Enhanced energy-storage performance of (1-x)(0.72Bi0.5Na0.5TiO3-0.28Bi0.2Sr0.7□0.1TiO3)-xLa ceramics

Leed-free ferroelectric (1-x)(0.72Bi0.5Na0.5TiO3-0.28Bi0.2Sr0.7□0.1TiO3)-xLa (NBST-xLa; x = 0, 0.5%, 1.5%, 2%) ceramics were synthesized using a conventional solid-state reaction method and the effect of La-doping on the microstructure and electrical properties was investigated. The introduction of La could reduce the grain size and improve the porosity of NBST ceramics. Temperature-dependent dielectric permittivity illustrated that the relaxation properties of NBST-xLa ceramics changed parabolically with the increase of La content. The introduction of La gave rise to a large dielectric breakdown strength and maximum polarization when x = 0.5%, which was attributed to the variation of the microstructure and the relaxation properties of NBST-xLa ceramics, respectively. The optimum effective energy storage density of 1.2 J/cm3 at 90 kV/cm was achieved when x = 0.5%. These results indicated that NBST-0.5%La ceramic may provide a practical perspective for energy storage ceramics research.