Thermally stable mesoporous barium-iron mixed oxide phases

Thermally stable mesoporous Ba-Fe and Co-Ti-Ba-Fe mixed oxide phases, have been prepared by employing non-ionic oligomeric surfactants as structure directing agents. The mesostructure formation was achieved by controlling hydrogen bonding interactions at the inorganic-organic interface in the vicinity of the isoelectric point of the Fe ions. The use of Tween-20, Brij-35, Triton X-114 as structure directing agents led to the formation of thermally stable robust mesoporous phases displaying unimodal pores in the 4-12 nm range and remarkable high specific surface areas up to 260 m2/g. The observed low saturation magnetization and coercitivity values for these novel mesophases, make them highly attractive for superparamagnetic applications. To the best of our knowledge this is the first successful example of mesoporous Ba-Fe and Co-Ti-Ba-Fe mixed oxide phases.