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All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Stabilization of Preternatural Barium Oxidation States as an Unexpected Byproduct of β-Decay: Discovery of a New Halide Semiconductor Alloy

137 Cs has a wide range of roles in the nuclear industry. The solid material, safely encapsulated in CsCl as 137 CsCl, is stored as fission product waste from nuclear power production and legacy waste from nuclear weapons production; it has also served as a radiation source in food and sewage irradiators as well as medical devices. However, because of the solubility of the chloride salt and the relatively high specific activity of 137 Cs, damaged or broken capsules can lead to severe radiological accidents. Safe capsule design and material recycling are complicated by the unclear structural evolution during β-decay, which remains ambiguous due to the differing oxidation states of Cs (1+) and Ba (2+). Here, in this study, we use first-principles calculations to investigate the evolving structure–property relationships of Cs 1–x Ba x Cl during β-decay. Despite the well-established 2+ formal oxidation state of alkali-earth metals, we find that Ba 1+ can be stabilized in the form of a mixed-valence alloy at low concentrations. Specifically, we identify three regimes for the β-decay of 137 Cs into CsCl: Ba-doped CsCl (Ba ≤ 14%), wherein Ba has the expected 2+ oxidation state; Cs–Ba–Cl alloys, where Ba has a mix of the usual Ba 2+ and highly unusual Ba 1+ oxidation state in the form of a quasi-disordered mixed-valence alloy (Ba = 25%); and phase separation into a CsCl + BaCl 2 + Ba (m) mechanical mixture, where Ba reverts to its expected 2+ oxidation state (Ba > 25%). Surprisingly, the Cs 0.75 Ba 0.25 Cl mixed-valence alloy is a narrow indirect band gap semiconductor (1.05 eV) despite the insulating nature of both CsCl and BaCl 2 . It also exhibits strongly excitonic polarized optical properties, has glass-like ultralow thermal conductivity (directional average of 0.21 W/mK at 300 K), and shows greater resistance to deformation under both tensile and volumetric strengths compared with the original CsCl structure (e.g., shear and Young’s modulus of 9.04 and 31.62 GPa, respectively). These findings imply that transmutation of 137 Cs leads to highly unusual chemical bonding that stabilizes Ba 1+ in local regions of the quasi-disordered Cs 0.25 Ba 0.75 Cl, resulting in anomalous physical properties. Moreover, this discovery provides valuable insight for safe nuclear waste capsule design, which can aid in preventing environmental or human exposure to radioactive materials.

Fuhr, Addis S. [Oak Ridge National Laboratory (ORN↗
DOE OSTI2020

Revisiting heat treatment and surface activation of GaAs photocathodes: In situ studies using scanning tunneling microscopy and photoelectron spectroscopy

The lifetime of GaAs photocathodes in polarized electron guns is limited due to the delicate activation layer. An atomically clean and smooth GaAs surface is needed to deposit a robust activation layer, such as Cs 2 Te, with longer lifetime compared to traditional (Cs,O) activation. A previous experiment with Cs 2 Te activation on GaAs used heat cleaning temperatures around 400°C to avoid an increase in surface roughness [Bae et al., Appl. Phys. Lett. 112, 154101 (2018)]. Furthermore, high-temperature heat cleaning around 580°C, which results in a relatively contamination-free surface, could be one possible way to improve quantum efficiency. However, one should be cautious about surface roughness degradation during high-temperature heat cleaning. In this paper, we report results of surface roughness measurements on native, heat cleaned, and (Cs,O) activated GaAs photocathodes under vacuum. The results, measured by ultrahigh vacuum scanning tunneling microscopy, show that the surface roughness improves as the heat cleaning temperature is increased, by at least a factor of three for 580°C heat cleaning, compared to the native sample. Activation with (Cs,O) is shown to increase surface roughness by a factor of four compared to a 580°C heat cleaned sample. This confirms that high-temperature heat cleaning can be useful for depositing good quality robust activation layers on GaAs. Additionally, we also report chemical analysis for each step of preparation for p-doped GaAs photocathodes using X-ray photoelectron spectroscopy (XPS), angle-resolved XPS, and ultraviolet photoelectron spectroscopy. Our results indicate that the (Cs,O) activation layer forms a sandwich structure consists of Cs and oxygen. We found no formation of any specific compound such as Cs 2 O or Cs 11 O 3 .

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Cooled Spray Technology for Particulate Reduction in a Heavy-Duty Engine

Cooled spray (CS) technology passively reduces particulate matter (PM) emissions from diesel engines compared to non-CS-equipped diesel engines. CS inserts are mounted near the injector nozzle and control mixing so that the fuel and air can premix while limiting combustion near fuel-rich zones, thereby reducing the formation of particulate matter. CS components contain no moving parts and could be installed as a retrofit or built into new engines. However, CS technology is early in its development, and further investigations are needed to understand the overall performance implications and practicality of the technology. In this paper, we investigate several important aspects of CS, providing a clearer picture of some challenges and potential benefits of CS. Two alignment techniques are used to characterize measurement ease and bias, namely, an optical alignment and spray-plug impact alignment. While the optical technique facilitates alignment more easily, a bias was measured between the optical and spray-plug techniques, suggesting the optical technique may have insufficient accuracy without additional corrections. We also evaluate the engine performance of a well-aligned and poorly aligned CS insert, compared to the baseline configuration. The poorly aligned insert shows slower combustion than the baseline and mixed overall performance. However, the well-aligned insert shows faster combustion than the baseline and PM emission reduction at most operating conditions, with some conditions showing PM reduction up to 80%. Furthermore, the results of this paper highlight the alignment challenges of CS technology as well as the potential PM reduction benefit of the technology.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2024

Assessing Suitable Geologic Carbon Storage Sites Across Utah

Utah has a wealth of potential geological reservoirs for carbon dioxide storage (CS) and a long history of geologic research resulting in an abundance of available subsurface data to evaluate CS potential. Reservoirs may include sandstone, carbonate, and basalt; these rock types are plentiful in Utah’s subsurface and the complex Phanerozoic history throughout the state requires evaluating each geologic region individually for promising reservoir-seal pairs for CO2 storage. Classifying Utah by geologic provinces (or “geo-regions”) allows for customized thinking about suitable CS reservoir and seal distribution, CO2 point sources, land use, and existing infrastructure. Preliminary results from this study highlight the geologic CS potential across 15 geo-regions. Four regions stand out as having high CS potential: the Uinta Basin, San Rafael Swell, Paradox Basin, and the southern Basin and Range Province. The Uinta Basin and San Rafael Swell geo-regions are well suited for CS and have several projects ongoing to evaluate Cretaceous Frontier and Naturita Formations, Jurassic Navajo Sandstone and Entrada Sandstone, and Permian Weber Sandstone reservoir units that lie beneath robust sealing units like the ~5000-ft-thick Mancos Shale and Carmel Formation. Reservoirs such as the Navajo and Weber Sandstones have been demonstrated to be suitable reservoirs through a long history of oil and gas exploration in Utah. New areas of interest include the southern Basin and Range in southwest Utah, where the Jurassic Navajo Sandstone is overlain by the sealing Carmel Formation at suitable depths (>3000 ft), and has good porosities based on outcrop analogue data. Just to the north (e.g., central Basin and Range), legacy wells and 2D seismic data show possible salt and subsurface basalt flows that may provide additional possible CS reservoirs and seals. This geo-region also has the advantage of being coupled with geothermal energy resources that may be used to power burgeoning direct air capture technologies. In the Paradox Basin of southeastern Utah, the Leadville Limestone is a potential storage reservoir beneath the thick (4000–5000 ft), salt-bearing Pennsylvanian Paradox Formation. Although the northern and western parts of Utah offer CS potential, these areas typically contain less infrastructure and subsurface penetrations, creating geologic uncertainty associated with subsurface seals and reservoirs due to a lack of data. Overall, this statewide assessment and ranking is the first step to aid in evaluating CS potential across Utah and provides a foundation for future research in the most favorable locations.

58 GEOSCIENCES↗
DOE OSTI2024

On the connection between least squares, regularization, and classical shadows

Classical shadows (CS) offer a resource-efficient means to estimate quantum observables, circumventing the need for exhaustive state tomography. Here, we clarify and explore the connection between CS techniques and least squares (LS) and regularized least squares (RLS) methods commonly used in machine learning and data analysis. By formal identification of LS and RLS ``shadows'' completely analogous to those in CS---namely, point estimators calculated from the empirical frequencies of single measurements---we show that both RLS and CS can be viewed as regularizers for the underdetermined regime, replacing the pseudoinverse with invertible alternatives. Through numerical simulations, we evaluate RLS and CS from three distinct angles: the tradeoff in bias and variance, mismatch between the expected and actual measurement distributions, and the interplay between the number of measurements and number of shots per measurement. Compared to CS, RLS attains lower variance at the expense of bias, is robust to distribution mismatch, and is more sensitive to the number of shots for a fixed number of state copies---differences that can be understood from the distinct approaches taken to regularization. Conceptually, our integration of LS, RLS, and CS under a unifying ``shadow'' umbrella aids in advancing the overall picture of CS techniques, while practically our results highlight the tradeoffs intrinsic to these measurement approaches, illuminating the circumstances under which either RLS or CS would be preferred, such as unverified randomness for the former or unbiased estimation for the latter.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS2021

Going Beyond Hooked Participants: The Nibble- and-Drop Framework for Classifying Citizen Science Participation

Many citizen science (CS) programs aim to grow and sustain a pool of enthusiastic participants who consistently contribute their efforts to a specific scientific endeavor. Consequently, much research has explored CS participants’ motivations and their relationship to participant recruitment and retention. However, much of this research has focused on actively participating citizen scientists. If researchers want to elucidate the relationship between participant factors (such as demographics and motivations) and participant retention, it is necessary to develop a more comprehensive picture of the different degrees of participation in CS. This paper presents a framework for classifying participation throughout the participant’s engagement in a CS project/program. We suggest a CS participation model that captures the dynamic nature of participation across an arc of volunteering. Called the Nibble-and-Drop Framework, the model describes multiple exit points and stages of contribution typical of participation in a CS program. Applying the framework to the NASA GLOBE Observer (GO) CS program, we found that it captured the dynamics of participation in a global-scale, mobile, app-based, contributory style CS project. The framework guided our analysis of how different participant factors correlate with degrees of participation. We found that participants were motivated to initially participate because they wanted to contribute to NASA research and science. Participants who dropped out of the program at various points often initially engaged through specific collection events and did not feel the need to continue contributing beyond the event; other drop-outs doubted whether their contributions were meaningful, showing again the need to ensure that participants understand the value of their engagement in a CS project.

Heather Fischer↗
DOE OSTI2022

Corrosion of Stainless and Carbon Steel in Aqueous Piperazine for CO2 Capture

Current obstacles that prevent commercial implementation of amine-scrubbing CO2 capture are the high costs. Reducing capital costs by appropriate selection of construction materials, which requires knowledge of material corrosion performance for the process, will improve the economic feasibility of this technology. Corrosion was evaluated in three pilot plant campaigns using aqueous piperazine with the Advanced Stripper (PZAS). 316L stainless steel (SS) experienced higher corrosion than 304 SS and 2205 duplex SS, and the corrosion rate showed strong dependence on the temperature. 304 and 2205 performed well at all locations and should be good construction materials for PZAS. Degraded PZ exacerbated 316L corrosion, and removal of PZ degradation products using a carbon adsorption bed significantly reduced corrosion. Carbon steel (CS) corrosion showed a weak temperature effect because the corrosion was more dependent on the protective siderite film. The protectiveness of the films was related to fluid velocity. Ni-based alloys corroded in PZ, and the rate increased with temperature. Corrosion of C1010 CS and SS (304, 316L, 430) was measured at absorber and water wash conditions on the bench-scale. Corrosion rate decreases with increasing PZ. 8 With more than 0.003 m PZ in solution, CS has acceptable corrosion performance. Corrosion of CS increases with increasing partial pressure of CO2, suggesting loading is another dominant parameter for carbon steel corrosion. Temperature has a less significant effect than PZ concentration and loading. CS corrosion increases with increasing flow velocity at both absorber and water wash conditions. SS had little corrosion at this lower temperature. Performance of siderite (FeCO3) protective films on CS was studied at representative stripper conditions on the bench-scale. Siderite films can deposit on the surface of CS in CO2-loaded PZ solution at temperatures >100 °C and protect CS from corrosion. The protection may fail in degraded PZ. Ethylenediamine (EDA) is one of the major contributors for the loss of film protectiveness or can be the surrogate for the effect of PZ degradation on siderite film protection. A link between protectiveness and the apparent density of siderite films was discovered. The apparent density of siderite films decreases with increasing flow velocity and decreasing CO2 loading, resulting in higher corrosion of CS.

Liu, Ching-Ting↗
DOE OSTI2020

Materials Data on Cs2PtC2(OF)4 by Materials Project

Cs2PtC2(OF)4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded to four O2- and eight F1- atoms to form distorted CsO4F8 cuboctahedra that share corners with two equivalent CsO4F8 cuboctahedra, a cornercorner with one PtO2F4 octahedra, faces with two equivalent CsO4F8 cuboctahedra, and faces with three PtO2F4 octahedra. The corner-sharing octahedral tilt angles are 17°. There are a spread of Cs–O bond distances ranging from 3.25–3.36 Å. There are a spread of Cs–F bond distances ranging from 3.13–3.28 Å. In the second Cs1+ site, Cs1+ is bonded in a 11-coordinate geometry to four O2- and seven F1- atoms. There are a spread of Cs–O bond distances ranging from 3.19–3.41 Å. There are a spread of Cs–F bond distances ranging from 3.11–3.29 Å. In the third Cs1+ site, Cs1+ is bonded to four O2- and eight F1- atoms to form distorted CsO4F8 cuboctahedra that share corners with two equivalent CsO4F8 cuboctahedra, a cornercorner with one PtO2F4 octahedra, faces with two equivalent CsO4F8 cuboctahedra, and faces with three PtO2F4 octahedra. The corner-sharing octahedral tilt angles are 16°. There are a spread of Cs–O bond distances ranging from 3.19–3.32 Å. There are a spread of Cs–F bond distances ranging from 3.16–3.33 Å. In the fourth Cs1+ site, Cs1+ is bonded in a 11-coordinate geometry to four O2- and seven F1- atoms. There are a spread of Cs–O bond distances ranging from 3.22–3.44 Å. There are a spread of Cs–F bond distances ranging from 3.12–3.32 Å. There are two inequivalent Pt2+ sites. In the first Pt2+ site, Pt2+ is bonded to two O2- and four F1- atoms to form PtO2F4 octahedra that share a cornercorner with one CsO4F8 cuboctahedra and faces with three CsO4F8 cuboctahedra. Both Pt–O bond lengths are 2.01 Å. There are a spread of Pt–F bond distances ranging from 1.97–2.01 Å. In the second Pt2+ site, Pt2+ is bonded to two O2- and four F1- atoms to form PtO2F4 octahedra that share a cornercorner with one CsO4F8 cuboctahedra and faces with three CsO4F8 cuboctahedra. There are one shorter (2.01 Å) and one longer (2.02 Å) Pt–O bond lengths. There are a spread of Pt–F bond distances ranging from 1.97–2.01 Å. There are four inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.23 Å) and one longer (1.32 Å) C–O bond length. In the second C4+ site, C4+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.22 Å) and one longer (1.33 Å) C–O bond length. In the third C4+ site, C4+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.23 Å) and one longer (1.32 Å) C–O bond length. In the fourth C4+ site, C4+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.22 Å) and one longer (1.33 Å) C–O bond length. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Cs1+, one Pt2+, and one C4+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to two Cs1+ and one C4+ atom. In the third O2- site, O2- is bonded in a distorted water-like geometry to two Cs1+, one Pt2+, and one C4+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Cs1+, one Pt2+, and one C4+ atom. In the fifth O2- site, O2- is bonded in a single-bond geometry to two Cs1+ and one C4+ atom. In the sixth O2- site, O2- is bonded in a single-bond geometry to two Cs1+ and one C4+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Cs1+, one Pt2+, and one C4+ atom. In the eighth O2- site, O2- is bonded in a single-bond geometry to two Cs1+ and one C4+ atom. There are eight inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted single-bond geometry to four Cs1+ and one Pt2+ atom. In the second F1- site, F1- is bonded in a distorted single-bond geometry to four Cs1+ and one Pt2+ atom. In the third F1- site, F1- is bonded in a distorted single-bond geometry to four Cs1+ and one Pt2+ atom. In the fourth F1- site, F1- is bonded in a distorted single-bond geometry to four Cs1+ and one Pt2+ atom. In the fifth F1- site, F1- is bonded in a distorted single-bond geometry to three Cs1+ and one Pt2+ atom. In the sixth F1- site, F1- is bonded in a distorted single-bond geometry to four Cs1+ and one Pt2+ atom. In the seventh F1- site, F1- is bonded in a distorted single-bond geometry to three Cs1+ and one Pt2+ atom. In the eighth F1- site, F1- is bonded in a distorted single-bond geometry to four Cs1+ and one Pt2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsSn by Materials Project

CsSn crystallizes in the tetragonal I4_1/acd space group. The structure is three-dimensional. there are two inequivalent Cs sites. In the first Cs site, Cs is bonded in a 6-coordinate geometry to six equivalent Sn atoms. There are a spread of Cs–Sn bond distances ranging from 4.06–4.21 Å. In the second Cs site, Cs is bonded in a 12-coordinate geometry to eight equivalent Sn atoms. There are a spread of Cs–Sn bond distances ranging from 4.09–4.19 Å. Sn is bonded in a 10-coordinate geometry to seven Cs and three equivalent Sn atoms. There are one shorter (2.99 Å) and two longer (3.00 Å) Sn–Sn bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cs4Li2(Si2O5)3 by Materials Project

Cs4Li2(Si2O5)3 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are eight inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded in a 2-coordinate geometry to eight O2- atoms. There are a spread of Cs–O bond distances ranging from 3.08–3.61 Å. In the second Cs1+ site, Cs1+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Cs–O bond distances ranging from 3.12–3.67 Å. In the third Cs1+ site, Cs1+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Cs–O bond distances ranging from 3.19–3.75 Å. In the fourth Cs1+ site, Cs1+ is bonded in a 5-coordinate geometry to four O2- atoms. There are two shorter (3.12 Å) and two longer (3.20 Å) Cs–O bond lengths. In the fifth Cs1+ site, Cs1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Cs–O bond distances ranging from 3.20–3.42 Å. In the sixth Cs1+ site, Cs1+ is bonded in a 12-coordinate geometry to twelve O2- atoms. There are a spread of Cs–O bond distances ranging from 3.17–3.66 Å. In the seventh Cs1+ site, Cs1+ is bonded in a 11-coordinate geometry to eleven O2- atoms. There are a spread of Cs–O bond distances ranging from 3.19–3.56 Å. In the eighth Cs1+ site, Cs1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are two shorter (3.06 Å) and two longer (3.23 Å) Cs–O bond lengths. There are two inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.87 Å) and two longer (1.88 Å) Li–O bond length. In the second Li1+ site, Li1+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.87 Å) and two longer (1.88 Å) Li–O bond length. There are six inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.59–1.66 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.59–1.67 Å. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.59–1.67 Å. In the fourth Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.58–1.67 Å. In the fifth Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There is one shorter (1.59 Å) and three longer (1.66 Å) Si–O bond length. In the sixth Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.59–1.67 Å. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to one Cs1+ and two equivalent Si4+ atoms. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to four Cs1+, one Li1+, and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cs1+ and two Si4+ atoms. In the fourth O2- site, O2- is bonded in a linear geometry to two Cs1+ and two equivalent Si4+ atoms. In the fifth O2- site, O2- is bonded in a distorted linear geometry to four Cs1+, one Li1+, and one Si4+ atom. In the sixth O2- site, O2- is bonded in a distorted linear geometry to three Cs1+, one Li1+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to two Cs1+ and two Si4+ atoms. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cs1+ and two Si4+ atoms. In the ninth O2- site, O2- is bonded in a bent 150 degrees geometry to two Cs1+ and two Si4+ atoms. In the tenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cs1+ and two Si4+ atoms. In the eleventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cs1+, one Li1+, and one Si4+ atom. In the twelfth O2- site, O2- is bonded in a linear geometry to two Cs1+ and two equivalent Si4+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to three Cs1+, one Li1+, and one Si4+ atom. In the fourteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cs1+, one Li1+, and one Si4+ atom. In the fifteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cs1+ and two Si4+ atoms. In the sixteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two Cs1+ and two equivalent Si4+ atoms. In the seventeenth O2- site, O2- is bonded in a distorted linear geometry to one Cs1+ and two equivalent Si4+ atoms. In the eighteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two Cs1+ and two equivalent Si4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cs3Bi2 by Materials Project

Bi2Cs3 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are two inequivalent Cs sites. In the first Cs site, Cs is bonded in a 6-coordinate geometry to six equivalent Bi atoms. There are a spread of Cs–Bi bond distances ranging from 4.15–4.27 Å. In the second Cs site, Cs is bonded in a 6-coordinate geometry to six equivalent Bi atoms. There are a spread of Cs–Bi bond distances ranging from 3.95–4.30 Å. Bi is bonded in a 10-coordinate geometry to nine Cs and one Bi atom. The Bi–Bi bond length is 2.99 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cs4Re6C4S9N4 by Materials Project

Cs4Re6C4N4S9 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are four inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded in a 1-coordinate geometry to two N3- and four S2- atoms. There are one shorter (3.13 Å) and one longer (3.45 Å) Cs–N bond lengths. There are a spread of Cs–S bond distances ranging from 3.48–3.69 Å. In the second Cs1+ site, Cs1+ is bonded in a 1-coordinate geometry to one N3- and two S2- atoms. The Cs–N bond length is 3.13 Å. There are one shorter (3.71 Å) and one longer (3.78 Å) Cs–S bond lengths. In the third Cs1+ site, Cs1+ is bonded in a 1-coordinate geometry to one N3- and two S2- atoms. The Cs–N bond length is 3.06 Å. There are one shorter (3.57 Å) and one longer (3.58 Å) Cs–S bond lengths. In the fourth Cs1+ site, Cs1+ is bonded in a 1-coordinate geometry to two equivalent N3- and five S2- atoms. There are one shorter (3.10 Å) and one longer (3.57 Å) Cs–N bond lengths. There are a spread of Cs–S bond distances ranging from 3.52–3.85 Å. There are six inequivalent Re3+ sites. In the first Re3+ site, Re3+ is bonded in a rectangular see-saw-like geometry to four S2- atoms. There are a spread of Re–S bond distances ranging from 2.42–2.44 Å. In the second Re3+ site, Re3+ is bonded to five S2- atoms to form corner-sharing ReS5 square pyramids. There are three shorter (2.43 Å) and two longer (2.44 Å) Re–S bond lengths. In the third Re3+ site, Re3+ is bonded to five S2- atoms to form corner-sharing ReS5 square pyramids. There are a spread of Re–S bond distances ranging from 2.42–2.44 Å. In the fourth Re3+ site, Re3+ is bonded in a rectangular see-saw-like geometry to four S2- atoms. All Re–S bond lengths are 2.43 Å. In the fifth Re3+ site, Re3+ is bonded in a rectangular see-saw-like geometry to four S2- atoms. There are a spread of Re–S bond distances ranging from 2.41–2.43 Å. In the sixth Re3+ site, Re3+ is bonded in a rectangular see-saw-like geometry to four S2- atoms. There are a spread of Re–S bond distances ranging from 2.42–2.44 Å. There are four inequivalent C2+ sites. In the first C2+ site, C2+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.18 Å. In the second C2+ site, C2+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.18 Å. In the third C2+ site, C2+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.18 Å. In the fourth C2+ site, C2+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.18 Å. There are four inequivalent N3- sites. In the first N3- site, N3- is bonded in a 1-coordinate geometry to two equivalent Cs1+ and one C2+ atom. In the second N3- site, N3- is bonded in a distorted single-bond geometry to one Cs1+ and one C2+ atom. In the third N3- site, N3- is bonded in a 1-coordinate geometry to two Cs1+ and one C2+ atom. In the fourth N3- site, N3- is bonded in a distorted single-bond geometry to one Cs1+ and one C2+ atom. There are nine inequivalent S2- sites. In the first S2- site, S2- is bonded in a 4-coordinate geometry to two Cs1+ and two Re3+ atoms. In the second S2- site, S2- is bonded in a 4-coordinate geometry to one Cs1+ and three Re3+ atoms. In the third S2- site, S2- is bonded in a 5-coordinate geometry to two Cs1+ and three Re3+ atoms. In the fourth S2- site, S2- is bonded in a 5-coordinate geometry to two Cs1+ and three Re3+ atoms. In the fifth S2- site, S2- is bonded in a 5-coordinate geometry to two Cs1+ and three Re3+ atoms. In the sixth S2- site, S2- is bonded in a 5-coordinate geometry to three Re3+ atoms. In the seventh S2- site, S2- is bonded in a 5-coordinate geometry to two equivalent Cs1+ and three Re3+ atoms. In the eighth S2- site, S2- is bonded in a 6-coordinate geometry to one Cs1+ and three Re3+ atoms. In the ninth S2- site, S2- is bonded in a 7-coordinate geometry to one Cs1+ and three Re3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cs2CeO3 by Materials Project

Cs2CeO3 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded to seven O2- atoms to form distorted CsO7 pentagonal bipyramids that share corners with two equivalent CsO7 pentagonal bipyramids, a cornercorner with one CeO4 tetrahedra, and edges with four CeO4 tetrahedra. There are a spread of Cs–O bond distances ranging from 3.02–3.52 Å. In the second Cs1+ site, Cs1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Cs–O bond distances ranging from 3.06–3.53 Å. In the third Cs1+ site, Cs1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Cs–O bond distances ranging from 2.97–3.52 Å. In the fourth Cs1+ site, Cs1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Cs–O bond distances ranging from 3.09–3.52 Å. In the fifth Cs1+ site, Cs1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Cs–O bond distances ranging from 3.03–3.55 Å. In the sixth Cs1+ site, Cs1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Cs–O bond distances ranging from 2.96–3.55 Å. In the seventh Cs1+ site, Cs1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Cs–O bond distances ranging from 3.12–3.49 Å. In the eighth Cs1+ site, Cs1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Cs–O bond distances ranging from 2.97–3.52 Å. There are four inequivalent Ce4+ sites. In the first Ce4+ site, Ce4+ is bonded to four O2- atoms to form CeO4 tetrahedra that share corners with two equivalent CeO4 tetrahedra and an edgeedge with one CsO7 pentagonal bipyramid. There are a spread of Ce–O bond distances ranging from 2.04–2.21 Å. In the second Ce4+ site, Ce4+ is bonded to four O2- atoms to form CeO4 tetrahedra that share corners with two equivalent CeO4 tetrahedra and an edgeedge with one CsO7 pentagonal bipyramid. There are a spread of Ce–O bond distances ranging from 2.04–2.21 Å. In the third Ce4+ site, Ce4+ is bonded to four O2- atoms to form corner-sharing CeO4 tetrahedra. There are a spread of Ce–O bond distances ranging from 2.04–2.22 Å. In the fourth Ce4+ site, Ce4+ is bonded to four O2- atoms to form CeO4 tetrahedra that share a cornercorner with one CsO7 pentagonal bipyramid, corners with two equivalent CeO4 tetrahedra, and edges with two equivalent CsO7 pentagonal bipyramids. There are a spread of Ce–O bond distances ranging from 2.04–2.21 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cs1+ and two Ce4+ atoms. In the second O2- site, O2- is bonded in a 1-coordinate geometry to five Cs1+ and one Ce4+ atom. In the third O2- site, O2- is bonded in a 6-coordinate geometry to five Cs1+ and one Ce4+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to five Cs1+ and one Ce4+ atom. In the fifth O2- site, O2- is bonded in a 6-coordinate geometry to five Cs1+ and one Ce4+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cs1+ and two Ce4+ atoms. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to two Cs1+ and two Ce4+ atoms. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to five Cs1+ and one Ce4+ atom. In the ninth O2- site, O2- is bonded in a 6-coordinate geometry to five Cs1+ and one Ce4+ atom. In the tenth O2- site, O2- is bonded in a 6-coordinate geometry to five Cs1+ and one Ce4+ atom. In the eleventh O2- site, O2- is bonded in a distorted single-bond geometry to five Cs1+ and one Ce4+ atom. In the twelfth O2- site, O2- is bonded in a 2-coordinate geometry to two Cs1+ and two Ce4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsSi by Materials Project

SiCs crystallizes in the tetragonal I4_1/acd space group. The structure is three-dimensional. there are two inequivalent Cs sites. In the first Cs site, Cs is bonded in a 8-coordinate geometry to eight equivalent Si atoms. There are a spread of Cs–Si bond distances ranging from 3.75–4.08 Å. In the second Cs site, Cs is bonded in a 6-coordinate geometry to six equivalent Si atoms. There are a spread of Cs–Si bond distances ranging from 3.81–3.99 Å. Si is bonded in a 10-coordinate geometry to seven Cs and three equivalent Si atoms. There are two shorter (2.43 Å) and one longer (2.44 Å) Si–Si bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsGe by Materials Project

GeCs crystallizes in the tetragonal I4_1/acd space group. The structure is three-dimensional. there are two inequivalent Cs sites. In the first Cs site, Cs is bonded in a 12-coordinate geometry to eight equivalent Ge atoms. There are a spread of Cs–Ge bond distances ranging from 3.88–4.08 Å. In the second Cs site, Cs is bonded in a 6-coordinate geometry to six equivalent Ge atoms. There are four shorter (3.91 Å) and two longer (4.02 Å) Cs–Ge bond lengths. Ge is bonded in a distorted q6 geometry to seven Cs and three equivalent Ge atoms. All Ge–Ge bond lengths are 2.63 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cs4P2PdSe8 by Materials Project

Cs4PdP2Se8 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded in a 9-coordinate geometry to nine Se2- atoms. There are a spread of Cs–Se bond distances ranging from 3.72–4.26 Å. In the second Cs1+ site, Cs1+ is bonded in a 9-coordinate geometry to nine Se2- atoms. There are a spread of Cs–Se bond distances ranging from 3.71–4.22 Å. In the third Cs1+ site, Cs1+ is bonded in a 9-coordinate geometry to nine Se2- atoms. There are a spread of Cs–Se bond distances ranging from 3.74–4.19 Å. In the fourth Cs1+ site, Cs1+ is bonded in a 9-coordinate geometry to nine Se2- atoms. There are a spread of Cs–Se bond distances ranging from 3.72–4.18 Å. In the fifth Cs1+ site, Cs1+ is bonded in a 9-coordinate geometry to nine Se2- atoms. There are a spread of Cs–Se bond distances ranging from 3.64–4.30 Å. In the sixth Cs1+ site, Cs1+ is bonded in a 9-coordinate geometry to nine Se2- atoms. There are a spread of Cs–Se bond distances ranging from 3.64–4.30 Å. In the seventh Cs1+ site, Cs1+ is bonded in a 9-coordinate geometry to nine Se2- atoms. There are a spread of Cs–Se bond distances ranging from 3.62–4.27 Å. In the eighth Cs1+ site, Cs1+ is bonded in a 9-coordinate geometry to nine Se2- atoms. There are a spread of Cs–Se bond distances ranging from 3.65–4.25 Å. There are two inequivalent Pd2+ sites. In the first Pd2+ site, Pd2+ is bonded in a square co-planar geometry to four Se2- atoms. There are two shorter (2.48 Å) and two longer (2.49 Å) Pd–Se bond lengths. In the second Pd2+ site, Pd2+ is bonded in a square co-planar geometry to four Se2- atoms. There are two shorter (2.48 Å) and two longer (2.49 Å) Pd–Se bond lengths. There are four inequivalent P5+ sites. In the first P5+ site, P5+ is bonded in a tetrahedral geometry to four Se2- atoms. There are a spread of P–Se bond distances ranging from 2.19–2.29 Å. In the second P5+ site, P5+ is bonded in a tetrahedral geometry to four Se2- atoms. There are a spread of P–Se bond distances ranging from 2.18–2.29 Å. In the third P5+ site, P5+ is bonded in a tetrahedral geometry to four Se2- atoms. There are a spread of P–Se bond distances ranging from 2.19–2.29 Å. In the fourth P5+ site, P5+ is bonded in a tetrahedral geometry to four Se2- atoms. There are a spread of P–Se bond distances ranging from 2.19–2.29 Å. There are sixteen inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 2-coordinate geometry to four Cs1+, one Pd2+, and one P5+ atom. In the second Se2- site, Se2- is bonded in a 2-coordinate geometry to four Cs1+, one Pd2+, and one P5+ atom. In the third Se2- site, Se2- is bonded in a 2-coordinate geometry to four Cs1+, one Pd2+, and one P5+ atom. In the fourth Se2- site, Se2- is bonded in a 2-coordinate geometry to four Cs1+, one Pd2+, and one P5+ atom. In the fifth Se2- site, Se2- is bonded in a 1-coordinate geometry to five Cs1+ and one P5+ atom. In the sixth Se2- site, Se2- is bonded in a 1-coordinate geometry to five Cs1+ and one P5+ atom. In the seventh Se2- site, Se2- is bonded in a 1-coordinate geometry to five Cs1+ and one P5+ atom. In the eighth Se2- site, Se2- is bonded in a 1-coordinate geometry to five Cs1+ and one P5+ atom. In the ninth Se2- site, Se2- is bonded in a 2-coordinate geometry to four Cs1+, one Pd2+, and one P5+ atom. In the tenth Se2- site, Se2- is bonded in a 2-coordinate geometry to four Cs1+, one Pd2+, and one P5+ atom. In the eleventh Se2- site, Se2- is bonded in a 2-coordinate geometry to four Cs1+, one Pd2+, and one P5+ atom. In the twelfth Se2- site, Se2- is bonded in a 2-coordinate geometry to four Cs1+, one Pd2+, and one P5+ atom. In the thirteenth Se2- site, Se2- is bonded in a 1-coordinate geometry to five Cs1+ and one P5+ atom. In the fourteenth Se2- site, Se2- is bonded in a 1-coordinate geometry to five Cs1+ and one P5+ atom. In the fifteenth Se2- site, Se2- is bonded in a 1-coordinate geometry to five Cs1+ and one P5+ atom. In the sixteenth Se2- site, Se2- is bonded in a 1-coordinate geometry to five Cs1+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cs4Si3O8 by Materials Project

Cs4Si3O8 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are eight inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Cs–O bond distances ranging from 3.01–3.56 Å. In the second Cs1+ site, Cs1+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Cs–O bond distances ranging from 3.07–3.60 Å. In the third Cs1+ site, Cs1+ is bonded in a 5-coordinate geometry to eight O2- atoms. There are a spread of Cs–O bond distances ranging from 3.12–3.56 Å. In the fourth Cs1+ site, Cs1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Cs–O bond distances ranging from 3.06–3.61 Å. In the fifth Cs1+ site, Cs1+ is bonded in a 8-coordinate geometry to nine O2- atoms. There are a spread of Cs–O bond distances ranging from 3.01–3.52 Å. In the sixth Cs1+ site, Cs1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Cs–O bond distances ranging from 2.99–3.66 Å. In the seventh Cs1+ site, Cs1+ is bonded in a 1-coordinate geometry to eight O2- atoms. There are a spread of Cs–O bond distances ranging from 3.06–3.66 Å. In the eighth Cs1+ site, Cs1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Cs–O bond distances ranging from 3.14–3.34 Å. There are six inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.60–1.68 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There is two shorter (1.61 Å) and two longer (1.71 Å) Si–O bond length. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.60–1.68 Å. In the fourth Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.59–1.68 Å. In the fifth Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There is two shorter (1.61 Å) and two longer (1.71 Å) Si–O bond length. In the sixth Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.60–1.67 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to three Cs1+ and two Si4+ atoms. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to three Cs1+ and two Si4+ atoms. In the third O2- site, O2- is bonded in a distorted single-bond geometry to five Cs1+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to four Cs1+ and two Si4+ atoms. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to five Cs1+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to five Cs1+ and one Si4+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Cs1+ and two Si4+ atoms. In the eighth O2- site, O2- is bonded in a single-bond geometry to five Cs1+ and one Si4+ atom. In the ninth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to three Cs1+ and two Si4+ atoms. In the tenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to four Cs1+ and two Si4+ atoms. In the eleventh O2- site, O2- is bonded in a single-bond geometry to five Cs1+ and one Si4+ atom. In the twelfth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to three Cs1+ and two Si4+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted single-bond geometry to five Cs1+ and one Si4+ atom. In the fourteenth O2- site, O2- is bonded in a distorted single-bond geometry to five Cs1+ and one Si4+ atom. In the fifteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to three Cs1+ and two Si4+ atoms. In the sixteenth O2- site, O2- is bonded in a single-bond geometry to five Cs1+ and one Si4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsMg6B by Materials Project

CsMg6B crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Cs is bonded in a 12-coordinate geometry to two equivalent Cs and eight Mg atoms. Both Cs–Cs bond lengths are 3.49 Å. There are a spread of Cs–Mg bond distances ranging from 3.86–3.99 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded in a distorted single-bond geometry to one Cs, two equivalent Mg, and one B atom. Both Mg–Mg bond lengths are 3.26 Å. The Mg–B bond length is 2.83 Å. In the second Mg site, Mg is bonded in an L-shaped geometry to two equivalent Cs, one Mg, and two equivalent B atoms. The Mg–Mg bond length is 3.32 Å. Both Mg–B bond lengths are 2.47 Å. In the third Mg site, Mg is bonded in a water-like geometry to two equivalent Cs and two equivalent B atoms. Both Mg–B bond lengths are 2.32 Å. In the fourth Mg site, Mg is bonded in a 8-coordinate geometry to eight Mg atoms. Both Mg–Mg bond lengths are 3.49 Å. B is bonded in a 6-coordinate geometry to eight Mg atoms.

36 MATERIALS SCIENCE↗