DPG Tagung, O27, Phasenübergänge, Berlin 2005 Surface freezing and surface phase transition studied at the liquid eutectic AuSi surface 1. Surface layering.

Slides:

Advertisements

Similar presentations

Phase Diagrams Continued

Advertisements

The Structures of Magmas No Phase Diagrams!. The Structures of Magmas Melt structure controls: The physical properties of magmas The chemical behaviour.

X-ray Scattering: Liquid Metal/Vapor Interfaces P.S. Pershan SEAS & Dept of Physics, Harvard Univ., Cambridge, MA, US X-ray Liquid Surface: Experimental.

9th Int. Conf on Surf. X-ray and Neutron Scan (Taiwan, Jul.’06). 1 Surface Structure and Chemical Composition of Liquid Metal Alloys P. S. Pershan HSEAS.

Wetting of Liquid Crystal Surfaces and Induced Smectic Layering at the Nematic-Liquid Interface* Masafumi Fukuto, 1 Oleg Gang, 2 Kyle J. Alvine, 3 Benjamin.

The Structure Liquid Surfaces P. S. Pershan DEAS & Dept. Of Physics, Harvard Univ. Cambridge, MA DMR ; NSF ; DE-FG02-88-ER45379 O.

X-ray Scattering: Liquid Metal/Vapor Interfaces P.S. Pershan SEAS & Dept of Physics, Harvard Univ., Cambridge, MA, US I: Liquid Metal/Vapor Interfaces.

Formation of 2D crystalline surface phases on liquid Au-based metallic glass forming alloys S. Mechler, P. S. Pershan, S. E. Stoltz, S. Sellner Department.

System and experimental setup Studied a wetting film of binary mixture MC/PFMC on Si(100), in equilibrium with the binary vapor and bulk liquid mixture.

Liquid Metal Surfaces P. S. Pershan SEAS & Dept of Physics, Harvard Univ., Cambridge, MA, USA Colleagues Pershan/CARS Balagurusamy, V. S. K. Berman, E.

The Structure Liquid Surfaces P. S. Pershan DEAS & Dept. Of Physics, Harvard Univ. Cambridge, MA DMR ; NSF ; DE-FG02-88-ER45379 O.

Non-Harvard Collaborators: Ben Ocko, Elaine DiMasi, Olaf Magnussen Physics Dept. Brookhaven National Laboratory Moshe Deutsch: Bar Ilan University, Israel.

Liquid Metal Surfaces P. S. Pershan SEAS & Dept of Physics, Harvard Univ., Cambridge, MA, USA Colleagues Pershan/ESRF Balagurusamy, V. S. K. Berman, E.

Introduction to Materials Science, Chapter 9, Phase Diagrams University of Virginia, Dept. of Materials Science and Engineering 1 Development of microstructure.

EXPERIMENT # 9 Instructor: M.Yaqub

Phase Equilibria (CH-203)

Introduction The properties and behavior of metals (and alloys) depend on their: Structure Processing history and Composition Engr 241.

Quantum Electronic Effects on Growth and Structure of Thin Films P. Czoschke, Hawoong Hong, L. Basile, C.-M. Wei, M. Y. Chou, M. Holt, Z. Wu, H. Chen and.

Why bother ? How to bother ? Was it worth bothering ? Should we keep bothering ? OUTLINE ( motivation & history ) ( experimental) ( some of the results)

Introduction to Materials Science, Chapter 9, Phase Diagrams University of Virginia, Dept. of Materials Science and Engineering 1 Growth of Solid Equilibrium.

Tetra Point Wetting at the Free Surface of a Binary Liquid Metal Patrick Huber, Oleg Shpyrko, Peter Pershan, Holger Tostmann*, Elaine DiMasi**, Ben Ocko**,

The Atomic Pair Distribution Function Method Getting to know your atomic neighborhood.

Úvod do tímového projektu Peter Ballo Katedra fyziky Fakulta elektrotechniky a informatiky.

1 1 Figure 10.1 Considerations for effective dispersion strengthening: (a) The precipitate phase should be hard and discontinuous. (c)2003 Brooks/Cole,

1 SHIMIZU Group ONODA Suzue Metallization and molecular dissociation of SnI 4 under pressure Ref: A.L. Chen, P.Y. Yu, M.P. Pasternak, Phys. Rev. B. 44,

X-ray Standing Wave Fluorescence for the Analysis of Bacterial Biofilms X-ray Standing Wave Fluorescence for the Analysis of Bacterial Biofilms C. A. Crot,¹.

Peak effect in Superconductors - Experimental aspects G. Ravikumar Technical Physics & Prototype Engineering Division, Bhabha Atomic Research Centre, Mumbai.

Thermodynamic data A tutorial course Session 6: Modelling Surface Tension Alan Dinsdale “Thermochemistry of Materials” SRC.

Thursday, October 24, 2014 In your journal, write today’s date. Then write the following notes. Physical Properties of Matter Characteristics observed.

Characteristic Physical Properties. Characteristic physical properties are properties that are unique to a substance and can be used to identify it. For.

EBB 512 – Phase Diagram and Equilibria Lecture 1.

PHASE CHANGES Each state of matter is called a PHASE

Steam Engine Sliding valve Steam enters chamber from

Chapter 5 Phase Equilibria

Unit Test and NB due Thursday

© 2016 Cengage Learning Engineering. All Rights Reserved.

Wrinkles/Folds and the Role of Interfacial Thermodynamics

5.3 Properties of Matter Our goals for learning

Structural Quantum Size Effects in Pb/Si(111)

Matter Vocabulary Week 1

5.3 Properties and Phases of Matter

Chemical and Physical Changes

Chapter 2 Matter and Change 2.1 Properties of Matter 2.2 Mixtures

Physical Properties Properties of Matter.

Chapter 4 Revision.

Phase Separation of Water/Glycerol Binary Mixtures

Sit quietly and begin your warm up. No writing on the lab tables

Matter Vocabulary Week 1

Solidification of Metals and Alloys

Physical Properties Properties of Matter.

Why does an ice cube melt in the mouth?

Understanding the Growth Mechanisms

Eutectic Type Phase Diagrams

The States of Matter.

Chapter 13 Phase Changes Notes #8b.

Boiling is a liquid-to-vapor phase change process just like evaporation, but there are significant differences between the two. Evaporation occurs at.

The Phase Rule.

T l s Full solubility liquid Phase diagram solid g(n) Gibbs Energy

Mechanical Properties of Isomorphous Alloys

Presentation transcript:

DPG Tagung, O27, Phasenübergänge, Berlin 2005 Surface freezing and surface phase transition studied at the liquid eutectic AuSi surface 1. Surface layering at liquid/vapor interface of metals/alloys 2. Surface freezing of AuSi above bulk melting temperature 3. Solid-solid surface phase transition Reinhard Streitel, Oleg Shpyrko, Alexei Grigoriev Supervisor: Prof. P. Pershan, DEAS, Harvard University

Surface-Induced Layering Disordered Interface (classical Van-der-Waals description 1873) Ordered Interface Surface-Induced Layering (perdicted 1984, S. A. Rice) Liquid-vapor interface

Layering observed in liquid metals and alloys Experimental measurements (NSLS & APS): Simple Liquids (Pershan Group, ) Gallium, Mercury, Indium, Potassium, Tin Binary Liquids (Pershan, Rice, Freyland groups; ) GaIn, BiIn, GaPb, BiPb, HgAu, GaBi, KNa, AuGe, BiSn, AuSi Scattering geometry layering peak: (a atomic radii) a ~ 1.0–1.5Å q z peak =  /a q z peak ~ Å -1

Reflectivity of eutectic AuSi (1) Eutectic composition Au 0.81 Si 0.19 (atomic %) T M (bulk) = °C Phase diagram different T =371°C (about 10 °C above T M (bulk) !) change in reflectivity for high q z T M (Au)=1063°C T M (Si)=1410°C Transition at T M + 10 °C

Surface-Normal (Layering) Structure Normalized X-ray Reflectivity R/R F Electron Density Profile Electron Density z, Angstroms - Reflectivity and structure related through Fourier Transform - Width / Height of quasi-Bragg peak determined by layering decay length

Reflectivity of eutectic AuSi (2)

Surface Phase Transition at 371 o C First-Order Transition Reversible in Temperature

In-Plane Structure: X-GID Surface freezing and surface phase transition

Surface freezing - Surface freezes above bulk melting point (!): 2D solid surface layer coexists with liquid bulk phase - Surface freezing in other systems e.g. dilute Pb on liquid Ga (S. A. Rice) BUT surface and bulk chemically different S.A. Rice et al., Phys. Rev. B 62, (2000) liquid Ga Pb

Structure model: low temperature phase AuSi C 9.4 C 12 atoms 4 Au, 8 Si Au Si

Summary surface layering observed in liquid metals and alloys liquid AuSi eutectic shows temperature dependence in reflectivity for high q z a reversible solid-solid phase transition occurs at about 10 °C above bulk melting temperature 2D AuSi 2 structure describes high temperature phase GID peaks future: reflectivity at even higher temperature understanding details of structural changes

Acknowledgments For more info visit Harvard: Prof. Peter Pershan Oleg Shpyrko Alexei Grigoriev CARS, U. Chicago: Jim Viccaro, Binhua Lin Tim Graber, Mati Meron Jeff Gebhardt Ben Ocko Prof. Mosche Deutsch Research was supported by US DOE grant (DE-FG02-88-ER45379). The work was performed in ChemMatCARS sector of Advanced Photon Source, Argonne National Lab. ChemMatCARS at the APS is supported by NSF/ DOE grant number CHE Bar-Ilan, Israel: Brookhaven: