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Deng Y, Zhang R, Pekin TC, Gammer C, Ciston J, Ercius P, Ophus C, Bustillo K, Song C, Zhao S, Guo H, Zhao Y, Dong H, Chen Z, Minor AM. Functional Materials Under Stress: In Situ TEM Observations of Structural Evolution. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1906105. [PMID: 31746516 DOI: 10.1002/adma.201906105] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 10/07/2019] [Indexed: 06/10/2023]
Abstract
The operating conditions of functional materials usually involve varying stress fields, resulting in structural changes, whether intentional or undesirable. Complex multiscale microstructures including defects, domains, and new phases, can be induced by mechanical loading in functional materials, providing fundamental insight into the deformation process of the involved materials. On the other hand, these microstructures, if induced in a controllable fashion, can be used to tune the functional properties or to enhance certain performance. In situ nanomechanical tests conducted in scanning/transmission electron microscopes (STEM/TEM) provide a critical tool for understanding the microstructural evolution in functional materials. Here, select results on a variety of functional material systems in the field are presented, with a brief introduction into some newly developed multichannel experimental capabilities to demonstrate the impact of these techniques.
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Affiliation(s)
- Yu Deng
- Solid State Microstructure National Key Lab and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Ruopeng Zhang
- National Center of Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Thomas C Pekin
- National Center of Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Christoph Gammer
- Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Jahnstrasse 12, 8700, Leoben, Austria
| | - Jim Ciston
- National Center of Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Peter Ercius
- National Center of Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Colin Ophus
- National Center of Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Karen Bustillo
- National Center of Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Chengyu Song
- National Center of Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Shiteng Zhao
- National Center of Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Hua Guo
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX, 77251, USA
| | - Yunlei Zhao
- Solid State Microstructure National Key Lab and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Hongliang Dong
- Center for High Pressure Science and Technology Advanced Research, Shanghai, 201203, China
| | - Zhiqiang Chen
- Center for High Pressure Science and Technology Advanced Research, Shanghai, 201203, China
| | - Andrew M Minor
- National Center of Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
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Cordero F. Elastic Properties and Enhanced Piezoelectric Response at Morphotropic Phase Boundaries. MATERIALS (BASEL, SWITZERLAND) 2015; 8:8195-8245. [PMID: 28793707 PMCID: PMC5458858 DOI: 10.3390/ma8125452] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 11/13/2015] [Accepted: 11/18/2015] [Indexed: 11/29/2022]
Abstract
The search for improved piezoelectric materials is based on the morphotropic phase boundaries (MPB) between ferroelectric phases with different crystal symmetry and available directions for the spontaneous polarization. Such regions of the composition x - T phase diagrams provide the conditions for minimal anisotropy with respect to the direction of the polarization, so that the polarization can easily rotate maintaining a substantial magnitude, while the near verticality of the TMPB(x) boundary extends the temperature range of the resulting enhanced piezoelectricity. Another consequence of the quasi-isotropy of the free energy is a reduction of the domain walls energies, with consequent formation of domain structures down to nanoscale. Disentangling the extrinsic and intrinsic contributions to the piezoelectricity in such conditions requires a high level of sophistication from the techniques and analyses for studying the structural, ferroelectric and dielectric properties. The elastic characterization is extremely useful in clarifying the phenomenology and mechanisms related to ferroelectric MPBs. The relationship between dielectric, elastic and piezoelectric responses is introduced in terms of relaxation of defects with electric dipole and elastic quadrupole, and extended to the response near phase transitions in the framework of the Landau theory. An account is provided of the anelastic experiments, from torsional pendulum to Brillouin scattering, that provided new important information on ferroelectric MPBs, including PZT, PMN-PT, NBT-BT, BCTZ, and KNN-based systems.
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Affiliation(s)
- Francesco Cordero
- CNR-ISC, Istituto dei Sistemi Complessi, Area della Ricerca di Roma-Tor Vergata, Via del Fosso del Cavaliere 100, Roma I-00133, Italy.
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