Origin of composition-insensitive electrostrictive coefficient and continuous decrease of domain wall density in (1-x)NaNbO3-xBaTiO3 lead-free ferroelectrics

Abstract Perovskite ferroelectric ceramics with giant electrostrictive coefficient Q 33 have attracted much attention due to their high strain response with ultralow hysteresis. In this work, the electrostrictive properties as well as domain morphology of the lead-free (1− x )NaNbO 3 - x BaTiO 3 (NN- x BT) (0.10 ≤  x  ≤ 0.27) system were investigated systematically. A composition-insensitive Q 33 of 0.0406 m 4 /C 2 is identified in the NN- x BT ceramics (0.15 ≤  x  ≤ 0.27). An ab initio computation indicates that transverse Q 12 would play an important role in understanding of the composition-insensitive Q 33 . Furthermore, distinctively banding domains and inhomogeneous distribution of nanodomains were observed in NN- x BT by piezoresponse force microscopy. A continuous decrease of domain wall density was identified with respect to the increase of x . This study would not only deepen our understanding of the origin of composition-insensitive Q 33 in NN-BT and other related systems, but also provide a way to enhance the Q 33 , i.e ., by forming the solid solutions with end members, which possess high Q 12 .