BaTiO 3 -BaFe 12 O 19 multiferroic composites have attracted increasing interest due to promising applications in electric and magnetic devices. However, the lower resistivity and the worse temperature stability of dielectric properties hinder their practical application. Here, BaTiO 3 -BaFe 12 O 19 multiferroic composites with different BaTiO 3 /Fe 3 O 4 ratio of 2, 4, 6 (referred as BF2, BF4 and BF6) have been prepared via low temperature sintering and in-situ formation of BaFe 12 O 19 ferromagnetic phase from the reaction between BaTiO 3 and Fe 3 O 4 . XRD, Raman and SEM suggest that plate grains of BaFe 12 O 19 phase disperse in the core-shell BaTiO 3 matrix with fine sphere grains. With the increase of Fe 3 O 4 content, the break-down electric field E b and the resistivity are significantly enhanced from 10 kV/cm and 2.71 × 106 Ω.cm for BF2 to 70 kV/cm and 2.55 × 1010 Ω.cm for BF6, respectively. BF6 exhibits the high permittivity beyond 500 and the low dielectric loss (<0.03) at 1 MHz in the temperature range from -55 °C to 150 °C. Excellent temperature stability of dielectric properties is achieved for the BaTiO 3 -BaFe 12 O 19 composites, the temperature coefficient of capacitance (TCC, i.e. (C-C 25 °C)/C 25 °C) of BF6 meets the X7D specification, below 3.3% in the temperature range from -55 °C to 125 °C. The ferroelectric properties of electric polarization Pr = 2.15 µC/cm 2 and coercive electric field Ec = 18.00 kV/cm have been achieved for the BF6 multiferroic composites together with ferromagnetic characteristics of magnetic polarization Mr = 3.9 emu/g and coercivity magnetic field Hc = 2.266 kOe. In this work, a simple strategy is provided to prepare BaTiO 3 -based multiferroic composites with excellent thermal stability of dielectric properties and high resistivity for industrial applications.
Lin et al. (Fri,) studied this question.