Enhanced energy storage properties in Nb-modified Bi0.5Na0.5TiO3–SrTiO3 lead-free electroceramics
Lead-free (1 − x)Bi0.5Na0.5TiO3–xSrTiO3 + ywt%Nb2O5 electroceramics were synthesized using the conventional method to investigate the influences of SrTiO3 content and Nb2O5 doping on the material’s phase structure, microstructure, and energy storage properties. All the investigated compositions possessed a single perovskite phase structure of pseudocubic symmetry. The introduction of SrTiO3 and Nb2O5 led to a weakened relaxor characteristic and a decrease of Tm. The microstructure was refined by Nb2O5 doping, and the average grain size of the 0.6Bi0.5Na0.5TiO3–0.4SrTiO3 sample decreased drastically from ~ 10 to ~ 1 µm when 2.5 wt% Nb2O5 was added. Enhanced electrical breakdown and polarization were achieved for the samples with the refined microstructure. Among the various Bi0.5Na0.5TiO3-based ceramics, 0.6Bi0.5Na0.5TiO3–0.4SrTiO3 + 2.5 wt%Nb2O5 ceramic exhibited excellent energy-storage properties with thermal stability, in which large recoverable energy-storage density Wrec ~ 1.82 J/cc and efficiency η ~ 81% were both achieved. Our results indicate that this ceramic is a promising material for lead-free energy storage applications.
This work was supported by National Nature Science Foundation of China (Grant No. 51402297) and Youth Innovation Promotion Association CAS (Grant No. 2016334).
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