Percolative effects and giant dielectric tunability of BaTiO3-LuFe2O4 composites

We report on exotic dielectric properties of composite materials consisting of traditional ferroelectric BaTiO3 and electronic ferroelectric LuFe2O4. The composites were synthesized by a simple ceramic processing method with properties that can be tailored by adjusting LuFe2O4 concentration. A percolative effect was observed at the volume fraction of ∼0.26, which led to an abrupt increase in the dielectric permittivity. For composites with high LuFe2O4 fractions, a giant dielectric tunability was observed over a broad temperature interval, which is in strong contrast to traditional ferroelectrics.