Large Remanent Polarization and Low Leakage Current in High-Tc 0.2Bi (Ni1/2Ti1/2)O3-0.8PbTiO3 Ferroelectric Thin Films

High Curie-temperature (Tc) polycrystalline 0.2Bi (Ni1/2Ti1/2)O3-0.8PbTiO3 (0.2BNT-0.8PT) thin films were fabricated on Pt (111)/Ti/SiO2/Si substrates via an aqueous chemical solution deposition (CSD) technique. The thin films exhibited good crystalline quality and dense, uniform microstructures with an average grain size of 55 nm. The dielectric, piezoelectric and ferroelectric properties of the films was investigated. The permittivity peak appeared at 485 °C, which was 100 °C higher than that of Pb (Zr,Ti)O3 thin films. The local effective piezoelectric coefficient d33 was 45 pm/V at 3V. Moreover, a large remnant polarization with 2Pr up to 92 uC/cm2 and a small leakage current of 2.2×10-5 A/cm2 under an electric field of 400 kV/cm were obtained. The magnitude of the measured polarization and the high Curie temperature make the 0.2BNT-0.8PT films promising candidates for application in high-temperature ferroelectric and piezoelectric devices.