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Temperature Dependent Fracture Toughness of KNN-Based Lead-Free Piezoelectric Ceramics

25 Pages Posted: 15 Apr 2019 Publication Status: Accepted

See all articles by Yingwei Li

Yingwei Li

Wuhan University - State Key Laboratory of Water Resources and Hydropower Engineering Science; Wuhan University - School of Civil Engineering

Yixuan Liu

Tsinghua University - State Key Laboratory of New Ceramics and Fine Processing

Paul-Erich Öchsner

Friedrich-Alexander-Universität Erlangen-Nürnberg - Department of Materials Science and Engineering

Daniel Isaia

Technical University of Darmstadt - Institute of Materials Science

Yichi Zhang

Tsinghua University - State Key Laboratory of New Ceramics and Fine Processing

Ke Wang

Tsinghua University - State Key Laboratory of New Ceramics and Fine Processing

Kyle G. Webber

Friedrich-Alexander-Universität Erlangen-Nürnberg - Department of Materials Science and Engineering

Jing-Feng Li

Tsinghua University - State Key Laboratory of New Ceramics and Fine Processing

Jürgen Rödel

Technical University of Darmstadt - Department of Materials and Earth Sciences

Abstract

The fracture toughness of lead-free KNN-based piezoelectric ceramics with the composition of 0.92KNN-0.02Bi0.5Li0.5TiO3-0.06BaZrO3 was investigated by near-tip crack opening displacement (COD), surface crack in flexure (SCF), as well as single edge V-notch beam (SEVNB) techniques. Results reveal that the intrinsic fracture toughness (KI0), evaluated by the COD technique, is the lowest with a value of 0.70 MPa∙m0.5. The long (through-thickness) crack fracture toughness (KIvnb), obtained by the SEVNB technique, is the highest, with a value of 0.95 MPa∙m0.5. Intermediate short surface crack fracture toughness (KIsc) of 0.86 MPa∙m0.5 was determined by the SCF technique. These results were rationalized by the toughening behavior of the material combined with the crack geometry-dependent stress intensity evolution during crack propagation. With increasing temperature, KIvnb and KIsc decrease. At 350 °C, they are nearly identical, suggesting an absence of toughening. Nonlinear stress-strain analysis of the material was also employed during compression and four-point bending in order to quantify crack tip shielding by domain switching and in order to quantify the actual stress at the point of instable crack propagation.

Keywords: potassium-sodium niobate, lead-free piezoceramics, fracture toughness, domain switching, toughening

Suggested Citation

Li, Yingwei and Liu, Yixuan and Öchsner, Paul-Erich and Isaia, Daniel and Zhang, Yichi and Wang, Ke and Webber, Kyle G. and Li, Jing-Feng and Rödel, Jürgen, Temperature Dependent Fracture Toughness of KNN-Based Lead-Free Piezoelectric Ceramics (April 11, 2019). Available at SSRN: https://ssrn.com/abstract=3370284 or http://dx.doi.org/10.2139/ssrn.3370284

Yingwei Li (Contact Author)

Wuhan University - State Key Laboratory of Water Resources and Hydropower Engineering Science ( email )

Wuhan University - School of Civil Engineering ( email )

Yixuan Liu

Tsinghua University - State Key Laboratory of New Ceramics and Fine Processing

Beijing
China

Paul-Erich Öchsner

Friedrich-Alexander-Universität Erlangen-Nürnberg - Department of Materials Science and Engineering

Erlangen
Germany

Daniel Isaia

Technical University of Darmstadt - Institute of Materials Science

Universitaets- und Landesbibliothek Darmstadt
Magdalenenstrasse 8
Darmstadt, Hesse D-64289
Germany

Yichi Zhang

Tsinghua University - State Key Laboratory of New Ceramics and Fine Processing

Beijing
China

Ke Wang

Tsinghua University - State Key Laboratory of New Ceramics and Fine Processing

Beijing
China

Kyle G. Webber

Friedrich-Alexander-Universität Erlangen-Nürnberg - Department of Materials Science and Engineering

Erlangen
Germany

Jing-Feng Li

Tsinghua University - State Key Laboratory of New Ceramics and Fine Processing

Beijing
China

Jürgen Rödel

Technical University of Darmstadt - Department of Materials and Earth Sciences ( email )

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