Enhanced piezoelectricity and reduced leakage current of a novel (1-x)Bi0.5Na0.5TiO3-x(Sr0.7Bi0.20.1)TiO3 thin film

Lead-free (1-x)Bi0.5Na0.5TiO3-x(Sr0.7Bi0.20.1)TiO3 (x = 0.0, 0.1, 0.2 and 0.3, denoted as BNT-xSBT) thin films were deposited on Pt(111)/Ti/SiO2/Si substrates by the sol-gel method, and their microstructure and dielectric, ferroelectric and piezoelectric properties were investigated in detail. All thin films present a single perovskite structure as demonstrated. In particular, appropriate Mn doping modifies the concentration of oxygen vacancies in thin films, resulting in a marked decline in leakage current. In this way, an ultra-high inverse piezoelectric coefficient (d(33)* similar to 144.11 pm V-1) can be obtained from a 0.8BNT-0.2SBT thin film, and a maximum polarization P-m of 46.88 mu C cm(-2) is observed under an electric field of 700 kV cm(-1). Meanwhile, a BNT-SBT thin film has flexible dielectric tunability. All results strongly suggest that the ultra-high piezoelectric property of BNT-0.2SBT is derived from the ferroelectric-to-relaxor transition. As described, this work indicates that the BNT-SBT thin film is an ideal lead-free piezoelectric substituted material. Moreover, BNT-SBT is a novel system of thin films, which has a great development prospect.

Automated summary

The lead-free thin films BNT-xSBT deposited on Pt/Ti/SiO2/Si substrates by the sol-gel method exhibit excellent piezoelectric properties and flexible dielectric tunability. Mn doping in appropriate amounts significantly reduces leakage current in the films, resulting in an ultra-high inverse piezoelectric coefficient.