Thermal analysis of phase transitions in perovskite electroceramics

Abstract

Perovskite oxide ceramics have found wide applications in energy storage capacitors, electromechanical transducers, and infrared imaging devices due to their unique dielectric, piezoelectric, pyroelectric, and ferroelectric properties. These functional properties are intimately related to the complex displacive phase transitions that readily occur. In this study, these solid-solid phase transitions are characterized with dielectric measurements, dynamic mechanical analysis, thermomechanical analysis, and differential scanning calorimetry in an antiferroelectric lead-containing composition, Pb0.99Nb0.02 [(Zr0.57Sn0.43)0.92Ti0.08]0.98O3, and in a relaxor ferrielectric lead-free composition, (Bi1/ 2Na1/2)0.93Ba0.07TiO3. The (Bi1/2Na1/2)0.93Ba0.07TiO3 ceramic develops strong piezoelectricity through electric field-induced phase transitions during the poling process. The combined thermal analysis techniques clearly reveal the differences in unpoled and poled ceramics.

(Na1/2Bi1/2)TiO3‐based lead‐free co‐fired multilayer actuators with large strain and high fatigue resistance

“…The average stress in the relaxor, however, is estimated to be only in the order of 10 MPa tension due to the thin Pt layer. 18 In this study, the internal residual stress in the MLA was generated during and after sintering due to the constrained sintering and thermal expansion misfit between the ceramic layer (coefficient of thermal expansion, CTE:~10.0 × 10 −6 K −1 , 26 Young's modulus:120 GPa. 27 ) and the Pt electrode (CTE:9-12 × 10 −6 K −1 , 28 Young's modulus:170 GPa.…”

Polarization alignment, phase transition, and piezoelectricity development in polycrystalline0.5Ba(Zr0.2Ti0.8)O3−Guo1, Voas2, Zhang3 et al. 2014Phys. Rev. B806360View full textAdd to dashboardCite

“…First, the virgin state of this composition at room temperature is a mixture of rhombohedral and tetragonal phases [26]. Second, the orthorhombic phase of this composition has an exceptionally low elastic modulus [5], much lower than those of (Bi 1/2 Na 1/2 )TiO 3 -based and Pb(Zr,Ti)O 3 -based ceramics [28,29]. During electrical poling of polycrystalline ferroelectrics for piezoelectricity, the domain polarization alignment cannot be complete and many domains persist at grain boundary regions even at very high poling fields in order to accommodate the incompatible piezoelectric strain across the grain boundary [30].…”

Unique single-domain state in a polycrystalline ferroelectric ceramic

“…Previous symmetry analysis reveals that the 0.5Ba(Zr 0.2 Ti 0.8 )O 3 -0.5(Ba 0.7 Ca 0.3 )TiO 3 ceramic can exist in rhombohedral, orthorhombic, tetragonal, or any combination of these phases at room temperature [34]. Detailed dynamic mechanical analysis indicates that the intermediate orthorhombic phase displays an elastic storage modulus below 50 GPa [35], which is not only the lowest among all phases in this particular composition, but also much lower than that of (Bi 1/2 Na 1/2 )TiO 3 -based and PbZrO 3 -based ceramics [36,37]. A very recent TEM study with convergent beam electron diffraction analysis shows that the 0.5Ba(Zr 0.2 Ti 0.8 )O 3 -0.5(Ba 0.7 Ca 0.3 )TiO 3 ceramic is a mixture of rhombohedral and tetragonal phases in its virgin state at room temperature [38].…”