Preparation of the percolative nickel-zinc ferrite/barium titanate composite ceramics with liquid-solid hybrid method

Ni_0.5Zn_0.5Fe₂O₄/ BaTiO₃ composite powders are synthesized by the liquid-solid hybrid method through mixing BaTiO₃ sol and Ni_0.5Zn_0.5Fe₂O₄ powder together, in which the BaTiO₃ sol is prepared by sol-gel method and the Ni_0.5Zn_0.5Fe₂O₄ powder is synthesized by self-combustion method. The Ni_0.5Zn_0.5Fe₂O₄/ BaTiO₃ composite ceramics are successfully prepared by pressing powder into green pellets and rings, and then sintering at different temperatures. The influences of ferrite phase on both the dielectric and magnetic properties of the composite are studied. The results show that, similar to the percolation behavior, the dielectric constant increases exponentially with increasing ferrite phase when its mole fraction is below 50% in the composite; while it remains almost a constant of about 10 000 F/m when the ferrite phase is more than 50%. The permeability of the composite increases from 5 to 18 H/m as ferrite phase increases from about 50% to 90%. It is clear that the composite ceramics with high dielectric constant and acceptable permeability can be obtained via the liquid-solid hybrid method.