Optimization of switching charge and recoverable energy density mediated by structural transformation in Sr-substituted BaNiO3 perovskites

Abstract

Because of their distinctive characteristics, ferroelectric perovskites are considered among the most potent and auspicious candidates for energy storage and pulsed power devices. But their energy storage properties and switching capabilities need to be further enhanced which can be done by substitutions of appropriate cations. Hence, a series of lead-free Ba_1−xSr_xNiO₃ (x = 0.00, 0.33, 0.67, and 1.00) ceramics was fabricated using a sol–gel auto combustion technique. Rietveld's refinement of X-ray diffraction plots verified the complete development of the required hexagonal perovskite structure. Scanning electron microscopy images revealed a gradual increase in average grain sizes and agglomeration with the increase in Sr-content. Moreover, the existence of all the constituent elements exactly in proportion to their stoichiometric ratios was verified by energy dispersive X-ray spectroscopy. The characteristic parameters of ferroelectric materials such as ferroelectric response, electrical conductivity, and switching charge density were also determined. The P–E loops indicated that with the increase in Sr-content, the coercive field, remanent polarization, and maximum polarization all decreased gradually, but the recoverable energy density (W_rec) increased as the loops became slimmer. The maximum value of W_rec was found in the Ba_0.33Sr_0.67NiO₃ sample. Moreover, SrNiO₃ exhibited minimum energy loss with the highest efficiency of ∼47.21%. The existence of a current barrier in all the samples was proved from the low leakage current values (∼10⁻⁷ A). In addition, the pure SrNiO₃ showed a low electrical conductivity and minimum value of switching charge density. All these findings make SrNiO₃ a promising candidate for fast switching and energy storage applications.