J. Phys. IV France 07 (1997) C1-755-C1-756
Nanoparticles of Barium Ferrite Synthesised Using a Water-in-Oil MicroemulsionD.A. Rawlinson and P.A. Sermon
Solids and Surfaces Research Group, Department of Chemistry, Brunel University, UXBRIDGE, Middlesex, UB8 3PH, U.K.
The application of barium ferrite (BaFe12O19 ; BaF) in the magnetic media industry requires materials with strict control of homogeneity, morphology and magnetic properties resulting from their preparation and pretreatment. Here the use of water-in-oil microemulsions for the synthesis of nanoparticles of BaF is considered. Two microemulsions (containing an aqueous phase, cetyltrimethylammonium bromide surfactant, n-butanol co-surfactant and octane) were used. The aqueous phase of the first microemulsion contained ferric/barium salts and the second co-precipitant ammonium carbonate. On mixing, the aqueous cores acted as microreactors for co-precipitation of the BaF precursor which was then separated, dried and annealed (1198K, 24h) to form BaF. It is shown that microemulsions prepared with different surfactant concentrations lead to particles with variable but controlled morphology and magnetic properties. In particular, it is shown that selecting a microemulsion with a specific concentration can allow coercivity and particle size of product to be nano-engineered.
© EDP Sciences 1997