Thermally-stable high energy-storage performance over a wide temperature range in relaxor-ferroelectric Bi1/2Na1/2TiO3-based ceramics

In this study, lead-free zirconium (Zr)-modified Bi-1/2(Na0.78K0.22)(1/2)TiO3 (BNKT) ceramics were synthesized by the conventional solid-state reaction method. The co-existence of two phases (tetragonal; P4mm and cubic phases; Pm (3) over barm) with definite phase fractions were observed for all samples. The lattice parameters were gradually enhanced by the addition of Zr-content in the BNKT ceramics, which strongly support the relaxor-ferroelectric response. All of the samples are well-dense with no noticeable pores detected. Definite grains with clear grain boundaries were observed through SEM analysis. The temperature-dependent (25-200 degrees C) ferroelectric polarization response of all specimens were studied in detail under the constant applied electric field (60 kV cm(-1)). Thermally-stable high energy-storage properties (W-rec approximate to 0.72 J cm(-3), and eta approximate to 98%) with an extended operating temperature range (25-200 degrees C) within +/- 15% variation was observed for the Zr-modified BNKT composition. The enhancement of energy-storage properties can be attributed to the Zr addition, which increased the phase fraction of cubic crystal structure and assisted the ferroelectric to relaxor-ferroelectric phase transition. This study provides a comprehensive analysis of the energy-storage response of the lead-free ceramics for energystorage devices.

Automated summary

Lead-free zirconium-modified Bi-1/2(Na0.78K0.22)(1/2)TiO3 ceramics were synthesized in this study, showing the presence of different phases and studying the ferroelectric polarization response under temperature variations. The results demonstrate that the addition of Zr can enhance the energy-storage properties of the ceramics, extending the operating temperature range and benefiting the application of energy storage devices.