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At least 163 records · Page 9
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DOE OSTI2020

Materials Data on Ho(SiOs)2 by Materials Project

HoOs2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ho3+ is bonded in a 8-coordinate geometry to eight equivalent Os+1.50- atoms. All Ho–Os bond lengths are 3.19 Å. Os+1.50- is bonded in a 4-coordinate geometry to four equivalent Ho3+ and four equivalent Si atoms. All Os–Si bond lengths are 2.40 Å. Si is bonded in a 5-coordinate geometry to four equivalent Os+1.50- and one Si atom. The Si–Si bond length is 2.46 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(NiP)2 by Materials Project

HoNi2P2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ho3+ is bonded in a distorted body-centered cubic geometry to eight equivalent P3- atoms. All Ho–P bond lengths are 2.96 Å. Ni+1.50+ is bonded to four equivalent P3- atoms to form a mixture of edge and corner-sharing NiP4 tetrahedra. All Ni–P bond lengths are 2.27 Å. P3- is bonded in a 9-coordinate geometry to four equivalent Ho3+, four equivalent Ni+1.50+, and one P3- atom. The P–P bond length is 2.29 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(MnSi)2 by Materials Project

HoMn2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ho3+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Ho–Si bond lengths are 3.01 Å. Mn+2.50+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing MnSi4 tetrahedra. All Mn–Si bond lengths are 2.36 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Ho3+, four equivalent Mn+2.50+, and one Si4- atom. The Si–Si bond length is 2.47 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Active Sites in the Dealuminated Beta Zeolite-Supported Cobalt Catalyst for Non-Oxidative Ethane Dehydrogenation

Dispersed metal species in siliceous zeolites have been actively studied for non-oxidative dehydrogenation of ethane (NDE). Fundamental insights into the dynamics of metal species in zeolites under reaction conditions have rarely been explored. Herein, we report an atomic level understanding of the dynamics and activity of cobalt (Co) sites in dealuminated Beta zeolite (DeAl-BEA) for NDE during induction and reaction conditions with extensive characterization techniques such as diffuse reflectance UV–vis, solid state nuclear magnetic resonance and X-ray photoelectron, X-ray diffraction along with in situ Fourier transform infrared and X-ray absorption spectroscopy. For a catalyst with 0.5 mass % Co loading, tetrahedral Co 2+ mononuclear sites, di-coordinated to the zeolite framework and with two silanol groups in vicinity (i.e., (≡SiO) 2 Co(HO–Si≡) 2 ), form upon exposure to hydrogen during induction and persist through the NDE reaction. Increasing the Co loading to 3.0 mass % yielded Co sites with similar electronic and coordination structures but slightly elongated Co–O bonds. Upon cooling to room temperature, the Co sites persisted in the same coordination environment, though the disappearance of a feature in the Co K-edge near-edge region revealed changes in the active site’s electronic structure coinciding with modest shifts in bond lengths. The electronic structure and activity of (≡SiO) 2 Co(HO–Si≡) 2 sites were studied comparatively to a few other hypothetical Co 2+ coordination structures, using electronic structure calculations and microkinetic simulations. The simulations showed that NDE is controlled by β-hydride elimination following C–H bond activation and that Co-sites possessing flexibility because of neighboring silanol defects are more active. Interestingly, dinuclear Co–O–Co sites (i.e., (≡SiO)Co(HO–Si≡) 2 –O–(HO–Si≡) 2 Co(≡SiO)) were more active than the mononuclear (≡SiO) 2 Co(HO–Si≡) 2 sites because of favorable hydrogen bonding with the vicinal silanol groups. In conclusion, the present study bridges the gap between the knowledge acquired by ex-situ characterizations and the active sites under the reaction conditions in alkane dehydrogenation chemistry.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(Mo3Se4)2 by Materials Project

HoMo6Se8 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. Ho3+ is bonded in a body-centered cubic geometry to eight Se2- atoms. There are two shorter (2.81 Å) and six longer (3.10 Å) Ho–Se bond lengths. Mo+2.17+ is bonded to five Se2- atoms to form a mixture of edge and corner-sharing MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.54–2.75 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 1-coordinate geometry to one Ho3+ and three equivalent Mo+2.17+ atoms. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to one Ho3+ and four equivalent Mo+2.17+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Inefficient intramolecular vibrational energy redistribution for the H + HO2 reaction and negative internal energy dependence for its rate constant

Quasiclassical trajectories (QCT) and newly constructed global potential energy surfaces are used to compute thermal and nonthermal rate constants for the H + HO 2 reaction. The thermal QCTs rate constants are up to 50% smaller than transition state theory (TST) rate constants based on the same level of electronic structure theory. This reduction is demonstrated to result from inefficient intramolecular vibrational energy redistribution (IVR) in the transient H 2 O 2 well, with a significant fraction of trajectories that reach the H 2 O 2 well promptly dissociating back to reactants instead of via the heavily statistically favored 2OH channel. The nonstatistical reduction factor, κ IVR , that quantifies this effect is shown to increase in importance with temperature, with κ IVR = 0.81 at 300 K and 0.47 at 2500 K. Finally, we show that inefficient IVR causes H + HO 2 rate constants mediated by H 2 O 2 to depend inversely on the initial vibrational excitation of HO 2 .

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

Materials Data on Ho(Mo3S4)2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(BC)2 by Materials Project

HoB2C2 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Ho is bonded in a 8-coordinate geometry to eight equivalent B and eight equivalent C atoms. All Ho–B bond lengths are 2.73 Å. All Ho–C bond lengths are 2.67 Å. B is bonded in a distorted trigonal planar geometry to four equivalent Ho and three equivalent C atoms. There is one shorter (1.52 Å) and two longer (1.60 Å) B–C bond length. C is bonded in a 3-coordinate geometry to four equivalent Ho and three equivalent B atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(FeGe)2 by Materials Project

HoFe2Ge2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ho is bonded in a 8-coordinate geometry to eight equivalent Fe and eight equivalent Ge atoms. All Ho–Fe bond lengths are 3.32 Å. All Ho–Ge bond lengths are 3.05 Å. Fe is bonded to four equivalent Ho and four equivalent Ge atoms to form a mixture of edge, corner, and face-sharing FeHo4Ge4 tetrahedra. All Fe–Ge bond lengths are 2.43 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Ho, four equivalent Fe, and one Ge atom. The Ge–Ge bond length is 2.51 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(NiGe)2 by Materials Project

HoNi2Ge2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ho is bonded in a 8-coordinate geometry to eight equivalent Ni and eight equivalent Ge atoms. All Ho–Ni bond lengths are 3.18 Å. All Ho–Ge bond lengths are 3.13 Å. Ni is bonded in a 4-coordinate geometry to four equivalent Ho and four equivalent Ge atoms. All Ni–Ge bond lengths are 2.35 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Ho, four equivalent Ni, and one Ge atom. The Ge–Ge bond length is 2.51 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(CoGe)2 by Materials Project

HoCo2Ge2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ho is bonded in a 8-coordinate geometry to eight equivalent Co and eight equivalent Ge atoms. All Ho–Co bond lengths are 3.21 Å. All Ho–Ge bond lengths are 3.08 Å. Co is bonded to four equivalent Ho and four equivalent Ge atoms to form a mixture of distorted corner, edge, and face-sharing CoHo4Ge4 tetrahedra. All Co–Ge bond lengths are 2.33 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Ho, four equivalent Co, and one Ge atom. The Ge–Ge bond length is 2.57 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(CuGe)2 by Materials Project

HoCu2Ge2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ho is bonded in a 8-coordinate geometry to eight equivalent Cu and eight equivalent Ge atoms. All Ho–Cu bond lengths are 3.28 Å. All Ho–Ge bond lengths are 3.11 Å. Cu is bonded to four equivalent Ho and four equivalent Ge atoms to form a mixture of distorted face, edge, and corner-sharing CuHo4Ge4 tetrahedra. All Cu–Ge bond lengths are 2.43 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Ho, four equivalent Cu, and one Ge atom. The Ge–Ge bond length is 2.46 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(GePd)2 by Materials Project

HoPd2Ge2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ho is bonded in a 8-coordinate geometry to eight equivalent Pd and eight equivalent Ge atoms. All Ho–Pd bond lengths are 3.32 Å. All Ho–Ge bond lengths are 3.25 Å. Pd is bonded in a 4-coordinate geometry to four equivalent Ho and four equivalent Ge atoms. All Pd–Ge bond lengths are 2.52 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Ho, four equivalent Pd, and one Ge atom. The Ge–Ge bond length is 2.43 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(MnGe)2 by Materials Project

HoMn2Ge2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ho is bonded in a 8-coordinate geometry to eight equivalent Ge atoms. All Ho–Ge bond lengths are 3.06 Å. Mn is bonded to four equivalent Ge atoms to form a mixture of corner and edge-sharing MnGe4 tetrahedra. All Mn–Ge bond lengths are 2.43 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Ho, four equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.57 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(Fe5Si)2 by Materials Project

HoFe10Si2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Ho is bonded in a 12-coordinate geometry to sixteen Fe and four equivalent Si atoms. There are a spread of Ho–Fe bond distances ranging from 2.93–3.18 Å. All Ho–Si bond lengths are 3.09 Å. There are four inequivalent Fe sites. In the first Fe site, Fe is bonded in a 10-coordinate geometry to one Ho, eleven Fe, and two equivalent Si atoms. There are a spread of Fe–Fe bond distances ranging from 2.33–2.91 Å. Both Fe–Si bond lengths are 2.60 Å. In the second Fe site, Fe is bonded in a 10-coordinate geometry to one Ho, eleven Fe, and two equivalent Si atoms. There are a spread of Fe–Fe bond distances ranging from 2.41–2.67 Å. Both Fe–Si bond lengths are 2.53 Å. In the third Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Ho, eight Fe, and two equivalent Si atoms. All Fe–Fe bond lengths are 2.44 Å. Both Fe–Si bond lengths are 2.61 Å. In the fourth Fe site, Fe is bonded to two equivalent Ho, eight Fe, and two equivalent Si atoms to form distorted FeHo2Fe8Si2 cuboctahedra that share corners with four equivalent SiHo2Fe10 cuboctahedra, corners with ten equivalent FeHo2Fe8Si2 cuboctahedra, edges with two equivalent SiHo2Fe10 cuboctahedra, edges with four equivalent FeHo2Fe8Si2 cuboctahedra, faces with four equivalent SiHo2Fe10 cuboctahedra, and faces with six equivalent FeHo2Fe8Si2 cuboctahedra. Both Fe–Fe bond lengths are 2.38 Å. Both Fe–Si bond lengths are 2.39 Å. Si is bonded to two equivalent Ho and ten Fe atoms to form distorted SiHo2Fe10 cuboctahedra that share corners with six equivalent SiHo2Fe10 cuboctahedra, corners with eight equivalent FeHo2Fe8Si2 cuboctahedra, edges with three equivalent SiHo2Fe10 cuboctahedra, edges with four equivalent FeHo2Fe8Si2 cuboctahedra, a faceface with one SiHo2Fe10 cuboctahedra, and faces with eight equivalent FeHo2Fe8Si2 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(Fe2Ge)2 by Materials Project

HoFe4Ge2 crystallizes in the tetragonal P4_2/mnm space group. The structure is three-dimensional. Ho is bonded in a 6-coordinate geometry to twelve equivalent Fe and six equivalent Ge atoms. There are four shorter (3.17 Å) and eight longer (3.27 Å) Ho–Fe bond lengths. There are two shorter (2.91 Å) and four longer (2.94 Å) Ho–Ge bond lengths. Fe is bonded in a 3-coordinate geometry to three equivalent Ho and three equivalent Ge atoms. There are one shorter (2.43 Å) and two longer (2.44 Å) Fe–Ge bond lengths. Ge is bonded in a 9-coordinate geometry to three equivalent Ho and six equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(CrSi)2 by Materials Project

HoCr2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ho3+ is bonded in a body-centered cubic geometry to eight equivalent Si4- atoms. All Ho–Si bond lengths are 2.98 Å. Cr+2.50+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing CrSi4 tetrahedra. All Cr–Si bond lengths are 2.40 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Ho3+, four equivalent Cr+2.50+, and one Si4- atom. The Si–Si bond length is 2.45 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(CoB)2 by Materials Project

HoCo2B2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ho3+ is bonded in a body-centered cubic geometry to eight equivalent B3- atoms. All Ho–B bond lengths are 2.87 Å. Co+1.50+ is bonded to four equivalent B3- atoms to form a mixture of edge and corner-sharing CoB4 tetrahedra. All Co–B bond lengths are 2.01 Å. B3- is bonded in a 4-coordinate geometry to four equivalent Ho3+ and four equivalent Co+1.50+ atoms.

36 MATERIALS SCIENCE↗