Low-temperature sintering processes of Mg_0.8Zn_0.2TiO₃ through K_0.5Na_0.5VO₃ and Bi₂O₃ addition correlated to the dielectric properties

Abstract

This study reports the sintering of Mg_0.8Zn_0.2TiO₃ (MZT) with an addition of K_0.5Na_0.5VO₃ (KNV) and Bi₂O₃. The sintering temperature was performed at 950°C for 4 h and attained a maximum relative density of 97.71% in a composition of 85% mol MZT–10% mol KNV–5% Bi₂O₃ (MZT85). Structure, microstructure and phase present in the sample were analysed using X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. MgZnTiO₃, KNaVO₃ and BiVO₄ were found, besides, the non-crystalline phase was also detected and supposed to be the Bi₂O₃ melted amorphous phase. Furthermore, with an increase of the lattice parameter and cell volume of samples, it was believed that the sintering aid dissolved partially in the MZT matrix. The electrical properties characterization discovered that at low frequencies (1 Hz–32 MHz) a broader range of space charge polarization was observed, meanwhile, at high frequency (X-band) an enhancement of the permittivity and quality factor Qxf. The relative permittivity ɛ_r ≈ 16.08, the dielectric loss (tan δ) ~10⁻² and Qxf = 11.386 GHz at 10 GHz for the MZT85 sample was observed.