title: Unravelling the complex nanostructure of La0.5-xLi0.5-xSr2xTiO3 Li ionic conductors.
abstract: The origin of the intricate nanostructure of La0.5-xLi0.5-xSr2xTiO3 (0.0625 ≤ x ≤ 0.25) perovskite-type Li ion conductors has been investigated. Reciprocal space electron diffraction analysis and aberration-corrected STEM by combining annular bright field (ABF) and high angle annular dark field (HAADF) imaging methods have been used to elucidate the complex local atomic arrangements which cannot be adequately described by average crystal structure models. Two different local crystal structures endotaxially-related at the nanoscale without compositional phase separation associated, constituting the crystals. Self-organization of the two different ordered regions arises as a consequence of the competition between two distortive forces in the crystal lattice: octahedral tilting and second-order Jahn-Teller distortion of TiO6 octahedra. Changes in the distribution of A species suggest different Li ion conduction pathways for the two structures and this scenario has difficult long-range Li mobility. The detailed study performed may be helpful in understanding the local structural changes affecting Li and their relation to the conductivity in LLTO-derived ionic conductors.
authors.affiliation: Departamento Química Inorgánica, Facultad de Ciencias Químicas, Universidad Complutense, 28040 Madrid, Spain. esterg@quim.ucm.es.
authors.forename: Ester
authors.initials: E
authors.lastname: García-González
authors.affiliation: ICTS-Centro Nacional de Microscopia Electrónica, Universidad Complutense, 28040, Madrid, Spain.
authors.forename: Esteban
authors.initials: E
authors.lastname: Urones-Garrote
authors.affiliation: Departamento de Ciencia e Ingeniería de Materiales, Universidad Carlos III de Madrid, Avda. Universidad, 3028911 Leganés, Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Várez
authors.affiliation: Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Cantoblanco, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Sanz