Effects of BaTiO3Content and Mn Doping on Ferroelectric Properties of NaNbO3–BaTiO3Thin Films Prepared by Chemical Solution Deposition

Lead-free ferroelectric NaNbO 3 –BaTiO 3 thin films were prepared by chemical solution deposition. Perovskite single-phase NaNbO 3 –BaTiO 3 thin films were successfully fabricated at 550 °C on Pt/TiO x /SiO 2 /Si substrates. The ferroelectric properties of the NaNbO 3 –BaTiO 3 thin films depended on the BaTiO 3 content of NaNbO 3 –BaTiO 3 . Among NaNbO 3 –BaTiO 3 films with various BaTiO 3 concentrations, the 0.95NaNbO 3 –0.05BaTiO 3 thin films showed relatively large polarization at -190 °C, although the insulating resistance of the films was not sufficiently high at room temperature. To improve the electrical resistivity at ambient temperatures, Mn doping of 0.95NaNbO 3 –0.05BaTiO 3 was examined. The leakage current density of the films was found to be greatly reduced by a small amount of Mn doping. 1.0 mol % Mn-doped 0.95NaNbO 3 –0.05BaTiO 3 thin films showed well-shaped slim ferroelectric polarization–electric field ( P – E ) hysteresis loops at room temperature. The remanent polarization ( P r ) and coercive field ( E c ) values of the 1.0 mol % Mn-doped 0.95NaNbO 3 –0.05BaTiO 3 thin films at 1 kHz were approximately 5 µC/cm 2 and 50 kV/cm, respectively. Furthermore, the ferroelectric P – E loops of the 1.0 mol % Mn-doped 0.95NaNbO 3 –0.05BaTiO 3 thin films showed good frequency dependence and could be characterized at a frequency as low as 1 Hz.