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Title: Macroscopic 3D Nanoporosity Formation by Dry Oxidation of AgAu Alloys

Authors:
ORCiD logo; ; ; ; ; ;  [1]; ;  [1];
  1. Nanoscale Synthesis and Characterization Laboratory, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Integrated Mesoscale Architectures for Sustainable Catalysis (IMASC)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1388601
DOE Contract Number:
SC0012573
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry. C; Journal Volume: 121; Journal Issue: 9; Related Information: IMASC partners with Harvard University (lead); Fritz Haber Institute; Lawrence Berkeley National Laboratory; Lawrence Livermore National Laboratory; University of Kansas; Tufts University
Country of Publication:
United States
Language:
English
Subject:
catalysis (heterogeneous), mesostructured materials, materials and chemistry by design, synthesis (novel materials)

Citation Formats

Barroo, Cédric, Montemore, Matthew M., Janvelyan, Nare, Zugic, Branko, Akey, Austin J., Magyar, Andrew P., Ye, Jianchao, Kaxiras, Efthimios, Biener, Juergen, and Bell, David C. Macroscopic 3D Nanoporosity Formation by Dry Oxidation of AgAu Alloys. United States: N. p., 2017. Web. doi:10.1021/acs.jpcc.6b12847.
Barroo, Cédric, Montemore, Matthew M., Janvelyan, Nare, Zugic, Branko, Akey, Austin J., Magyar, Andrew P., Ye, Jianchao, Kaxiras, Efthimios, Biener, Juergen, & Bell, David C. Macroscopic 3D Nanoporosity Formation by Dry Oxidation of AgAu Alloys. United States. doi:10.1021/acs.jpcc.6b12847.
Barroo, Cédric, Montemore, Matthew M., Janvelyan, Nare, Zugic, Branko, Akey, Austin J., Magyar, Andrew P., Ye, Jianchao, Kaxiras, Efthimios, Biener, Juergen, and Bell, David C. Fri . "Macroscopic 3D Nanoporosity Formation by Dry Oxidation of AgAu Alloys". United States. doi:10.1021/acs.jpcc.6b12847.
@article{osti_1388601,
title = {Macroscopic 3D Nanoporosity Formation by Dry Oxidation of AgAu Alloys},
author = {Barroo, Cédric and Montemore, Matthew M. and Janvelyan, Nare and Zugic, Branko and Akey, Austin J. and Magyar, Andrew P. and Ye, Jianchao and Kaxiras, Efthimios and Biener, Juergen and Bell, David C.},
abstractNote = {},
doi = {10.1021/acs.jpcc.6b12847},
journal = {Journal of Physical Chemistry. C},
number = 9,
volume = 121,
place = {United States},
year = {Fri Feb 24 00:00:00 EST 2017},
month = {Fri Feb 24 00:00:00 EST 2017}
}
  • The bcc-based Heusler alloys exhibit a series of order-disorder phase transitions as a function of temperature. The high-temperature phase is a disordered bcc solid solution, and the low-temperature phase is the Heusler structure. An intermediate ordered phase is also typically observed in real systems. A prototype cluster variation method (CVM) analysis is presented that shows that the relative stabilities of the Heusler and intermediate phases can vary continuously, depending on a fine balance between ordering tendencies in the constituent binary systems. Given these basic conclusions, a first-principles analysis of order-disorder transitions in Cd{sub 2}AgAu was performed. A cluster expansion Hamiltonianmore » was constructed based on a series of linearized muffin-tin orbital calculations in the atomic sphere approximation. CVM calculations were then performed in the ternary bcc tetrahedron approximation. In addition to the transition temperatures, long-range order parameters, and sublattice occupations for Cd{sub 2}AgAu, an isoplethal section of the ternary phase diagram was also calculated. In general, agreement with experiment is excellent, given the first-principles nature of the calculation. This study clearly demonstrates the ability of first-principles statistical-mechanical calculations to treat complex ordering phenomena in {ital ternary} systems. {copyright} {ital 1996 The American Physical Society.}« less
  • No abstract.<>15:021103No abstract.
  • The effects of microalloying on glass formation and stability were systematically investigated by substituting 0.5 at.% of all 3d transition metals for Al in Al{sub 88}Y{sub 7}Fe{sub 5} alloys. X-ray diffraction and isothermal differential scanning calorimetry studies indicate that samples containing microadditions of Ti, V, Cr, Mn, Fe and Co were amorphous, while those alloyed with Ni and Cu were not. The onset temperatures for crystallization (devitrification) of the amorphous alloys were increased with microalloying and some showed a supercooled liquid region ({Delta}T{sub x} = T{sub x} - T{sub g}) of up to 40 C. In addition, microalloying changes themore » glass structure and the devitrification sequence, as determined by differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), differential thermal analysis (DTA) and high energy X-ray diffraction. The results presented here suggest that the order induced in the alloy by the transition metal microaddition decreases the atomic mobility in the glass and raises the barrier for the nucleation of {alpha}-Al, the primary devitrifying phase in most cases. New intermetallic phases also appear with microalloying and vary for different transition metal additions.« less
  • We have studied the dislocation structures that occur in films of Ag, Au, and Ag{sub 0.5}Au{sub 0.5} alloy on a Ru(0001) substrate. Monolayer (ML) films form herringbone phases while films two or more layers thick contain triangular patterns of dislocations. We use scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED) to determine how the film composition affects the structure and periodicity of these ordered structures. One layer of Ag forms two different herringbone phases depending on the exact Ag coverage and temperature. Low-energy electron microscopy (LEEM) establishes that a reversible, first-order phase transition occurs between these two phases atmore » a certain temperature. We critically compare our 1 ML Ag structures to conflicting results from an X-ray scattering study [H. Zajonz et al., Phys. Rev. B 67 (2003) 155417]. Unlike Ag, the herringbone phases of Au and AgAu alloy are independent of the exact film coverage. For two layer films in all three systems, none of the dislocations in the triangular networks thread into the second film layer. In all three systems, the in-plane atomic spacing of the second film layer is nearly the same as in the bulk. Film composition does, however, affect the details of the two layer structures. Ag and Au films form interconnected networks of dislocations, which we refer to as 'trigons.' In 2 ML AgAu alloy, the dislocations form a different triangular network that shares features of both trigon and moire structures. Yet another well-ordered structure, with square symmetry, forms at the boundaries of translational trigon domains in 2 ML Ag films but not in Au films.« less