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Effect of Sc Doping on the Structure and Electrical Properties of (Na 0.85 K 0.15 ) 0.5 Bi 0.5 TiO 3 Thin Films Prepared by Sol–Gel Processing
Author(s) -
Wu Yunyi,
Wang Xiaohui,
Li Longtu
Publication year - 2011
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2011.04428.x
Subject(s) - raman spectroscopy , materials science , scanning electron microscope , dopant , analytical chemistry (journal) , doping , thin film , curie temperature , sol gel , nanotechnology , chemistry , optics , composite material , chromatography , physics , optoelectronics , quantum mechanics , ferromagnetism
(Na 0.85 K 0.15 ) 0.5 Bi 0.5 TiO 3 (NKBT) and B‐site‐substituted NKBT by Sc, i.e. (Na 0.85 K 0.15 ) 0.5 Bi 0.5 Ti (1− x ) Sc x O 3 (NKBT‐Sc x , x =0.05, 0.1, 0.15, 0.2, 0.25, 0.3, and 0.4) thin films were prepared on Pt/Ti/SiO 2 /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 Sc 3+ for Ti 4+ . 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/cm 2 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.