Structural, optical and electrical properties of BaTiO3 – NiFe2O4 based multifunctional composites

Abstract

The composites with composition of (1-x)BaTiO3(BTO) – (x)NiFe2O4(NF) with x=0.25 and 0.75 were synthesized by sintering the mixtures of highly ferroelectric and highly magnetostructive magnetic phaseobtained by auto combustion method. Structural study using Reitveld refinement of X-ray diffraction (XRD) pattern indicated a tetragonal structure (space group P4mm) for BTO phase while to that NF compound crystallizes in cubic structure (space group Fd3m). XRD pattern show that BTO and NF phase exists independently in NiFe2O4 doped composites without the presence of undesirable phases. The energy band gap (Eg) of both the composites have been measured using Diffuse Reflectance Spectroscopy (DRS). Band gaps are found to be 3.13 eV and 2.75 respectively for x=0.25 and 0.75. With the increase of NF ferrite phase, band gap is found to decrease. This is due to the fact that band gap value of the Nickel Ferriteis less as compared to Barium Titanate. This indicate the possibility of easy manipulation of the band gap over a range of energies by mere control of the molar ratio of phases. The electrical study of these materials were investigated using ferroelectric (P-E) loop tracer. For x=0.25 composite has shown better electrical property in comparison to other investigated composite for x=0.75. Remnant polarization and coercive field decreased with the increase of the content of magnetic phase.