Dielectric and ferroelectric properties of (Bi0.5Na0.5)TiO3-(Bi0.5K0.5)TiO3-BaTiO3 thin films deposited via chemical solution deposition

Polycrystalline ferroelectric lead-free 85 mol% (Bi0.5Na0.5)TiO3-10 mol% (Bi0.5K0.5)TiO3-5 mol% BaTiO3 (85BNT-10BKT-5BT) thin films were fabricated via chemical solution deposition on platinized silicon substrates. The permittivity and dielectric loss at 1 kHz were 610 and ∼3.5%, respectively. The ferroelectric properties at room temperature and as a function of the temperature up to 125 °C were also investigated. The polarization hysteresis loop at room temperature showed a PMAX of 31 μC/cm2 and Pr of 6 μC/cm2 at 200 Hz. The shapes of the hysteresis loops at room temperature and 125 °C were nearly identical, indicating good temperature stability. A dense surface morphology was observed and cross sectional microscopy revealed equiaxed grain growth. Based on these measurements, 85BNT-10BKT-5BT thin films may be a good candidate for lead-free piezoelectric-based microelectromechanical systems (MEMS).