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Title: Creating Binary Cu–Bi Compounds via High-Pressure Synthesis: A Combined Experimental and Theoretical Study

Abstract

Exploration beyond the known phase space of thermodynamically stable compounds into the realm of metastable materials is a frontier of materials chemistry. The application of high pressure in experiment and theory provides a powerful vector by which to explore this uncharted phase space, allowing discovery of complex new structures and bonding in the solid state. We harnessed this approach for the Cu–Bi system, where the realization of new phases offers potential for exotic properties such as superconductivity. This potential is due to the presence of bismuth, which, by virtue of its status as one of the heaviest stable elements, forms a critical component in emergent materials such as superconductors and topological insulators. To fully investigate and understand the Cu–Bi system, we welded theoretical predictions with experiment to probe the Cu–Bi system under high pressures. By employing the powerful approach of in situ X-ray diffraction in a laser-heated diamond anvil cell (LHDAC), we thoroughly explored the high-pressure and high-temperature (high-PT) phase space to gain insight into the formation of intermetallic compounds at these conditions. We employed density functional theory (DFT) calculations to calculate a pressure versus temperature phase diagram, which correctly predicts that CuBi is stabilized at lower pressures than Cu11Bi7,more » and allows us to uncover the thermodynamic contributions responsible for the stability of each phase. Detailed comparisons between the NiAs structure type and the two high-pressure Cu–Bi phases, Cu11Bi7 and CuBi, reveal the preference for elemental segregation within the Cu–Bi phases, and highlight the unique channels and layers formed by ordered Cu vacancies. The electron localization function from DFT calculations account for the presence of these “voids” as a manifestation of the lone pair orientation on the Bi atoms. Our study demonstrates the power of joint experimental–computational work in exploring the chemistry occurring at high-PT conditions. The existence of multiple high-pressure-stabilized phases in the Cu–Bi binary system, which can be readily identified with in situ techniques, offers promise for other systems in which no ambient pressure phases are known to exist.« less

Authors:
; ; ;  [1];  [1];  [2]; ORCiD logo; ORCiD logo; ORCiD logo
  1. GeoSoilEnviroCARS, Center for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois 60637, United States
  2. HPCAT, Geophysical Laboratory, Carnegie Institution of Washington, Argonne, Illinois 60439, United States
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1368342
Resource Type:
Journal Article
Resource Relation:
Journal Name: Chemistry of Materials; Journal Volume: 29; Journal Issue: 12
Country of Publication:
United States
Language:
ENGLISH
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Clarke, Samantha M., Amsler, Maximilian, Walsh, James P. S., Yu, Tony, Wang, Yanbin, Meng, Yue, Jacobsen, Steven D., Wolverton, Chris, and Freedman, Danna E. Creating Binary Cu–Bi Compounds via High-Pressure Synthesis: A Combined Experimental and Theoretical Study. United States: N. p., 2017. Web. doi:10.1021/acs.chemmater.7b01418.
Clarke, Samantha M., Amsler, Maximilian, Walsh, James P. S., Yu, Tony, Wang, Yanbin, Meng, Yue, Jacobsen, Steven D., Wolverton, Chris, & Freedman, Danna E. Creating Binary Cu–Bi Compounds via High-Pressure Synthesis: A Combined Experimental and Theoretical Study. United States. doi:10.1021/acs.chemmater.7b01418.
Clarke, Samantha M., Amsler, Maximilian, Walsh, James P. S., Yu, Tony, Wang, Yanbin, Meng, Yue, Jacobsen, Steven D., Wolverton, Chris, and Freedman, Danna E. Tue . "Creating Binary Cu–Bi Compounds via High-Pressure Synthesis: A Combined Experimental and Theoretical Study". United States. doi:10.1021/acs.chemmater.7b01418.
@article{osti_1368342,
title = {Creating Binary Cu–Bi Compounds via High-Pressure Synthesis: A Combined Experimental and Theoretical Study},
author = {Clarke, Samantha M. and Amsler, Maximilian and Walsh, James P. S. and Yu, Tony and Wang, Yanbin and Meng, Yue and Jacobsen, Steven D. and Wolverton, Chris and Freedman, Danna E.},
abstractNote = {Exploration beyond the known phase space of thermodynamically stable compounds into the realm of metastable materials is a frontier of materials chemistry. The application of high pressure in experiment and theory provides a powerful vector by which to explore this uncharted phase space, allowing discovery of complex new structures and bonding in the solid state. We harnessed this approach for the Cu–Bi system, where the realization of new phases offers potential for exotic properties such as superconductivity. This potential is due to the presence of bismuth, which, by virtue of its status as one of the heaviest stable elements, forms a critical component in emergent materials such as superconductors and topological insulators. To fully investigate and understand the Cu–Bi system, we welded theoretical predictions with experiment to probe the Cu–Bi system under high pressures. By employing the powerful approach of in situ X-ray diffraction in a laser-heated diamond anvil cell (LHDAC), we thoroughly explored the high-pressure and high-temperature (high-PT) phase space to gain insight into the formation of intermetallic compounds at these conditions. We employed density functional theory (DFT) calculations to calculate a pressure versus temperature phase diagram, which correctly predicts that CuBi is stabilized at lower pressures than Cu11Bi7, and allows us to uncover the thermodynamic contributions responsible for the stability of each phase. Detailed comparisons between the NiAs structure type and the two high-pressure Cu–Bi phases, Cu11Bi7 and CuBi, reveal the preference for elemental segregation within the Cu–Bi phases, and highlight the unique channels and layers formed by ordered Cu vacancies. The electron localization function from DFT calculations account for the presence of these “voids” as a manifestation of the lone pair orientation on the Bi atoms. Our study demonstrates the power of joint experimental–computational work in exploring the chemistry occurring at high-PT conditions. The existence of multiple high-pressure-stabilized phases in the Cu–Bi binary system, which can be readily identified with in situ techniques, offers promise for other systems in which no ambient pressure phases are known to exist.},
doi = {10.1021/acs.chemmater.7b01418},
journal = {Chemistry of Materials},
number = 12,
volume = 29,
place = {United States},
year = {Tue Jun 13 00:00:00 EDT 2017},
month = {Tue Jun 13 00:00:00 EDT 2017}
}
  • The structural behavior of CsCdF{sub 3} under pressure is investigated by means of theory and experiment. High-pressure powder x-ray diffraction experiments were performed up to a maximum pressure of 60 GPa using synchrotron radiation. The cubic Pm{sub 3}{sup -} m crystal symmetry persists throughout this pressure range. Electronic structure calculations were carried out using the full-potential linear muffin-tin orbital method within the local-density approximation and the generalized gradient approximation for exchange and correlation effects. The calculated ground-state properties - the equilibrium lattice constant, bulk modulus and elastic constants - are in good agreement with experimental results. The calculations reveal thatmore » CsCdF{sub 3} is an indirect-gap insulator under ambient conditions, with the gap increasing under pressure.« less
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  • The initial hydrogenation of MgB 2occursviaa multi-step process, which can result in the direct production of [BH 4] -complexes.
  • Mg(BH 4) 2 is a promising solid-state hydrogen storage material, releasing 14.9 wt% hydrogen upon conversion to MgB 2. Although several dehydrogenation pathways have been proposed, the hydrogenation process is less well understood. Here, we present a joint experimental–theoretical study that elucidates the key atomistic mechanisms associated with the initial stages of hydrogen uptake within MgB 2. Fourier transform infrared, X-ray absorption, and X-ray emission spectroscopies are integrated with spectroscopic simulations to show that hydrogenation can initially proceed via direct conversion of MgB 2 to Mg(BH 4) 2 complexes. The associated energy landscape is mapped by combining ab initio calculationsmore » with barriers extracted from the experimental uptake curves, from which a kinetic model is constructed. The results from the kinetic model suggest that initial hydrogenation takes place via a multi-step process: molecular H 2 dissociation, likely at Mg-terminated MgB 2 surfaces, is followed by migration of atomic hydrogen to defective boron sites, where the formation of stable B–H bonds ultimately leads to the direct creation of Mg(BH 4) 2 complexes without persistent BxHy intermediates. As a result, implications for understanding the chemical, structural, and electronic changes upon hydrogenation of MgB 2 are discussed.« less
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