Liquid–Gas Interfacial Chemistry of Gallium–Indium Eutectic in the Presence of Oxygen and Water Vapor

Abstract

Gallium−indium eutectic (eGaIn) is a liquid metal being explored in a number of applications because of its high thermal/electrical conductivity and favorable deformability. A key function regulating the mechanical properties of eGaIn is the ability to rapidly form a passivating oxide layer, which is known to occur upon exposure to air under ambient conditions. Nevertheless, little is known about the molecular level surface reactivity of eGaIn toward oxygen and water vapor under in situ conditions. Herein we present ambient pressure X-ray photoelectron spectroscopy results examining the liquid− gas interface of eGaIn in the presence of oxygen and water vapor. By examining each gas independently, results reveal that both oxygen and water vapor react with Ga in eGaIn to form the same oxidized products: Ga 3+ oxide (Ga 2 O 3 ) as an outer layer and Ga 1+ oxide (Ga 2 O) as an interlayer. Despite similar product formation, stark differences are observed in pressure-dependence and adsorbate-induced binding energy shifts. The results herein suggest both oxygen and water vapor uniquely contribute to the oxidative passivation of eGaIn under ambient conditions.

Bipolar Resistive Switching in Junctions of Gallium Oxide and p-type Silicon

“…When compared to pure gallium, the presence of indium (24.5 wt %) in EGaIn or indium (21.5 wt %) and tin (10 wt %) in galinstan does not change the switching behavior in these devices, as shown in Figure S1. The thickness of the native oxide formed conformally on the surface of liquid gallium ,,,,− or EGaIn − has previously been shown to range between 1–3 nm, with GaO x comprising the majority species . Based upon ellipsometry, the thickness of the native SiO 2 formed on the surface of piranha-cleaned p + -Si was determined to be 2.5 ± 0.5 nm.…”

“…The thickness of the native oxide formed conformally on the surface of liquid gallium 3,6,7,14,82−84 or EGaIn 85−88 has previously been shown to range between 1−3 nm, with GaO x comprising the majority species. 89 Based upon ellipsometry, the thickness of the native SiO 2 formed on the surface of piranha-cleaned p + -Si was determined to be 2.5 ± 0.5 nm.…”

Interfacial Engineering of Room Temperature Liquid Metals

“…The oxidation process of liquid metal surfaces in the presence of water vapor has been explored. [ 51 ] Eutectic GaIn alloy (EGaIn) droplets are respectively treated with an oxygen atmosphere and water vapor (550K) atmosphere, and then obtained the same results that the outer layer was Ga 2 O 3 and the inner layer was Ga 2 O (Figure 2B). Although formational products were similar, significant differences were observed in pressure dependence and adsorption‐induced binding energy transfer.…”

“…Reproduced with permission. [ 51 ] Copyright 2019, American Chemical Society. C) The Schematic process of the PPC‐assisted deterministic transfer technique for TMDCs/Ga 2 O 3 .…”

Sequential Oxidation Strategy for the Fabrication of Liquid Metal Electrothermal Thin Film with Desired Printing and Functional Property

“…Oxidation offers a cost-effective avenue for the improvement of the interfacial adhesion and chemical activity of liquid metal [17][18][19]. The wettability of the liquid metal on the diverse substrates can be effectively altered by adjusting the thickness and constituent of the oxide layer, and the thickness of the layer will also significantly change the conductive properties of the liquid metal [17][18][19][20][21][22]. However, the current attractive attentions are in the self-limiting and chemical properties of the natural oxide layer on the surface of liquid metal, and there are few reports on the adhesion properties after sufficient oxidation [23,24].…”