Structural, dielectric and magnetic properties of particulate composites of relaxor (BaTi0.85Sn0.15O3) and ferrite (NiFe2O4) synthesized by gel-combustion method

Particulate composites of (1-x) BaTi0.85Sn0.15O3 - x NiFe2O4 (with x = 5, 10,15 and 20 wt%) were synthesized using the solid-state reaction method by sintering at 1350 A degrees C for 4 h. Formation of the diphase composites was confirmed by X-ray diffraction (XRD) and Fourier Transform Infra-red (FTIR) techniques. Temperature (RT-200 A degrees C) and frequency (20 Hz- 1 MHz) dependent of AC conductivity, dielectric constant and dissipation have been studied. The dielectric constant exhibits strong frequency dispersion in the range 20 Hz-1 kHz which is attributed to Maxwell-Wagner interfacial polarization occurring at grain-grain-boundaries interface/interface of grains of BTS-NF. The M-H curve of all the composites exhibited a hysteresis loops typical charcateistic of a ferromagnetic material. The ferromagnetic ordering in the composites on account of NiFe2O4 as a constituent is explained using bound magnetic polarons (BMPs) model. The experimental magnetic data have been fitted to BMP model. Value of M-s is smaller, whereas of H-c and M-r are higher of the composites compared to value for NiFe2O4. The temperature at which divergence in the M vs. T plot in ZFC and FC starts is higher for the composites than for NiFe2O4.