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SUMMARY:Interfacial States and Thermodynamic Transitions at Interfaces
DTSTART:20161114T131500
DTEND:20161114T141500
DTSTAMP:20260610T042428Z
UID:f81673c96e708cc2053accbabc7ab8ca62ac3436d9846375a9a10850
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Wayne D. Kaplan\, Department of Materials Science and En
 gineering Technion – Israel Institute of Technology\nSince the 1980s it 
 has been recognized that the structure of grain boundaries in polycrystall
 ine ceramics can have a diffuse nature\, characterized by a ~1nm thick nom
 inally 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 (somet
 imes termed complexions).  As an example\, surface reconstruction is a fi
 rst order complexion transition\, equivalent to a discontinuous change in 
 the level of adsorbed excess.  As such complexions for interfaces are ana
 logous to phases in bulk\, although they are not bulk phases.  In the pas
 t these conclusions had been reached based on structural characterization 
 of grain boundaries and interfaces correlated with mechanical and electric
 al properties\, and more recently it has been shown that specific complexi
 ons can have a significant influence on grain boundary mobility\, and thus
  the morphology of an evolving microstructure.\nTo date\, almost all of th
 ese studies have been conducted at grain boundaries in single phase polycr
 ystalline systems\, which by definition are not at equilibrium\, and in so
 me 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 u
 sed to form the samples may be very far from equilibrium.\nThis presentati
 on will focus on an experimental approach to address the structure\, chemi
 stry and energy of (metal-ceramic) interfaces which are fully equilibrated
 \, from which it can be demonstrated that formation of a distinct structur
 al and chemical state at equilibrium minimizes interface energy.  This wi
 ll be compared with solid-liquid interfaces\, where a region of ordered li
 quid exists adjacent to the interface at equilibrium\, and the details of 
 a reconstructed solid-solid interfaces where the reconstructed interface s
 tructure accommodates lattice mismatch for a nominally incoherent interfac
 e.  These three systems will be compared to known reconstructed solid sur
 faces\, which can also be described within a more generalized Gibbs adsorp
 tion isotherm. References Hadas Sternlicht\, Wolfgang Rheinheimer\, Michae
 l 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 kine
 tics\, Acta Materialia\, 81[0]:304-314\, 2014. Wayne D Kaplan\, Dominique 
 Chatain\, Paul Wynblatt\, W. Craig Carter\, A review of wetting versus ads
 orption\, complexions\, and related phenomena: the rosetta stone of wettin
 g\, Journal of Materials Science\, 48[17]:5681-5717\, 2013. Maria Gandman\
 , Yaron Kauffmann\, Christoph T. Koch\, Wayne D. Kaplan\, Direct Quantific
 ation of Ordering at a Solid-Liquid Interface Using Aberration Corrected T
 ransmission 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\, S
 cience\, 332[6026]:206-209\, 2011.   Bio: Wayne D. Kaplan is the Executiv
 e 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 B
 Sc in Mechanical Engineering\, and his MSc and DSc in Materials at the Tec
 hnion.  He then spent a year as a Humboldt Fellow at the Max-Planck Insti
 tute in Stuttgart Germany before joining the Technion faculty in 1995. Dur
 ing the past 20 years Kaplan's research activities at the Technion have fo
 cused 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 transi
 tions\, and their role in interface properties.  In addition to his funda
 mental research\, Kaplan works on the development of electron microscopy t
 echniques for characterization at the sub-nanometer length-scale\, which h
 eavily relies on aberration corrected microscopy.    
LOCATION:MXF 1 https://plan.epfl.ch/?room==MXF%201
STATUS:CONFIRMED
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