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All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Atomic structure considerations for the low-temperature opacity of Xenon

Here, we have begun a preliminary investigation into the opacity of Xe at low temperatures (<50 eV). The emissivity and opacity of Xe is a crucial factor in determining the utility of Xe in EUV lithography, with numerous industrial applications. To this end, we have been exploring the accuracy of some approximations used in opacity models for the relevant ion stages of Xe (6 times ionized through 20 times ionized). Due to the complexity of Xe atomic structure, one needs to use full configuration-interaction to properly describe the strong mixing in the various n=4 sub-shells that give rise to the Δn=0 and Δn=1 transitions that dominate the opacity spectrum at low temperatures. Since calculations that include full configuration-interaction for large numbers of configurations quickly become computationally prohibitive, we have explored hybrid calculations, in which full configuration-interaction is retained for the most important transitions, while intermediate coupling is employed for all other transitions. After verifying atomic structure properties, local-thermodynamic-equilibrium (LTE) opacities are generated using the ATOMIC code at selected temperatures and densities and compared to various experimental results.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

A PIPS + SrI 2 (Eu) detector for atmospheric radioxenon monitoring

The PIPS–SrI 2 (Eu) is a prototype atmospheric radioxenon detection system designed at Oregon State University in support of international efforts towards monitoring clandestine nuclear weapon testing activities. This detector aims to address some shortcomings found in currently deployed beta–gamma atmospheric radioxenon detection systems, such as lackluster energy resolution and memory effect, by employing modern detection materials and readout. The system uses a PIPSBox, a silicon-based gas cell, for electron detection, and a pair of ultrabright, D-shaped SrI 2 (Eu) scintillators coupled to silicon photomultipliers for photon detection. A custom eight-channel digital pulse processor equipped with a field programmable gate-array (FPGA) identifies electron–photon coincidences between the volumes in near real-time. Gas samples of the four radioxenon isotopes of interest were independently measured with the PIPS–SrI 2 (Eu) detection system to determine energy resolution and efficiency. Application of FPGA-based coincidence discrimination in near real-time reduced the ambient background count rate by 95.85 ± 0.04%. Using parameters from the Xenon International gas processing unit and assuming a blank sample and zero memory effect the minimum detectable concentrations (MDCs) for the isotopes were calculated to be 0.12 ± 0.03, 0.27 ± 0.05, 0.15 ± 0.02, and 1.00 ± 0.08 mBq/m 3 air for 131m Xe, 133 Xe, 133m Xe, and 135 Xe, respectively. These MDC estimates compare well with other radioxenon detection systems employed in the International Monitoring System (IMS) and indicate that the PIPS–SrI 2 (Eu) is in compliance with the Comprehensive Nuclear Test-Ban-Treaty Organization (CTBTO) sensitivity requirement of ≤ 1 mBq/m 3 for 133 Xe.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

Investigating the Role of Silver Oxidation State on the Thermodynamic Interactions between Xenon and Silver-Functionalized Zeolites

The molecular level understanding of the strong adsorption of Xe to silver-modified zeolites remains elusive. Here, we probe the effect of silver oxidation state on the thermodynamics of Xe sorption in silver-functionalized zeolites by measuring the enthalpies of adsorption after various treatments using inverse gas chromatography (IGC). The enthalpy of adsorption was measured for silver-functionalized chabazites (AgCHA) before and after hydrogen reduction and subsequent reoxidation. The sorption enthalpy (ΔH) for AgCHA was 35.2 kJ/mol, which decreased to 25.8 kJ/mol with hydrogen reduction. After reoxidation (O 2 -AgCHA), 95% of the binding strength was restored. Hydrogen reduction of the base chabazite (CHA) did not influence Xe adsorption. Henry’s law constant for Xe adsorption increased in the order AgCHA > O 2 -AgCHA > H 2 -AgCHA > CHA. A decrease in enthalpy and Henry’s constant with silver reduction and increase with reoxidation suggest that ionic silver is playing a role in Xe binding. The effect of reduction and reoxidation on the zeolite microstructure was analyzed using surface area analysis, powder X-ray diffraction (p-XRD), scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS), and X-ray photoelectron spectroscopy (XPS). Finally, these results lay the groundwork for better material design of strong noble gas adsorbents.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Supramolecular Assembly of One-Dimensional Coordination Polymers for Efficient Separation of Xenon and Krypton

Efficient separation and purification of xenon (Xe) from krypton (Kr) represent an industrially crucial but challenging process. While the adsorption-based separation of these atomic gases represents an energy-efficient process, achieving highly selective adsorbents remains a difficult task. Here, we demonstrate a supramolecular assembly of coordination polymers, termed as M(II)-dhbq (M = Mg, Mn, Co, and Zn; dhbq = 2,5-dihydroxy-1,4-benzoquinone), with high-density open metal sites (5.3 nm –3 ) and optimal pore size (5.5 Å), which are able to selectively capture Xe among other chemically inert gases including Kr, Ar, N 2 , and O 2 . Among M(II)-dhbq materials, Mn-dhbq exhibits the highest Xe uptake capacity of 3.1 mmol/g and a Xe/Kr selectivity of 11.2 at 298 K and 1.0 bar, outperforming many state-of-the-art adsorbents reported so far. Remarkably, the adsorption selectivity of Mn-dhbq for Xe/O 2 , Xe/N 2 , and Xe/Ar at ambient conditions reaches as high as 70.0, 139.3, and 64.0, respectively. Direct breakthrough experiments further confirm that all M(II)-dhbq materials can efficiently discriminate Xe atoms from other inert gases. Furthermore, it is revealed from the density functional theory calculations that the strong affinity between Xe and the coordination polymer is mainly attributed to the polarization by open metal sites.

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

Xenon–metal pair formation in UO 2 investigated using DFT + U

A recent experimental study on a spent uranium dioxide (UO 2 ) fuel sample from Belgium Reactor 3 identified a unique pair structure formed by the noble metal phase (NMP) and fission gas [xenon (Xe)] precipitate. However, the fundamental mechanism behind this structure remains unclear. The present study aims to provide an understanding of the interaction between five different metal precipitates [molybdenum (Mo), ruthenium (Ru), palladium (Pd), technetium (Tc), and rhodium (Rh)] and the Xe fission gas atoms in UO 2 , by using density functional theory (DFT) in combination with the Hubbard U correction to compute the formation energies involved. All DFT + U calculations were performed with occupation matrix control to ensure antiferromagnetic ordering of UO 2 . The calculated formation and binding energies of the Xe and solid fission products in the NMP reveal that these metal precipitates form stable pair structures with Xe. Notably, the formation energy of Xe–metal pairs is lower than that of the isolated single defects in all instances, with Pd and Mo showing the most favorable binding energy, likely accounting for the observed pair structure formation.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Planar multifrequency mid-IR microwave-pumped lasers

The characteristics of planar repetitively pulsed diffusion-cooled HF, DF, HF – DF, Xe, and HF – DF – Xe(Kr) lasers pumped by a microwave discharge (2.45 GHz) are studied depending on the pump pulse duration (10 – 40 μs) and repletion rate (50 – 400 Hz), as well as on the composition and pressure of the working gas mixture (30 – 200 Torr) at low (to 0.6 L s{sup −1}) gas flow rates. It is demonstrated for the first time that a HF – DF – Xe gas-discharge laser may simultaneously operate as a HF – DF chemical molecular laser and a recombination laser based on xenon atom transitions and generate broadband (octave) radiation in the range 2.0 – 4.2 μm with an average output power of 43 mW and an efficiency of 0.9 %. With substitution of xenon for krypton, lasing in a HF – DF – Kr laser is obtained at wavelengths of 2.52 – 4.15 μm. Lasing in a HF – DF laser was achieved simultaneously in two spectral regions (2.7 – 2.9 and 3.6 – 4.2 μm) with an output power of ∼50 mW. It is found that a decrease in the pump pulse duration with a simultaneous increase in the pulse repletion rate for retaining the average energy deposition leads to an increase in the average output power and efficiency of the laser. At low pulse repetition rates (50 – 100 Hz) and a low gas mixture flow rate, helium buffer gas can be effectively substituted for neon. Operation of the Xe laser was achieved in the spectral range 2.03 – 3.65 μm with an average output power of 580 Mw at a pump pulse duration of 20 μs, a pulse repetition rate to 10 kHz, and a maximum efficiency of 55 %. The obtained experimental results demonstrate the possibility of creating broadband HF – DF – Xe lasers emitting in the frequency range 2 – 4 μm with a desired ratio of intensities in different spectral ranges. (paper)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

A dry ancient plume mantle from noble gas isotopes

Primordial volatiles were delivered to terrestrial reservoirs during Earth’s accretion, and the mantle plume source is thought to have retained a greater proportion of primordial volatiles compared with the upper mantle. This study shows that mantle He, Ne, and Xe isotopes require that the plume mantle had low concentrations of volatiles like Xe and H 2 O at the end of accretion compared with the upper mantle. A lower extent of mantle processing alone is not sufficient to explain plume noble gas signatures. Ratios of primordial isotopes are used to determine proportions of solar, chondritic, and regassed atmospheric volatiles in the plume mantle and upper mantle. The regassed Ne flux exceeds the regassed Xe flux but has a small impact on the mantle Ne budget. Pairing primordial isotopes with radiogenic systems gives an absolute concentration of 130 Xe in the plume source of ∼1.5 × 10 7 atoms 130 Xe/g at the end of accretion, ∼4 times less than that determined for the ancient upper mantle. A record of limited accretion of volatile-rich solids thus survives in the He-Ne-Xe signatures of mantle rocks today. A primordial viscosity contrast originating from a factor of ∼4 to ∼250 times lower H 2 O concentration in the plume mantle compared with the upper mantle may explain (a) why giant impacts that triggered whole mantle magma oceans did not homogenize the growing planet, (b) why the plume mantle has experienced less processing by partial melting over Earth’s history, and (c) how early-formed isotopic heterogeneities may have survived ∼4.5 Gy of solid-state mantle convection.

58 GEOSCIENCES↗
DOE OSTI2022

Impact of xenon doping in the scintillation light in a large liquid-argon TPC

The use of xenon-doped liquid argon (Xe-doped LAr) is a promising alternative for large-scale liquid argon Time Projection Chambers (LAr-TPC), since it mitigates the light suppression due to impurities and it also improves the photon-detection efficiency and uniformity with the distance. This study analyses the impact of using Xe-doped LAr in ProtoDUNE Dual-Phase, a 750 ton Dual-Phase LAr-TPC placed at CERN. ProtoDUNE Dual-Phase completed a Xe-doping data-taking campaign in summer 2020 by re-filling the detector with 230 tons of Xe-doped LAr contaminated with nitrogen, and performing dedicated nitrogen injections. The effects of the presence of Xe at 5.8 ppm in the scintillation light production and propagation are analysed in this paper, showing an increase of the collected photons, but a suppression of the light signal amplitude. A 60% increase of the light attenuation length is measured. The impact on the scintillation time profile is also studied. A model to fit the time profile is proposed and the time constants of the physics processes are obtained.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

Kiloton-scale xenon detectors for neutrinoless double beta decay and other new physics searches

We report that large detectors employing xenon are a leading technology in existing and planned searches for new physics, including searches for neutrinoless double beta decay (0νββ) and dark matter. While upcoming detectors will employ target masses of a ton or more, further extending gas- or liquid-phase Xe detectors to the kton scale would enable extremely sensitive next-generation searches for rare phenomena. The key challenge to extending this technology to detectors well beyond the ton scale is the acquisition of the Xe itself. We describe the motivation for extending Xe time-projection chambers to the kton scale and possible avenues for Xe acquisition that avoid existing supply chains. If acquisition of Xe in the required quantities is successful, kton-scale detectors of this type could enable a new generation of experiments, including searches for 0νββ at half-life sensitivities as long as 10 30 yr.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Spoofing Cross-Entropy Measure in Boson Sampling

Cross-entropy (XE) measure is a widely used benchmark to demonstrate quantum computational advantage from sampling problems, such as random circuit sampling using superconducting qubits and boson sampling (BS). We present a heuristic classical algorithm that attains a better XE than the current BS experiments in a verifiable regime and is likely to attain a better XE score than the near-future BS experiments in a reasonable running time. The key idea behind the algorithm is that there exist distributions that correlate with the ideal BS probability distribution and that can be efficiently computed. The correlation and the computability of the distribution enable us to postselect heavy outcomes of the ideal probability distribution without computing the ideal probability, which essentially leads to a large XE. Our method scores a better XE than the recent Gaussian BS experiments when implemented at intermediate, verifiable system sizes. Much like current state-of-the-art experiments, we cannot verify that our spoofer works for quantum-advantage-size systems. However, we demonstrate that our approach works for much larger system sizes in fermion sampling, where we can efficiently compute output probabilities. Finally, we provide analytic evidence that the classical algorithm is likely to spoof noisy BS efficiently.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Cryogenic tracer irradiation facility at the university of Texas at Austin

We report on a cryogenic gas irradiation facility in the 1.1 MW TRIGA reactor at The University of Texas at Austin. The system was designed to produce radioactive xenon and argon for environmental studies, and it can be applied to produce other gaseous radiotracers. The system design includes modeling accident scenarios to ensure operation does not risk damage to the reactor and minimizes risk of release of radioactive material. In conclusion, the SCALE code was used to model a 30-day irradiation of one liter of Xe-126 and the predicted activity is 0.9 Ci of Xe-127 at irradiation end.

Ar-37↗
DOE OSTI2020

Materials Data on RuXeF7 by Materials Project

XeRuF7 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four XeRuF7 clusters. Xe is bonded in a linear geometry to two F atoms. There are one shorter (2.00 Å) and one longer (2.23 Å) Xe–F bond lengths. Ru is bonded in an octahedral geometry to six F atoms. There are a spread of Ru–F bond distances ranging from 1.87–2.03 Å. There are seven inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Ru atom. In the second F site, F is bonded in a single-bond geometry to one Ru atom. In the third F site, F is bonded in a single-bond geometry to one Ru atom. In the fourth F site, F is bonded in a single-bond geometry to one Xe atom. In the fifth F site, F is bonded in a distorted bent 120 degrees geometry to one Xe and one Ru atom. In the sixth F site, F is bonded in a single-bond geometry to one Ru atom. In the seventh F site, F is bonded in a single-bond geometry to one Ru atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AsXeF7 by Materials Project

XeAsF7 is alpha Niobium phosphide-derived structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four XeAsF7 clusters. Xe is bonded in a linear geometry to two F atoms. There are one shorter (2.00 Å) and one longer (2.22 Å) Xe–F bond lengths. As is bonded in an octahedral geometry to six F atoms. There are a spread of As–F bond distances ranging from 1.74–1.97 Å. There are seven 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 Xe atom. In the third F site, F is bonded in a bent 120 degrees geometry to one Xe and one As atom. In the fourth F site, F is bonded in a single-bond geometry to one As atom. In the fifth F site, F is bonded in a single-bond geometry to one As atom. In the sixth F site, F is bonded in a single-bond geometry to one As atom. In the seventh F site, F is bonded in a single-bond geometry to one As atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuSb2(XeF5)4 by Materials Project

CuSb(Xe2F7)2SbF6 crystallizes in the tetragonal I-4 space group. The structure is one-dimensional and consists of two SbF6 clusters and two CuSb(Xe2F7)2 ribbons oriented in the (0, 0, 1) direction. In each SbF6 cluster, Sb is bonded in an octahedral geometry to six F atoms. There is four shorter (1.92 Å) and two longer (1.93 Å) Sb–F bond length. There are two inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Sb atom. In the second F site, F is bonded in a single-bond geometry to one Sb atom. In each CuSb(Xe2F7)2 ribbon, Xe is bonded in a linear geometry to two F atoms. There are one shorter (2.02 Å) and one longer (2.18 Å) Xe–F bond lengths. Cu is bonded to six F atoms to form CuF6 octahedra that share corners with two equivalent SbF6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (1.93 Å) and two longer (2.30 Å) Cu–F bond lengths. Sb is bonded to six F atoms to form SbF6 octahedra that share corners with two equivalent CuF6 octahedra. The corner-sharing octahedral tilt angles are 0°. There is four shorter (1.91 Å) and two longer (1.95 Å) Sb–F bond length. There are four inequivalent F sites. In the first F site, F is bonded in a bent 120 degrees geometry to one Xe and one Cu atom. In the second F site, F is bonded in a single-bond geometry to one Xe 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 linear geometry to one Cu and one Sb atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgAs2(XeF8)2 by Materials Project

MgAs2(XeF8)2 crystallizes in the orthorhombic Pbam space group. The structure is one-dimensional and consists of two MgAs2(XeF8)2 ribbons oriented in the (1, 0, 0) direction. Xe is bonded in a linear geometry to two F atoms. There are one shorter (2.02 Å) and one longer (2.14 Å) Xe–F bond lengths. Mg is bonded to six F atoms to form MgF6 octahedra that share corners with four equivalent AsF6 octahedra. The corner-sharing octahedral tilt angles are 30°. There are two shorter (1.96 Å) and four longer (2.05 Å) Mg–F bond lengths. As is bonded to six F atoms to form AsF6 octahedra that share corners with two equivalent MgF6 octahedra. The corner-sharing octahedral tilt angles are 30°. There are a spread of As–F bond distances ranging from 1.75–1.83 Å. There are six 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 bent 150 degrees geometry to one Mg and one As atom. In the third F site, F is bonded in a single-bond geometry to one Xe atom. In the fourth F site, F is bonded in a single-bond geometry to one As atom. In the fifth F site, F is bonded in a single-bond geometry to one As atom. In the sixth F site, F is bonded in a linear geometry to one Xe and one Mg atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CdB2XeF10 by Materials Project

XeCdB2F10 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of one XeCdB2F10 sheet oriented in the (0, 0, 1) direction. Xe is bonded in a linear geometry to two F atoms. There are one shorter (2.04 Å) and one longer (2.14 Å) Xe–F bond lengths. Cd is bonded in a 8-coordinate geometry to eight F atoms. There are a spread of Cd–F bond distances ranging from 2.31–2.42 Å. There are two inequivalent B sites. In the first B site, B is bonded in a tetrahedral geometry to four F atoms. There are a spread of B–F bond distances ranging from 1.38–1.44 Å. In the second B site, B is bonded in a tetrahedral geometry to four F atoms. There is one shorter (1.41 Å) and three longer (1.42 Å) B–F bond length. There are ten inequivalent F sites. In the first F site, F is bonded in a distorted single-bond geometry to one Cd and one B atom. In the second F site, F is bonded in a single-bond geometry to one B atom. In the third F site, F is bonded in a bent 120 degrees geometry to one Xe and one Cd atom. In the fourth F site, F is bonded in a distorted single-bond geometry to one Cd and one B atom. In the fifth F site, F is bonded in a distorted single-bond geometry to one Cd and one B atom. In the sixth F site, F is bonded in a distorted single-bond geometry to one Cd and one B atom. In the seventh F site, F is bonded in a distorted single-bond geometry to one Cd and one B atom. In the eighth F site, F is bonded in a distorted single-bond geometry to one Cd and one B atom. In the ninth F site, F is bonded in a single-bond geometry to one Xe atom. In the tenth F site, F is bonded in a distorted single-bond geometry to one Cd and one B atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuSb2(XeF4)6 by Materials Project

Cu(XeF2)6(SbF6)2 is Fluorite structured and crystallizes in the trigonal R-3 space group. The structure is zero-dimensional and consists of three Cu(XeF2)6 clusters and six SbF6 clusters. In each Cu(XeF2)6 cluster, Xe is bonded in a linear geometry to two F atoms. There are one shorter (2.03 Å) and one longer (2.17 Å) Xe–F bond lengths. Cu is bonded in an octahedral geometry to six equivalent F atoms. All Cu–F bond lengths are 2.02 Å. There are two inequivalent F sites. In the first F site, F is bonded in a bent 120 degrees geometry to one Xe and one Cu atom. In the second F site, F is bonded in a single-bond geometry to one Xe atom. In each SbF6 cluster, Sb is bonded in an octahedral geometry to six F atoms. There is three shorter (1.92 Å) and three longer (1.93 Å) Sb–F bond length. There are two inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Sb atom. In the second F site, F is bonded in a single-bond geometry to one Sb atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SbTe7SXeCl(OF4)9 by Materials Project

XeTeSCl(OF2)3SbTe6(OF5)6 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two SbTe6(OF5)6 clusters and two XeTeSCl(OF2)3 clusters. In one of the SbTe6(OF5)6 clusters, Sb is bonded to six O atoms to form SbO6 octahedra that share corners with six TeOF5 octahedra. The corner-sharing octahedra tilt angles range from 36–42°. There are a spread of Sb–O bond distances ranging from 1.99–2.01 Å. There are three inequivalent Te sites. In the first Te site, Te is bonded to one O and five F atoms to form TeOF5 octahedra that share a cornercorner with one SbO6 octahedra. The corner-sharing octahedral tilt angles are 42°. The Te–O bond length is 1.90 Å. There are a spread of Te–F bond distances ranging from 1.87–1.89 Å. In the second Te site, Te is bonded to one O and five F atoms to form TeOF5 octahedra that share a cornercorner with one SbO6 octahedra. The corner-sharing octahedral tilt angles are 36°. The Te–O bond length is 1.88 Å. There are a spread of Te–F bond distances ranging from 1.87–1.89 Å. In the third Te site, Te is bonded to one O and five F atoms to form TeOF5 octahedra that share a cornercorner with one SbO6 octahedra. The corner-sharing octahedral tilt angles are 40°. The Te–O bond length is 1.88 Å. There is one shorter (1.87 Å) and four longer (1.88 Å) Te–F bond length. There are three inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to one Sb and one Te atom. In the second O site, O is bonded in a bent 150 degrees geometry to one Sb and one Te atom. In the third O site, O is bonded in a bent 150 degrees geometry to one Sb and one Te atom. There are fifteen inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Te atom. In the second F site, F is bonded in a single-bond geometry to one Te atom. In the third F site, F is bonded in a single-bond geometry to one Te atom. In the fourth F site, F is bonded in a single-bond geometry to one Te atom. In the fifth F site, F is bonded in a single-bond geometry to one Te atom. In the sixth F site, F is bonded in a single-bond geometry to one Te atom. In the seventh F site, F is bonded in a single-bond geometry to one Te atom. In the eighth F site, F is bonded in a single-bond geometry to one Te atom. In the ninth F site, F is bonded in a single-bond geometry to one Te atom. In the tenth F site, F is bonded in a single-bond geometry to one Te atom. In the eleventh F site, F is bonded in a single-bond geometry to one Te atom. In the twelfth F site, F is bonded in a single-bond geometry to one Te atom. In the thirteenth F site, F is bonded in a single-bond geometry to one Te atom. In the fourteenth F site, F is bonded in a single-bond geometry to one Te atom. In the fifteenth F site, F is bonded in a single-bond geometry to one Te atom. In one of the SbTe6(OF5)6 clusters, Sb is bonded to six O atoms to form SbO6 octahedra that share corners with six TeOF5 octahedra. The corner-sharing octahedral tilt angles are 42°. There are four shorter (2.00 Å) and two longer (2.01 Å) Sb–O bond lengths. There are three inequivalent Te sites. In the first Te site, Te is bonded to one O and five F atoms to form TeOF5 octahedra that share a cornercorner with one SbO6 octahedra. The corner-sharing octahedral tilt angles are 42°. The Te–O bond length is 1.89 Å. There is three shorter (1.87 Å) and two longer (1.88 Å) Te–F bond length. In the second Te site, Te is bonded to one O and five F atoms to form TeOF5 octahedra that share a cornercorner with one SbO6 octahedra. The corner-sharing octahedral tilt angles are 42°. The Te–O bond length is 1.89 Å. There are a spread of Te–F bond distances ranging from 1.87–1.89 Å. In the third Te site, Te is bonded to one O and five F atoms to form TeOF5 octahedra that share a cornercorner with one SbO6 octahedra. The corner-sharing octahedral tilt angles are 42°. The Te–O bond length is 1.89 Å. There are a spread of Te–F bond distances ranging from 1.87–1.89 Å. There are three inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to one Sb and one Te atom. In the second O site, O is bonded in a bent 150 degrees geometry to one Sb and one Te atom. In the third O site, O is bonded in a bent 150 degrees geometry to one Sb and one Te atom. There are fifteen inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Te atom. In the second F site, F is bonded in a single-bond geometry to one Te atom. In the third F site, F is bonded in a single-bond geometry to one Te atom. In the fourth F site, F is bonded in a single-bond geometry to one Te atom. In the fifth F site, F is bonded in a single-bond geometry to one Te atom. In the sixth F site, F is bonded in a single-bond geometry to one Te atom. In the seventh F site, F is bonded in a single-bond geometry to one Te atom. In the eighth F site, F is bonded in a single-bond geometry to one Te atom. In the ninth F site, F is bonded in a single-bond geometry to one Te atom. In the tenth F site, F is bonded in a single-bond geometry to one Te atom. In the eleventh F site, F is bonded in a single-bond geometry to one Te atom. In the twelfth F site, F is bonded in a single-bond geometry to one Te atom. In the thirteenth F site, F is bonded in a single-bond geometry to one Te atom. In the fourteenth F site, F is bonded in a single-bond geometry to one Te atom. In the fifteenth F site, F is bonded in a single-bond geometry to one Te atom. In each XeTeSCl(OF2)3 cluster, Xe is bonded in a linear geometry to two O atoms. There are one shorter (2.07 Å) and one longer (2.45 Å) Xe–O bond lengths. Te is bonded in an octahedral geometry to one O and five F atoms. The Te–O bond length is 1.98 Å. There are a spread of Te–F bond distances ranging from 1.86–1.88 Å. S is bonded in a distorted tetrahedral geometry to two O, one Cl, and one F atom. There is one shorter (1.42 Å) and one longer (1.46 Å) S–O bond length. The S–Cl bond length is 1.96 Å. The S–F bond length is 1.56 Å. There are three inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one S atom. In the second O site, O is bonded in a bent 120 degrees geometry to one Xe and one Te atom. In the third O site, O is bonded in a distorted single-bond geometry to one Xe and one S atom. Cl is bonded in a single-bond geometry to one S atom. There are six inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Te atom. In the second F site, F is bonded in a single-bond geometry to one Te atom. In the third F site, F is bonded in a single-bond geometry to one Te atom. In the fourth F site, F is bonded in a single-bond geometry to one Te atom. In the fifth F site, F is bonded in a single-bond geometry to one Te atom. In the sixth F site, F is bonded in a single-bond geometry to one S atom.

36 MATERIALS SCIENCE↗