An Sr doping 0.65(Bi0.5Na0.5) TiO3-0.35 (Sr0.7+x+ Bi0.2) TiO3 Ceramic with Tunable Crystal Structures and Energy Storge Performances

Abstract A series of 0.65(Bi0.5 Na0.5 )TiO3 -0.35(Sr0.7+x +Bi0.2 )TiO3 (BNT-S0.7+x BT) composite ceramic pellets are synthesized using the traditional solid sintering method, where a tunable x, that is the changeable volume of Sr, is expected to tailor energy storage through the adjustments of the A-site stoichiometry in BNT-S0.7+x BT. We find that a small excess of Sr2+ ions results in an extensively tunning on the crystal grain size and even contributes to the A-site disorder and charge fluctuation of BNT-S0.7+x BT. As such, the BNT-S0.7+x BT exhibits a minimum average grain size and a highly compact crystal morphology. Meanwhile, a relatively thin polarization-electric field (P-E) loop with a high maximum polarization of 42μC/cm2 and a low remnant electric polarization of 5μC/cm2 are obtained in a BNT-S0.75 BT sample under 100 kV/cm, which corresponds to a large energy density of 9.81 J cm-3 . Attractively, this ceramic possesses an excellent temperature stability of polarization performances and strain under high electric field of 100kV/cm, which favors of the energy storage of relaxor ferroelectric ceramics and is valuable to a supercapacitor serving at evaluated high temperature.