title: Selective reduction of layers at low temperature in artificial superlattice thin films.
abstract: Reduction and oxidation in transition-metal oxides are keys to develop technologies related to energy and the environment. Here we report the selective topochemical reduction observed when artificial superlattices with transition-metal oxides are treated at a temperature below 300 °C with CaH(2). [CaFeO(2)](m)/[SrTiO(3)](n) infinite-layer/perovskite artificial superlattice thin films were obtained by low-temperature reduction of [CaFeO(2.5)](m)/[SrTiO(3)](n) brownmillerite/perovskite artificial superlattice thin films. By the reduction only the CaFeO(2.5) layers in the artificial superlattices were reduced to the CaFeO(2) infinite layers whereas the SrTiO(3) layers were unchanged. The observed low-temperature reduction behaviors strongly suggest that the oxygen ion diffusion in the artificial superlattices is confined within the two-dimensional brownmillerite layers. The reduced artificial superlattice could be reoxidized, and thus, the selective reduction and oxidation of the constituent layers in the perovskite-structure framework occur reversibly.
authors.affiliation: Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Matsumoto
authors.forename: Mitsutaka
authors.initials: M
authors.lastname: Haruta
authors.forename: Masanori
authors.initials: M
authors.lastname: Kawai
authors.forename: Aya
authors.initials: A
authors.lastname: Sakaiguchi
authors.forename: Noriya
authors.initials: N
authors.lastname: Ichikawa
authors.forename: Hiroki
authors.initials: H
authors.lastname: Kurata
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Shimakawa