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Title: Liquid gallium and the eutectic gallium indium (EGaIn) alloy: Dielectric functions from 1.24 to 3.1 eV by electrochemical reduction of surface oxides

Abstract

Liquid metals based on gallium are promising materials for soft, stretchable, and shape reconfigurable electromagnetic devices. The behavior of these metals relates directly to the thicknesses of their surface oxide layers, which can be determined nondestructively by ellipsometry if their dielectric functions ε are known. This paper reports on the dielectric functions of liquid gallium and the eutectic gallium indium (EGaIn) alloy from 1.24 to 3.1 eV at room temperature, measured by spectroscopic ellipsometry. Overlayer-induced artifacts, a continuing problem in optical measurements of these highly reactive metals, are eliminated by applying an electrochemically reductive potential to the surface of the metal immersed in an electrolyte. This technique enables measurements at ambient conditions while avoiding the complications associated with removing overlayers in a vacuum environment. The dielectric responses of both metals are closely represented by the Drude model. The EGaIn data suggest that in the absence of an oxide the surface is In-enriched, consistent with the previous vacuum-based studies. Possible reasons for discrepancies with previous measurements are discussed.

Authors:
; ;  [1]; ;  [2]
  1. Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695-7905 (United States)
  2. Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202 (United States)
Publication Date:
OSTI Identifier:
22590496
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 109; Journal Issue: 9; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ALLOYS; DIELECTRIC MATERIALS; ELECTROCHEMISTRY; ELECTROLYTES; ELLIPSOMETRY; EUTECTICS; GALLIUM; INDIUM; LAYERS; LIQUID METALS; OXIDES; SURFACES; THICKNESS

Citation Formats

Morales, Daniel, Yu, Zhiyuan, Dickey, Michael D., E-mail: mddickey@ncsu.edu, E-mail: aspnes@ncsu.edu, Stoute, Nicholas A., and Aspnes, David E., E-mail: mddickey@ncsu.edu, E-mail: aspnes@ncsu.edu. Liquid gallium and the eutectic gallium indium (EGaIn) alloy: Dielectric functions from 1.24 to 3.1 eV by electrochemical reduction of surface oxides. United States: N. p., 2016. Web. doi:10.1063/1.4961910.
Morales, Daniel, Yu, Zhiyuan, Dickey, Michael D., E-mail: mddickey@ncsu.edu, E-mail: aspnes@ncsu.edu, Stoute, Nicholas A., & Aspnes, David E., E-mail: mddickey@ncsu.edu, E-mail: aspnes@ncsu.edu. Liquid gallium and the eutectic gallium indium (EGaIn) alloy: Dielectric functions from 1.24 to 3.1 eV by electrochemical reduction of surface oxides. United States. doi:10.1063/1.4961910.
Morales, Daniel, Yu, Zhiyuan, Dickey, Michael D., E-mail: mddickey@ncsu.edu, E-mail: aspnes@ncsu.edu, Stoute, Nicholas A., and Aspnes, David E., E-mail: mddickey@ncsu.edu, E-mail: aspnes@ncsu.edu. 2016. "Liquid gallium and the eutectic gallium indium (EGaIn) alloy: Dielectric functions from 1.24 to 3.1 eV by electrochemical reduction of surface oxides". United States. doi:10.1063/1.4961910.
@article{osti_22590496,
title = {Liquid gallium and the eutectic gallium indium (EGaIn) alloy: Dielectric functions from 1.24 to 3.1 eV by electrochemical reduction of surface oxides},
author = {Morales, Daniel and Yu, Zhiyuan and Dickey, Michael D., E-mail: mddickey@ncsu.edu, E-mail: aspnes@ncsu.edu and Stoute, Nicholas A. and Aspnes, David E., E-mail: mddickey@ncsu.edu, E-mail: aspnes@ncsu.edu},
abstractNote = {Liquid metals based on gallium are promising materials for soft, stretchable, and shape reconfigurable electromagnetic devices. The behavior of these metals relates directly to the thicknesses of their surface oxide layers, which can be determined nondestructively by ellipsometry if their dielectric functions ε are known. This paper reports on the dielectric functions of liquid gallium and the eutectic gallium indium (EGaIn) alloy from 1.24 to 3.1 eV at room temperature, measured by spectroscopic ellipsometry. Overlayer-induced artifacts, a continuing problem in optical measurements of these highly reactive metals, are eliminated by applying an electrochemically reductive potential to the surface of the metal immersed in an electrolyte. This technique enables measurements at ambient conditions while avoiding the complications associated with removing overlayers in a vacuum environment. The dielectric responses of both metals are closely represented by the Drude model. The EGaIn data suggest that in the absence of an oxide the surface is In-enriched, consistent with the previous vacuum-based studies. Possible reasons for discrepancies with previous measurements are discussed.},
doi = {10.1063/1.4961910},
journal = {Applied Physics Letters},
number = 9,
volume = 109,
place = {United States},
year = 2016,
month = 8
}
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