Is electrostrain >1% in oxygen deficient Na0.5Bi0.5TiO3 a composition effect?

Abstract

For over two decades Na0.5Bi0.5TiO3 (NBT) -based lead-free piezoelectrics have attracted attention due to its ability to exhibit large electric-field driven strain. Compared to the popular Pb(Zr, Ti)O3 (PZT)-based piezoelectrics, which exhibit electrostrain of about 0.3%, the derivatives of NBT-based lead-free piezoelectrics at the ergodic—non ergodic relaxor crossover exhibit larger electric-field driven strain ∼0.45%. In recent years, there has been a concerted effort to increase the maximum electrostrain in lead-free piezoceramics. Recent reports suggest that oxygen deficient NBT- based piezoceramics can exhibit electrostrain ∼1%. In this paper we explore this phenomenon and show that the ultra high electric field driven strain measured is primarily a consequence of reducing the thickness of the disc dimension below 500 microns and not an exclusive effect of the composition.

Direct and converse piezoelectricity of thickness tuned BCZT ceramics: toward efficient bilayered magnetoelectric devices

“…As we are mainly focused on tuning the dimension of piezoceramics, a highly piezoelectric material with wellknown and fixed MPB composition has to be chosen here. The converse piezoelectricity of thickness tuned MPB compositions of PZT, Sn doped BaTiO 3 , KNN, and NBT have already been investigated earlier [2,[6][7][8].…”

“…But, the mechanisms such as field induced phase change, field induced transition of material from ergodic to ferroelectric nature, and reversible switching of ferroelastic domains can not be explained only by considering the compositions [6]. 0.74Na 0.5 Bi 0.5 TiO 3 -0.26SrTiO 3 , (KNa)NbO 3 (KNN) and its derivatives and (NaBi)TiO 3 (NBT) have been widely studied by them over a wide composition range and thickness variation [2,[6][7][8]. By performing all of these experiments, they have concluded that the thickness reduction of the bulk piezoceramics can effectively increase their electrostrain by reducing the mutual mechanical clamping between the grains [7].…”

“…Recently, Prof. Rajeev Ranjan's research group has shown that the dimension of the samples plays the main determining role of its converse piezoelectricity. According to them, not the composition and oxygen vacancy, the thickness of the bulk polycrystalline piezoceramics plays the main role for this purpose [2,[6][7][8]. Different lead-based and lead-free piezoceramics such as Pb(ZrTi)O 3 (PZT), BaTi 0.91 Sn 0.09 O 3 , RECEIVED…”