title: BaTiO3 supercages: unusual oriented nanoparticle aggregation and continuous ordering transition in morphology.
abstract: Here we report the organic-free mesocrystalline superstructured cages of BaTiO3, i.e., the BaTiO3 supercages, which are synthesized by a one-step templateless and additive-free route using molten hydrated salt as the reaction medium. An unusual three-dimensional oriented aggregation of primary BaTiO3 nanoparticles in the medium of high ionic strength, which normally favors random aggregation, is identified to take place at the early stage of the synthesis. The spherical BaTiO3 aggregates further experience a remarkable continuous ordering transition in morphology, consisting of nanoparticle faceting and nanosheet formation steps. This ordering transition in conjunction with Ostwald ripening-induced solid evacuation leads to the formation of unique supercage structure of BaTiO3. Benefiting from their structure, the BaTiO3 supercages exhibit improved microwave absorption property.
authors.affiliation: Department of Materials Science and Engineering, Aalto University , Espoo 02150, Finland.
authors.forename: Juan
authors.initials: J
authors.lastname: Li
authors.forename: Sami
authors.initials: S
authors.lastname: Hietala
authors.forename: Xuelin
authors.initials: X
authors.lastname: Tian
keywords: electric double layer; hollow structures; mesocrystals; microwave absorption; molten hydrated salt; ordering transition; oriented aggregation