Effect of the Firing Temperatures on the Phase Evolution and Electrical Properties of 0.85[0.94Bi0.5Na0.5TiO3-0.06BaTiO3]-0.15[Na0.73Bi0.09NbO3] Ceramics Synthesized via the Solid-State Combustion Method

Abstract

In this research paper, we describe 0.85[0.94Bi0.5Na0.5TiO3-0.06BaTiO3]-0.15[Na0.73Bi0.09NbO3] (BNT-BT-NBN) ceramics fabricated by the solid-state combustion technique. The phase evolution, microstructure, dielectric, ferroelectric and energy storage properties were examined. The BNT-BT-NBN powders and ceramics were calcined and sintered between 650–900 °C and 1100–1175 °C, respectively, for 2 h. All samples showed a typical perovskite structure, as revealed by X-ray diffraction. The Rietveld refinement analysis of the ceramics suggested the samples sintered between 1100 and 1150 °C had coexisting R + T phases, while the R + T+C phases were observed in the ceramics sintered at 1175 °C. The average grain size of the samples increased from 0.52 to 1.39 μm with increased sintering temperature. The density of the ceramics increased from 5.12 to 5.45 g/cm3 when the sintering temperature increased from 1100 to 1150 °C, and then decreased. Increasing the sintering temperature from 1100 to 1150 °C caused the dielectric constant at T s (ε s) and the dielectric constant at T m (ε m) to increase from 1727 to 1945 and 1564 to 1750, respectively, and then ε s and ε m declined. All BNT-BT-NBN ceramics had good dielectric temperature stability with only a±10% change when the temperature ranged from room temperature to ∼300 °C. The optimum energy-storage properties (W rec = 0.62 J/cm3 and η = 83.2%) were obtained from the BNT-BT-NBN ceramics sintered at 1150 °C for 2 h. This data indicates that BNT-BT-NBN ceramics can be useful as lead-free materials for high density energy-storage capacitors.