EFFECT OF FIRING TEMPERATURES ON THE PHASE STRUCTURE AND ELECTRICAL PROPERTIES OF BNT-BT-0.1NT CERAMICS SYNTHESIZED VIA THE SOLID-STATE COMBUSTION TECHNIQUE

Lead-free ceramic materials of 0.9(0.92Bi0.5Na0.5TiO3-0.08BaTiO3)-0.1NaTaO3 or BNT-BT-0.1NT were obtained using glycine as fuel by a solid-state combustion process. The significance of heat treatment conditions, including calcination at 600-800°C for 2 h and sintering at 1075-1175°C for 2 h, on the structure of the phase, microstructure, electrical and energy-storage properties of BNT-BT-0.1NT ceramics were performed. The perovskite phase was presented for all powder samples. BNT-BT-0.1NT powders calcined at the temperature of 750°C for 2 h showed a 100% pure perovskite phase. The particles morphology exhibited spherical shapes with a wide distribution. As the calcination temperature increased, the average particle size grew from 340 nm to 370 nm. Rietveld refinement confirmed that the BNT-BT-0.1NT ceramics possessed a uniform ABO3 structure with cohabiting of rhombohedral (R), tetragonal (T), and cubic (C) phases. With a rise in sintering temperature, the average grain size expanded from 0.85 µm to 2.66 µm, while the remnant polarization (Pr) and coercive field (Ec) decreased. The samples sintered at 1150oC for 2 h, the ceramic highlighted the highest dielectric constant (emax ~ 1827), high density of 5.83 g/cm3. Under an applied electric field of 70 kV/cm, the maximum energy storage density reached 0.71 J/cm3.