High Energy-Storage Performance Under Low Electric Fields and Excellent Temperature Stability of KF-Modified BNT-ST-AN Relaxor Ferroelectric Ceramics

Abstract

Homogeneous 0.722(Bi0.5Na0.5TiO3)-0.228(SrTiO3)-0.05(AgNbO3) (BNT-ST-AN) ceramics with various amounts of potassium fluoride addition were prepared by the solid-state combustion technique. The ceramics presented a single perovskite phase with coexisting rhombohedral (R), cubic (C) and orthorhombic (O) phases. The amount of the R phase decreased while the percentage of the C+O phase increased when KF addition increased from 0.0 mol.% to 3.0 mol.%. The smallest grain size, the highest density, and the maximum dielectric constant (εm) were achieved with a KF addition of 1.5 mol.%. Following this design composition of the ceramics, the highest recoverable energy-storage density (Wrec ~ 1.60 J/cm3) and η above 85.8% at a low electric field (100 kV/cm) were obtained from BNT-ST-AN with KF addition at 1.5 mol.%, because this composition contained a morphotropic phase boundary (MPB) region, and had the smallest grain size, which gave the lowest remnant polarization (Pr) and a large maximum polarization (Pm). Additionally, BNT-ST-AN with KF addition at 0.15 mol.% exhibits stability over a wide range of temperatures (25–150 °C) in a low electric field (100 kV/cm), which shows great potential in pulsed power system applications.