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At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Bay capping via acetylene addition to polycyclic aromatic hydrocarbons: Mechanism and kinetics

The bay-capping mechanism on PAH armchair edges and the kinetics of acetylene addition to 6–6–5 and 5–6–5 bays have been explored by ab initio/RRKM-ME calculations. The bays on the edges were modeled by C 21 H 11 and C 20 H 9 radicals produced by H abstractions from 7H-benzo[c]cyclopenta[e]pyrene and dicyclopenta[cf]pyrene. The C 20 H 9 + C 2 H 2 reaction is shown to have a low entrance barrier and to rapidly form the capped product, indaceno[2,1,8,7-cdefg]pyrene, along with ethynyl substituted dicyclopenta[cf]pyrene at temperatures above 1400 K. The reactivity of C 21 H 11 is shown to be governed by the location of the unpaired electron; the π radical R1 formed by H abstraction from the CH 2 group in 7H-benzo[c]cyclopenta[e]pyrene reacts with C 2 H 2 very slowly owing to a high entrance barrier, with the bay-capping rate constant approaching 10 -16 cm 3 molecule -1 s -1 only at temperatures above 2000K. Further, this result reaffirms that the growth of π aryl radicals via acetylene addition is inefficient and reflects the generally low reactivity of such radicals where the spin density is highly delocalized over the entire polyaromatic system. Alternatively, the σ C 21 H 11 radical R2 produced by H abstraction from the five-membered ring at the bay rapidly reacts with C 2 H 2 forming the bay-capped product, with the rate constant on the order of 10 -12 cm 3 molecule -1 s -1 at T≥1500K. Rate constants for the capping reactions at the 6–6–5 and 5–6–5 bays are compared with those at the 6–0–6, 6–6–6, and 6–5–6 bays. The site-specific bay-capping rate constants have been utilized in kMC simulations of the PAH growth and the results showed measurable differences when the 6–6–5 and 5–6–5 bay-capping reactions are taken into account, including an increase of the growth rate and the formation of closed-shell PAH and a rise of the number of embedded five-membered rings accompanied with a slight decrease of their overall amount.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

A late glacial paleoenvironmental and climate record from the Sierra de Juarez, Baja California

Ciénegas are desert wetlands that are strongly correlated with the stability of the hydrologic cycle in arid landscapes. However, these environments are particularly vulnerable to climate change, drought, water diversion, and fire suppression which all have contributed to the degradation of ciénegas along the U.S.-Mexican borderlands. Therefore, identifying the timing of precipitation patterns in this region is of particular interest because of its relationship to many ecological responses of the landscape such as groundwater recharge and fire. Here, we present the first-ever fire paleoenvironmental record from Ciénega Chimeneas, a ciénega complex in the Sierra de Juárez of Baja California. We explore how changes in the amount and seasonality of moisture affected ciénega complexes and fire activity from across the southwestern North American region over the past 45,000 years. Further, our record suggests that during the late glacial period, 41,000–21,000 cal yr BP, the increase of Larrea and Quercus indicate an increase in summer precipitation. Subsequently, when summer precipitation increased, pollen preservation and pollen accumulation rates (PAR) also increased. Increased vegetation allowed for increased fire activity during the late glacial period. Regionally, most of the comparison sites also indicated wet conditions during the full glacial period. However, around 21,000 cal yr BP, effective moisture decreased resulting in a dramatic change in the vegetation assemblage. Specifically, the summer wet taxa disappeared, while pollen preservation and PAR decreased, suggesting a dry period until ~14,000 cal yr BP. Little fire activity is recorded after 21,000 cal yr BP, likely due to the absence of fuels. At ~14,000 cal yr BP, Larrea and Quercus reappear suggesting increased summer precipitation. However, the appearance of Cyperaceae and increases in grasses suggest increased winter precipitation. We suggest that the combination of summer wet and winterwet taxa ~14,000 cal yr BP represents an increase in ENSO conditions, while the summer moisture controls remained relatively constant.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Simulated aging processes of black carbon and its impact during a severe winter haze event in the Beijing-Tianjin- Hebei region

Black carbon (BC) can mitigate or worsen air pollution through perturbing meteorological conditions. BC aging processes are important for the evolution of particle size, concentration, and optical properties of BC that determines its influence on the meteorology. Here we use the online coupled Weather Research and Forecasting-Chemistry (WRF-Chem) model to quantify the role of BC aging processes, including physical processes (PP) and absorption enhancements (AE), in exerting BC-induced meteorological changes and the associated feedback to PM2.5 (particulate matter less than 2.5 µm in diameter) and O3 concentrations during a severe haze event in Beijing-Tianjin-Hebei (BTH) region during 21-27 February 2014. Our results show that, compared to the simulation without the PP treatment, the simulated near-surface BC concentration and BC mass loading in BTH region is lowered by 6.6 % and 12.1 %, respectively, during the haze event with the PP included. PP increases the proportion of large-size BC (particle diameter greater than 0.312 µm) from 28 %-33 % to 59 %-64 % below 1000 m in BTH region. Both PP and AE enhance the “dome effect” of BC. With both PP and AE considered, a reduction in PBL height due to BC-PBL interaction is 116.3 m (20.7 %), compared to 75.7 m (13.5 %) without AE and 66.6 m (11.9 %) without both PP and AE. However, during this haze event, anomalous northeasterly winds are produced by the direct radiative effect of BC, which further affects the mixing and transport of aerosols. When PBL height is decreased (from 10:00 to 21:00), combining all the impacts on multiple meteorological factors, BC effect without PP and AE, without AE, and with PP and AE, respectively, increases surface concentrations of PM2.5 by 8.3 µg m-3 (6.1 % relative to the mean value), 6.1 µg m-3 (4.5 %) and 9.6 µg m-3 (7.0 %) but decreases surface O3 concentrations by 2.8 ppbv (7.4 %), 4.0 ppbv (9.0 %) and 5.0 ppbv (10.8 %) in BTH region averaged over 21-27 February 2014. Our results highlight the importance of the aging processes and absorption enhancements of BC in simulating weather and air quality.

Chen, Donglin↗
DOE OSTI2020

The many-body expansion for aqueous systems revisited: 1. Water-water interactions

We revisit the Many-Body Expansion (MBE) for water-water interactions by examining the effects of the basis set, including those resulting from the Basis Set Superposition Error (BSSE) correction, on the various terms for selected sizes of water clusters up to n = 21. The analysis is performed at the second order Møller-Plesset (MP2) perturbation theory with the family of augmented correlation consistent basis sets up to five zeta quality for the (H2O)n, n = 7, 10, 13, 16 and 21 clusters, for which we report either the complete MBE (n = 7, 10) or the one through the 6-body (n = 13) and the 5-body terms (n = 16, 21). Our results suggest that any sizeable contributions to the total cluster binding energy arising from the 5-body and larger terms are solely an artifact of the size of the basis set. Indeed, all terms above the 4-body converge monotonically to practically zero at the Complete Basis Set (CBS) limit. The magnitudes of the 5-body and above terms are accurately reproduced even with the smaller basis set of the series (aug-cc-pVDZ) once the BSSE correction is taken into account. The same level of theory (MP2/aug-cc-pVDZ, BSSEcorrected) also accurately reproduces the MP2/CBS values of the 3- and 4-body terms. The contribution of electron correlation to the 3- and 4-body terms is quite small, so that neglecting the correlation contribution in all terms above the 3-body results in an error of ??(0.1%). The BSSE correction to the largest 2-body term in the MBE was accurately estimated from the function ?? [1 + erf(-?? ??)], which is proportional to the common (overlapping) area between two Gaussian distributions whose centers are separated by R, with the constants ??, ?? fitted to the calculated BSSE corrections for the individual 2-body terms of the clusters with each basis set. Our results unquestionably demonstrate that the MBE for water-water interactions converges to the 4-body term, since any finite terms above the 4-body are artifacts of the size of the basis set and can be safely truncated at the 4-body term when either a very large basis set is used or BSSE corrections are taken into account even with the aug-cc-pVDZ basis set. We expect these findings to have important consequences in the pursuit of accurate many-body molecular dynamics simulations for aqueous systems.

Heindel, Joseph↗
DOE OSTI2023

Magic Numbers and Stabilities of Photoionized Water Clusters: Computational and Experimental Characterization of the Nanosolvated Hydronium Ion

The stability and distributions of small water clusters generated in a supersonic beam expansion are interrogated by tunable vacuum ultraviolet (VUV) radiation generated at a synchrotron. Time-of-flight mass spectrometry reveals enhanced population of various protonated water clusters (H + (H 2 O) $n$ ) based upon ionization energy and photoionization distance from source, suggesting there are "magic" numbers below the traditional $n$ = 21 that predominates in the literature. These intensity distributions suggest that VUV threshold photoionization (11.0-11.5 eV) of neutral water clusters close to the nozzle exit leads to a different nonequilibrium state compared to a skimmed molecular beam. This results in the appearance of a new magic number at 14. Metadynamics conformer searches coupled with modern density functional calculations are used to identify the global minimum energy structures of protonated water clusters between $n$ = 2 and 21, as well as the manifold of low-lying metastable minima. New lowest energy structures are reported for the cases of $n$ = 5, 6, 11, 12, 16, and 18, and special stability is identified by several measures. These theoretical results are in agreement with the experiments performed in this work in that $n$ = 14 is shown to exhibit additional stability, based on the computed second-order stabilization energy relative to most cluster sizes, though not to the extent of the well-known $n$ = 21 cluster. Other cluster sizes that show some additional energetic stability are $n$ = 7, 9, 12, 17, and 19. To gain insight into the balance between ion-water and water-water interactions as a function of the cluster size, an analysis of the effective two-body interactions (which sum exactly to the total interaction energy) was performed. In conclusion, this analysis reveals a crossover as a function of cluster size between a water-hydronium-dominated regime for small clusters and a water-water-dominated regime for larger clusters around $n$ = 17.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Source of Bright Near-Infrared Luminescence in Gold Nanoclusters

Gold nanoclusters with near-infrared (NIR) photoluminescence (PL) have great potential as sensing and imaging materials in biomedical and bioimaging applications. In this work, Au 21 (S-Adm) 15 and Au 38 S 2 (S-Adm) 20 are used to unravel the underlying mechanisms for the improved quantum yields (QY), large Stokes shifts and long PL lifetimes in gold nanoclusters. Both nanoclusters show decent PL QY. In particular, the Au 38 S 2 (S-Adm) 20 nanocluster shows a bright NIR PL at 900 nm with QY up to 15% in normal solvents (such as toluene) at ambient conditions. The relatively lower QY for Au 21 (S-Adm) 15 (4%) compared to Au 38 S 2 (S-Adm) 20 is attributed to the lowest-lying excited state being symmetry-disallowed, as evidenced by the pressure-dependent anti-spectral shift of the absorption spectra compared to PL. Yet, Au 21 (S-Adm) 15 maintains some emissive properties due to a nearby symmetry-allowed excited state. Furthermore, our results show that suppression of non-radiative decay due to the surface “lock rings” which encircle the Au kernel and the surface “lock atoms” which bridge the fundamental Au-kernel units (e.g., tetrahedra, icosahedra, etc.) is the key to obtain high QYs in gold nanoclusters. Here, the complicated excited-state processes and the small absorption coefficient of the band-edge transition lead to the large Stokes shifts and the long PL lifetimes that are widely observed in gold nanoclusters.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Shock compression response of an insensitive high explosive single crystal: 1,1-diamino-2,2-dinitroethene (FOX-7)

Insensitive high explosives (IHEs) – that do not compromise performance – are of immense interest as a safer alternative to conventional high explosives, such as pentaerythritol tetranitrate (PETN) and cyclotrimethylenetrinitramine (RDX). Despite the strong interest in using IHEs, shock compression experiments on IHE single crystals have not been reported. To address this need, plate impact experiments were conducted to measure wave profiles in 1,1-diamino-2,2-dinitroethene (FOX-7) single crystals – a representative IHE crystal – shocked to 21 GPa longitudinal stress. Particle velocity histories, measured using laser interferometry, show a clear two-wave structure (elastic-inelastic response) at modest stresses (<3.8 GPa). Wave profiles at higher stresses show a single (overdriven) wave. Measured shock velocities and wave profiles provide accurate Hugoniot data to 21 GPa. The measured wave profiles to 21 GPa show no sign of energy release due to chemical decomposition and constitute the first demonstration of an IHE single crystal insensitivity under plane shock compression. Numerical simulations using a phenomenological material model developed for FOX-7 showed good agreement with the measured wave profiles. The experimental results and continuum simulations presented here constitute a significant first step in gaining insight into the shock compression response of IHE single crystals.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2021

Mind the gap: the power of combining photometric surveys with intensity mapping

The long wavelength modes lost to bright foregrounds in the interferometric 21-cm surveys can partially be recovered using a forward modeling approach that exploits the non-linear coupling between small and large scales induced by gravitational evolution. In this work, we build upon this approach by considering how adding external galaxy distribution data can help to fill in these modes. We consider supplementing the 21-cm data at two different redshifts with a spectroscopic sample (good radial resolution but low number density) loosely modeled on DESI-ELG at z=1 and a photometric sample (high number density but poor radial resolution) similar to LSST sample at z=1 and z=4 respectively. We find that both the galaxy samples are able to reconstruct the largest modes better than only using 21-cm data, with the spectroscopic sample performing significantly better than the photometric sample despite much lower number density. Here, we demonstrate the synergies between surveys by showing that the primordial initial density field is reconstructed better with the combination of surveys than using either of them individually. Methodologically, we also explore the importance of smoothing the density field when using bias models to forward model these tracers for reconstruction.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2026

Effects of primordial black holes on IGM history

Currently the asteroid mass window (mass ∼ 10$^{17}$- 10$^{21}$ grams) remains unconstrained for Primordial Black Holes (PBHs) to make up all of the dark matter content of the universe. Given these PBHs have very small masses, their Hawking temperature can be up to hundreds of keV. This study investigates the potential impacts of PBH Hawking radiation on the intergalactic medium from z ∼ 800-25, namely studying the ionization history, kinetic gas temperature, and ultimately the 21 cm signature. We find that for masses on the low edge of the asteroid mass window, there are up two orders of magnitude increases in the ionization fraction and kinetic gas temperature by redshift 25, and the 21 cm spin temperature can differ from non-PBH cosmology by factors of a few. This analysis results in maximum differential brightness temperatures of +17 mK for our lightest PBH masses of 2.12 × 10$^{16}$g. We also show maximal 53 mK discrepancies in differential brightness temperatures between our PBH and non-PBH cosmologies for our lightest PBH mass, while our heaviest PBH mass of 1.65 × 10$^{17}$g shows only 0.5 mK variations. We find the Hawking-radiated electrons and positrons are instrumental in driving these IGM modifications. This study shows the necessity for a rigorous treatment of Hawking radiation in PBH cosmological observables from the dark ages through cosmic dawn.

dark matter theory↗
DOE OSTI2022

Electron spin coherence on a solid neon surface

We report a single electron floating on the surface of a condensed noble-gas liquid or solid can act as a spin qubit with ultralong coherence time, thanks to the extraordinary purity of such systems. Previous studies suggest that the electron spin coherence time on a superfluid helium (He) surface can exceed 100 s. In this paper, we present theoretical studies of the electron spin coherence on a solid neon (Ne) surface, motivated by our recent experimental realization of single-electron charge qubit on solid Ne. The major spin decoherence mechanisms investigated include the fluctuating Ne diamagnetic susceptibility due to thermal phonons, the fluctuating thermal current in normal metal electrodes, and the quasi-statically fluctuating nuclear spins of the 21 Ne ensemble. We find that at a typical experimental temperature about 10 mK in a fully superconducting device, the electron spin decoherence is dominated by the third mechanism via electron–nuclear spin–spin interaction. For natural Ne with 2700 ppm abundance of 21 Ne, the estimated inhomogeneous dephasing time ${T}_{2}^{*}$ is around 0.16 ms, already better than most semiconductor quantum-dot spin qubits. For commercially available, isotopically purified Ne with 1 ppm of 21 Ne, ${T}_{2}^{*}$ can be 0.43 s. Under the application of Hahn echoes, the coherence time T 2 can be improved to 30 ms for natural Ne and 81 s for purified Ne. Therefore, the single-electron spin qubits on solid Ne can serve as promising new spin qubits.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2025

Measurement of Reactor Antineutrino Oscillation at SNO+

SNO+ Collaboration reports its second spectral analysis of reactor antineutrino oscillation using 286 ton-yr of new data. The measured energies of reactor antineutrino candidates were fitted to obtain the second-most precise determination of the neutrino mass-squared difference Δ⁢𝑚$^{2}_{21}$=⁢(7.96$^{+0.48}_{ −0.42}$) × 10 −5 eV2. Constraining Δ⁢𝑚$^{2}_{21}$ and sin 2 ⁡𝜃 12 with measurements from long-baseline reactor antineutrino and solar neutrino experiments yields Δ⁢𝑚$^{2}_{21}$=(7.58$^{+0.18}_{−0.17}$) × 10 −5 eV 2 and sin 2 ⁡𝜃 12 = 0.308 ± 0.013. This fit also yields a first measurement of the flux of geoneutrinos in the Western Hemisphere, with 73$^{+47}_{−43}$ TNU at SNO+.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Solar neutrino measurements using the full data period of Super-Kamiokande-IV

An analysis of solar neutrino data from the fourth phase of Super-Kamiokande (SK-IV) from October 2008 to May 2018 is performed and the results are presented. The observation time of the dataset of SK-IV corresponds to 2970 days and the total live time for all four phases is 5805 days. For more precise solar neutrino measurements, several improvements are applied in this analysis: lowering the data acquisition threshold in May 2015, further reduction of the spallation background using neutron clustering events, precise energy reconstruction considering the time variation of the PMT gain. The observed number of solar neutrino events in 3.49–19.49 MeV electron kinetic energy region during SK-IV is 65,443 − 388 + 390 ( stat . ) ± 925 ( syst . ) events. Corresponding B 8 solar neutrino flux is ( 2.314 ± 0.014 ( stat . ) ± 0.040 ( syst . ) ) × 10 6 cm − 2 s − 1 , assuming a pure electron-neutrino flavor component without neutrino oscillations. The flux combined with all SK phases up to SK-IV is ( 2.336 ± 0.011 ( stat . ) ± 0.043 ( syst . ) ) × 10 6 cm − 2 s − 1 . Based on the neutrino oscillation analysis from all solar experiments, including the SK 5805 days dataset, the best-fit neutrino oscillation parameters are sin 2 θ 12 , solar = 0.306 ± 0.013 and Δ m 21 , solar 2 = ( 6.1 0 − 0.81 + 0.95 ) × 10 − 5 eV 2 , with a deviation of about 1.5 σ from the Δ m 21 2 parameter obtained by KamLAND. The best-fit neutrino oscillation parameters obtained from all solar experiments and KamLAND are sin 2 θ 12 , global = 0.307 ± 0.012 and Δ m 21 , global 2 = ( 7.5 0 − 0.18 + 0.19 ) × 10 − 5 eV 2 . Published by the American Physical Society 2024

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Exploring solar neutrino oscillation parameters with the liquid scintillator counter at Yemilab with a comparison to JUNO

We investigate the sensitivities of the liquid scintillator counter (LSC) at Yemilab and JUNO to solar neutrino oscillation parameters, focusing on θ 12 and Δ m 21 2 . We compare the potential of JUNO with LSC at Yemilab utilizing both reactor and solar data in determining those parameters. We find that the solar neutrino data of LSC at Yemilab is highly sensitive to θ 12 enabling its determination with a higher precision compared to reactor experiments. Our study also reveals that if Δ m 21 2 is larger, with a value close to the best-fit value of KamLAND, JUNO reactor data will have about two times better precision than the reactor LSC at Yemilab. On the other hand, if Δ m 21 2 is smaller and closer to the best-fit value of solar neutrino experiments, the precision of the reactor LSC at Yemilab will be better than JUNO. Published by the American Physical Society 2024

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Improving cosmological analyses of HI clustering by reducing stochastic noise

High-number-density tracers of large-scale structure, such as the HI-rich galaxies measured by 21 cm intensity mapping, have low sampling noise, making them particularly promising as cosmological probes. At large scales, this sampling noise can be subdominant to other scale-independent contributions to the power spectrum; such contributions arise from nonlinear bias, and exceed the sampling noise if at least one of the associated bias coefficients is sufficiently large. This has important consequences for cosmological constraints obtained from such tracers, since it indicates that using the power spectrum does not lead to optimal constraints even in the linear regime. In this paper, we provide a conservative estimate of the possible improvement in constraining power of a 21 cm survey if one were to use an optimal analysis strategy (such as field-level analysis), where only the true sampling noise enters the error budget. We find that improvements in uncertainties on some cosmological parameters can be as large as 50%, depending on redshift, foreground cleaning efficiency, scales used in the analysis, and instrumental noise. One byproduct of our work is measurements of bias parameters and stochasticity for neutral hydrogen in the IllustrisTNG simulation over a wide range of redshifts; we provide simple fitting formulas for these measurements. Furthermore, our results motivate further exploration of new optimal analysis techniques and provide important insights into the constraining power of current and future 21 cm surveys.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

Initial measurement of reactor antineutrino oscillation at SNO+

The SNO+ collaboration reports its first spectral analysis of long-baseline reactor antineutrino oscillation using 114 tonne-years of data. Fitting the neutrino oscillation probability to the observed energy spectrum yields constraints on the neutrino mass-squared difference Δ$m^2_{21}$. In the ranges allowed by previous measurements, the best-fit Δ$m^2_{21}$ is ($8.85^{+1.10}_{-1.33}$) × 10 -5 eV 2 . This measurement is continuing in the next phases of SNO+ and is expected to surpass the present global precision on Δ$m^2_{21}$ with about three years of data. In the following, we first describe the configuration of the SNO+ detector when it was partially filled with scintillator, and a characterization of the detector response using intrinsic radioactivity. Next, we detail the event selection and expectations for reactor IBDs and (α, n) reactions. Then, we present the results of an energy spectrum analysis using 114 tonne-years of data. We conclude with prospects of future results from the SNO+ detector, which has been operating fully-filled with 780 tonnes of scintillator

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Materials Data on Ba4Sm2Cd3S10 by Materials Project

Ba4Sm2Cd3S10 crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. there are four inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Ba–S bond distances ranging from 3.17–3.68 Å. In the second Ba2+ site, Ba2+ is bonded to seven S2- atoms to form distorted BaS7 pentagonal bipyramids that share corners with two equivalent SmS6 octahedra, corners with two equivalent BaS7 pentagonal bipyramids, edges with three SmS6 octahedra, edges with three equivalent BaS7 pentagonal bipyramids, edges with two equivalent CdS4 tetrahedra, edges with two equivalent CdS4 trigonal pyramids, and faces with two equivalent BaS7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 16°. There are a spread of Ba–S bond distances ranging from 3.13–3.33 Å. In the third Ba2+ site, Ba2+ is bonded to seven S2- atoms to form distorted BaS7 pentagonal bipyramids that share corners with two equivalent SmS6 octahedra, corners with two equivalent BaS7 pentagonal bipyramids, corners with two equivalent CdS4 tetrahedra, corners with five CdS4 trigonal pyramids, edges with three SmS6 octahedra, edges with three equivalent BaS7 pentagonal bipyramids, an edgeedge with one CdS4 trigonal pyramid, and faces with two equivalent BaS7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 21°. There are a spread of Ba–S bond distances ranging from 3.18–3.38 Å. In the fourth Ba2+ site, Ba2+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Ba–S bond distances ranging from 3.15–3.59 Å. There are two inequivalent Sm3+ sites. In the first Sm3+ site, Sm3+ is bonded to six S2- atoms to form SmS6 octahedra that share corners with two equivalent BaS7 pentagonal bipyramids, edges with two equivalent SmS6 octahedra, edges with three BaS7 pentagonal bipyramids, and edges with four CdS4 trigonal pyramids. There are a spread of Sm–S bond distances ranging from 2.80–2.88 Å. In the second Sm3+ site, Sm3+ is bonded to six S2- atoms to form SmS6 octahedra that share corners with two equivalent BaS7 pentagonal bipyramids, corners with three equivalent CdS4 tetrahedra, edges with two equivalent SmS6 octahedra, and edges with three BaS7 pentagonal bipyramids. There are a spread of Sm–S bond distances ranging from 2.81–2.85 Å. There are three inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to four S2- atoms to form CdS4 tetrahedra that share corners with three equivalent SmS6 octahedra, corners with two equivalent BaS7 pentagonal bipyramids, corners with two equivalent CdS4 tetrahedra, a cornercorner with one CdS4 trigonal pyramid, and edges with two equivalent BaS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 5–72°. There are a spread of Cd–S bond distances ranging from 2.49–2.71 Å. In the second Cd2+ site, Cd2+ is bonded to four S2- atoms to form distorted CdS4 trigonal pyramids that share corners with two equivalent BaS7 pentagonal bipyramids, corners with two equivalent CdS4 trigonal pyramids, edges with two equivalent SmS6 octahedra, and an edgeedge with one BaS7 pentagonal bipyramid. There are a spread of Cd–S bond distances ranging from 2.46–2.74 Å. In the third Cd2+ site, Cd2+ is bonded to four S2- atoms to form distorted CdS4 trigonal pyramids that share corners with three equivalent BaS7 pentagonal bipyramids, a cornercorner with one CdS4 tetrahedra, corners with two equivalent CdS4 trigonal pyramids, edges with two equivalent SmS6 octahedra, and edges with two equivalent BaS7 pentagonal bipyramids. There are a spread of Cd–S bond distances ranging from 2.55–2.70 Å. There are ten inequivalent S2- sites. In the first S2- site, S2- is bonded to three Ba2+ and two equivalent Sm3+ atoms to form distorted SBa3Sm2 trigonal bipyramids that share corners with six SBa4Cd square pyramids, edges with two equivalent SBa4SmCd octahedra, edges with two SBa3Sm2 square pyramids, and edges with two equivalent SBa3Sm2 trigonal bipyramids. In the second S2- site, S2- is bonded to three Ba2+ and two equivalent Sm3+ atoms to form distorted SBa3Sm2 square pyramids that share corners with four equivalent SBa4Cd2 octahedra, corners with two equivalent SBa2SmCd2 square pyramids, corners with two equivalent SBa3Sm2 trigonal bipyramids, edges with five SBa4Cd2 octahedra, edges with three SBa3Sm2 square pyramids, and an edgeedge with one SBa3Sm2 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 40–51°. In the third S2- site, S2- is bonded in a 5-coordinate geometry to two equivalent Ba2+, one Sm3+, and two equivalent Cd2+ atoms. In the fourth S2- site, S2- is bonded to two equivalent Ba2+, one Sm3+, and two equivalent Cd2+ atoms to form distorted SBa2SmCd2 square pyramids that share corners with two equivalent SBa4Cd2 octahedra, corners with four SBa3Sm2 square pyramids, edges with three SBa4Cd2 octahedra, and edges with three SBa3Sm2 square pyramids. The corner-sharing octahedral tilt angles are 54°. In the fifth S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to two Ba2+, one Sm3+, and two equivalent Cd2+ atoms. In the sixth S2- site, S2- is bonded to four Ba2+ and one Cd2+ atom to form distorted SBa4Cd square pyramids that share corners with two equivalent SBa4SmCd octahedra, corners with two equivalent SBa2SmCd2 square pyramids, corners with four equivalent SBa3Sm2 trigonal bipyramids, an edgeedge with one SBa4SmCd octahedra, edges with two equivalent SBa4Cd square pyramids, and an edgeedge with one SBa3Sm2 trigonal bipyramid. The corner-sharing octahedral tilt angles are 40°. In the seventh S2- site, S2- is bonded to four Ba2+ and two Cd2+ atoms to form distorted SBa4Cd2 octahedra that share corners with six SBa4SmCd octahedra, corners with six SBa3Sm2 square pyramids, edges with two equivalent SBa4Cd2 octahedra, edges with two SBa2SmCd2 square pyramids, and faces with two SBa4SmCd octahedra. The corner-sharing octahedra tilt angles range from 41–58°. In the eighth S2- site, S2- is bonded to four Ba2+, one Sm3+, and one Cd2+ atom to form SBa4SmCd octahedra that share corners with four SBa4Cd2 octahedra, corners with two equivalent SBa4Cd square pyramids, edges with three SBa4SmCd octahedra, edges with three SBa3Sm2 square pyramids, edges with two equivalent SBa3Sm2 trigonal bipyramids, and a faceface with one SBa4Cd2 octahedra. The corner-sharing octahedra tilt angles range from 21–54°. In the ninth S2- site, S2- is bonded in a 6-coordinate geometry to three Ba2+, two equivalent Sm3+, and one Cd2+ atom. In the tenth S2- site, S2- is bonded to three Ba2+, two equivalent Sm3+, and one Cd2+ atom to form SBa3Sm2Cd octahedra that share corners with six SBa4Cd2 octahedra, edges with three SBa4SmCd octahedra, edges with four SBa3Sm2 square pyramids, and a faceface with one SBa4Cd2 octahedra. The corner-sharing octahedra tilt angles range from 21–58°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba4Tb2Cd3S10 by Materials Project

Ba4Tb2Cd3S10 crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. there are four inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Ba–S bond distances ranging from 3.16–3.76 Å. In the second Ba2+ site, Ba2+ is bonded to seven S2- atoms to form distorted BaS7 pentagonal bipyramids that share corners with two equivalent TbS6 octahedra, corners with two equivalent BaS7 pentagonal bipyramids, edges with three TbS6 octahedra, edges with three equivalent BaS7 pentagonal bipyramids, edges with two equivalent CdS4 tetrahedra, edges with two equivalent CdS4 trigonal pyramids, and faces with two equivalent BaS7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 16°. There are a spread of Ba–S bond distances ranging from 3.11–3.33 Å. In the third Ba2+ site, Ba2+ is bonded to seven S2- atoms to form distorted BaS7 pentagonal bipyramids that share corners with two equivalent TbS6 octahedra, corners with two equivalent BaS7 pentagonal bipyramids, corners with two equivalent CdS4 tetrahedra, corners with five CdS4 trigonal pyramids, edges with three TbS6 octahedra, edges with three equivalent BaS7 pentagonal bipyramids, an edgeedge with one CdS4 trigonal pyramid, and faces with two equivalent BaS7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 21°. There are a spread of Ba–S bond distances ranging from 3.17–3.36 Å. In the fourth Ba2+ site, Ba2+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Ba–S bond distances ranging from 3.14–3.57 Å. There are two inequivalent Tb3+ sites. In the first Tb3+ site, Tb3+ is bonded to six S2- atoms to form TbS6 octahedra that share corners with two equivalent BaS7 pentagonal bipyramids, edges with two equivalent TbS6 octahedra, edges with three BaS7 pentagonal bipyramids, and edges with four CdS4 trigonal pyramids. There are a spread of Tb–S bond distances ranging from 2.77–2.84 Å. In the second Tb3+ site, Tb3+ is bonded to six S2- atoms to form TbS6 octahedra that share corners with two equivalent BaS7 pentagonal bipyramids, corners with three equivalent CdS4 tetrahedra, edges with two equivalent TbS6 octahedra, and edges with three BaS7 pentagonal bipyramids. There are a spread of Tb–S bond distances ranging from 2.77–2.81 Å. There are three inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to four S2- atoms to form CdS4 tetrahedra that share corners with three equivalent TbS6 octahedra, corners with two equivalent BaS7 pentagonal bipyramids, corners with two equivalent CdS4 tetrahedra, a cornercorner with one CdS4 trigonal pyramid, and edges with two equivalent BaS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 6–70°. There are a spread of Cd–S bond distances ranging from 2.48–2.72 Å. In the second Cd2+ site, Cd2+ is bonded to four S2- atoms to form distorted CdS4 trigonal pyramids that share corners with two equivalent BaS7 pentagonal bipyramids, corners with two equivalent CdS4 trigonal pyramids, edges with two equivalent TbS6 octahedra, and an edgeedge with one BaS7 pentagonal bipyramid. There are a spread of Cd–S bond distances ranging from 2.46–2.73 Å. In the third Cd2+ site, Cd2+ is bonded to four S2- atoms to form CdS4 trigonal pyramids that share corners with three equivalent BaS7 pentagonal bipyramids, a cornercorner with one CdS4 tetrahedra, corners with two equivalent CdS4 trigonal pyramids, edges with two equivalent TbS6 octahedra, and edges with two equivalent BaS7 pentagonal bipyramids. There are a spread of Cd–S bond distances ranging from 2.55–2.70 Å. There are ten inequivalent S2- sites. In the first S2- site, S2- is bonded to three Ba2+ and two equivalent Tb3+ atoms to form distorted SBa3Tb2 trigonal bipyramids that share corners with six SBa4Cd square pyramids, edges with two equivalent SBa4TbCd octahedra, edges with two SBa3Tb2 square pyramids, and edges with two equivalent SBa3Tb2 trigonal bipyramids. In the second S2- site, S2- is bonded to three Ba2+ and two equivalent Tb3+ atoms to form distorted SBa3Tb2 square pyramids that share corners with four equivalent SBa4Cd2 octahedra, corners with two equivalent SBa2TbCd2 square pyramids, corners with two equivalent SBa3Tb2 trigonal bipyramids, edges with five SBa4Cd2 octahedra, edges with three SBa3Tb2 square pyramids, and an edgeedge with one SBa3Tb2 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 40–50°. In the third S2- site, S2- is bonded in a 5-coordinate geometry to two equivalent Ba2+, one Tb3+, and two equivalent Cd2+ atoms. In the fourth S2- site, S2- is bonded to two equivalent Ba2+, one Tb3+, and two equivalent Cd2+ atoms to form distorted SBa2TbCd2 square pyramids that share corners with two equivalent SBa4Cd2 octahedra, corners with four SBa3Tb2 square pyramids, edges with three SBa4Cd2 octahedra, and edges with three SBa3Tb2 square pyramids. The corner-sharing octahedral tilt angles are 54°. In the fifth S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to two Ba2+, one Tb3+, and two equivalent Cd2+ atoms. In the sixth S2- site, S2- is bonded to four Ba2+ and one Cd2+ atom to form distorted SBa4Cd square pyramids that share corners with two equivalent SBa4TbCd octahedra, corners with two equivalent SBa2TbCd2 square pyramids, corners with four equivalent SBa3Tb2 trigonal bipyramids, an edgeedge with one SBa4TbCd octahedra, edges with two equivalent SBa4Cd square pyramids, and an edgeedge with one SBa3Tb2 trigonal bipyramid. The corner-sharing octahedral tilt angles are 41°. In the seventh S2- site, S2- is bonded to four Ba2+ and two Cd2+ atoms to form distorted SBa4Cd2 octahedra that share corners with six SBa4TbCd octahedra, corners with six SBa3Tb2 square pyramids, edges with two equivalent SBa4Cd2 octahedra, edges with two SBa2TbCd2 square pyramids, and faces with two SBa4TbCd octahedra. The corner-sharing octahedra tilt angles range from 41–59°. In the eighth S2- site, S2- is bonded to four Ba2+, one Tb3+, and one Cd2+ atom to form SBa4TbCd octahedra that share corners with four SBa4Cd2 octahedra, corners with two equivalent SBa4Cd square pyramids, edges with three SBa4TbCd octahedra, edges with three SBa3Tb2 square pyramids, edges with two equivalent SBa3Tb2 trigonal bipyramids, and a faceface with one SBa4Cd2 octahedra. The corner-sharing octahedra tilt angles range from 21–54°. In the ninth S2- site, S2- is bonded in a 6-coordinate geometry to three Ba2+, two equivalent Tb3+, and one Cd2+ atom. In the tenth S2- site, S2- is bonded to three Ba2+, two equivalent Tb3+, and one Cd2+ atom to form distorted SBa3Tb2Cd octahedra that share corners with six SBa4Cd2 octahedra, edges with three SBa4TbCd octahedra, edges with four SBa3Tb2 square pyramids, and a faceface with one SBa4Cd2 octahedra. The corner-sharing octahedra tilt angles range from 21–59°.

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