Synthesis and magnetic properties of BaTiO₃-Co _xFe_3-xO₄ core-shell particles by homogeneous coprecipitation

BaTiO₃-Co_xFe_3-xO₄ (x is regulated by the R value, R = M (FeCl₂•4H₂O)/M (CoCl₂•6H₂O), the molar ratio of FeCl ₂•4H₂O to CoCl₂•6H₂O) core-shell particles were synthesized by facile homogeneous coprecipitation method utilizing urea as pH adjuster and air as oxidizer. The morphology, microstructure and the chemical compositions of the core-shell particles were characterized by TEM, XRD and EDX, respectively. The results showed that a compact, continuous and pure spinel structure Co_xFe _3-xO₄ shell was formed on the surface of BaTiO₃ particles after the homogeneous coprecipitation processes at low temperature (<100 C). The results of vibrating sample magnetometer (VSM) showed that with the R value increasing from 1.5 to 4, the saturation magnetization and coercivity of the BaTiO₃-Co_xFe_3-xO₄ core-shell particles increased from 16.2 emu/g to 38.7 emu/g and 136.6 Oe to 386.5 Oe, respectively. The magnetism of BaTiO₃-Co_xFe _3-xO₄ core-shell particles can be controlled by regulating the R.