Effect of Rb doping on ferroelectric and piezoelectric properties of Bi0.5Na0.5TiO3–BaTiO3 thin films

• Rb-doped BNT–BT films were grown on Pt substrate by metal organic solution deposition technique.
• All Rb-doped BNT–BT films have a single phase perovskite structure with no secondary phase.
• Optimal electrical properties were obtained for 5 mol% Rb doped BNT–BT films.

Rb doped 0.94Bi0.5Na0.5TiO3–0.06BaTiO3 (BNT–BT–Rbx) thin films with x mol% Rb (x = 0, 2.5, 5, 7.5, 10) were deposited on Pt/Ti/SiO2/Si substrate by metal-organic solution deposition method. Experiments were conducted to investigate the effect of Rb doping on phase formation, microstructure, leakage current, and the resulting ferroelectric and piezoelectric property. It was found that substantial enhancement in structural, morphological and electrical properties can be achieved by Rb doping of BNT–BT thin films. Optimal electrical properties were obtained for 5 mol% Rb doped BNT–BT thin films, with a dielectric constant, remnant polarization, and effective piezoelectric constant of ∼681, ∼28.9 μC/cm2 and ∼86 pm/V, respectively. It was suggested that the enhanced electrical properties in the case of 5 mol% Rb BNT–BT thin films can be attributed to domain wall movement induced by A-site substitutions, large grain size, and lattice distortion.