Remarkably enhanced recoverable energy density in lead-free relaxor Ba0.94Ca0.06Ti1−xSnxO3 ceramics by the synergistic effect of nano-domains and refined grains.

• Through modifying Sn4+ content, the breakdown strength is increased by 112.3%. • The recoverable energy density enhanced by 276.2% via incorporation of Sn4+. • The doping of Sn4+ inhibits the migration of grain boundary and refines grains. • The delayed polarization saturation result from Sn4+ with d10 substitutes Ti4+ with d0. [Display omitted] High-performance dielectric ceramic capacitors is a promising candidate in energy storage devices. In this work, the energy storage performance of Ba 0.94 Ca 0.06 Ti 1−x Sn x O 3 (x = 0.04, 0.08, 0.12, 0.16) ceramics was systematically studied. Through modifying Sn4+ doping content, the breakdown strength of the ceramics is enhanced by 112.3% from 133.4 kV/cm (Ba 0.94 Ca 0.06 Ti 0.96 Sn 0.04 O 3) to 283.2 kV/cm (Ba 0.94 Ca 0.06 Ti 0.84 Sn 0.16 O 3). Accordingly, the recoverable energy density is greatly increased by 276.2%, that is, from 0.42 J/cm3 grow to 1.58 J/cm3. The enhanced energy storage properties could be ascribed to the following aspects: (1) the doping of Sn4+ with a larger ionic radius inhibits the migration of grain boundaries and therefore refines grains, resulting in a higher activation energy and a larger E b ; (2) the long range polar order is broke and polar nano-regions are formed, giving rise to lower energy barrier and smaller P r ; (3) the weakened ferroelectricity and delayed polarization saturation lead to higher W rec owing to the fact that Sn4+ with d10 electronic configurations substitutes Ti4+ with d0. Our work provides a novel approach for enhancing energy storage performance in dielectric ceramic capacitors. [ABSTRACT FROM AUTHOR]