Non-180° domain contributions in Bi0.5(Na0.82K0.18)0.5TiO3 lead-free piezoelectric thick films

Piezoelectric responses of Bi-0.5(Na0.82K0.18)(0.5)TiO3 (NKBT) ceramic films with thickness of 10-100 mu m have been studied in a wide range of ac electric field and frequency. By the Rayleigh law fit, the typical irreversible Rayleigh coefficient, alpha, for piezoelectric response is 39.69 +/- 0.41 x 10(-18) m(2) V-2, which is much larger than that of the piezoelectric thin films, indicating significantly enhanced non-180 degrees domain wall motions in NKBT thick films. The logarithmic frequency dependence of the piezoelectric response is associated with domain wall pinning in NKBT thick films, and the frequency dispersion increases with increasing ac field amplitude, which is attributed to the relaxation of non-180 degrees domains. (C) 2015 Elsevier Ltd and Team Group S.r.l. All rights reserved.