CoFe_2O_4-BaTiO_3 multiferroic composites: role of ferrite and ferroelectric phases on the structural, magneto dielectric properties

摘要

Cobalt ferrite (CoFe_2O_4) and Barium titanate (BaTiO_3) nanoparticles have been prepared by the microwave hydrothermal technique at 150 °C/60 min. The synthesized powders have been characterized using transmission electron microscopy, X-ray diffraction (XRD) and fourier transformation infrared spectroscopy. The XRD analysis confirms the formation of desired phase with crystallite sizes 25 nm for CoFe_2O_4 and 20 nm for BaTiO_3. The prepared powders were mixed at different weight proportions to obtain nanocomposites of (1 − x)CoFe_2O_4 + (x)BaTiO_3 (0 ≤ x ≤ 1) and densified at 910 °C/50 min via the microwave sintering process. The presence of two phases (CoFe_2O_4 and BaTiO_3) was confirmed using XRD and field emission scanning electron microscopy (FESEM). Ferroelectric (P-E) and magnetic (M-H) hysteresis loops have been studied at room temperature. In P-E loops, the coercive field and remanent polarization show light asymmetric behaviour with an increase of CoFe_2O_4phase concentration. The M-H loops infer that the magnetic saturation of the composite samples drops with increasing of BaTiO_3 phase concentration. The frequency dependent permittivity and permeability properties have been measured over a wide frequency range (100 kHz-1.8 GHz). The static magneto-electric (ME) voltage coefficient (dE/dH)_H is measured by vary in ME output voltage against the dc-bias magnetic field (H) at room temperature.