Abstract: The ZrO₂ buffer layer was coated on CoFe₂O₄(CFO) powder via a Sol-Gel method. The coated CFO and 0.92(Bi_0.5Na_0.5)TiO₃-0.02(Bi_0.5K_0.5)TiO₃-0.06BaTiO₃(BNBT) ceramic powder were mixed according to the chemical formula of xCFO/(1-x) BNBT (weight fraction x = 0.05, 0.10, 0.15, 0.20, 0.25, 0.30). Using polyvinyl alcohol (PVA) as binder, the mixture was pressed into disks. After sintered at 1050℃, the xCFO/(1-x) BNBT 0-3 composite ceramic disks were prepared. The X-ray diffraction results show that the ZrO₂ layer can buffer the Fe³⁺ and Co²⁺ ions diffusing from CFO to BNBT during the sintering process. The break-down voltage of the co-fired composites is measured to be 75kV/cm. It is found that the piezoelectric constant, electromechanical coefficient, remnant polarization and dielectric permittivity decrease as the CFO content increasing. Magnetoelectric coefficient (ME) and dielectric loss increase with the CFO content increasing. For a composite disk with dimension of -35mm×1.5mm, the ME coefficient at resonance frequency of 90 kHz is 1.39V/A under a DC magnetic bias of 199 kA/m.

Key words: magnetoelectric, 0-3 composite, ferroelectric, ferromagnetic