Excellent energy storage properties over a wide temperature range under low driving electric fields in NBT-BSN lead-free relaxor ferroelectric ceramics

To develop environment-friendly dielectric capacitors with low working electric field and wide useable temperature, in this work, we fabricate (1-x)Na0.46Bi0.54TiO3-xBaSnO(3) ((1-x)NBT-xBSN) lead-free relaxor fermelectric ceramics by adding BaSnO3 into Na0.46Bi0.54TiO3 matrix. BSN exhibits slim polarization-electric field (P-E) loops, small remnant polarization (P-r) and good temperature stability because of its room-temperature paraelectric characteristics, and has different cation ionic radii with Na0.46Bi0.54TiO3. Therefore, when BSN is introduced into NBT, the relaxor behavior of the (1-x)NBT-xBSN ceramics is more pronounced and the P-E loops are much slimmer. Besides, because the substitution of Ba2+ ions with higher valence for Na+ ions neutralizes the hole carriers, which are caused by the volatilization of Na2O, the resistivity and breakdown strength are improved with increasing BSN content. As a consequence, at x = 0.30, the ceramic exhibits simultaneously a large recoverable energy density (W-rec) of 1.51 J/cm(3) and high energy efficiency (eta) of 81.2% at a low driving electric field of 145.3 kV/cm because of the collaborative enhancement effect of the high breakdown strength and low remnant polarization. More interestingly, variations of the W-rec and the eta for this kind of ceramic are respectively as small as 10% and 0.8% over a wide temperature range of 20-140 degrees C, demonstrating superior temperature stability. In this report, we provide a new and efficient way for designing and fabricating environment-friendly dielectric capacitors with good reliability and superior high-temperature energy storage capacity.