Large electromechanical strain at high temperatures of novel <001> textured BiFeGaO3-BaTiO3 based ceramics

BiFeGaO3-BaTiO3(BFG-BT)based ceramics with a large piezoelectric coefficient are potential high performance lead-free piezoelectric compounds.In this work,textured and random BFG-BT ceramics were realized by the solid state reaction method with and without BaTiO3(BT)templates.Textured ceramics were obtained by a reactive templated grain growth(RTGG)method leading to a high-temperature electromechanical strain of S=0.27%at 40 kV/cm and to an effective piezoelectric coefficient(d33*)up to 685 pm/V at 180℃.The easy movement of oriented domains enhanced the electromechanical strain under an applied electric field in textured sample(Lotgering factor f=66.3%).Structural investigations reveal that the proportion and degree of distortion of BFG-BT rhombohedral phase(R3c)reached its maximum in textured ceramics,resulting in large ferrodistortive displacements under electric fields.In addition,the dense nanodomains with low domain wall energies,inferred from the high-resolution transmission electron microscope(HR-TEM)observations,contribute to the extra displacement of the textured sample under an applied electric field.In textured ceramics,the remnant polarization was stable(about 17μC/cm2)from room temperature to 180℃,contributing to the stable ferroelectric property at high temperatures.Through the introduction of BT templates,high-density nanodomains were formed and the Burns temperature was enhanced in textured ceramics.The electromechanical strain,polarization and dielectric behavior were correlated to the textured or random forms of the BFG-BT based ceramics.