Preparation and investigation of K0.5Na0.5NbO3-Bi(Sr0.5Hf0.5)O3 transparent energy storage ceramic

Potassium niobate sodium-based ceramics with unique optical and electrical properties are used to develop transparent energy storage capacitors. The (1- x )K 0.5 Na 0.5 NbO 3 - x Bi(Sr 0.5 Hf 0.5 )O 3 (KNN-BSH, x  = 0, 0.025, 0.05, 0.075, 0.1) ceramics are prepared and intensively investigated in this work. The results show that the average grain of KNN-BSH ceramics reaches a minimum of 0.64 μm, owing to the effective suppression of grain growth by (Sr 0.5 Hf 0.5 ) 3+ doping at the B-site. The KNN-BSH ceramics exhibit pseudo-cubic phases and are excellent relaxation ferroelectric ceramics. In particular, the total energy storage density ( W total ) of 0.95KNN-0.05BSH ceramic is 3.94 J/cm 3 , the recoverable energy storage density ( W rec ) is 2.85 J/cm 3 , and the discharge time ( t 0.9 ) is 0.92 μs, which is optimal for comprehensive performance. Besides, the band gap of 0.975KNN-0.025BSH reaches a maximum value of 3.13 eV with a high transmittance of about 57.3 % at a wavelength of 950 nm. The results indicate that KNN-BSH ceramics can be an alternative for transparent energy storage materials.