A series of lead-free dielectric energy storage ceramics BNT-BT-KNN with a composition ratio of 0.94Bi0.5Na0.5TiO3-(0.06-x)BaTiO3-xK0.5Na0.5NbO3(BNT-BT+xKNN,x=0.00～0.04)were prepared by solid state reaction method.The effect of KNN doping on the crystal structure,micro-structure,dielectric,ferroelectric properties and energy storage efficiency of BNT-BT-based ceramic was investigated.The results show that all the samples exhibit the pure perovskite structure with uniform and dense grains in the medium after sintering at 1 150 ℃.The addition of KNN further broadens the dielectric peak at Tm which resulted in better temperature stability and relaxation.With the increase of KNN dopant,the hysteresis curves(P-E curves)of the samples gradually change from"broad and fat"to"slender"and the residual polarization(Pr)of the ceramic samples decrease,thus the energy storage performance of BNT-BT ceramics are further improved.The optimal energy storage density of Wrec=0.048 J/cm3 was achieved at x=0.03 under a field strength of 2 kV/mm,which corresponds to an energy storage efficiency of η=43％,which proves that this material has a promising potential for application in energy storage capacitors.
关键词
BNT-BT陶瓷/KNN掺杂/固相反应法/弛豫/铁电性能/介电性能/储能
Key words
BNT-BT/KNN doping/solid state reaction method/relaxor/ferroelectric property/dielectric property/energy storage
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