title: Ferroelectric hollow particles obtained by solid-state reaction.
abstract: Hollow particles of barium titanate were obtained by a two-step process combining colloidal chemistry and solid-state reaction. BaCO(3) crystals (size ≈1 µm) suspended in a peroxy-Ti(IV) aqueous solution were coated with an amorphous TiO(2) shell using a precipitation process. Calcination of the BaCO(3)@TiO(2) core-shell particles at 700 °C resulted in the formation of BaTiO(3) hollow particles (shell thickness of ≈70 nm) which retain the morphology of the BaCO(3) crystals. Formation of the cavity occurs because out-diffusion of the core phase is much faster than in-diffusion of the shell material. X-ray diffraction (XRD) and Raman spectroscopy indicate that the hollow particles possess a tetragonal ferroelectric structure with axial ratio c/a = 1.005. Piezoresponse force microscopy has shown strong piezoactivity and 180° ferroelectric domains. The process described provides a general route to fabricate hollow ferroelectric structures of several compounds.
authors.affiliation: Institute of Energetics and Interphases, National Research Council, Via De Marini 6, I-16149 Genoa, Italy.
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Buscaglia
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Buscaglia
authors.forename: Massimo
authors.initials: M
authors.lastname: Viviani
authors.forename: Giovanni
authors.initials: G
authors.lastname: Dondero
authors.forename: Serge
authors.initials: S
authors.lastname: Röhrig
authors.forename: Andreas
authors.initials: A
authors.lastname: Rüdiger
authors.forename: Paolo
authors.initials: P
authors.lastname: Nanni