Mesostructured and mesoporous pure and substituted barium hexaferrite phases

摘要

Mesostructured pure barium hexaferrites (BaFe_(12)O_(19)) and substituted Co-Ti barium hexaferrites (BaCo_xTi_xFe_(12-2x)O_(19)) have been prepared by employing ionic and non-ionic surfactants as structure directing agents. The mesostructure formation was achieved by controlling the electrostatic and hydrogen bonding interactions at the organic-inorganic interface depending on the nature of the surfactant polar headgroup and pH of solution. The use of non-ionic oligomeric surfactants (Tween 20, Brij 35, Triton X-114) as structure directing agents led to the formation of thermally stable mesoporous phases displaying unimodal pores in the 4-12 nm range and specific surface areas up to 275 m~2 /g. To the best of our knowledge this is the first successful example of mesostructured and mesoporous pure and substituted barium hexaferrites phases. These novel phases are promising catalytic and magnetic materials due to their remarkable high surface areas, thermal stability and ordered pore architectures in the nanoscopic regime.