Dynamic hysteresis and scaling behaviours of lead-free 0.94Bi0.5Na0.5TiO3–0.06BaTiO3 bulk ceramics

Abstract

Bismuth sodium titanate–barium titanate (1 − x)Bi_0.5Na_0.5TiO₃–xBaTiO₃ (BNT–xBT) ceramics have drawn extensive attention of late as lead-free alternatives to lead zirconate titanate PbZr_1−xTi_xO₃ (PZT). In this work, the ferroelectric hysteresis loops of a morphotropic phase boundary (MPB) composition of BNT–6BT were measured under electric fields in the frequency range of 0.01 to 10 Hz and fields ranging from 10 to 70 kV cm⁻¹. The relaxor ferroelectric BNT–6BT exhibits a three-stage evolution of scaling behaviours between the logarithm of hysteresis area 〈A〉 and the logarithm of the amplitude of field E₀ at medium–high frequencies (herein 0.1 Hz ≤ f ≤ 10 Hz) and two-stage linear scaling behaviours at low frequency (herein f = 0.01 Hz) in the electric field amplitude E₀ term (10 kV cm⁻¹ ≤ E₀ ≤ 70 kV cm⁻¹). The emergence of three-stage and two-stage dynamic hysteresis scaling behaviours in the relaxor ferroelectric BNT–6BT are attributed to the complex couple contributions of 180° and non-180° domain walls. The three-stage and two-stage scaling behaviours are integrated considering the time-dependent domain wall switching processes.