High quality barium titanate nanofibers for flexible piezoelectric device applications

Piezoelectric and ferroelectric nanostructures and devices have attracted extensive attention because they can realize the conversion between mechanical and electrical energies for sensors and energy harvesting applications. In the present work high quality lead-free BaTiO3 nanofibers were obtained by a sol-gel based electrospinning technique. X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and piezoresponse force microscopy (PFM) were utilized to characterize the morphologies, phase and domain structures along with the nanoscale electromechanical response. Well-crystallized BaTiO3 fibers were obtained with good local piezoelectric response (d33,eff of ∼40 pm/V using PFM). Further, a flexible piezoelectric device was fabricated by combining aligned BaTiO3 nanofibers and a PDMS polymer matrix. An inter-digital electrode on a flexible substrate was incorporated to enhance the output signal. The proposed device displayed an output peak-peak voltage of ∼0.45 V at a load resistance of 1 MΩ under a periodic bending excitation of ∼45 Hz. It has the advantages of small-size, ease of processing, high flexibility and strain tolerance, and high-sensitivity to external vibration at low-frequency which may open up a range of new applications.