High recoverable energy storage density and large piezoelectric response in (Bi0.5Na0.5)TiO3-PbTiO3 thin films prepared by a sol-gel method

Low-lead-content (1-x)(Bi0.5Na0.5)TiO3-xPbTiO3 (x = 0, 0.05, 0.10, 0.15, 0.25) (hereafter abbreviated as BNT-xPT) thin films were prepared by a sol-gel method, and their crystal structure, dielectric properties, recoverable energy-storage density and piezoelectric response were investigated as a function of PT concentration. Combining the XRD patterns and Raman spectroscopy indicate the phase structures go through rhombohedral (R) - rhombohedral + tetragonal (R + T) - tetragonal (T) evolution with increasing of PT content. A high recoverable energy storage density of 13.02 ± 0.39 J/cm3 was achieved in the BNT-0.10PT thin films due to the high field endurance and significantly enhanced polarizability. Moreover, a superior piezoelectric response (d33* = 120 ± 5 pm/V) was also obtained in the 10% PT-modified BNT films, which can be attributed to easy polarization rotation due to low polarization anisotropy on the R-T phase boundary. These properties indicate that BNT-0.10PT films might be promising multifunctional materials for piezoelectric micro-actuator and energy storage embedded capacitor applications.