Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Xe”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

The dating of pre-exposure times of lunar rocks and soils

Xenon produced by fission of uranium, thorium and plutonium has repeatedly been observed in lunar rocks and soils. In two basaltic rocks and in two soils Xe was found originating from fission of U-235 induced by neutrons which are due to the interactions of cosmic ray particles with lunar matter. Two facts lead to this conclusion: (1) fission Xe is present in excess of that expected for the U, Th, and Pu concentrations and for the gas retention age of the samples; and (2) the Xe-134/Xe-136 ratio of excess fission Xe is close to 1.25 as expected for neutron induced fission of U-235. Information on the duration of the exposure to cosmic rays was obtained from the Kr-81-Kr systematics whereas the effective shielding conditions were derived from the depth sensitive cosmogenic ratio Xe-131/Xe-126. For the four samples the exposure to cosmic rays in the lunar regolith is described by a two stage exposure model. The history of the four samples was derived in terms of duration and shielding depth of the two stages.

Eugster, O.↗
NASA NTRS1986

Xenon and other noble gases in shergottites

The isotopic composition of the xenon component trapped in EETA 79001's lithologies B and C has been determined, and other noble gases were measured in some samples. The Xe component was found to have light isotope ratios indistinguishable from those of the terrestrial atmosphere. The trapped component has a Xe-129/Xe-132 ratio of about 2.4, and is enhanced in Xe-134 and Xe-136 relative to the terrestrial atmosphere or the average carbonaceous chondrite. Similarities between values for Ar-40/Ar-36, Xe-129/Xe-132, and N-15/N-14 and the corresponding Martian atmospheric values suggest Martian origin of the trapped gases.

Swindle, T. D.↗
NASA NTRS1992

How Mars lost its atmosphere

There is a widespread suspicion that Mars thin atmosphere is in some way attributable to the planet's size. Another possibility is that the atmosphere was never degassed or outgassed in the first place. I prefer escape. Hydrodynamic escape (vigorous thermal escape) and impact erosion (expulsion of atmosphere by impacts) are two processes that should have been operative early. Although in principle hydrodynamic escape could have shrunk Mars atmosphere a hundredfold while leaving the composition of the remnant atmosphere nearly unaltered, very high escape fluxes are required. The implicated escape mechanism must have been efficient, nearly non-fractionating, and vastly more potent for Mars than for Earth or Venus. Impact erosion is an appealing candidate. Noble gases are the obvious first test. Noble gases are the most volatile elements and so are the most likely to have been affected by impact erosion and the easiest to address quantitatively. Xenon in particular imposes three constraints on how Mars lost its atmosphere: (1) the very low abundance of nonradiogenic Xe abundance of nonradiogenic Xe compared to Earth, Venus, and likely meteoritic sources; (2) its nonradiogenic isotopes distinct from likely meteoritic sources; and (3) the relatively high absolute abundance of radiogenic daughter of the extinct radionuclide I-129 (half-life 17 Myr). In impact erosion, the first two become constraints on the composition, mass distribution, and orbital elements of the impactors. The third requires that Mars lost its nonradiogenic Xe early, probably before it was 100 Myr old. Impact erosion can explain Mars by any of three stories. (1) Mars in unlikely. In a sort of planetary brinkmanship, impact erosion almost removed the entire atmosphere but was arrested just in time. (2) Martian noble gases are cometary and cometary Xe is as isotopically mass fractionated as Martian and terrestrial Xe. This is most easily accomplished if a relatively thick geochemically controlled CO2 atmosphere protected trace atmophiles against escape. (3) Mars was indeed stripped of its early atmosphere but a small remnant was safely stored in the regolith, later released as a byproduct of water mobilization.

Zahnle, Kevin↗
NASA NTRS1992

A comparison of solar wind and estimated solar system xenon abundances - A test for solid/gas fractionation in the solar nebula

The solar Xe elemental abundance is determined here using solar wind measurements from lunar ilmenites which are normalized to Si by spacecraft data. The results are compared with estimated abundances assuming no fractionation. When corrected for solar wind/photospheric fractionation, the Xe-130 abundance given by surface layer oxidation of ilmenite from solid 71501 exposed within the last 200 m.y. is 0.24 +/- 0.09 normalized to Si = 10 exp 6. This is indistinguishable from estimates made assuming no solid/gas fractionation. Results from breccia 79035 ilmenite exposed at least 1 Gyr ago indicate that the solar wind Xe flux may have been significantly higher relative to other noble gases, perhaps due to more efficient Xe ionization. If this is true, fluxes of C and S, which have first ionization potentials similar to Xe, should also be higher in the ancient solar wind from the same time period.

Wiens, Roger C.↗
NASA NTRS1993

Mass Spectrometric Measurement of Martian Krypton and Xenon Isotopic Abundance

The Viking gas chromatograph mass spectrometer experiment provided significant data on the atmospheric composition at the surface of Mars, including measurements of several isotope ratios. However, the limited dynamic range of this mass spectrometer resulted in marginal measurements for the important Kr and Xe isotopic abundance. The Xe-129 to Xe-132 ratio was measured with an uncertainty of 70%, but none of the other isotope ratios for these species were obtained. Accurate measurement of the Xe and Kr isotopic abundance in this atmosphere provides an important data point in testing theories of planetary formation and atmospheric evolution. The measurement is also essential for a stringent test for the Martian origin of the SNC meteorites, since the Kr and Xe fractionation pattern seen in gas trapped in glassy nodules of an SNC (EETA 79001) is unlike any other known solar system resevoir. Current flight mass spectrometer designs combined with the new technology of a high-performance vacuum pumping system show promise for a substantial increase in gas throughput and the dynamic range required to accurately measure these trace species. Various aspects of this new technology are discussed.

Mahaffy, P.↗
NASA NTRS1992

Trapping of noble gases in proton-irradiated silicate smokes

We have measured Ne, Ar, Kr, and Xe in Si2O3 'smokes' that were condensed on Al substrates, vapor-deposited with various mixtures of CH4, NH3, H2O3 and noble gases at 10 K and subsequently irradiated with 1 MeV protons to simulate conditions during grain mantle formation in interstellar clouds. Neither Ne nor Ar is retained by the samples upon warming to room temperature, but Xe is very efficiently trapped and retained. Kr is somewhat less effectively retained, typically depleted by factors of about 10-20 relative to Xe. Isotopic fractionation favoring the heavy isotopes of Xe and Kr of about 5-10-percent/amu is observed. Correlations between the specific chemistry of the vapor deposition and heavy noble gas retention are most likely the result of competition by the various species for irradiation-produced trapping sites. The concentration of Xe retained by some of these smokes exceeds that observed in phase Q of meteorites and, like phase Q, they do not seem to be carriers of the light noble gases.

Nichols, R. H., Jr.↗
NASA NTRS1993

Noble gases in ancient asteroidal atmospheres

Analytical and numerical results presented here suggest that acceleration of photoions by the solar wind motional field is a significant loss process for Xe on asteroids about 200 km in radius or larger, if the Xe is thermalized by its interactions with the surface. For Ar, photoion acceleration can only become important for asteroids nearly 500 km in radius. Thus photoion acceleration, previously invoked for lunar samples, could be responsible for excess fission-produced Xe found associated with solar wind Xe in howarditic meteorites. The lack of such Xe in other types of meteorites may reflect either smaller parent bodies or later times of regolith exposure. Similarly, the failure to observe solar-wind-associated radiogenic Ar-40 in meteorites is consistent with the much smaller likelihood that Ar will be photoionized.

Swindle, Timothy D.↗
NASA NTRS1999

Anomalous Xenon in the Precambrian Nuclear Reactor in Okelobondo (Gabon): A Possible Connection to the Fission Component in the Terrestrial Atmosphere

Some CFF-Xe (Chemically Fractionated Fission Xenon), whose isotopic composition is established by simultaneous decay and migration of radioactive fission products, is probably present in the Earth's lithosphere, a conclusion based on available Xe data from various crustal and mantle rocks . Our recent isotopic analysis of Xe in alumophosphate from zone 13 of Okelobondo (southern extension of Oklo), along with the independent estimation of the isotopic composition of atmospheric fission Xe , supports the hypothesis that CFF-Xe was produced on a planetary scale. Additional information is contained in the original extended abstract.

Meshik, A. P.↗
NASA NTRS2004

Radiogenic Xenon-129 in Silicate Inclusions in the Campo Del Cielo Iron Meteorite

Iron meteorites present a challenge for the I-Xe dating technique because it is usually the inclusions, not metal, that contain radiogenic xenon and iodine. Silicate inclusions are frequent in only types IAB and IIE, and earlier studies of irons have demonstrated that I-Xe system can survive intact in these inclusions preserving valuable age information. Our previous studies of the I-Xe record in pyroxene grains from Toluca iron suggested an intriguing relationship between apparent I-Xe ages and (Mg+Fe)/Fe ratios. The I-Xe system in K-feldspar inclusions from Colomera (IIE) had the fingerprint of slow cooling, with an indicated cooling rate of 2-4 C/Ma. Here we present studies of the iodine-xenon system in a silicate-graphite-metal (SiGrMet) inclusion of the IA Campo del Cielo iron meteorite from the collection of the Museum of Natural History in Vienna.

Meshik, A.↗
NASA NTRS2016

Evaluation of Observed and Modelled Aerosol Lifetimes Using Radioactive Tracers of Opportunity and an Ensemble of 19 Global Models

Aerosols have important impacts on air quality and climate, but the processes affecting their removal from the atmosphere are not fully understood and are poorly constrained by observations. This makes modelled aerosol lifetimes uncertain. In this study, we make use of an observational constraint on aerosol lifetimes provided by radionuclide measurements and investigate the causes of differences within a set of global models. During the Fukushima Dai-Ichi nuclear power plant accident of March 2011, the radioactive isotopes cesium-137 (Cs-137) and xenon-133 (Xe-133) were released in large quantities. Cesium attached to particles in the ambient air, approximately according to their available aerosol surface area. Cs-137 size distribution measurements taken close to the power plant suggested that accumulation mode (AM) sulfate aerosols were the main carriers of cesium. Hence, Cs-137 can be used as a proxy tracer for the AM sulfate aerosol's fate in the atmosphere. In contrast, the noble gas Xe-133 behaves almost like a passive transport tracer. Global surface measurements of the two radioactive isotopes taken over several months after the release allow the derivation of a lifetime of the carrier aerosol. We compare this to the lifetimes simulated by 19 different atmospheric transport models initialized with identical emissions of Cs-137that were assigned to an aerosol tracer with each model's default properties of AM sulfate, and Xe-133 emissions that were assigned to a passive tracer. We investigate to what extent the modelled sulfate tracer can reproduce the measurements, especially with respect to the observed loss of aerosol mass with time. Modelled Cs-137and Xe-133 concentrations sampled at the same location and times as station measurements allow a direct comparison between measured and modelled aerosol lifetime. The e-folding lifetime e, calculated from station measurement data taken between 2 and 9 weeks after the start of the emissions, is 14.3 days (95% confidence interval 13.1-15.7 days). The equivalent modelled e lifetimes have a large spread, varying between 4.8 and 26.7 days with a model median of 9.42.3 days, indicating too fast a removal in most models. Because sufficient measurement data were only available from about 2 weeks after the release, the estimated lifetimes apply to aerosols that have undergone long-range transport, i.e. not for freshly emitted aerosol. However, modelled instantaneous lifetimes show that the initial removal in the first 2 weeks was quicker (lifetimes between 1 and 5 days) due to the emissions occurring at low altitudes and co-location of the fresh plume with strong precipitation. Deviations between measured and modelled aerosol lifetimes are largest for the northernmost stations and at later time periods, suggesting that models do not transport enough of the aerosol towards the Arctic. The models underestimate passive tracer (Xe-133) concentrations in the Arctic as well but to a smaller extent than for the aerosol (Cs-137) tracer. This indicates that in addition to too fast an aerosol removal in the models, errors in simulated atmospheric transport towards the Arctic in most models also contribute to the underestimation of the Arctic aerosol concentrations.

Radioactive isotopes↗
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↗