The effects of sintering temperature on structural, electrical, and magnetic properties of MgFe_1.92Bi_0.08O₄

In this article, MgFe_1.92Bi_0.08O₄ ceramics were prepared by the solid-state synthesis method followed by sintering at 1000, 1050, 1100, and 1150 °C. The effects of sintering temperature on structural, electrical, and magnetic properties were systematically investigated. The results showed that by increasing the sintering temperature, the lattice parameter was increased from 8.376 to 8.405 Å, the relative density was improved up to 97.1 %, the average grain size was increased from 1.92 to 4.12 μm, the d.c conductivity was increased from 38.4 to 5.8 MΩ.cm, the saturation magnetization was increased from 15.9 to 20.2 emu/g, and the coercive field was increased from 9.7 to 6.7 Oe. According to Maxwell and Wagner’s two-layer model, the dielectric behavior and AC conductivity of the samples were explained based on the space charge polarization. The sample sintered at 1050 °C revealed the optimum dielectric properties with a 0.016 dielectric loss and a 24.4 dielectric constant at 10 MHz. Further increasing the sintering temperature resulted in increasing the dielectric constant and dielectric loss up to 33.1, 0.156, respectively, due to the increased thermal activation of electron hopping between Fe²⁺ and Fe³⁺ ions.