Effect of sintering temperature on structural, electrical, magnetic and magnetoelectric properties of lead-free [85 wt% Ba0.95Ca0.05Ti0.95Sn0.05O3–15 wt% Ni0.7Zn0.3Fe2O4] particulate composite

In this work, effect of sintering temperature on magnetoelectric properties of lead-free [85 wt% Ba0.95Ca0.05Ti0.95Sn0.05O3 (BTCS)–15 wt% Ni0.7Zn0.3Fe2O4 (NZFO)] particulate composite has been studied. The composites were synthesized by solid-state reaction method and sintered at five different temperatures. Structure analysis of constituent phases of the composites has been examined by X-ray diffraction (XRD) technique. Rietveld refinement confirmed that the piezoelectric BTCS comprised two phases (tetragonal and orthorhombic) and inverse spinal NZFO has a cubic phase in the composites. Surface morphology study carried out by Field Emission Scanning Electron Microscope (FESEM) accounted the increase in uniform grain size and connectivity of the constituent phases with the increase of sintering temperature. Dielectric constant vs. temperature (Ɛr–T) graph showed two anomalies corresponding to the ferroelectric transition temperature of BTCS and the magnetic transition temperature of NZFO phase. Enhancement in saturation polarization (PS) and decrease in saturation magnetization (MS) at room temperature were observed with the increase of sintering temperature. The composite, sintered at 1300 °C for 4 h showed maximum change in magnetodielectric value (MD% ∼ 1.94 at 100 kHz frequency) at room temperature. This sample also exhibited the highest first and second order magnetoelectric coefficients (α/d = 2.37 mV/cm-Oe and β/d = 40.69 µV/cm-Oe2) at room temperature which was explained on the basis of sintering temperature-dependent ferroic properties of the individual phases.