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Title Development, characterization, and piezoelectric fatigue behavior of lead-free perovskite piezoelectric ceramics
Publication Date
Date Available
Date Accessioned
Degree PhD
Discipline/Department Materials Science
Degree Level doctoral
University/Publisher Oregon State University
Abstract Much recent research has focused on the development lead-free perovskite piezoelectrics as environmentally compatible alternatives to lead zirconate titanate (PZT). Two main categories of lead free perovskite piezoelectric ceramic systems were investigated as potential replacements to lead zirconate titanate (PZT) for actuator devices. First, solid solutions based on Li, Ta, and Sb modified (K₀.₅Na₀.₅)NbO₃ (KNN) lead-free perovskite systems were created using standard solid state methods. Secondly, Bi-based materials a variety of compositions were explored for (1-x)(Bi₀.₅Na₀.₅)TiO₃-xBi(Zn₀.₅Ti₀.₅)O₃ (BNT-BZT) and Bi(Zn₀.₅Ti₀.₅)O₃–(Bi₀.₅K₀.₅)TiO₃–(Bi₀.₅Na₀.₅)TiO₃ (BZT-BKT-BNT). It was shown that when BNT-BKT is combined with increasing concentrations of Bi(Zn[subscript 1/2]Ti[subscript 1/2])O₃ (BZT), a transition from normal ferroelectric behavior to a material with large electric field induced strains was observed. The higher BZT containing compositions are characterized by large hysteretic strains (> 0.3%) with no negative strains that might indicate domain switching. This work summarizes and analyzes the fatigue behavior of the new generation of Pb-free piezoelectric materials. In piezoelectric materials, fatigue is observed as a degradation in the electromechanical properties under the application of a bipolar or unipolar cyclic electrical load. In Pb-based materials such as lead zirconate titanate (PZT), fatigue has been studied in great depth for both bulk and thin film applications. In PZT, fatigue can result from microcracking or electrode effects (especially in thin films). Ultimately, however, it is electronic and ionic point defects that are the most influential mechanism. Therefore, this work also analyzes the fatigue characteristics of bulk polycrystalline ceramics of the modified-KNN and BNT-BKT-BZT compositions developed. The defect chemistry that underpins the fatigue behavior will be examined and the results will be compared to the existing body of work on PZT. It will be demonstrated that while some Pb-free materials show severe property degradation under cyclic loading, other materials such as BNT-BKT-BZT essentially exhibit fatigue-free piezoelectric properties with chemical doping or other modifications. Based on these results, these new Pb-free materials have great potential for use in piezoelectric applications requiring a large number of drive cycles such as MEMS devices or high frequency actuators.
Subjects/Keywords Lead-free Piezoelectric; Perovskite
Contributors Cann, David P. (advisor); Gibbons, Brady J. (committee member)
Language en
Country of Publication us
Record ID handle:1957/34828
Repository oregonstate
Date Indexed 2017-03-17
Grantor Oregon State University
Issued Date 2012-09-17 00:00:00
Note [] Graduation date: 2013; [peerreview] no;

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…35 2.7 Lead-Free Perovskite Piezoelectrics ........................................................................................ 36 2.7.1 (l(Na)NbOTBased Systems…

…67 Development. Characterization and Piezoelectric Fatigue Behavior of Lead- Free Perovskite Piezoelectric Ceramics 1 Introduction and Motivation Piezoelectric ceramics, particularly PbZr1-xTix03 (PZT), are the most widely used…

…currently in use throughout the electronics industry. Therefore, the search for lead-free alternatives to lead-zirconate-titanate (PZT) has been of increasing interest and gaining more attention as companies endeavor to reduce the environmental…

…piezoelectric properties. Fatigue of these lead-free systems will also be 2 evaluated in detail to determine if their behavior is as detrimental and if the mechanisms are the same as those found for PZT based systems. 1.1 Composition Studies 1…

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…measurements reported in units ofpCjN. The d33* values are often higher than d33Values found for poled samples through direct, low-field measurements. This is especially true for lead-free materials where the d33* values are at a more fully "poled"…

…71 TABLE OF CONTENTS (Continued) 5 Piezoelectric properties and unipolar fatigue behavior of KNN-based Pb-free piezoceramics…

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