resumo
The mechanosynthesis of nanocrystalline CaTi1-xMnxO3-delta is reported for the first time. Powdered CaO, TiO2 anatase and Mn2O3 (Aldrich) were weighed in the appropriate stoichiometric quantities in order to obtain CaTi1-xMnxO3-delta (x=0.05, 0.10, 0.15, 0.20, 0.30, 030 and 0.80) and dry milled in a planetary high-energy ball mill, using zirconia containers and balls, with a 10:1 ball/mass ratio. The planetary rotation was kept constant at 650 rpm and the container at 1300 rpm, in the opposite direction. Powder XRD patterns revealed a perovskite forming from the early milling stages and a completed reaction after 180 min, with no apparent crystalline or amorphous intermediates, indicating significant Mn solubility in CaTiO3. Patterns show a decrease in lattice volume upon Mn substitution, as expected from the lower Mn3+ or Mn4+ ionic radii when compared to Ti4-. The average crystallite size is in the range 5-30 nm, as determined from Williamson-Hall plots and confirmed by high resolution transmission electron microscopy.
palavras-chave
OXYGEN; CATI1-XFEXO3-DELTA; MICROSTRUCTURE; PEROVSKITES; PERMEATION; CONDUCTION; VACANCIES; CATIO3
categoria
Materials Science
autores
Goncalves, P; Canales-Vazquez, J; Figueiredo, FM
nossos autores
Filipe Miguel H Lebre R Figueiredo
Investigador Principalagradecimentos
This work was supported by FCT (project POCI/CTM/59727/2004), Portugal, and NoE FAME, CEC, Brussels. The authors are also grateful to the Serveis de Microscopia at UAB (Barcelona) for providing access to the TEM microscopes and the Albacete Science and Technology Park for funding.