Synthesis and piezoelectric properties of freestanding ferroelectric films based on barium strontium titanate

In this work, the membrane structures based on lead-free ferroelectric barium strontium titanate with composition Ba0.8Sr0.2TO3 (BSTO) were fabricated by a magnetron sputtering method. The formation of a single-phase Ba0.8Sr0.2TO3 with thickness of 300 nm sintered on Si substrate is confirmed by XRD analysis. It is shown that films without a silicon substrate exhibit ferroelectric and piezoelectric properties. The piezoelectric and ferroelectric behaviors of BSTO thin film without a silicon substrate were confirmed through a piezoelectric force microscopy and Kelvin probe force microscopy and measurements of the effective piezoelectric coefficients (d33 and d15). Images of the residual potential of polarized areas have been obtained on the membranes, which are stable over time despite the absence of a lower electrode. Additionally, a local of ferroelectric hysteresis loop has been observed. A combination of the structural and piezoelectric measurements reveals that it possible to create freestanding ferroelectric films based on Ba0.8Sr0.2TO3 system, establishing it as a promising candidate for high-performance electromechanical applications.