Effect of Strain Rate on Phase Transition and Microstructural Evolution in Ferroelectric PMN‐PT Single Crystals Through Nanoindentation

Abstract Controlling domain switching and phase transitions in ferroelectric materials under external fields is crucial for advanced device applications. However, the mechanism and kinetics governing mechanically induced phase transitions in relaxor ferroelectric Pb(Mg 1/3 Nb 2/3 )O 3 ‐PbTiO 3 remain some unclear understanding, especially under variable strain rates. To investigate this, localized mechanical stress is applied using nanoindentation to PMN‐PT single crystals. With the aid of Raman spectroscopy and high‐resolution transmission electron microscopy, irreversible phase transition pathways from the Rhombohedral to Tetragonal phase (R→T) are identified. The variation is also observed in the phase transition behavior with the strain rate during nanoindentation. Interestingly, the coexistence of the R and T phases within the indentation region suggests that an uneven force application via nanoindentation can induce morphotropic phase boundaries (MPBs). Further assessments of the phase‐transformation dynamics are conducted using the phase‐field method, which simulated the domain evolution process in PMN‐PT under various indentation strain rates. These findings provide new insights into how mechanical forces can modulate the microstructural evolution within relaxor ferroelectric materials, enhancing the understanding of this fascinating phenomenon.