Enhancement of the performance of flexible lead-free nanogenerators by doping in BaTiO3 nanoparticles

Barium Titanate (BaTiO3) lead-free ceramic has recently gained attention for the fabrication of nanogenerators. Herein, lead-free piezoceramics (Ba, Ca) (Zr, Ti)O-3 was synthesized using the sol-gel method. In order to improve the material properties, Ca2+ and Zr4+ were introduced into the BaTiO3 crystal network to replace Ba2+ and Ti4+, respectively. Subsequently, three flexible nanocomposites were chemically fabricated by mixing polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) with the commercial BT, the synthesized BZT and BCZT, using the solution-casting technique. The microstructure and morphology were characterized by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), and (SEM). This study illustrates that the combination of both addition Ca2+ and Zr4+ in barium titanate is promising for forming the electroactive beta-phase in the nano -composite. The XRD and FTIR confirmed the formation of the polar beta-phase, enhancing piezoelectric properties. The electrical conductivity of the nanocomposite increased with doping in both sites. A maximum output voltage (-1.8 V) and power (-1.9 mu W) were achieved for composite including BCZT particles. Besides, different sizes and concentrations of BCZT/PVDF-HFP based nanogenerators were constructed. The optimal performance was with nanogenerators of size 2 cm x 2.5 cm and 10 wt % of BCZT powders. Biomechanical foot-tapping achieved a maximum output voltage of 4.55 V, which was high enough to become a potential candidate for a self powered device in future applications.

Automated summary

This study successfully synthesized lead-free piezoceramics and prepared three flexible nanocomposites using the solution-casting technique. The addition of Ca2+ and Zr4+ improved the material properties and enhanced the piezoelectric performance. The nanogenerator with 10 wt% BCZT powders achieved optimal performance.