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Evolution of Nanoporous Surface Layers on Gas-Atomized Ti₆₀Cu₃₉Au? Powders during Dealloying.

ABSTRACT: Nanoporous golf ball-shaped powders with a surface porous layer consisting of fcc Cu and Cu?Au phases have been fabricated by selectively dissolving gas-atomized Ti₆₀Cu₃₉Au? powders in 0.13 M HF solution. The distribution profiles of the Ti?Cu and TiCu intermetallic phases and powder size play an important role of the propagation of the selective corrosion frontiers. The final nanoporous structure has a bimodal characteristic with a finer nanoporous structure at the ridges, and rougher structure at the shallow pits. The powders with a size of 18?75 m dealloy faster due to their high crystallinity and larger powder size, and these with a powder size of smaller than 18 m tend to deepen uniformly. The formation of the Cu?Au intermetallic phases and the finer nanoporous structure at the ridges proves that minor Au addition inhibits the fast diffusion of Cu adatoms and decreases surface diffusion by more than two orders. The evolution of the surface nanoporous structure with negative tree-like structures is considered to be controlled by a percolation dissolution mechanism.

SUBMITTER: Dan Z

PROVIDER: S-EPMC6116246 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature

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Evolution of Nanoporous Surface Layers on Gas-Atomized Ti60Cu39Au₁ Powders during Dealloying.

Dan Zhenhua Z Qu Jiahui J Yang Yulin Y Qin Fengxiang F Chang Hui H

Nanomaterials (Basel, Switzerland) 20180730 8

Nanoporous golf ball-shaped powders with a surface porous layer consisting of fcc Cu and Cu₃Au phases have been fabricated by selectively dissolving gas-atomized Ti60Cu39Au₁ powders in 0.13 M HF solution. The distribution profiles of the Ti₂Cu and TiCu intermetallic phases and powder size play an important role of the propagation of the selective corrosion frontiers. The final nanoporous structure has a bimodal characteristic with a finer nanoporous structure at the ridges, ...[more]

PMID: 30061477

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Project description:Anatase TiO2 nanoparticle aggregates were used as model systems for studying at different water activities the reactivity of electron centers at semiconductor surfaces. The investigated surface conditions evolve from a solid/vacuum interface to a solid/bulk electrolyte interface. Hydrogen-related electron centers were generated either chemically-upon sample exposure to atomic hydrogen at the semiconductor/gas interface-or electrochemically-upon bias-induced charge accumulation at the semiconductor/electrolyte interface. Based on their corresponding spectroscopic and electrochemical fingerprints, we investigated the reactivity of hydrogen-related electron centers as a function of the interfacial condition and at different levels of complexity, that is, (i) for dehydrated and (partially) dehydroxylated oxide surfaces, (ii) for oxide surfaces covered by a thin film of interfacial water, and (iii) for oxide surfaces in contact with a 0.1 M HClO4 aqueous solution. Visible (Vis) and infrared (IR) spectroscopy evidence a chemical equilibrium between hydrogen atoms in the gas phase and-following their dissociation-electron/proton centers in the oxide. The excess electrons are either localized forming (Vis-active) Ti3+ centers or delocalized as (IR-active) free conduction band electrons. The addition of molecular oxygen to chemically reduced anatase TiO2 nanoparticle aggregates leads to a quantitative quenching of Ti3+ centers, while a fraction of ∼10% of hydrogen-derived conduction band electrons remains in the oxide pointing to a persistent hydrogen doping of the semiconductor. Neither trapped electrons (i.e., Ti3+ centers) nor conduction band electrons react with water or its adsorption products at the oxide surface. However, the presence of an interfacial water layer does not impede the electron transfer to molecular oxygen. At the semiconductor/electrolyte interface, inactivity of trapped electrons with regard to water reduction and electron transfer to oxygen were evidenced by cyclic voltammetry.

Dataset Information

Evolution of Nanoporous Surface Layers on Gas-Atomized Ti₆₀Cu₃₉Au? Powders during Dealloying.

Publications

Evolution of Nanoporous Surface Layers on Gas-Atomized Ti<sub>60</sub>Cu<sub>39</sub>Au₁ Powders during Dealloying.

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Dataset Information

Evolution of Nanoporous Surface Layers on Gas-Atomized Ti60Cu39Au? Powders during Dealloying.

Publications

Evolution of Nanoporous Surface Layers on Gas-Atomized Ti<sub>60</sub>Cu<sub>39</sub>Au₁ Powders during Dealloying.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Evolution of Nanoporous Surface Layers on Gas-Atomized Ti₆₀Cu₃₉Au? Powders during Dealloying.