Magnetic, dielectric and magnetoelectric properties of CoFe ₂O₄-Bi_0.85La_0.15FeO₃ multiferroic composites

Multiferroic composite nanoparticles of xCoFe₂O ₄-(1-x)Bi_0.85La_0.15FeO₃ (x = 0.1, 0.2, 0.3 and 0.4) were prepared by a two-step wet chemical procedure, combining co-precipitation and sol-gel techniques. Phase composition, magnetic property, dielectric property and magnetoelectric coupling effect were characterized by XRD, multifunctional magnetic physical testing system, Mössbauer spectroscopy and LCR HiTester. The composites consisted of spinel CoFe ₂O₄ and perovskite Bi_0.85La _0.15FeO₃ phases. Magnetization of the composites was found to increase with increasing CoFe₂O₄ molar fraction. Both Mössbauer spectroscopic analysis and magnetic measurement confirmed the coupling interaction between the magnetic phase and ferroelectric phase. The higher values of dielectric constant and dielectric loss were observed at lower frequencies in the low frequency range (100 Hz-1 MHz). CoFe₂O ₄ molar fraction in the composites had effect on dielectric resonance in the high frequency range (10-120 MHz). Magnetocapacitance coefficient of the composites was controlled by CoFe₂O₄ molar fraction at high frequency 100 MHz.