Effect of annealing temperature on piezoelectric and mechanical properties of (Bi0.5Na0.5)TiO3-(Bi0.5K0.5)TiO3-BaTiO3 thin films

Polycrystalline piezoelectric lead-free 85 mol% (Bi0.5Na0.5)TiO3-10 mol% (Bi0.5K0.5)TiO3-5 mol% BaTiO3 (85BNT-10BKT-5BT) thin films were fabricated at different annealing temperatures by a chemical solution deposition method on Pt/Ti/SiO2/Si substrates. Perovskite phase was achieved during annealing at 650-800 °C. The effect of annealing temperature on piezoelectric and mechanical properties was investigated. The results show that 85BNT-10BKT-5BT thin films annealed at 700 °C exhibit the largest effective d33 value of 140.4 pm/V, and the highest elastic modulus 142.0 GPa. The optimal properties can be attributed to dense domain and homogenous microstructure. Results show that 85BNT-10BKT-5BT thin films may be a good candidate for lead-free piezoelectric-based micro-electromechanical systems.