High energy storage density and temperature-stable dielectric properties for (1-x)Bi_0.38Na_0.38Sr_0.24TiO₃-xBaSnO₃ lead-free relaxor ceramics

Relaxor ferroelectrics are promising candidates for energy storage equipment due to their excellent energy-storage properties. Lead-free (1-x)Bi_0.38Na_0.38Sr_0.24TiO₃-xBaSnO₃ (abbreviated as BNST-100xBS) relaxor ceramics were synthesized by a traditional solid-phase sintering method. The influences of the addition of BaSnO₃ dopants for the energy storage and dielectric temperature-stable properties of BNST-100xBS ceramics were systemically investigated. All samples exhibited a typical pseudo-cubic symmetry structure and obtained the dense microstructure. The ergodic relaxor behavior of all ceramics was observed and revealed a trend of increase as a function of composition. All samples showed a single grain conduction mechanism and the activation energy decreased with the addition of composition. It is related to the generation of oxygen vacancies induced by the defect dipoles. BNST-2.5BS ceramic exhibited an outstanding recoverable energy density of ~1.42 J/cm³ with the corresponding efficiency of ~79.7% at 115 kV/cm field. In addition, excellent temperature-stable permittivity (43–255 °C) was obtained for BNST-7.5BS ceramic. Hence, BNST-2.5BS ceramic revealed excellent energy density properties and BNST-7.5BS exhibited outstanding temperature-stable dielectric permittivity, which was beneficial to use in energy storage equipment and other device applications.