Studies on dielectric and magnetic properties of (x) Ni0.2Co0.8Fe2O4+(1−x) barium lead zirconate titanate magnetoelectric composites

Abstract

The piezomagnetic (ferrite)–piezoelectric (ferroelectric) composites with compositions (x) Ni0.2Co0.8Fe2O4+(1−x) Ba0.8Pb0.2Zr0.8Ti0.2O3 [barium lead zirconate titanate (BPZT)] in which x varies as 0.0, 0.15, 0.30, 0.45, and 1.0 mol % were prepared by conventional ceramic double-sintering method. The presence of constituent phases in the composites was confirmed by x-ray diffraction studies and the average grain size was calculated by using scanning electron microscopy. The dielectric constant (ε′) and loss tangent (tan δ) were measured as a function of frequency in the frequency range 20 Hz–1 MHz. Variation of the dielectric constant and loss tangent with temperature at four fixed frequencies (1, 10, and 100 KHz and 1 MHz) was studied. The ac conductivity was studied to understand the conduction mechanism in terms of small polarons. The hysteresis behavior was studied to understand the magnetic properties such as saturation magnetization (Ms) and magnetic moment (μB). The static magnetoelectric (ME) voltage coefficient was measured as function of applied dc magnetic field and variation in ME response has been explained in terms of the content of piezomagnetic phase and the intensity of applied magnetic field. The maximum ME conversion factor of 536 μV/cm Oe was observed for 15% Ni0.2Co0.8Fe2O4+85% BPZT composite.