Anisotropy free energy contribution of the ferroelectric domain dynamics in PMN‐PT and PIN‐PMN‐PT relaxor ferroelectrics

Abstract A direct correlation between the materials property behavior with its associated ferroelectric domain mechanisms and the anisotropic component of the Landau free energy is established for binary PMN‐PT (generation I) and ternary PIN‐PMN‐PT (generation II) relaxor ferroelectric single crystal material systems. In addition to their trade‐off in material properties, the observed ferroelectric domain dynamic and the determined free energy anisotropies, especially as approaching phase transition, provide direct insights into the materials field‐dependent behavior between the binary and ternary ferroelectric systems. Domain configuration features such as lamellar structures in binary PMN‐PT and concentric oval‐like structures in ternary PIN‐PMN‐PT result in different material responses to external stimuli. Compared to binary PMN‐PT, the concentric oval‐like domain structures of ternary PIN‐PMN‐PT result in a 20°C higher temperature range of field‐dependent linear behavior, 40% increase in coercive electric field higher elastic stiffness during ferroelectric domain switching, and lower electromechanical energy losses. Separation of the isotropic and anisotropic components in the Landau free energy reveals a higher anisotropic free energy contribution from the ternary system, especially at temperature for practical applications. The high anisotropic free energy found in the ternary PIN‐PMN‐PT system implies that the concentric oval‐like domain structure contributes to reduced electromechanical energy losses and enhanced stability under external applied fields.