Effect of Sc Doping on the Structure and Electrical Properties of (Na
(Na0.85K0.15)0.5Bi0.5TiO3 (NKBT) and B‐site‐substituted NKBT by Sc, i.e. (Na0.85K0.15)0.5Bi0.5Ti(1−x)Sc x O3 (NKBT‐Scx, x=0.05, 0.1, 0.15, 0.2, 0.25, 0.3, and 0.4) thin films were prepared on Pt/Ti/SiO2/Si(100) substrates by an aqueous sol–gel method. Structures and electrical characteristics of the films were studied as functions of Sc composition. Structures were investigated by X‐ray diffraction (XRD), scanning probe microscopy, scanning electron microscopy, and Raman spectroscopy. XRD indicates that a secondary phase peak appears when Sc‐doping concentration increases above x=0.25 due to the limited substitution tolerance of Sc3+ for Ti4+. With increasing Sc‐doping composition, generally, the octahedra‐related vibration modes show a high‐frequency shift. The remnant polarization (P r) value is a maximum for the NKBT‐Sc0.25 films of 18.62 μC/cm2 and decreases with both decreasing and increasing doping concentration. The NKBT‐Sc thin film with an optimized Sc‐doping concentration of x=0.25 shows the effective piezoelectric coefficient d 33 * of 67 pm/V. The Curie temperature (T c) of the NKBT thin film shifted to higher temperature by adding Sc dopant.
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Document Type: Research Article
Affiliations: State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
Publication date: August 1, 2011