Piezoelectric response enhancement in the proximity of grain boundaries of relaxor-ferroelectric thin films

Abstract

The influence of surface morphology on the local piezoelectric response of highly (100)-textured 0.70PbMg2/3Nb1/3O3-0.30PbTiO3 thin films is studied using piezoresponse force microscopy in band-excitation mode. The local electromechanical response is mostly suppressed in direct proximity of the grain boundaries. However, within 100–200 nm of the grain boundary, the piezoresponse is substantially enhanced, before decaying again within a region at the center of the grain itself. Nested piezoresponse hysteresis curves confirm the influence of topography descriptors on parameters affecting the hysteresis loop shape. The enhancement of the electromechanical response is rationalized through reduced lateral clamping in the grains with deep trenched boundaries, as well as an expected lower energy for complex domain wall structures, due to curved ferroelectric surfaces. The lower piezoresponse at the center of the grain is assigned to the lateral clamping by the surrounding piezoelectric material.

Decoupling Mesoscale Functional Response in PLZT across the Ferroelectric–Relaxor Phase Transition with Contact Kelvin Probe Force Microscopy and Machine Learning

“…Understanding the overall macroscopic behavior of these heterogeneous materials as well as micro-and nanoscale applications necessitate assessment of local characteristics, which is widely studied using piezoresponse force microscopy (PFM) and related switching spectroscopy techniques. [9][10][11][12][13] PFM is based on detecting cantilever oscillation corresponding to periodic sample deformation in response to an alternating voltage (Vac) due to the converse piezoelectric effect. 14 However, Vac excitation also leads to detection of electrostatic forces between tip and sample, which can contribute to the measured signal in PFM.…”

“…The remarkably high electrostrictive response observed in relaxor ferroelectrics combined with their large dielectric and electro-optic constants have awoken significant interest in these materials for applications such as electromechanical transducers, capacitive energy storage, and electro-optic modulators. − Moreover, phase transitions between ferroelectric and relaxor states yield additional functionality in terms of pyroelectric energy harvesting or temperature-dependent electromechanical sensing, for which lead lanthanum zirconate titanate (PLZT) is a highly suitable material as it exhibits low phase transition temperatures near room temperature and large electrostriction. ,,,, Although the underlying physical phenomena warrant high scientific interest in itself, knowledge on the functional material response to an electric field at operating temperatures is also key to device design. Understanding the overall macroscopic behavior of these heterogeneous materials as well as micro- and nanoscale applications necessitates assessment of local characteristics, which is widely studied using the piezoresponse force microscopy (PFM) and related switching spectroscopy techniques. − …”