Dielectric and magnetic properties of xCoFe2O4–(1 − x)[0.5Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3)TiO3] composites

•Spinel–perovskite xCoFe2O4–(1 − x)(0.5Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3)TiO3) composites have been synthesized by solid state reaction method.•Two anomalies in dielectric constant have been identified, and the composites show relaxor behaviour.•The magnetic properties of the composites improve with increasing concentration of CoFe2O4.•Enhanced magnetodielectric effect is found, and magnetoelectric coupling has been confirmed by Δϵ ∼ γM2 relation.•Optical band gap energy of these composites has been reported for the first time.

xCoFe2O4–(1 − x)(0.5Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3)TiO3) composites with x = 0.1, 0.2, 0.3 and 0.4 have been synthesized by solid state reaction method. X-ray diffraction analysis and field emission secondary electron microscopy have been used for structural and morphological analysis, respectively. The spinel CoFe2O4 and perovskite 0.5Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3)TiO3 phase could be identified in the composites. Two anomalies in dielectric constant have been identified: first one is close to ferroelectric to paraelectric phase transition of 0.5Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3)TiO3 ceramic and the other lies near the magnetic transition temperature of CoFe2O4. There is an increase in magnetocapacitance and saturation magnetization of the composites at room temperature with increase in CoFe2O4 content. The magnetoelectric coupling coefficient (γ) was approximated by Δϵ ∼ γM2 relation. The optical band gap energy of the composites decreases with increase in CoFe2O4 content.

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