Study of structural, electrical, magnetic and optical properties of 0.65BaTiO3–0.35Bi0.5Na0.5TiO3–BiFeO3 multiferroic composite

Abstract

Conventional solid state reaction method was used to prepare (1 − x)[0.65BaTiO3–0.35Bi0.5Na0.5TiO3]–xBiFeO3 [where x=0.0, 0.10, 0.15 and 0.20] composite. The presence of constituent phases in composite was confirmed by X-ray diffraction (XRD) studies. Average grain size was calculated by using field effect scanning electron microscope (FESEM) which increases from 356nm to 577nm with increase in ferrite content. Dielectric study confirms the presence of both ferroelectric and ferrite phases. We also found that the dielectric constant (ε) and Curie temperature (Tc) for ferrite phase increases with increase in the BiFeO3 content. Remnant polarization and coercive field for 0.65BaTiO3–0.35Bi0.5Na0.5TiO3 are found to be 7.63μC/cm2 and 9.55kV/cm respectively, afterward these values decreases with increase in the ferrite content. Magnetic hysteresis were measured at temperature 300K and 5K using superconducting quantum interference device which shows that 0.65BaTiO3–0.35Bi0.5Na0.5TiO3–BiFeO3 has antiferromagnetic nature with unsaturated hysteresis loops so only able to obtain the magnetization (MH) at 7T. The antiferromagnetic nature of composite ceramics was also confirmed from the ZFC–FC curve. The presence of magnetocapacitance depicts the magnetoelectric coupling at room temperature. Impedance analysis provides the evidence of space charge accumulation in the samples, which vanish at higher frequencies and temperature. The electrical conductivity was observed to increase with rise in temperature which corresponds to the negative temperature coefficient of resistance (NTCR) behavior analogous to a semiconductor. Optical study shows that the band gap energies decrease with increase of BiFeO3 content.