Modulation of electrostriction and strain response in bismuth sodium titanate-based ceramics

The electrostriction and strain response of lead-free Bi0.5Na0.5TiO3-BaTiO3 piezoceramics with La and Nb [(Bi0.47Na0.47Ba0.06)(1-x)LaxTi1-yNbyO3] were modified by optimizing the depolarization temperature. The influences of La and Nb on their phase structure and electrical properties were systematically investigated. All the ceramics exhibited a pseudocubic phase, which is independent of the addition of La and Nb. The strain values increased gradually with the addition of La, and a high strain of similar to 0.5% (80 kV/cm) was attained without any remnant strain when the compositions had a value of x = 0.015. Instead, the piezoelectric constant d(33) dropped down similar to 20 pC/N due to the shift of the T-d (or Tf-r) to room temperature. Interestingly, by establishing the relationship between T-d and strain values, it should be feasible to optimize the strain property of Bi0.5Na0.5TiO3 (BNT)-based ceramics by regulating T-d to ambient temperature. In addition, a very high electrostriction coefficient Q(33) of similar to 0.0758 m(4) C-2 can be found under high temperatures of 125 and 150 degrees C. We believe that the strain and electrostriction behavior of BNT-based ceramics can be well modified by the modulation of depolarization temperature.