Temperature‐Dependent Electrical Properties of 0.94Bi _0.5 Na _0.5 TiO ₃ –0.06BaTiO ₃ Ceramics

Abstract

Temperature‐dependent electrical properties of lead‐free 0.94Bi 0.5 Na 0.5 TiO 3 –0.06BaTiO 3 (BNT–BT) ceramics were investigated. Below 100°C, this rhombohedral–tetragonal morphotropic phase‐boundary composition shows dominant ferroelectric order with typical ferroelectric polarization–electric field ( P ( E )) loop and butterfly bipolar strain–electric ( S ( E )) curve. Antiferroelectric order tends to prevail when temperature reaches about 100°C, characterized by a pinched P ( E ) loop and altered bipolar S ( E ) butterfly. Near the ferroelectric–antiferroelectric transition temperature, the composition shows a giant bipolar and unipolar strain of 0.40% and 0.42%, respectively. The highest value of maximum strain divided by the applied field (i.e., S max / E max ) reaches 700 pm/V at 100°C. With a further increase of temperature to 200°C, a slight decrease of the strain is observed. Especially, it is found that the hysteresis of the unipolar S ( E ) curve decreases with increasing temperature. These results may be helpful for further understanding and thus designing new BNT‐based lead‐free piezoelectric systems.