A complex lead-free (Na, Bi, Ba)(Ti, Fe)O3 single phase perovskite ceramic with a high energy-density and high discharge-efficiency for solid state capacitor applications

We have investigated a series of compositions in the pseudo-ternary lead-free alloy system Na1/2Bi1/2TiO3-BaTiO3-BiFeO3 with regard to its energy storage density and discharge efficiency. A composition 0.4(Na0.5Bi0.5TiO3)-0.225BaTiO3-0.375BiFeO3 of this series was identified to give the best energy density and discharge efficiency. While conventional sintering gave energy density of 0.77 J/cm3 and discharge efficiency of 67%, we achieved a remarkable increase in energy storage density (∼1.4 J/cm3) and discharge efficiency (∼90%) by using spark plasma sintering of this composition. Our results suggest that this alloy system can be a potential lead-free candidate for high electric energy storage and discharge efficiency.