Effects of Mn doping on dielectric and ferroelectric properties of (Pb,Sr) TiO₃ films on (111) Pt/Ti/ SiO₂ /Si substrates

A series of Mn doped Pb_0.5 Sr_0.5 TiO₃ (PSMT) films with dopant concentrations from 0 to 10 mol % was fabricated on (111) Pt/Ti/ SiO₂ /Si substrates by chemical solution deposition. Their microstructure, ferroelectric, and dielectric properties were investigated, and Mn doping was found to have a significant influence on the properties of (Pb,Sr) TiO₃ film. The improved microstructure with increased grain size, remnant polarization, dielectric permittivity and its tunability by dc electric field, and reduced coercive field and dielectric loss was observed in the Mn doped samples. A PSMT film with 0.5 mol % Mn dopants exhibits the optimum characteristics with maximal remnant polarization (2Pr=25.28 μC/ cm²), dielectric permittivity (1427) and tunability (74.5%, at 100 kHz), and minimal dielectric loss (0.015) at 1 kHz. The improvement was attributed to the improved microstructure, enhanced displacement of polar ions, and, most importantly, the suppression of oxygen-vacancy-induced ferroelectric domain pinning, which was well verified in terms of Rayleigh law. Finally, the evolution of oxygen-vacancy concentration modulated by the Mn doping in PSMT films was discussed.