient layer, while, at room temperature, they are spread over a wide area and migrate following the 2c-4f-2c or 2c-2d-2c tie line on the (002) layer. The probability density of Li cations has a minimum between the 2c and 4f or between the 2c and 2d positions on the diffusion path in contrast to the previous reports where the bottleneck has been thought to be located at the 2c, 2d, and 4f positions. On the basis of the present structural model, the Li-cation conductivity is discussed in terms of a two-dimensional bond-percolation model for Li-cation diffusion. It was found that the vacancy at the La site is essential for the Li-cation conduction.

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Lamellar domain spacings (D) of blends of a styrene-2-vinylpyridine (SP) diblock copolymer and homopolymers corresponding to the block polymers (S and/or P), of which molecular weights are lower than that of the block polymer, were examined by small-angle X-ray scattering (SAXS), and the dimensions of block chains in the lamellae were investigated by small-angle neutron scattering (SANS). The D's for SP/S/P ternary and SP/S (or SP/P) binary blends increase with increasing the molecular weight of the homopolymers, MH, as well as the volume fraction of the homopolymers, ΦH, in the corresponding lamella. The variations of the D's with ΦH for the blends with homopolymers having different MH's reveal that homopolymers with higher MH are localized at the center of the corresponding lamella, while those with lower MH are distributed throughout the lamella. Moreover, the comparison between the D's for ternary and binary blends with homopolymers having equal MH's implies that the homopolymers in binary blends are more localized than those in ternary blends. In these ternary and binary blends the radii of gyration of styrene block chains along the direction parallel to lamellar interface are not much different from that for a pure diblock copolymer irrespective of ΦH as well as MH.

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