Balancing the seesaw effect between Td and d33 in 0.93Bi0.5Na0.5TiO3-0.07BaTiO3 ceramic by circumventing the temperature-driven ferroelectric pinching behavior

Achieving a high piezoelectric coefficient ( d 33 ) together with a relatively large depolarization temperature ( T d ) in Bi 0.5 Na 0.5 TiO 3 -based (BNT-based) ceramics remains challenging due to the inherent seesaw effect between T d and d 33 , where an enhancement in one typically compromises the other. Herein, an effective strategy of designing the two-step sintering is proposed to build the multi-shaped ferroelectric domains to broaden the phase transition peak between ferroelectric state (FEs) and relaxor state (REs), thereby circumventing the temperature-driven ferroelectric pinching behavior in 0.93Bi 0.5 Na 0.5 TiO 3 -0.07BaTiO 3 ceramic. By this strategy, the BNT-7BT ceramic exhibited a marked increase in T d from 77 °C to 110 °C, alongside excellent temperature stability in the real-time d 33 (the d 33 increases only from 190 pC/N to 200 pC/N over the temperature range of 30-100 °C). High d 33 originates from the morphotropic phase boundary (MPB) with the coexistence of rhombohedral ( R 3 c ) and tetragonal ( P 4 bm ) phases, as well as refinement of ferroelectric domains. The enhanced thermal stability arises from an appropriate R3c/P4bm phase ratio and the broader FEs-REs phase transition peak. Therefore, this work presents a viable avenue for mitigating the seesaw effect between T d and d 33 in BNT-based piezoceramics.