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At least 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Dy2CO5 by Materials Project

Dy2O2CO3 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Dy3+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Dy–O bond distances ranging from 2.29–2.61 Å. C4+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.28 Å) and two longer (1.30 Å) C–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent Dy3+ and one C4+ atom. In the second O2- site, O2- is bonded to four equivalent Dy3+ atoms to form a mixture of corner and edge-sharing ODy4 tetrahedra. In the third O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Dy3+ and one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YbBO3 by Materials Project

YbBO3 crystallizes in the orthorhombic Ama2 space group. The structure is three-dimensional. Yb3+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Yb–O bond distances ranging from 2.30–2.70 Å. B3+ is bonded in a trigonal planar geometry to three O2- atoms. All B–O bond lengths are 1.38 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent Yb3+ and one B3+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Yb3+ and one B3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La2CO5 by Materials Project

La2O2CO3 crystallizes in the orthorhombic Ama2 space group. The structure is three-dimensional. La3+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of La–O bond distances ranging from 2.42–2.84 Å. C4+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.29 Å) and two longer (1.30 Å) C–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent La3+ and one C4+ atom. In the second O2- site, O2- is bonded to four equivalent La3+ atoms to form a mixture of edge and corner-sharing OLa4 tetrahedra. In the third O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent La3+ and one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2021

The evolution of seafloor venting from hydrate-sealed gas reservoirs

Here we use 3D seismic data to show that three rows of seafloor gas mounds can be traced downward to leak points that lie at the hydrate-gas contact within three individual dipping coarse-grained sand bodies in the Terrebonne Basin, Walker Ridge block 313, northern Gulf of Mexico. We predict the overpressure within the sand bodies by assuming that the gas pressure at the vent points equal the least principal stress. We interpret that free gas accumulates at the base of the hydrate stability zone, trapped by the overlying sand which has a high methane hydrate saturation. The free gas accumulates until the gas pressure at the base of the hydrate stability zone reaches the least principal stress in the overlying mudrock, whereupon hydraulic fractures form and fluids are vented to the surface. The warm rising fluids and perhaps localized exothermic formation of hydrate raise the local salinity and temperature. This process progressively shifts the base of the hydrate stability zone to shallower depths and dissociates the hydrate seal within the sand, which creates new leak points and results in the observed migration of the seafloor vents. Within the southwest corner of the Terrebonne Basin, this process has repeated multiple times within the Blue, Orange, and Green sands. Here this study shows how the hydrate stability zone can influence the location of fluid expulsion and in turn be affected by the warm, rising, saline fluids sealed by hydrate.

58 GEOSCIENCES↗
DOE OSTI2025

Uncertainties in Simulating Flooding During Hurricane Harvey Using 2D Shallow Water Equations

Abstract Flooding is one of the most impactful weather‐related natural hazards. Numerical models that solve the two dimensional (2D) shallow water equations (SWE) represent the first‐principles approach to simulate all types of spatial flooding, such as pluvial, fluvial, and coastal flooding, and their compound dynamics. High spatial resolution (e.g., () m) is needed in 2D SWE simulations to capture flood dynamics accurately, resulting in formidable computational challenges. Thus, relatively coarser spatial resolutions are used for large‐scale simulations of flooding, which introduce uncertainties in the results. It is unclear how the uncertainty associated with the model resolution compares to the uncertainties in precipitation data sets and assumptions regarding boundary conditions when channelized flows interact with other water bodies. In this study, we compare these three sources of uncertainties in 2D SWE simulations for the 2017 Houston flooding event. Our results show that precipitation uncertainty and mesh resolution have more significant impacts on the simulated streamflow and inundation dynamics than the choice of the downstream boundary condition at the watershed outlet. We point out the viability to confine the uncertainty of coarsening mesh resolution by using the variable resolution mesh (VRM) which refines critical topographic features with far fewer grid cells. Specifically, in simulations with VRM, the simulated inundation depths over the refined region are comparable to that use the finest uniform mesh. This study contributes to understanding the challenges and pathways for applying 2D SWE models to improve the realism of flood simulations over large scales.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Ambiguity, invisibility, and negativity *

Abstract Many widely different problems have a common mathematical structure wherein limited knowledge leads to ambiguity that can be captured conveniently using a concept of invisibility that requires the introduction of negative values for quantities that are inherently positive. Here I analyze three examples taken from perception theory, rigid body mechanics, and quantum measurement.

Physics↗
DOE OSTI2025

Structure and dynamics of open-shell nuclei from spherical coupled-cluster theory

We extend the spherical coupled-cluster ab initio method for open-shell nuclei where two nucleons are removed from a shell subclosure. Following the recent implementation of the two-particle-attached approach [Phys. Rev. C 110, 044306 (2024)], we focus on the two-particle-removed method. Using the equations-of-motion framework, we address both nuclear structure and dipole response functions by coupling coupled-cluster theory with the Lorentz integral transform technique. We perform calculations using chiral interactions, including three-nucleon forces, and estimate many-body uncertainties by comparing different coupled-cluster truncation schemes. Here, we validate our approach by studying ground-state energies, excited states, and electric dipole polarizabilities in the oxygen and calcium isotopic chains. For binding energies and selected low-lying excited states, we achieve an accuracy comparable to that of the established closed-shell coupled-cluster theory and generally agree with experiment. Finally, we underestimate experimental data for electric dipole polarizabilities, particularly in calcium isotopes.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Materials Data on LaMo6(SeS)4 by Materials Project

LaMo6(SeS)4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. La3+ is bonded in a body-centered cubic geometry to four Se2- and four S2- atoms. There are a spread of La–Se bond distances ranging from 3.08–3.20 Å. There are a spread of La–S bond distances ranging from 2.85–3.18 Å. There are six inequivalent Mo+2.17+ sites. In the first Mo+2.17+ site, Mo+2.17+ is bonded to three Se2- and two S2- atoms to form a mixture of edge and corner-sharing MoSe3S2 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.56–2.70 Å. There are one shorter (2.41 Å) and one longer (2.53 Å) Mo–S bond lengths. In the second Mo+2.17+ site, Mo+2.17+ is bonded to three Se2- and two S2- atoms to form a mixture of edge and corner-sharing MoSe3S2 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.57–2.72 Å. There are one shorter (2.42 Å) and one longer (2.47 Å) Mo–S bond lengths. In the third Mo+2.17+ site, Mo+2.17+ is bonded to two Se2- and three S2- atoms to form a mixture of edge and corner-sharing MoSe2S3 square pyramids. There are one shorter (2.58 Å) and one longer (2.69 Å) Mo–Se bond lengths. There are a spread of Mo–S bond distances ranging from 2.42–2.54 Å. In the fourth Mo+2.17+ site, Mo+2.17+ is bonded to two Se2- and three S2- atoms to form a mixture of edge and corner-sharing MoSe2S3 square pyramids. There are one shorter (2.60 Å) and one longer (2.68 Å) Mo–Se bond lengths. There are a spread of Mo–S bond distances ranging from 2.42–2.68 Å. In the fifth Mo+2.17+ site, Mo+2.17+ is bonded to three Se2- and two S2- atoms to form a mixture of edge and corner-sharing MoSe3S2 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.60–2.74 Å. There are one shorter (2.42 Å) and one longer (2.48 Å) Mo–S bond lengths. In the sixth Mo+2.17+ site, Mo+2.17+ is bonded to three Se2- and two S2- atoms to form a mixture of edge and corner-sharing MoSe3S2 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.58–2.69 Å. There are one shorter (2.41 Å) and one longer (2.67 Å) Mo–S bond lengths. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to one La3+ and four Mo+2.17+ atoms. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to one La3+ and four Mo+2.17+ atoms. In the third Se2- site, Se2- is bonded in a 5-coordinate geometry to one La3+ and four Mo+2.17+ atoms. In the fourth Se2- site, Se2- is bonded in a 5-coordinate geometry to one La3+ and four Mo+2.17+ atoms. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a 4-coordinate geometry to one La3+ and three Mo+2.17+ atoms. In the second S2- site, S2- is bonded in a 4-coordinate geometry to one La3+ and three Mo+2.17+ atoms. In the third S2- site, S2- is bonded in a 5-coordinate geometry to one La3+ and four Mo+2.17+ atoms. In the fourth S2- site, S2- is bonded in a 5-coordinate geometry to one La3+ and four Mo+2.17+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba4Na(FeAs)10 by Materials Project

NaBa4(FeAs)10 is alpha bismuth trifluoride-derived structured and crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. Na1+ is bonded in a body-centered cubic geometry to eight equivalent As3- atoms. All Na–As bond lengths are 3.37 Å. Ba2+ is bonded in a body-centered cubic geometry to eight As3- atoms. There are a spread of Ba–As bond distances ranging from 3.36–3.43 Å. There are two inequivalent Fe+2.10+ sites. In the first Fe+2.10+ site, Fe+2.10+ is bonded to four As3- atoms to form a mixture of edge and corner-sharing FeAs4 tetrahedra. There are three shorter (2.32 Å) and one longer (2.33 Å) Fe–As bond lengths. In the second Fe+2.10+ site, Fe+2.10+ is bonded to four equivalent As3- atoms to form a mixture of edge and corner-sharing FeAs4 tetrahedra. All Fe–As bond lengths are 2.33 Å. There are two inequivalent As3- sites. In the first As3- site, As3- is bonded in a 8-coordinate geometry to one Na1+, three equivalent Ba2+, and four Fe+2.10+ atoms. In the second As3- site, As3- is bonded in a 8-coordinate geometry to four equivalent Ba2+ and four equivalent Fe+2.10+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca3Fe7(SiO4)6 by Materials Project

Ca3Fe7(SiO4)6 crystallizes in the cubic I4_132 space group. The structure is three-dimensional. Ca2+ is bonded in a distorted body-centered cubic geometry to eight equivalent O2- atoms. There are four shorter (2.38 Å) and four longer (2.50 Å) Ca–O bond lengths. There are two inequivalent Fe+2.57+ sites. In the first Fe+2.57+ site, Fe+2.57+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six equivalent SiO4 tetrahedra. There are three shorter (2.01 Å) and three longer (2.05 Å) Fe–O bond lengths. In the second Fe+2.57+ site, Fe+2.57+ is bonded in a distorted body-centered cubic geometry to eight equivalent O2- atoms. There are four shorter (2.29 Å) and four longer (2.45 Å) Fe–O bond lengths. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with four equivalent FeO6 octahedra. The corner-sharing octahedra tilt angles range from 47–50°. All Si–O bond lengths are 1.66 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Fe+2.57+ and one Si4+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ca2+, one Fe+2.57+, and one Si4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U4BiO10 by Materials Project

U4BiO10 is alpha bismuth trifluoride-derived structured and crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. U+4.25+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of U–O bond distances ranging from 2.32–2.35 Å. Bi3+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Bi–O bond lengths are 2.43 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to three equivalent U+4.25+ and one Bi3+ atom to form a mixture of edge and corner-sharing OU3Bi tetrahedra. In the second O2- site, O2- is bonded to four equivalent U+4.25+ atoms to form a mixture of edge and corner-sharing OU4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaDy(Pd3O4)2 by Materials Project

NaDy(Pd3O4)2 crystallizes in the cubic Pm-3 space group. The structure is three-dimensional. Na1+ is bonded in a body-centered cubic geometry to eight O2- atoms. All Na–O bond lengths are 2.62 Å. Dy3+ is bonded in a body-centered cubic geometry to eight O2- atoms. All Dy–O bond lengths are 2.42 Å. Pd2+ is bonded in a square co-planar geometry to four O2- atoms. All Pd–O bond lengths are 2.06 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to one Na1+, one Dy3+, and three equivalent Pd2+ atoms to form a mixture of edge and corner-sharing ONaDyPd3 trigonal bipyramids. In the second O2- site, O2- is bonded to one Na1+, one Dy3+, and three equivalent Pd2+ atoms to form a mixture of edge and corner-sharing ONaDyPd3 trigonal bipyramids. All O–Pd bond lengths are 2.06 Å. In the third O2- site, O2- is bonded to one Na1+, one Dy3+, and three equivalent Pd2+ atoms to form a mixture of edge and corner-sharing ONaDyPd3 trigonal bipyramids. All O–Pd bond lengths are 2.06 Å. In the fourth O2- site, O2- is bonded to one Na1+, one Dy3+, and three equivalent Pd2+ atoms to form a mixture of edge and corner-sharing ONaDyPd3 trigonal bipyramids. In the fifth O2- site, O2- is bonded to one Na1+, one Dy3+, and three equivalent Pd2+ atoms to form a mixture of edge and corner-sharing ONaDyPd3 trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaYb(Pd3O4)2 by Materials Project

NaYb(Pd3O4)2 crystallizes in the cubic Pm-3 space group. The structure is three-dimensional. Na1+ is bonded in a body-centered cubic geometry to eight O2- atoms. All Na–O bond lengths are 2.57 Å. Yb3+ is bonded in a body-centered cubic geometry to eight O2- atoms. All Yb–O bond lengths are 2.43 Å. Pd2+ is bonded in a square co-planar geometry to four O2- atoms. All Pd–O bond lengths are 2.05 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to one Na1+, one Yb3+, and three equivalent Pd2+ atoms to form a mixture of edge and corner-sharing ONaYbPd3 trigonal bipyramids. In the second O2- site, O2- is bonded to one Na1+, one Yb3+, and three equivalent Pd2+ atoms to form a mixture of edge and corner-sharing ONaYbPd3 trigonal bipyramids. All O–Pd bond lengths are 2.05 Å. In the third O2- site, O2- is bonded to one Na1+, one Yb3+, and three equivalent Pd2+ atoms to form a mixture of edge and corner-sharing ONaYbPd3 trigonal bipyramids. All O–Pd bond lengths are 2.05 Å. In the fourth O2- site, O2- is bonded to one Na1+, one Yb3+, and three equivalent Pd2+ atoms to form a mixture of edge and corner-sharing ONaYbPd3 trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaEr(Pd3O4)2 by Materials Project

NaEr(Pd3O4)2 crystallizes in the cubic Pm-3 space group. The structure is three-dimensional. Na1+ is bonded in a body-centered cubic geometry to eight O2- atoms. All Na–O bond lengths are 2.62 Å. Er3+ is bonded in a body-centered cubic geometry to eight O2- atoms. All Er–O bond lengths are 2.42 Å. Pd2+ is bonded in a square co-planar geometry to four O2- atoms. All Pd–O bond lengths are 2.06 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to one Na1+, one Er3+, and three equivalent Pd2+ atoms to form a mixture of edge and corner-sharing ONaErPd3 trigonal bipyramids. In the second O2- site, O2- is bonded to one Na1+, one Er3+, and three equivalent Pd2+ atoms to form a mixture of edge and corner-sharing ONaErPd3 trigonal bipyramids. All O–Pd bond lengths are 2.06 Å. In the third O2- site, O2- is bonded to one Na1+, one Er3+, and three equivalent Pd2+ atoms to form a mixture of edge and corner-sharing ONaErPd3 trigonal bipyramids. All O–Pd bond lengths are 2.06 Å. In the fourth O2- site, O2- is bonded to one Na1+, one Er3+, and three equivalent Pd2+ atoms to form a mixture of edge and corner-sharing ONaErPd3 trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaTm(Pd3O4)2 by Materials Project

NaTm(Pd3O4)2 crystallizes in the cubic Pm-3 space group. The structure is three-dimensional. Na1+ is bonded in a body-centered cubic geometry to eight O2- atoms. All Na–O bond lengths are 2.63 Å. Tm3+ is bonded in a body-centered cubic geometry to eight O2- atoms. All Tm–O bond lengths are 2.40 Å. Pd2+ is bonded in a square co-planar geometry to four O2- atoms. All Pd–O bond lengths are 2.06 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to one Na1+, one Tm3+, and three equivalent Pd2+ atoms to form a mixture of corner and edge-sharing ONaTmPd3 trigonal bipyramids. In the second O2- site, O2- is bonded to one Na1+, one Tm3+, and three equivalent Pd2+ atoms to form a mixture of corner and edge-sharing ONaTmPd3 trigonal bipyramids. All O–Pd bond lengths are 2.06 Å. In the third O2- site, O2- is bonded to one Na1+, one Tm3+, and three equivalent Pd2+ atoms to form a mixture of corner and edge-sharing ONaTmPd3 trigonal bipyramids. In the fourth O2- site, O2- is bonded to one Na1+, one Tm3+, and three equivalent Pd2+ atoms to form a mixture of corner and edge-sharing ONaTmPd3 trigonal bipyramids. In the fifth O2- site, O2- is bonded to one Na1+, one Tm3+, and three equivalent Pd2+ atoms to form a mixture of corner and edge-sharing ONaTmPd3 trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Motif magnetism and quantum many-body scars

In this work, we generally expect quantum systems to thermalize and satisfy the eigenstate thermalization hypothesis (ETH), which states that finite-energy-density eigenstates are thermal. However, some systems, such as many-body localized systems and systems with quantum many-body scars, violate ETH and have high-energy athermal eigenstates. In systems with scars, most eigenstates thermalize, but a few atypical scar states do not. Scar states can give rise to a periodic revival when time-evolving particular initial product states, which can be detected experimentally. Recently, a family of spin Hamiltonians was found with magnetically ordered three-colored eigenstates that are quantum many-body scars [Lee et al., Phys. Rev. B 101, 241111(R) (2020)]. These models can be realized in any lattice that can be tiled by triangles, such as the triangular or kagome lattices, and have been shown to have close connections to the physics of quantum spin liquids in the Heisenberg kagome antiferromagnet. In this paper, we introduce a generalized family of n-colored Hamiltonians with “spiral colored” eigenstates made from n-spin motifs such as polygons or polyhedra. We show how these models can be realized in many different lattice geometries and provide numerical evidence that they can exhibit quantum many-body scars with periodic revivals that can be observed by time-evolving simple product states. The simple structure of these Hamiltonians makes them promising candidates for future experimental studies of quantum many-body scars.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SmMo6(SeS)4 by Materials Project

SmMo6(SeS)4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. Sm3+ is bonded in a body-centered cubic geometry to four Se2- and four S2- atoms. There are a spread of Sm–Se bond distances ranging from 2.84–3.11 Å. There are a spread of Sm–S bond distances ranging from 2.91–3.26 Å. There are six inequivalent Mo+2.17+ sites. In the first Mo+2.17+ site, Mo+2.17+ is bonded to two Se2- and three S2- atoms to form a mixture of edge and corner-sharing MoSe2S3 trigonal bipyramids. There are one shorter (2.53 Å) and one longer (2.73 Å) Mo–Se bond lengths. There are a spread of Mo–S bond distances ranging from 2.46–2.53 Å. In the second Mo+2.17+ site, Mo+2.17+ is bonded to three Se2- and two S2- atoms to form a mixture of edge and corner-sharing MoSe3S2 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.53–2.72 Å. There are one shorter (2.44 Å) and one longer (2.54 Å) Mo–S bond lengths. In the third Mo+2.17+ site, Mo+2.17+ is bonded to two Se2- and three S2- atoms to form MoSe2S3 square pyramids that share corners with three MoSe3S2 square pyramids, a cornercorner with one MoSe2S3 trigonal bipyramid, edges with four MoSe3S2 square pyramids, and an edgeedge with one MoSe2S3 trigonal bipyramid. There are one shorter (2.52 Å) and one longer (2.58 Å) Mo–Se bond lengths. There are a spread of Mo–S bond distances ranging from 2.46–2.64 Å. In the fourth Mo+2.17+ site, Mo+2.17+ is bonded to three Se2- and two S2- atoms to form MoSe3S2 square pyramids that share corners with four MoSe3S2 square pyramids, edges with four MoSe3S2 square pyramids, and an edgeedge with one MoSe2S3 trigonal bipyramid. There are a spread of Mo–Se bond distances ranging from 2.52–2.68 Å. There are one shorter (2.48 Å) and one longer (2.72 Å) Mo–S bond lengths. In the fifth Mo+2.17+ site, Mo+2.17+ is bonded to two Se2- and three S2- atoms to form MoSe2S3 square pyramids that share corners with three MoSe2S3 square pyramids, a cornercorner with one MoSe2S3 trigonal bipyramid, edges with four MoSe3S2 square pyramids, and an edgeedge with one MoSe2S3 trigonal bipyramid. There are one shorter (2.53 Å) and one longer (2.69 Å) Mo–Se bond lengths. There are a spread of Mo–S bond distances ranging from 2.45–2.70 Å. In the sixth Mo+2.17+ site, Mo+2.17+ is bonded to two Se2- and three S2- atoms to form MoSe2S3 square pyramids that share corners with three MoSe3S2 square pyramids, a cornercorner with one MoSe2S3 trigonal bipyramid, edges with four MoSe3S2 square pyramids, and an edgeedge with one MoSe2S3 trigonal bipyramid. There are one shorter (2.52 Å) and one longer (2.58 Å) Mo–Se bond lengths. There are a spread of Mo–S bond distances ranging from 2.49–2.64 Å. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to one Sm3+ and four Mo+2.17+ atoms. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to one Sm3+ and four Mo+2.17+ atoms. In the third Se2- site, Se2- is bonded in a 1-coordinate geometry to one Sm3+ and three Mo+2.17+ atoms. In the fourth Se2- site, Se2- is bonded in a 1-coordinate geometry to one Sm3+ and three Mo+2.17+ atoms. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a 5-coordinate geometry to one Sm3+ and four Mo+2.17+ atoms. In the second S2- site, S2- is bonded in a 5-coordinate geometry to one Sm3+ and four Mo+2.17+ atoms. In the third S2- site, S2- is bonded in a 5-coordinate geometry to one Sm3+ and four Mo+2.17+ atoms. In the fourth S2- site, S2- is bonded in a 5-coordinate geometry to one Sm3+ and four Mo+2.17+ atoms.

36 MATERIALS SCIENCE↗