Interfacial States and Thermodynamic Transitions at Interfaces
Event details
| Date | 14.11.2016 |
| Hour | 13:15 › 14:15 |
| Speaker | Prof. Wayne D. Kaplan, Department of Materials Science and Engineering Technion – Israel Institute of Technology |
| Location | |
| Category | Conferences - Seminars |
Since the 1980s it has been recognized that the structure of grain boundaries in polycrystalline ceramics can have a diffuse nature, characterized by a ~1nm thick nominally amorphous film. More recently, the structure of grain boundaries has been described following diffuse interface theory, stating that the structure and chemistry of grain boundaries, interfaces and surfaces can go through two dimensional transitions between thermodynamic states (sometimes termed complexions). As an example, surface reconstruction is a first order complexion transition, equivalent to a discontinuous change in the level of adsorbed excess. As such complexions for interfaces are analogous to phases in bulk, although they are not bulk phases. In the past these conclusions had been reached based on structural characterization of grain boundaries and interfaces correlated with mechanical and electrical properties, and more recently it has been shown that specific complexions can have a significant influence on grain boundary mobility, and thus the morphology of an evolving microstructure.
To date, almost all of these studies have been conducted at grain boundaries in single phase polycrystalline systems, which by definition are not at equilibrium, and in some cases it is not even clear if the identified complexions are at steady-state. Similar questions have been raised for studies focusing on metal-ceramic interfaces from thin film studies, where the deposition process used to form the samples may be very far from equilibrium.
This presentation will focus on an experimental approach to address the structure, chemistry and energy of (metal-ceramic) interfaces which are fully equilibrated, from which it can be demonstrated that formation of a distinct structural and chemical state at equilibrium minimizes interface energy. This will be compared with solid-liquid interfaces, where a region of ordered liquid exists adjacent to the interface at equilibrium, and the details of a reconstructed solid-solid interfaces where the reconstructed interface structure accommodates lattice mismatch for a nominally incoherent interface. These three systems will be compared to known reconstructed solid surfaces, which can also be described within a more generalized Gibbs adsorption isotherm. References Hadas Sternlicht, Wolfgang Rheinheimer, Michael J Hoffmann, Wayne D. Kaplan, The mechanism of grain boundary motion in SrTiO3, Journal of Materials Science, 51[1]:467-475, 2016. Galit Atiya, Dominique Chatain, Vissarion Mikhelashvili, Gadi Eisenstein, Wayne D. Kaplan, The role of abnormal grain growth on solid-state dewetting kinetics, Acta Materialia, 81[0]:304-314, 2014. Wayne D Kaplan, Dominique Chatain, Paul Wynblatt, W. Craig Carter, A review of wetting versus adsorption, complexions, and related phenomena: the rosetta stone of wetting, Journal of Materials Science, 48[17]:5681-5717, 2013. Maria Gandman, Yaron Kauffmann, Christoph T. Koch, Wayne D. Kaplan, Direct Quantification of Ordering at a Solid-Liquid Interface Using Aberration Corrected Transmission Electron Microscopy, Physical Review Letters, 110[8]:086106, 2013. Mor Baram, Dominique Chatain, Wayne D. Kaplan, Nanometer-Thick Equilibrium Films: The Interface Between Thermodynamics and Atomistics, Science, 332[6026]:206-209, 2011. Bio: Wayne D. Kaplan is the Executive Vice President for Research at the Technion, and is a full professor in the Department of Materials Science and Engineering at the Technion where he holds the Karl Stoll Chair in Advanced Materials. He completed his BSc in Mechanical Engineering, and his MSc and DSc in Materials at the Technion. He then spent a year as a Humboldt Fellow at the Max-Planck Institute in Stuttgart Germany before joining the Technion faculty in 1995. During the past 20 years Kaplan's research activities at the Technion have focused on the structure, chemistry and energy of interfaces between metals and ceramics, where combined microscopy and wetting experiments have led to a merged atomistic-continuum approach. This has recently focused on 2-D structural transitions at interfaces correlated with adsorption transitions, and their role in interface properties. In addition to his fundamental research, Kaplan works on the development of electron microscopy techniques for characterization at the sub-nanometer length-scale, which heavily relies on aberration corrected microscopy.
To date, almost all of these studies have been conducted at grain boundaries in single phase polycrystalline systems, which by definition are not at equilibrium, and in some cases it is not even clear if the identified complexions are at steady-state. Similar questions have been raised for studies focusing on metal-ceramic interfaces from thin film studies, where the deposition process used to form the samples may be very far from equilibrium.
This presentation will focus on an experimental approach to address the structure, chemistry and energy of (metal-ceramic) interfaces which are fully equilibrated, from which it can be demonstrated that formation of a distinct structural and chemical state at equilibrium minimizes interface energy. This will be compared with solid-liquid interfaces, where a region of ordered liquid exists adjacent to the interface at equilibrium, and the details of a reconstructed solid-solid interfaces where the reconstructed interface structure accommodates lattice mismatch for a nominally incoherent interface. These three systems will be compared to known reconstructed solid surfaces, which can also be described within a more generalized Gibbs adsorption isotherm. References Hadas Sternlicht, Wolfgang Rheinheimer, Michael J Hoffmann, Wayne D. Kaplan, The mechanism of grain boundary motion in SrTiO3, Journal of Materials Science, 51[1]:467-475, 2016. Galit Atiya, Dominique Chatain, Vissarion Mikhelashvili, Gadi Eisenstein, Wayne D. Kaplan, The role of abnormal grain growth on solid-state dewetting kinetics, Acta Materialia, 81[0]:304-314, 2014. Wayne D Kaplan, Dominique Chatain, Paul Wynblatt, W. Craig Carter, A review of wetting versus adsorption, complexions, and related phenomena: the rosetta stone of wetting, Journal of Materials Science, 48[17]:5681-5717, 2013. Maria Gandman, Yaron Kauffmann, Christoph T. Koch, Wayne D. Kaplan, Direct Quantification of Ordering at a Solid-Liquid Interface Using Aberration Corrected Transmission Electron Microscopy, Physical Review Letters, 110[8]:086106, 2013. Mor Baram, Dominique Chatain, Wayne D. Kaplan, Nanometer-Thick Equilibrium Films: The Interface Between Thermodynamics and Atomistics, Science, 332[6026]:206-209, 2011. Bio: Wayne D. Kaplan is the Executive Vice President for Research at the Technion, and is a full professor in the Department of Materials Science and Engineering at the Technion where he holds the Karl Stoll Chair in Advanced Materials. He completed his BSc in Mechanical Engineering, and his MSc and DSc in Materials at the Technion. He then spent a year as a Humboldt Fellow at the Max-Planck Institute in Stuttgart Germany before joining the Technion faculty in 1995. During the past 20 years Kaplan's research activities at the Technion have focused on the structure, chemistry and energy of interfaces between metals and ceramics, where combined microscopy and wetting experiments have led to a merged atomistic-continuum approach. This has recently focused on 2-D structural transitions at interfaces correlated with adsorption transitions, and their role in interface properties. In addition to his fundamental research, Kaplan works on the development of electron microscopy techniques for characterization at the sub-nanometer length-scale, which heavily relies on aberration corrected microscopy.
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Organizer
- Fabien Sorin and Michele Ceriotti
Contact
- Fabien Sorin and Michele Ceriotti