Microstructural properties and ultrahigh energy storage density in Ba0·9Ca0·1TiO3–NaNb0.85Ta0·15O3 relaxor ceramics

The microstructural and ferroelectric properties of high dielectric constant Ba0·9Ca0·1TiO3 (BCT) have been tailored by substituting various volume fractions of NaNb0·85Ta0·15O3 (NNT). Morphological, ferroelectric, dielectric, breakdown strength, and electromechanical properties of composites were systematically investigated. This work proposes a facile and commercially viable technique for the synthesis of (1-x)BCT-xNNT composites with moderately high dielectric properties and high breakdown strength. The results indicate that the substitution of NNT in BCT can significantly improve the density of ceramics along with transformation from conventional ferroelectric to relaxor, which has led to a significant enhancement in the energy storage performance of the composites. The sample with x = 0.15 NNT concentration has shown the best microstructural density, highest energy density (2.53 J/cm3) along with high energy efficiency (86.6%). Well defined polarization loop combined with a stable capacitive response with extension up to high temperature in composites ensures their promising application in energy storage capacitors.