Abstract: Innovative binary BNT-based lead-free ceramics which is composed by (Sr0.7Bi0.2)TiO3 relaxor ferroelectric and (Bi0.5Na0.5)TiO3 ferroelectric, (1-x)(Bi0.5Na0.5)TiO3-x(Sr0.7Bi0.2)TiO3(BNT-xSBT for short, x=10mol;, 20mol;, 30mol; and 40mol;) was designed.All the BNT-xSBT ceramics were fabricated by the traditional solid-state processing route , and the effect of ( Sr0.7 Bi0.2 ) TiO3 on the structure , phase transition , ferroelectric property and energy-storage property of BNT-xSBT ceramics was investigated .The results show that BNT-xSBT ceramics exhibit pseudo-cubic phase at room temperature , and coexistence phase structure of polar rhombohedral ( R3c) and non-polar tetragonal ( P4bm) for BNT-xSBT ceramics was identified by dielectric and ferroelectric property .BNT-xSBT ceramics with co-occupied in A-site are relaxor ferroelectric, and Tm decreases with increasing of (Sr0.7Bi0.2)TiO3 content. The dielectric abnormal peak at low temperature ( Td ) derives from a slow transition which is caused by structure (rhombohedral and tetragonal) fluctuation.With increasing of (Sr0.7Bi0.2)TiO3 content, Td of BNT-xSBT ceramics decreases , tetragonal phase and non-polar nano-regions increases , resulting in weak ferroelectric property and distorted ferroelectric hysteresis loop .For x =30mol;, BNT-xSBT ceramics show a large Pmax =26.8 μC/cm2 , a small Pr =1.4 μC/cm2 , good energy storage density W=0.74 J/cm3 and energy storage efficiency η=68.5;(@70 kV/cm).

Key words: Innovative binary BNT-based lead-free ceramics which is composed by (Sr0.7Bi0.2)TiO3 relaxor ferroelectric and (Bi0.5Na0.5)TiO3 ferroelectric, (1-x)(Bi0.5Na0.5)TiO3-x(Sr0.7Bi0.2)TiO3(BNT-xSBT for short, x=10mol;, 20mol;, 30mol; and 40mol;) was designed.All the BNT-xSBT ceramics were fabricated by the traditional solid-state processing route , and the effect of ( Sr0.7 Bi0.2 ) TiO3 on the structure , phase transition , ferroelectric property and energy-storage property of BNT-xSBT ceramics was investigated .The results show that BNT-xSBT ceramics exhibit pseudo-cubic phase at room temperature , and coexistence phase structure of polar rhombohedral ( R3c) and non-polar tetragonal ( P4bm) for BNT-xSBT ceramics was identified by dielectric and ferroelectric property .BNT-xSBT ceramics with co-occupied in A-site are relaxor ferroelectric, and Tm decreases with increasing of (Sr0.7Bi0.2)TiO3 content. The dielectric abnormal peak at low temperature ( Td ) derives from a slow transition which is caused by structure (rhombohedral and tetragonal) fluctuation.With increasing of (Sr0.7Bi0.2)TiO3 content, Td of BNT-xSBT ceramics decreases , tetragonal phase and non-polar nano-regions increases , resulting in weak ferroelectric property and distorted ferroelectric hysteresis loop .For x =30mol;, BNT-xSBT ceramics show a large Pmax =26.8 μC/cm2 , a small Pr =1.4 μC/cm2 , good energy storage density W=0.74 J/cm3 and energy storage efficiency η=68.5;(@70 kV/cm).