Enhanced energy storage performance of high entropy (1-x) (Na0.5Li0.5NbO3)-x(Sr0.5Bi0.5)(Fe0.5Ti0.25Zr0.25)O3 dielectric ceramics through non-equivalent ion doping

High entropy dielectric ceramics with excellent relaxation characteristics are ideal materials for pulse capacitors. In this study, a high entropy dielectric ceramic based on NaNbO3 was engineered to enhance relaxation properties through non-equivalent ion substitution and increased entropy. The composition studied was (1-x) (Na0.5Li0.5NbO3)- x(Sr0.5Bi0.5)(Fe0.5Ti0.25Zr0.25)O3 (NLN-SBFTZ) with x = 0, 0.15, 0.20, and 0.25. The introduction of non-equivalent ions (Sr0.5Bi0.5)5/2+ and (Fe0.5Ti0.25Zr0.25)7/2+, significantly increases the configurational entropy (Delta Sconfig). With a breakdown field strength of 500 kV/cm, the modified ceramics sample (x = 0.20) shows a recoverable energy density (Wrec) of 4.70 J/cm3 and an energy efficiency (eta) of 83.5 %, surpassing the performance of undoped samples (Wrec= 0.15 J/cm3, eta = 43.2 %). These results confirm that the high entropy design strategy via non-equivalent ion doping effectively enhances the energy storage capabilities of lead-free dielectric materials.