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High Piezoelectric Properties of KNN ‐Based Thick Films with Abnormal Grain Growth
Author(s) -
Han Guifang,
Ryu Jungho,
Ahn CheolWoo,
Yoon WoonHa,
Choi JongJin,
Hahn ByungDong,
Kim JongWoo,
Choi JoonHwan,
Park DongSoo
Publication year - 2012
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.1551-2916.2012.05139.x
Subject(s) - grain size , materials science , microstructure , ferroelectricity , analytical chemistry (journal) , grain growth , sapphire , piezoelectricity , phase (matter) , hysteresis , crystallography , composite material , chemistry , dielectric , chromatography , optics , laser , physics , optoelectronics , organic chemistry , quantum mechanics
Over 10 μm‐thick ( K , N a) N b O 3 KNN ‐based films doped with complex‐perovskite‐materials ( CP s) were deposited on platinized sapphire substrates by aerosol deposition ( AD ). Three CP s were selected: B a( C u 1/3 N b 2/3 ) O 3 ( BCN ), C u( C u 1/3 N b 2/3 ) O 3 ( CCN ), and S r( C u 1/3 N b 2/3 ) O 3 ( SCN ). The films of 0.985( N a 0.5 K 0.5 ) N b O 3 ‐0.015 CP s ( KNN ‐ CP s) were post annealed at 1050°C for 1 h in air without any serious phase decomposition. The microstructure showed abnormal grain growth due to C u‐rich liquid phase. The KNN – BCN film had the largest abnormal grain size of over 10 μm, whereas the KNN – SCN film had the smallest grain size and also the smallest frequency of abnormal grains. All the films exhibited typical characteristics of ferroelectric hysteresis similar to those of the bulk materials without any leakage. The KNN – BCN films possessing the biggest abnormal grains also exhibited the highest density, piezoelectric constant, and piezoelectric voltage constant of 110 pC/N and 15.45 × 10 −3 Vm/N, respectively, which are the highest values reported so far for KNN ‐based films. This indicated that KNN ‐ CP s lead‐free films are suitable candidates for sensor applications.