STRUCTURE AND PROPERTIES OF PIEZOELECTRIC NANOFIBERS FOR ELECTROMECHANICAL COUPLING APPLICATIONS

Abstract

Many emerging applications demand flexible materials for efficient electromechanical conversions. With potential to improve flexibility and electromechanical coupling performance, due to the finite size effect and high specific surface areas, one-dimensional (1D) nanostructured piezoelectric materials are attractive. The objective of this research is to investigate the effects of 1D nanostructures on the structural and properties of piezoelectric materials and develop high performance piezoelectric polymer and lead-free ceramic nanofibers for electromechanical coupling applications. Polyvinylidene fluoride (PVDF) nanofibers were fabricated by electrospinning process using a precursor solution modified with hydrated salt. Introducing hydrated salts in PVDF precursor solution proves very effective in improving the polar β-phase content, promoted by hydrogen bonds formation between fluorine and hydroxyl group. Apart from piezoelectric polymers, lead-free potassium sodium niobate (KNN) ceramic nanofibers were fabricated by electrospinning process using precursor solution with excess of K/Na and modified with polyvinylpyrrolidone (PVP) for mitigating the loss of alkali constituents. Finally, a thick film of aligned PVDF fibers was explored for mechanical energy harvesting. The results and analyses show the great potential of piezoelectric fiber materials with appropriately controlled nanostructures and polarizations as high-performance functional materials for electromechanical coupling applications.