High-temperature energy storage performances in (1-x)(Na0.50Bi0.50TiO3)-xBaZrO3 lead-free relaxor ceramics

In this study, in order to obtain superior energy storage performances over a wide temperature range in lead-free dielectric ceramics, we develop and prepare (1-x)(Na0.50Bi0.50TiO3)-xBaZrO3 ((1-x)NBT-xBZ) relaxor ferroelectric ceramics by introducing BaZrO3 into Na0.50Bi0.50TiO3. BZ possesses small remnant polarization (Pr) and slim polarization-electric field (P-E) loops attributed to its room-temperature paraelectric phase structure characteristic. Thus, when it is added into NBT, the P-E loops of (1-x)NBT-xBZ ceramics are slimmer, and the Pr decreases. Besides, due to the donor doping effect resulting from the replacement of Ba2+ with higher valence for the Na+, with the increase of the BZ content, the grain sizes of the ceramics gradually decrease, resulting in the enhancement of the breakdown strength (Eb). All above these are in favour of improving energy storage properties, and as a result, by adjusting the BZ content reasonably, a large recoverable energy density (Wre) of 1.56 J/cm3 and high energy efficiency (η) of 80.56% are concurrently achieved in the 0.75NBT-0.25BZ ceramic. More interestingly, the ceramic exhibits excellent high-temperature energy storage capacity, which is superior to those of recently reported dielectric ceramics, and good fatigue properties. All these indicates that 0.75Na0.50Bi0.50TiO3-0.25BaZrO3 lead-free relaxor ferroelectric ceramic is a good candidate for preparing dielectric capacitors applicable in various environmental conditions.