Piezoelectric nanogenerator based on lead-free BiFeO3:Sr perovskite

The current work reports the synthesis of Bi1−xSrxFeO3 (SBFO; x = 0.0, 0.15, 0.25, 0.35) nanoparticles by sol-gel method and study of its structural and piezoelectric properties. X-ray diffraction identifies the phase transformation from rhombohedral to cubic of BiFeO3 upon doping of Sr. X-ray photoemission spectroscopy revealed that Sr doped BiFeO3 nanoparticles are rich with oxygen vacancies compared to the bare BiFeO3 nanoparticles. The highest maximal polarization value of 6.74 µC cm−2 and remnant polarization 4.20 µC cm−2 are observed for BiFeO3 with 25% of Sr. The SBFO-PENG with 25% of Sr content device provides output voltage and current of 6.35 V and 0.64 μA under pushing tester with 1 Hz frequency, which is higher to that for a bare BiFeO3 PENG. It also exhibits high mechanical robustness, and much stable and durable output even after 1500 s. A maximum power density of ~ 0.31 µWcm−2 was achieve at a resistive load of 108 Ω. The SBFO-PENG device's feasibility is tested by trigging commercial electronics such as charging capacitors and lighting the LED, and it can drive a 0.47 μF capacitor to store the energy of 7.29 μJ within 500 s under pushing tester.