Enhanced Energy Storage Properties in Nb-doped (Na0.5bi0.5)tio3-Srtio3 Lead-Free Relaxor Ferroelectric Ceramics

In this article, optimized energy-storage density obtained at low electric field and accompanied with high efficiencies was achieved simultaneously by donor-doping Nb5+ into 0.65(Na1/2Bi1/2)TiO3-0.35SrTiO(3) system. The donor addition of Nb5+ may force Ti4+ to become Ti3+ due to the imbalance of ion valence after the Nb5+ substitution of Ti4+, leading to the formation of Ti3+-Nb5+ ion pair. The self-built electric field generated by Ti3+-Nb5+ ion pair is conducive to obtain slim P-E loops with high P (max) and negligible P (r). Accordingly, a high recoverable energy densities of 1.04 J/cm(3) with a high energy efficiencies of 86.7% was achieved under 82 kV/cm at x = 0.25 mol.% due to the enhanced E (b) and P (max)-P-r values. This work provides a promising approach for designing high-performance lead-free energy storage ceramics under low electric fields.