title: Long-range and short-range structures of cube-like shape SrTiO3 powders: microwave-assisted hydrothermal synthesis and photocatalytic activity.
abstract: We report herein a detailed study on the influence of microwave-assisted hydrothermal (MAH) treatment time on both long and short range structures around Ti atoms of SrTiO3 powders. Few studies have been carried out on short-order structural properties as well as the relationship between the local order and the SrTiO3 photocatalytic properties. We use X-ray diffraction to determine the long-range structure, while the local environment around the Ti atom is probed with X-ray absorption spectroscopy and the vibration frequencies are investigated by Raman spectroscopy. The faster crystallization of SrTiO3 powders provided by the MAH system resulted in large distortions of Ti-O bond lengths which remain unchanged even for a longer MAH treatment time. Despite the long-range structure being associated with ideal TiO6 clusters, X-ray absorption spectroscopy measurements identified the presence of undercoordinated TiO5 clusters. Compared with the reference bulk SrTiO3, the hierarchical SrTiO3 cube-like shape showed enhanced photocatalytic activity, which was associated with the presence of these TiO5 clusters. Field emission scanning electron microscopy (FE-SEM) revealed that the superstructures based on a cube-like shape are formed by an assembly process, becoming well defined as a function of MAH treatment time.
authors.affiliation: Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense, 400, 13566-590, São Carlos, SP, Brazil. lfsilva@ursa.ifsc.usp.br
authors.forename: Luís F
authors.initials: LF
authors.lastname: da Silva
authors.forename: Waldir
authors.initials: W
authors.lastname: Avansi
authors.forename: Juan
authors.initials: J
authors.lastname: Andrés
authors.forename: Caue
authors.initials: C
authors.lastname: Ribeiro
authors.forename: Mário L
authors.initials: ML
authors.lastname: Moreira
authors.forename: Elson
authors.initials: E
authors.lastname: Longo
authors.forename: Valmor R
authors.initials: VR
authors.lastname: Mastelaro