Work

Thermally and Electrically Induced Ferroelectric Transitions in NaNbO3 for Lead-Free Piezoelectric Composite Applications

Year: 2025

Type: article

Abstract: Ferroelectric (FE) polymer composites have received increasing attention for potential applications in flexible piezoelectric-based devices. The macroscopic performance of these devices is closely associated with the microscopic FE properties of the embedded oxides, which remain a topic of considerable research activity. In this study, we investigate the thermally and electrically induced antiferroelectric (AFE) to FE phase transition in hydrothermally synthesized NaNbO 3 (NNO) particles and demonstrate its potential for piezoelectric applications within composite devices. NNO submicron particles, initially synthesized by a hydrothermal method, exhibit a predominant AFE phase with a minor FE fraction. However, a phase transition from AFE to FE is observed after thermal annealing and tracked by detailed in situ X-ray diffraction (XRD) analysis during a complete heating–cooling cycle. The NNO particles can be incorporated into a poly(vinyl alcohol) (PVA) polymer matrix to form flexible composites. XRD analysis and piezoelectric measurements on the composites reveal a clear AFE-FE phase transition in the initial nonannealed NNO particles after electrical poling above a threshold field of 75 kV/cm, a result which is consistent with well-known AFE-FE phase transitions in NNO bulk materials. The PVA plus 50 wt % NNO composite displays a piezoelectric coefficient d 33 of approximately 4.0 pC/N, outperforming composites using commercial tetragonal BaTiO 3 (BTO) nanoparticles. We demonstrated that these PVA-NNO composites generated piezoelectric output voltages of 0.3 and 0.8 V when subjected to manual bending and compression, respectively. These findings indicate that NNO-based composites can be considered promising lead-free candidate materials for soft sensors and piezoelectric energy harvesting applications.

Source: ACS Applied Energy Materials

DOI: 10.1021/acsaem.5c01693

Authors: Minh-Thanh Do, Mario Maglione, Philippe Poulin, Sonia Buffière, Marie-Hélène Delville, Matthew R. Suchomel