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Title: Nanomechanics of Ferroelectric Thin Films and Heterostructures

Abstract

The focus of this chapter is to provide basic concepts of how external strains/stresses altering ferroelectric property of a material and how to evaluate quantitatively the effect of strains/stresses on phase stability, domain structure, and material ferroelectric properties using the phase-field method. The chapter starts from a brief introduction of ferroelectrics and the Landau-Devinshire description of ferroelectric transitions and ferroelectric phases in a homogeneous ferroelectric single crystal. Due to the fact that ferroelectric transitions involve crystal structure change and domain formation, strains and stresses can be produced inside of the material if a ferroelectric transition occurs and it is confined. These strains and stresses affect in turn the domain structure and material ferroelectric properties. Therefore, ferroelectrics and strains/stresses are coupled to each other. The ferroelectric-mechanical coupling can be used to engineer the material ferroelectric properties by designing the phase and structure. The followed section elucidates calculations of the strains/stresses and elastic energy in a thin film containing a single domain, twinned domains to complicated multidomains constrained by its underlying substrate. Furthermore, a phase field model for predicting ferroelectric stable phases and domain structure in a thin film is presented. Examples of using substrate constraint and temperature to obtain interested ferroelectricmore » domain structures in BaTiO3 films are demonstrated b phase field simulations.« less

Authors:
; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1327153
Report Number(s):
PNNL-SA-112982
DOE Contract Number:
AC05-76RL01830
Resource Type:
Book
Resource Relation:
Related Information: Multiscale Materials Modeling for Nanomechanics, 245:469-488
Country of Publication:
United States
Language:
English
Subject:
Ferroelectrics; Thin film; Phase transition; Polarization; Heterostructure; Nanomechanics; Phase field method

Citation Formats

Li, Yulan, Hu, Shenyang Y., and Chen , L.Q.. Nanomechanics of Ferroelectric Thin Films and Heterostructures. United States: N. p., 2016. Web. doi:10.1007/978-3-319-33480-6_15.
Li, Yulan, Hu, Shenyang Y., & Chen , L.Q.. Nanomechanics of Ferroelectric Thin Films and Heterostructures. United States. doi:10.1007/978-3-319-33480-6_15.
Li, Yulan, Hu, Shenyang Y., and Chen , L.Q.. 2016. "Nanomechanics of Ferroelectric Thin Films and Heterostructures". United States. doi:10.1007/978-3-319-33480-6_15.
@article{osti_1327153,
title = {Nanomechanics of Ferroelectric Thin Films and Heterostructures},
author = {Li, Yulan and Hu, Shenyang Y. and Chen , L.Q.},
abstractNote = {The focus of this chapter is to provide basic concepts of how external strains/stresses altering ferroelectric property of a material and how to evaluate quantitatively the effect of strains/stresses on phase stability, domain structure, and material ferroelectric properties using the phase-field method. The chapter starts from a brief introduction of ferroelectrics and the Landau-Devinshire description of ferroelectric transitions and ferroelectric phases in a homogeneous ferroelectric single crystal. Due to the fact that ferroelectric transitions involve crystal structure change and domain formation, strains and stresses can be produced inside of the material if a ferroelectric transition occurs and it is confined. These strains and stresses affect in turn the domain structure and material ferroelectric properties. Therefore, ferroelectrics and strains/stresses are coupled to each other. The ferroelectric-mechanical coupling can be used to engineer the material ferroelectric properties by designing the phase and structure. The followed section elucidates calculations of the strains/stresses and elastic energy in a thin film containing a single domain, twinned domains to complicated multidomains constrained by its underlying substrate. Furthermore, a phase field model for predicting ferroelectric stable phases and domain structure in a thin film is presented. Examples of using substrate constraint and temperature to obtain interested ferroelectric domain structures in BaTiO3 films are demonstrated b phase field simulations.},
doi = {10.1007/978-3-319-33480-6_15},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2016,
month = 8
}

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  • The author has grown epitaxial thin films of a new family of copper-oxide-based isotropic metallic oxides such as La{sub 6.4}Sr{sub 1.6}Cu{sub 8}O{sub 20}, La{sub 5}BaCu{sub 6}O{sub 13} and La{sub 6}BaYCu{sub 8}O{sub 20} in situ by 90{degree} off-axis sputtering. These metallic oxides are pseudo-cubic perovskites with essentially isotropic properties, which could be ideal normal metals for SNS junctions in superconducting devices. The author has also grown epitaxial SNS superconducting heterostructures (c-axis YBa{sub 2}Cu{sub 3}O{sub 7}/La{sub 6.4}Sr{sub 1.6}Cu{sub 8}O{sub 20}/c-axis YBa{sub 2}Cu{sub 3}O{sub 7}) with a copper-oxide-based isotropic metallic oxide (La{sub 6.4}Sr{sub 1.6}Cu{sub 8}O{sub 20}) normal metal barrier. X-ray diffraction and cross-sectionalmore » transmission electron microscopy reveal these heterostructures to have high crystalline quality and clean interfaces. This material will facilitate fabrication of ideal SNS Josephson junctions with low boundary resistance due to its excellent chemical compatibility and lattice match with cuprate superconductors and will be useful for determining the source of interface resistance in such heterostructures.« less
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  • The authors are reporting the successful deposition of single phase c-axis oriented ferroelectric thin films of PbTiO{sub 3} on Si (100) by pulsed laser deposition. It is shown that the formation of non ferroelectric Pb{sub 2}Ti{sub 2}O{sub 6} phase at the interface could be avoided by raising the substrate temperature sufficiently high. The film deposition conditions are optimized so as to achieve better ferroelectric properties.
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  • Basic scientific and technological advances on ferroelectric thin films and heterostructures are discussed in relation to the work on nonvolatile ferroelectric random access memories (NVFRAMs) performed by different groups during the last seven years. A reasonable understanding of the synthesis and microstructure-property relationships of ferroelectric thin films for NVFRAMs is demonstrated. Materials integration strategies developed to fabricate ferroelectric capacitors with practically no fatigue or imprint, long polarization retention, and low leakage current are discussed. These properties have been obtained using two ferroelectric materials, Pb(Zr{sub x}Ti{sub 1-x})O{sub 3} (PZT) and SrBi{sub 2}Ta{sub 2}O{sub 9} (SBT), that are the main candidates formore » application to the first generation of commercial NVFRAMs. A discussion of current knowledge and future research directions is presented.« less