Evaluation of the structural and electrical properties of perovskite NKN-LN ceramics for energy storage applications

Abstract

In this article, a way to prepare a family of lead-free piezoelectric perovskite sodium potassium niobate–lithium niobate ceramics with the chemical formula (1 − x)Na_0.535K_0.48NbO_3−xLiNbO₃ (NKN-LN) (when x = 0, 0.05, 0.10, 0.15) using a solid-state reaction technique is described. The impact of the LiNbO₃ content on the phase structure as well as the ferroelectric, piezoelectric, and temperature-dependent piezoelectric and ferroelectric characteristics and energy storage properties of the NKN-LN ceramics was explored. The X-ray diffraction pattern revealed a pure perovskite phase with no hints of secondary phases. The space group Amm2 was orthorhombic in both pure and LN-doped NKN ceramics. The surface morphology of the materials was studied using SEM, and an increase in the grain size was observed with an increase in the congregation of the LN content, demonstrating the immediate reliance of grain size on the convergence of LN in the NKN matrix. The ferroelectrics studied demonstrated that a higher electric field was adequate to achieve the most extreme polarization in LN-doped NKN ceramics compared with that of the unadulterated NKN ceramics. The expansion in both recoverable energy storage density (W₁) and energy-storage efficiency (η) boundaries was detected at an applied electric field of 200 kV cm⁻¹, revealing maximum values at around 0.78 J cm⁻³ and 91%, respectively, in the NKN-LN ceramics at x = 0.10 and x = 0.05 at room temperature, which suggest the considered system to be a suitable candidate for energy-storage capacitor applications.