High energy-storage density under low electric fields and improved optical transparency in novel sodium bismuth titanate-based lead-free ceramics

A novel (1-x)Na0.5Bi0.5TiO3-xBaHfO(3) (abbreviated as (1-x)NBT-xBH) transparent ceramic was fabricated by the solid state reaction method. X-ray diffraction analysis showed that NBT-based transparent ceramics exhibit a cubic-like perovskite structure and the solid solubility of BH in NBT reached to 0.15. The Landau-Devonshire theory and I-E curves revealed that the transition between the antiferroelectric like phase and the ferroelectric phase deeply relies on the variation of composition and free energy. One sample (x = 0.15) was found to show a high dielectric constant ((similar to)2418 +/- 10%) over the temperature range 57-400 degrees C. These ceramics also exhibited a high discharge energy density (W-d) of 2.1 J/cm(3) and a high maximum polarization P-m of 34 mu C/cm(2) under relatively low electric fields which were less than 175 kV/cm. There was also high transparency in the visible spectra (more than 0.5) when the sample thickness was 250 mu m.