Ultra-high strain responses in lead-free (Bi0.5Na0.5)TiO3-BaTiO3-NaNbO3 ferroelectric thin films
Zhe Wang, Jinyan Zhao, Gang Niu, Nan Zhang, Kun Zheng, Yi Quan, Lingyan Wang, Jian Zhuang, Genshui Wang, Xin Li, Henghui Cai, Ming Liu, Zhuangde Jiang, Yulong Zhao, Wei Ren
Abstract
Lead-free (Bi 0.5 Na 0.5 )TiO 3 (BNT)-based piezoelectric materials , have a great potential for high-precision actuators’ applications. In this work, the high-quality (0.94- x %)(Bi 0.5 Na 0.5 )TiO 3 -0.06BaTiO 3 - x %NaNbO 3 ( x = 2–10, BNT-6BT- x NN) thin films have been successfully deposited on Pt/TiO 2 /SiO 2 /Si substrates by sol-gel method. An ultra-high poling strain S pol value of 1.7% with a unipolar strain S uni value of 1.47% was reported in the BNT-6BT-6NN thin films . The coexistence of the ferroelectric phase and relaxor state was observed in the compositions of x = 2–8. Furthermore, the BNT-6BT-6NN thin films show more active domain switching compared to other compositions. It is demonstrated that the optimized strain responses in the BNT-6BT-6NN are attributed to a synergistic reaction of active domain switching and reversible electric-field-induced phase transition between the ferroelectric phase and relaxor state. Our systematic study demonstrates that the BNT-6BT- x NN thin films with an improved strain response are promising candidates for the applications of miniaturized actuators.