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At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Trailblazing Kr/Xe Separation: The Birth of the First Kr-Selective Material

Efficient separation of Kr from Kr/Xe mixtures is pivotal in nuclear waste management and dark matter research. Thus far, scientists have encountered a formidable challenge: the absence of a material with the ability to selectively adsorb Kr over Xe at room temperature. This study presents a groundbreaking transformation of the renowned metal–organic framework (MOF) CuBTC, previously acknowledged for its Xe adsorption affinity, into an unparalleled Kr-selective adsorbent. This achievement stems from an innovative densification approach involving systematic compression of the MOF, where the crystal size, interparticle interaction, defects, and evacuation conditions are synergistically modulated. The resultant densified CuBTC phase exhibits exceptional mechanical resilience, radiation tolerance, and notably an unprecedented selectivity for Kr over Xe at room temperature. Simulation and experimental kinetic diffusion studies confirm reduced gas diffusion in the densified MOF, attributed to its small pore window and minimal interparticle voids. The lighter Kr element demonstrates facile surface passage and higher diffusivity within the material, while the heavier Xe encounters increased difficulty entering the material and lower diffusivity. This Kr-selective MOF not only represents a significant breakthrough in Kr separation but also demonstrates remarkable processability and scalability to kilogram levels. Furthermore, the findings presented herein underscore the transformative potential of engineered MOFs in addressing complex challenges, heralding a new era of Kr separation technologies.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Rational design of a genetically encoded NMR zinc sensor

Elucidating the biochemical roles of the essential metal ion, Zn 2+ , motivates detection strategies that are sensitive, selective, quantitative, and minimally invasive in living systems. Fluorescent probes have identified Zn 2+ in cells but complementary approaches employing nuclear magnetic resonance (NMR) are lacking. Recent studies of maltose binding protein (MBP) using ultrasensitive 129 Xe NMR spectroscopy identified a switchable salt bridge which causes slow xenon exchange and elicits strong hyperpolarized 129 Xe chemical exchange saturation transfer (hyper-CEST) NMR contrast. To engineer the first genetically encoded, NMR-active sensor for Zn 2+ , we converted the MBP salt bridge into a Zn 2+ binding site, while preserving the specific xenon binding cavity. The zinc sensor (ZS) at only 1 μM achieved ‘turn-on’ detection of Zn 2+ with pronounced hyper-CEST contrast. This made it possible to determine different Zn 2+ levels in a biological fluid via hyper-CEST. ZS was responsive to low-micromolar Zn 2+ , only modestly responsive to Cu 2+ , and nonresponsive to other biologically important metal ions, according to hyper-CEST NMR spectroscopy and isothermal titration calorimetry (ITC). Protein X-ray crystallography confirmed the identity of the bound Zn 2+ ion using anomalous scattering: Zn 2+ was coordinated with two histidine side chains and three water molecules. Penta-coordinate Zn 2+ forms a hydrogen-bond-mediated gate that controls the Xe exchange rate. Metal ion binding affinity, 129 Xe NMR chemical shift, and exchange rate are tunable parameters via protein engineering, which highlights the potential to develop proteins as selective metal ion sensors for NMR spectroscopy and imaging.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Measurements and models of enhanced recombination following inner-shell vacancies in liquid xenon

Electron-capture decays of 125 Xe and 127 Xe , and double-electron-capture decays of 124 Xe , are backgrounds in searches for weakly interacting massive particles (WIMPs) conducted by dual-phase xenon time projection chambers such as LUX-ZEPLIN (LZ). These decays produce signals with more light and less charge than equivalent-energy 𝛽 decays and correspondingly overlap more with WIMP signals. We measure three electron-capture charge yields in LZ: the 1.1 keV M-shell, 5.2 keV L-shell, and 33.2 keV K-shell at drift fields of 193 and 96.5 V/cm. The LL double-electron-capture decay of 124 Xe exhibits even more pronounced shifts in charge and light. We provide a first model of double-electron-capture charge yields using the link between ionization density and electron-ion recombination, and identify a need for more accurate calculations. Finally, we discuss the implications of the reduced charge yield of these decays and other interactions creating inner-shell vacancies for future dark matter searches.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Development of bubble evolution model for new mechanistic transient fission gas release capability in BISON

This report summarizes efforts within NEAMS to investigate the mechanisms that govern fission gas behavior in UO 2 . In particular, the focus is on understanding how fission gas behavior causes transient fission gas release and fragmentation/pulverization of high burnup structure (HBS) in UO 2 . HBS forms in the periphery of the pellet where temperatures are relatively low. Previously, MD simulations were performed to determine the reaction energies for various Xe and U defects with bubbles, as a function of Xe to vacancy ratio or, equivalently, pressure. As had been shown in FY22, it was found that the unmodified version of the Simple Integrated Fission Gas Release and Swelling (SIFGRS) model within BISON greatly over-predicted the number gas atoms per vacancy in the bubbles in the outer rim of the pellet (a ratio of > 1 million). This was due to slow grain boundary vacancy diffusivity and not accounting for the pressure-dependent reaction energy for Xe interstitials with bubbles. The application of the pressure dependent reaction energies was able to restrict Xe to vacancy ratios to 2:1, which is far more realistic than those originally obtained from SIFGRS.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Xenon compatibility in magmatic processes: Hadean to current contexts

Xenon (Xe) behaviour in petrological processes, albeit essential to constrain mantle ingassing and degassing models, is elusive due to its volatile nature, and lack of direct investigation at the pressures (P) and temperatures (T) relevant to magma formation and crystallisation at depth. Xenon stands out amongst noble gases due to its unique reactivity with silicates of the lower crust and upper mantle, which could at least partially explain that published mineral/melt partitioning coefficients span up to six orders of magnitude. We report partition coefficients of Xe using in situ X-ray fluorescence at high P and T, and mass spectrometry analyses. Xenon is found to be moderately incompatible in anorthite-clinopyroxene mix in equilibrium with basalt (partition coefficient value of 0.16 ± 0.06), and compatible in olivine in equilibrium with basalt (partition coefficients in the range 88 ± 22 to 302 ± 46). While Xe is, thus, concentrated in basaltic melts coexisting with crystallising pyroxenes and feldspars, it is strongly retained in olivine at depth. Consequently, Xe originally contained in solid Earth has been preferentially retained at depth throughout Earth’s history, from the magma ocean stages to present day partial mantle melting processes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Real-time monitoring of trace noble gases using laser-induced breakdown spectroscopy—An investigation of the impact of bulk gas on plasma properties and sensitivity

The impact of Ar and He bulk gases on laser-induced breakdown spectroscopy (LIBS) real-time monitoring of trace Xe and Kr was assessed. LIBS is being developed as a monitoring tool for measuring noble gas transport in molten salt systems, in which traditional sensors may face challenges associated with radiation, corrosive materials, and/or mixed phases. The plasma temperature and electron densities of LIBS plasmas were measured in both static and various flowing Ar and He streams (0–5 L min −1 ). The use of an Ar bulk gas resulted in higher plasma temperature, greater electron densities by an order of magnitude, and extended plasma lifetime compared with when He bulk gas was used. Gas flow rate was found to have little impact on plasma temperature; however, its effect on electron density was significant, indicating the need to consider flow rate–specific models. Matrix effects on emission peaks were reported for both bulk gases. Due to these matrix effects, multivariate models were developed for Xe and Kr ranging from 0 to 700 ppm in both bulk gases. Although the predictive behavior was similar (root mean square error of prediction ranging from 11.1 to 20.6 ppm), the limits of detection were superior in He (Xe: 22.9 ppm, Kr: 30.4 ppm). Furthermore, these models were employed in demonstrative real-time tests (>1 h), which showed strong predictive precision (relative standard deviation <5 %) regardless of the bulk gas. Ultimately, this study provides a guide for the considerations required when developing gaseous LIBS models for real-time monitoring.

Gas flow effects↗
DOE OSTI2020

Materials Data on XeF2 by Materials Project

XeF2 is Cyanogen Chloride-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is zero-dimensional and consists of two XeF2 clusters. Xe is bonded in a linear geometry to two equivalent F atoms. Both Xe–F bond lengths are 2.08 Å. F is bonded in a single-bond geometry to one Xe atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on XeF4 by Materials Project

XeF4 is Protactinium structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of two XeF4 clusters. Xe is bonded in a square co-planar geometry to four equivalent F atoms. All Xe–F bond lengths are 2.04 Å. F is bonded in a single-bond geometry to one Xe atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on XeIF7 by Materials Project

XeF2IF5 is Heusler-derived structured and crystallizes in the tetragonal I4/m space group. The structure is zero-dimensional and consists of four IF5 clusters and four XeF2 clusters. In each IF5 cluster, I is bonded in a square pyramidal geometry to five F atoms. There is one shorter (1.87 Å) and four longer (1.93 Å) I–F bond length. There are two inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one I atom. In the second F site, F is bonded in a single-bond geometry to one I atom. In each XeF2 cluster, Xe is bonded in a linear geometry to two equivalent F atoms. Both Xe–F bond lengths are 2.09 Å. F is bonded in a single-bond geometry to one Xe atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HgSb3XeF17 by Materials Project

XeHgSb3F17 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of one XeHgSb3F17 sheet oriented in the (0, 0, 1) direction. Xe is bonded in a single-bond geometry to one Hg atom. The Xe–Hg bond length is 2.86 Å. Hg is bonded in a 5-coordinate geometry to one Xe and six F atoms. There are a spread of Hg–F bond distances ranging from 2.36–2.65 Å. There are three inequivalent Sb sites. In the first Sb site, Sb is bonded to six F atoms to form corner-sharing SbF6 octahedra. The corner-sharing octahedral tilt angles are 33°. There are a spread of Sb–F bond distances ranging from 1.88–2.07 Å. In the second Sb site, Sb is bonded to six F atoms to form corner-sharing SbF6 octahedra. The corner-sharing octahedral tilt angles are 33°. There are a spread of Sb–F bond distances ranging from 1.88–2.09 Å. In the third Sb site, Sb is bonded in an octahedral geometry to six F atoms. There are a spread of Sb–F bond distances ranging from 1.88–1.97 Å. There are seventeen inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Hg and one Sb atom. In the second F site, F is bonded in a distorted single-bond geometry to one Hg and one Sb atom. In the third F site, F is bonded in a single-bond geometry to one Sb atom. In the fourth F site, F is bonded in a bent 120 degrees geometry to one Hg and one Sb atom. In the fifth F site, F is bonded in a single-bond geometry to one Sb atom. In the sixth F site, F is bonded in a single-bond geometry to one Sb atom. In the seventh F site, F is bonded in a single-bond geometry to one Sb atom. In the eighth F site, F is bonded in a single-bond geometry to one Sb atom. In the ninth F site, F is bonded in a single-bond geometry to one Sb atom. In the tenth F site, F is bonded in a bent 150 degrees geometry to two Sb atoms. In the eleventh F site, F is bonded in a single-bond geometry to one Sb atom. In the twelfth F site, F is bonded in a single-bond geometry to one Sb atom. In the thirteenth F site, F is bonded in a single-bond geometry to one Sb atom. In the fourteenth F site, F is bonded in a distorted single-bond geometry to one Hg and one Sb atom. In the fifteenth F site, F is bonded in a single-bond geometry to one Sb atom. In the sixteenth F site, F is bonded in a distorted single-bond geometry to one Hg and one Sb atom. In the seventeenth F site, F is bonded in a bent 150 degrees geometry to one Hg and one Sb atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sb2Au(XeF6)2 by Materials Project

AuSb2(XeF6)2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of one AuSb2(XeF6)2 cluster. Xe is bonded in a single-bond geometry to one Au atom. The Xe–Au bond length is 2.77 Å. Au is bonded in a linear geometry to two equivalent Xe and two equivalent F atoms. Both Au–F bond lengths are 2.18 Å. Sb is bonded in an octahedral geometry to six F atoms. There are a spread of Sb–F bond distances ranging from 1.90–2.04 Å. There are six inequivalent F sites. In the first F site, F is bonded in a distorted bent 150 degrees geometry to one Au and one Sb atom. In the second F site, F is bonded in a single-bond geometry to one Sb atom. In the third F site, F is bonded in a single-bond geometry to one Sb atom. In the fourth F site, F is bonded in a single-bond geometry to one Sb atom. In the fifth F site, F is bonded in a single-bond geometry to one Sb atom. In the sixth F site, F is bonded in a single-bond geometry to one Sb atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na4XeO14 by Materials Project

XeNa4O14 crystallizes in the orthorhombic Pbcn space group. The structure is three-dimensional. Xe is bonded in a single-bond geometry to one O atom. The Xe–O bond length is 2.03 Å. There are two inequivalent Na sites. In the first Na site, Na is bonded in a 3-coordinate geometry to eight O atoms. There are a spread of Na–O bond distances ranging from 2.40–3.02 Å. In the second Na site, Na is bonded in a 5-coordinate geometry to five O atoms. There are a spread of Na–O bond distances ranging from 2.21–2.57 Å. There are eight inequivalent O sites. In the first O site, O is bonded in a bent 120 degrees geometry to two O atoms. There is one shorter (1.35 Å) and one longer (1.41 Å) O–O bond length. In the second O site, O is bonded in a distorted T-shaped geometry to two Na and one O atom. The O–O bond length is 1.27 Å. In the third O site, O is bonded in a distorted trigonal planar geometry to two Na and one O atom. In the fourth O site, O is bonded in a 4-coordinate geometry to three Na and one O atom. The O–O bond length is 1.37 Å. In the fifth O site, O is bonded in a 2-coordinate geometry to two equivalent Na and two equivalent O atoms. In the sixth O site, O is bonded in a 4-coordinate geometry to three Na and one O atom. In the seventh O site, O is bonded in a distorted T-shaped geometry to one Xe and two equivalent Na atoms. In the eighth O site, O is bonded in a distorted water-like geometry to one Na and one O atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BC10XeF17 by Materials Project

XeC3F2B(CF3)4(CF)3 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of twelve fluoromethane molecules, four B(CF3)4 clusters, and four XeC3F2 clusters. In each B(CF3)4 cluster, B is bonded in a tetrahedral geometry to four C atoms. All B–C bond lengths are 1.65 Å. There are four inequivalent C sites. In the first C site, C is bonded to one B and three F atoms to form corner-sharing CBF3 tetrahedra. All C–F bond lengths are 1.38 Å. In the second C site, C is bonded to one B and three F atoms to form corner-sharing CBF3 tetrahedra. There is two shorter (1.38 Å) and one longer (1.39 Å) C–F bond length. In the third C site, C is bonded to one B and three F atoms to form corner-sharing CBF3 tetrahedra. There is two shorter (1.37 Å) and one longer (1.41 Å) C–F bond length. In the fourth C site, C is bonded to one B and three F atoms to form corner-sharing CBF3 tetrahedra. There are a spread of C–F bond distances ranging from 1.37–1.39 Å. There are eleven inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one C atom. In the second F site, F is bonded in a single-bond geometry to one C atom. In the third F site, F is bonded in a single-bond geometry to one C atom. In the fourth F site, F is bonded in a single-bond geometry to one C atom. In the fifth F site, F is bonded in a single-bond geometry to one C atom. In the sixth F site, F is bonded in a single-bond geometry to one C atom. In the seventh F site, F is bonded in a single-bond geometry to one C atom. In the eighth F site, F is bonded in a single-bond geometry to one C atom. In the ninth F site, F is bonded in a single-bond geometry to one C atom. In the tenth F site, F is bonded in a single-bond geometry to one C atom. In the eleventh F site, F is bonded in a single-bond geometry to one C atom. In each XeC3F2 cluster, Xe is bonded in a single-bond geometry to one C atom. The Xe–C bond length is 2.13 Å. There are three inequivalent C sites. In the first C site, C is bonded in a single-bond geometry to one C and one F atom. The C–C bond length is 1.39 Å. The C–F bond length is 1.34 Å. In the second C site, C is bonded in a trigonal planar geometry to one Xe and two C atoms. The C–C bond length is 1.39 Å. In the third C site, C is bonded in a distorted single-bond geometry to one C and one F atom. The C–F bond length is 1.34 Å. There are two inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one C atom. In the second F site, F is bonded in a single-bond geometry to one C atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na4XeO12 by Materials Project

XeNa4O12 crystallizes in the orthorhombic Pbca space group. The structure is three-dimensional. Xe is bonded in a linear geometry to two equivalent O atoms. Both Xe–O bond lengths are 2.17 Å. There are two inequivalent Na sites. In the first Na site, Na is bonded in a 5-coordinate geometry to five O atoms. There are a spread of Na–O bond distances ranging from 2.24–2.64 Å. In the second Na site, Na is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of Na–O bond distances ranging from 2.33–3.00 Å. There are six inequivalent O sites. In the first O site, O is bonded to one Xe and three Na atoms to form corner-sharing ONa3Xe tetrahedra. In the second O site, O is bonded in a distorted trigonal non-coplanar geometry to two equivalent Na and one O atom. The O–O bond length is 1.26 Å. In the third O site, O is bonded in a distorted see-saw-like geometry to three Na and one O atom. The O–O bond length is 1.37 Å. In the fourth O site, O is bonded in a distorted trigonal planar geometry to two equivalent Na and one O atom. The O–O bond length is 1.36 Å. In the fifth O site, O is bonded in a 3-coordinate geometry to one Na and two O atoms. In the sixth O site, O is bonded in a bent 120 degrees geometry to one Na and one O atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na4XeO12 by Materials Project

XeNa4O12 crystallizes in the orthorhombic Pbca space group. The structure is three-dimensional. Xe is bonded in a linear geometry to two equivalent O atoms. Both Xe–O bond lengths are 2.16 Å. There are two inequivalent Na sites. In the first Na site, Na is bonded in a 7-coordinate geometry to six O atoms. There are a spread of Na–O bond distances ranging from 2.32–3.00 Å. In the second Na site, Na is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Na–O bond distances ranging from 2.36–3.03 Å. There are six inequivalent O sites. In the first O site, O is bonded to one Xe and three Na atoms to form corner-sharing ONa3Xe tetrahedra. In the second O site, O is bonded in a trigonal non-coplanar geometry to two equivalent Na and one O atom. The O–O bond length is 1.28 Å. In the third O site, O is bonded in a bent 120 degrees geometry to two equivalent Na atoms. In the fourth O site, O is bonded in a distorted rectangular see-saw-like geometry to three Na and one O atom. The O–O bond length is 1.27 Å. In the fifth O site, O is bonded in a distorted bent 120 degrees geometry to two equivalent Na and one O atom. In the sixth O site, O is bonded in a trigonal non-coplanar geometry to two equivalent Na and one O atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sb3Au2Xe2F19 by Materials Project

Xe2Au2Sb3F19 crystallizes in the triclinic P-1 space group. The structure is one-dimensional and consists of one Xe2Au2Sb3F19 ribbon oriented in the (0, 1, 1) direction. Xe is bonded in a single-bond geometry to one Au atom. The Xe–Au bond length is 2.69 Å. Au is bonded in a distorted T-shaped geometry to one Xe and three F atoms. There are a spread of Au–F bond distances ranging from 2.09–2.25 Å. There are two inequivalent Sb sites. In the first Sb site, Sb is bonded in an octahedral geometry to six F atoms. There are a spread of Sb–F bond distances ranging from 1.90–2.02 Å. In the second Sb site, Sb is bonded in an octahedral geometry to six F atoms. There are a spread of Sb–F bond distances ranging from 1.90–1.99 Å. There are nine inequivalent F sites. In the first F site, F is bonded in a linear geometry to two equivalent Au atoms. In the second F site, F is bonded in a bent 150 degrees geometry to one Au and one Sb atom. In the third F site, F is bonded in a single-bond geometry to one Sb atom. In the fourth F site, F is bonded in a single-bond geometry to one Sb atom. In the fifth F site, F is bonded in a single-bond geometry to one Sb atom. In the sixth F site, F is bonded in a single-bond geometry to one Sb atom. In the seventh F site, F is bonded in a single-bond geometry to one Sb atom. In the eighth F site, F is bonded in a distorted bent 150 degrees geometry to one Au and one Sb atom. In the ninth F site, F is bonded in a single-bond geometry to one Sb atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na4XeO12 by Materials Project

XeNa4O12 crystallizes in the orthorhombic Pbca space group. The structure is three-dimensional. Xe is bonded in a linear geometry to two equivalent Na atoms. Both Xe–Na bond lengths are 3.30 Å. There are two inequivalent Na sites. In the first Na site, Na is bonded in a 6-coordinate geometry to one Xe and six O atoms. There are a spread of Na–O bond distances ranging from 2.32–2.83 Å. In the second Na site, Na is bonded to seven O atoms to form a mixture of distorted corner and edge-sharing NaO7 hexagonal pyramids. There are a spread of Na–O bond distances ranging from 2.41–2.79 Å. There are six inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to one Na and one O atom. The O–O bond length is 1.27 Å. In the second O site, O is bonded in a distorted rectangular see-saw-like geometry to three Na and one O atom. The O–O bond length is 1.35 Å. In the third O site, O is bonded in a distorted trigonal non-coplanar geometry to two equivalent Na and one O atom. In the fourth O site, O is bonded in a distorted T-shaped geometry to two equivalent Na and one O atom. The O–O bond length is 1.30 Å. In the fifth O site, O is bonded in a trigonal planar geometry to two equivalent Na and one O atom. In the sixth O site, O is bonded in a 4-coordinate geometry to three Na and one O atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sb2AsAuXeF14 by Materials Project

XeAuAsF3Sb2F11 crystallizes in the orthorhombic Pna2_1 space group. The structure is zero-dimensional and consists of four Sb2F11 clusters and four XeAuAsF3 clusters. In each Sb2F11 cluster, there are two inequivalent Sb sites. In the first Sb site, Sb is bonded to six F atoms to form corner-sharing SbF6 octahedra. The corner-sharing octahedral tilt angles are 23°. There are a spread of Sb–F bond distances ranging from 1.89–2.08 Å. In the second Sb site, Sb is bonded to six F atoms to form corner-sharing SbF6 octahedra. The corner-sharing octahedral tilt angles are 23°. There are a spread of Sb–F bond distances ranging from 1.90–2.09 Å. There are eleven inequivalent F sites. In the first F site, F is bonded in a bent 150 degrees geometry to two Sb atoms. In the second F site, F is bonded in a single-bond geometry to one Sb atom. In the third F site, F is bonded in a single-bond geometry to one Sb atom. In the fourth F site, F is bonded in a single-bond geometry to one Sb atom. In the fifth F site, F is bonded in a single-bond geometry to one Sb atom. In the sixth F site, F is bonded in a single-bond geometry to one Sb atom. In the seventh F site, F is bonded in a single-bond geometry to one Sb atom. In the eighth F site, F is bonded in a single-bond geometry to one Sb atom. In the ninth F site, F is bonded in a single-bond geometry to one Sb atom. In the tenth F site, F is bonded in a single-bond geometry to one Sb atom. In the eleventh F site, F is bonded in a single-bond geometry to one Sb atom. In each XeAuAsF3 cluster, Xe is bonded in a single-bond geometry to one Au atom. The Xe–Au bond length is 2.67 Å. Au is bonded in a linear geometry to one Xe and one As atom. The Au–As bond length is 2.35 Å. As is bonded in a 4-coordinate geometry to one Au and three F atoms. All As–F bond lengths are 1.72 Å. There are three inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one As atom. In the second F site, F is bonded in a single-bond geometry to one As atom. In the third F site, F is bonded in a single-bond geometry to one As atom.

36 MATERIALS SCIENCE↗