High-strain actuation of lead-free perovskites : compositional effects, phenomenology and mechanism

An experimental study was carried out to map the compositional dependence of electromechanical behavior and ferroelectric phase stability in the barium, zirconium-codoped sodium bismuth titanate (BNBZT) system for barium concentrations up to 18 mol.% and zirconium concentrations up to 4 mol.%. A number of polycrystalline BNBZT samples has been electromechanically tested under applied electric fields of different frequencies (0.2-47 Hz). A novel model of electromechanical response capable of describing both dynamic and static hysteresis for pure and mixed cases of ferroelectric, antiferroelectric, ferroelastic and paraelectric behavior has been developed. Major electromechanical properties of polycrystalline BNBZT have been identified and compositionally mapped. The peak of electromechanical response (d33 = 400 pC/N) has been found at the composition (Bil/2Nal/2)0.93Bao.07Zro.02Tio.9803. The compositional dependence of ferroelectric phase stability has been mapped by means of a Landau type free energy expansion. A nanodomain relaxation mechanism of frequency dependent electromechanical response of BNBZT has been suggested and is supported by optical and transmission electron microscopy.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Materials Science and Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2002

Author dc:creator

• Soukhojak, Andrey N. (Andrey Nestorovich), 1972-

Advisor dc:contributor.advisor

• Yet-Ming Chiang.

• Materials Science and Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/16877

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/16877