Dielectric, Ferroelectric, Pyroelectric, and Piezoelectric Properties of La-Modified Lead-Free Sodium–Potassium Bismuth Titanate Thick Films
Abstract:La2O3-doped sodium–potassium bismuth titanate (Na0.82K0.18)0.5Bi0.5TiO3 (NKBT) lead-free thick films have been prepared on Pt-electroded alumina substrates using a combination of screen printing and subsequent infiltration of the corresponding composite sol. Their densification, microstructure, dielectric, ferroelectric, pyroelectric, and piezoelectric properties were investigated with variation of the La2O3 content. The resulting 40 m-thick NKBT films doped with 1.0 mol% La2O3 show minimum leakage current density of 1.56 × 10−9 A/cm2 at an applied field of 100 kV/cm, remanent polarization of 21.6 C/cm2, and coercive field of 58 kV/cm. The high pyroelectric coefficient of 2.0 × 10−4 C·(m2·°C)−1, the calculated detectivity figure of merit as high as 0.81 × 10−5 Pa−0.5, and the value of remanent d33eff of 108 pm/V at room temperature (20°C) were observed in 1.0 mol% La2O3-doped NKBT thick films, which can be comparable with that of the commonly used lead-based materials. The enhancement of the pyroelectric and piezoelectric performances is attributed to the reduction of lattice tetragonality, uniform microstructure, and improved densification in La-modified NKBT thick films.
Document Type: Research Article
Affiliations: 1: Department of Electronic Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China 2: Research Laboratory of Hydrothermal Chemistry, Faculty of Science, Kochi University, Kochi 780-8520, Japan 3: School of Materials Science and Engineering, State Key Laboratory of Material Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, China
Publication date: 2010-03-01