Electrostyictive Effect Of ?1-x?NaNbO₃-xBaTio₃ Ceramics

At present,with the increasing demand for high-sensitivity and high-precision micro-displacement positioniiig,the demand for functional materials with high electrostraia and low hysteresis is increasingly urgent.It is well known that perovskite ferroelectric ceramics have a higher inverse piezoelectric effect(larger d33),but a corresponding larger hysteresis effect.In addition,some ferroelectric ceramics also have higher electrostrictive effect(larger electrostrictive coefficient Q33)and lower corresponding hysteresis effect when they are in the paraelectric state.Therefore,the electrostrictive effect of such ferroelectric ceramic materials has been widely concerneed and studied.In this,paper,we studied the electrostrain effect of lead-free sodium niobate-barium titanate[NaNbO3-xBaTiO3,(NN-BT)]ferroelectric ceramics with low hysteresis.It was found that in the NN-xBT(0.10?x?0.27)system,a atetragonal-to-cubic transition is identified at x=0.22 by x-ray diffraction structural refinerment.It was found that the Curie temperature decreased at first and then increased with the increase of BT content x by dielectric temperature spectrum analysis.It was found that when BT content x was 0.10-0.22,unipolar large signal strain with extremely low hysteresis was obtained(<10%,40 kV/cm)by strain electric field(S-E)curve characterization.In addition,for BT content x = 0.1,when the temperature changes from 30 ? to 120 ?:,the maximum-strain changes lowly with temperature,showing a good temperature stability;The electric strain and electric field change almost linearly,showing a good linearity.Secondly,we systematically studied the electroelastic properties of the lead-free ferroelectric ceramics(1-x)NaNbO3-xBaTiO3(0.10?x?0.27)system,and found the composition-insensitive Q33 in the NN-xBT(0.15?x?0.27)system,whose value was about 0.0406 m4/C2.In addition,the calculations show the theoretical relationship between the transverse electrostriction coefficient Q12 and Q33,which helps us deepen our understanding of the insensitivity of Q33 to components.Finally,the morphology of the domain was studied by PFM.We observed the nano-domain in NN-xBT,and the distribution of nano-domain was not uniform,and the domain wall density continued to decrease with the increase of component x.On the one hand,this study will not only deepen our understanding of the origin of insensitive Q33 in NN-xBT and other related systems,but also provide a way to enhance the Q33,i.e.,by forming the an end solid solution with high Q12.On the other hand,this study shows that the NN-xBT system and related NN matrix materials have great potential applications in high-precision actuators.