An exploration for new strategy: Achieving both excellent temperature stability and good electrostrain in BiFeO3-BaTiO3-based relaxor ferroelectrics by domain engineering

In BiFeO3-xBaTiO3 (BF-xBT) ceramic systems, some of them exhibit good electrostrain, unfortunately, their electrostrain properties always fluctuate with temperature. To obtain good strain performance with excellent temperature stability, the BiFeO3-BaTiO3-xBi(Mg2/3Nb1/3)O3 (BF-0.4BT-xBMN) relaxor ferroelectrics were designed, and a new strategy of changing the temperature & electric field-dependent characteristics of nanodomains by doping was proposed for the first time. An excellent result (S = 0.27% @80 degrees C, fluctuating degree approximate to 2% during 80 degrees C-180 degrees C) was achieved, much better than previously reported results, presenting great potential in the application of high-temperature devices. Temperature-dependent dielectric permitivity combined with piezo-response force microscopic (PFM) techniques demonstrated that the doping of Bi(Mg2/3Nb1/3) O3 (BMN) decreased the high maximum-dielectric-constant temperature (Tm) and freezing temperature (Tf) as well as the proportion of nanodomains with strong piezo-response. What's more, the temperature-dependent dS/ dE curves combined with in-situ synchrotron X-Ray diffraction measurements during electric field loading revealed the transformation from nanodomain into macrodomain (n-m). The introduction of BMN resulted in an increase of the nanodomain-macrodomain transition electric field at room temperature together with the decrease of domain switching at high temperature, both of which were the key to improving the temperature stability of strain.