1 / 16

The Surface Structure of Liquid Metals and Alloys

The Surface Structure of Liquid Metals and Alloys. * Current associates are underlined. Non-Harvard Collaborators: Ben Ocko , Elaine DiMasi, Olaf Magnussen Physics Dept. Brookhaven National Laboratory Moshe Deutsch : Bar Ilan University, Israel

dena
Télécharger la présentation

The Surface Structure of Liquid Metals and Alloys

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Surface Structure of Liquid Metals and Alloys * Current associates are underlined Non-Harvard Collaborators: Ben Ocko, Elaine DiMasi, Olaf Magnussen Physics Dept. Brookhaven National Laboratory Moshe Deutsch:Bar Ilan University, Israel Binhua Lin, Mati Meron, Tim Graber, Jeff Gerbhardt, Advanced Photon Source Harvard Students/Postdocs Alexei Grigoriev,Patrick Huber, E.H. Kawamoto, Holger Tostmann, Mike Regan,Oleg Shpyrko. Oleg Shpyrko Support: DE-FG02-88-ER45379/NSF- DMR-0124936

  2. Metallic Liquids Dielectric Liquids Vapor: Neutral Atoms Interactions are Same in Vapor and Liquid Different Interactions Liquid: Positive Ions in Sea of Negative Fermi Liquid Liquid Surfaces: Metals/Non-Metals Are Different D'Evelyn & . Rice, J. Chem. Phys., 1983. 78: p. 5225. For Metals Particle-Particle InteractionsChange Across The Surface This influences the structure of the surface!

  3. Metallic Liquids: Layers @Free Surface Chapela & Saville, 1978 D'Evelyn & Rice, 1983 Hard Wall = > Layers Free Surface No-Layer Predictions of Monte Carlo Calculations Average Density <r(z)> vs Distance From Surface(z) Non-Metal Liquids Liquid/Vapor Surface Structure Factor F(Qz)

  4. Qz Surface Normal Wave vector Transfer Measured Hg (1995) Ga (1996) In (1999) Surface Structure Factor Hg R(Qz)~|F(Qz)|2 Prediction: Constructive Interference Qz=(4p/l)sin a =(2p/D) Ga In Note Difference X-ray Reflectivity: R(Qz) & F(Qz) Quantitative Measure of F(Qz)!

  5. Ideal Flat Surface: Fresnel RF(Qz) Structure Factor F(Qz) Thermal Factor R(Qz) = Thermal Roughness Phase Shifts Differential Cross Section: Parallel Surface Wave Vector Transfer Qx Thermal Effects on Reflectivity

  6. Liquid Solid Liquid Surface •2D SurfaceTension •Gravity(|x-x’|~mm) Resolution Independent of Resolution Depends on Resolution Liquid vs Solid Surfaces

  7. Ideal Flat Surface: Fresnel RF(Qz) R(Qz) Structure Factor F(Qz) Thermal Factor Q(Qz,T) R(Qz) = g : Surface Tension Measure of Structure Factor Requires Thermal Effects be Removed Large (T/g)Qz2 ••• No specular peak if h~2!•••

  8. Diffuse Scattering for Liquid Indium Solid Lines: Theory Known Surface Tension g is OnlyAdjustable Parameter To Understand Thermal EffectsDiffuse Scattering From Liquid Surface Qx=(2p/l)[cos a-cos b] Qz=(2p/l)[sin a+sin b]

  9. Electron Density Profile Average Electron Density Indium (with/without T effects). Electron Density: Ga and In Demonstration of Thermal Removed:Liquid Gallium

  10. Issue 1 What other metals can be studied? h (i.e. T/g) must be small P & T : low enough for UHV(Hg, K, Na are special) ElementTm (K)Tm/gP_melt(mm) Ga302.937180.42 Hg234.284980.471.2E-06 Sn505.1185600.90 In429.325560.77 K336.83880.87~1.0E-6 Zn692.737820.892.2E-01 Al933.529141.02 Cu1356.613031.049.7E-04 Cd594.15701.041.1E-01 Bi544.53781.44 Li (Chemistry)453.693981.14 Au1337.5811691.141.6E-05 Tl576.74641.24 Pb600.644581.31

  11. Ga In Debye-Waller X 10-2 K h Maximum Qz~0.85QPeak Measurement of Potassium Good: Oxides Dissolve in Bulk LiquidClean Surface Bad: Low g  h at layering peak is large, R(Qz) too small Data  Layering in K is same as Ga, In.

  12. Bump Not seen in Ga,In R(Qz) Possible Model Spacing of 1st Layer Reduced~10% Anomalous Layering of Liquid Sn Surface Bump  Surface Density Is Higher Than Bulk!

  13. R(Qz)/RF(Qz) R(Qz) Ga K H2O Is there experimental evidence that dielectric liquids are not layered? Water: g=73 dynes/cm K: g100 dynes/cm Water does not show indication of surface layering!

  14. GaBi: Binary Phase Diagram Thickness of heavier Bi rich layer. Bi Ga If we can’t study other pure metals, what can we do? •Alloys•Surface Chemistry of Liquid Metals (oxidation) Surface: Heavier Bi rich liquid Bulk: lighter Ga rich liquid! Short Range Wetting

  15. Low Temperature Eutectic AuSi Diffuse ScatteringAlloy is Liquid g=780 dynes/cm Keep Looking: i.e. Alloys for ElectronicsExample: AuSi

  16. Summary 1- To Measure Liquid Surface Structure Factor |F(Qz)|Effects of Capillary Waves. 2- |F(Qz)| of Free Surface of Liquid Metals Exhibits Atomic Layering! 3- Water does Not! What about other non-metallic liquids. 4- Surfaces of Liquid Alloys: Interesting Physics Sn: Anomalous Surface GaBi: Short Range Wetting AuSi: Enormously Intense Future

More Related