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At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Eu(InSe2)2 by Materials Project

Eu(InSe2)2 crystallizes in the orthorhombic Cccm space group. The structure is three-dimensional. Eu2+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are four shorter (3.30 Å) and four longer (3.39 Å) Eu–Se bond lengths. In3+ is bonded to four Se2- atoms to form edge-sharing InSe4 tetrahedra. There are a spread of In–Se bond distances ranging from 2.61–2.66 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 4-coordinate geometry to two equivalent Eu2+ and two equivalent In3+ atoms. In the second Se2- site, Se2- is bonded to two equivalent Eu2+ and two equivalent In3+ atoms to form a mixture of distorted edge and corner-sharing SeEu2In2 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(CdAs)2 by Materials Project

Eu(CdAs)2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Eu2+ is bonded to six equivalent As3- atoms to form EuAs6 octahedra that share corners with twelve equivalent CdAs4 tetrahedra, edges with six equivalent EuAs6 octahedra, and edges with six equivalent CdAs4 tetrahedra. All Eu–As bond lengths are 3.15 Å. Cd2+ is bonded to four equivalent As3- atoms to form CdAs4 tetrahedra that share corners with six equivalent EuAs6 octahedra, corners with six equivalent CdAs4 tetrahedra, edges with three equivalent EuAs6 octahedra, and edges with three equivalent CdAs4 tetrahedra. The corner-sharing octahedra tilt angles range from 15–56°. There are three shorter (2.75 Å) and one longer (2.86 Å) Cd–As bond lengths. As3- is bonded to three equivalent Eu2+ and four equivalent Cd2+ atoms to form a mixture of distorted edge and corner-sharing AsEu3Cd4 pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(SbS2)2 by Materials Project

Eu(SbS2)2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Eu2+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Eu–S bond distances ranging from 2.95–3.41 Å. There are two inequivalent Sb3+ sites. In the first Sb3+ site, Sb3+ is bonded to six S2- atoms to form SbS6 octahedra that share corners with three equivalent SbS7 pentagonal bipyramids, edges with four equivalent SbS6 octahedra, and edges with two equivalent SbS7 pentagonal bipyramids. There are a spread of Sb–S bond distances ranging from 2.55–3.13 Å. In the second Sb3+ site, Sb3+ is bonded to seven S2- atoms to form distorted SbS7 pentagonal bipyramids that share corners with three equivalent SbS6 octahedra, edges with two equivalent SbS6 octahedra, and edges with four equivalent SbS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 5–50°. There are a spread of Sb–S bond distances ranging from 2.67–2.99 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded to two equivalent Eu2+ and four Sb3+ atoms to form distorted SEu2Sb4 octahedra that share corners with four equivalent SEu2Sb3 square pyramids, corners with three equivalent SEu2Sb3 trigonal bipyramids, edges with four equivalent SEu2Sb4 octahedra, edges with three equivalent SEu2Sb3 trigonal bipyramids, and a faceface with one SEu2Sb3 square pyramid. In the second S2- site, S2- is bonded to two equivalent Eu2+ and three Sb3+ atoms to form distorted SEu2Sb3 trigonal bipyramids that share corners with three equivalent SEu2Sb4 octahedra, corners with six equivalent SEu2Sb3 square pyramids, edges with three equivalent SEu2Sb4 octahedra, edges with two equivalent SEu2Sb3 square pyramids, and edges with two equivalent SEu2Sb3 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 3–25°. In the third S2- site, S2- is bonded to two equivalent Eu2+ and three equivalent Sb3+ atoms to form distorted SEu2Sb3 square pyramids that share corners with four equivalent SEu2Sb4 octahedra, corners with six equivalent SEu2Sb3 trigonal bipyramids, edges with four equivalent SEu2Sb3 square pyramids, edges with two equivalent SEu2Sb3 trigonal bipyramids, and a faceface with one SEu2Sb4 octahedra. The corner-sharing octahedra tilt angles range from 55–62°. In the fourth S2- site, S2- is bonded in a 5-coordinate geometry to two equivalent Eu2+ and three Sb3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(MgAs)2 by Materials Project

Eu(MgAs)2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Mg2+ is bonded to four equivalent As3- atoms to form MgAs4 tetrahedra that share corners with six equivalent EuAs6 octahedra, corners with six equivalent MgAs4 tetrahedra, edges with three equivalent EuAs6 octahedra, and edges with three equivalent MgAs4 tetrahedra. The corner-sharing octahedra tilt angles range from 19–54°. There are three shorter (2.68 Å) and one longer (2.74 Å) Mg–As bond lengths. Eu2+ is bonded to six equivalent As3- atoms to form EuAs6 octahedra that share corners with twelve equivalent MgAs4 tetrahedra, edges with six equivalent EuAs6 octahedra, and edges with six equivalent MgAs4 tetrahedra. All Eu–As bond lengths are 3.17 Å. As3- is bonded to four equivalent Mg2+ and three equivalent Eu2+ atoms to form a mixture of distorted corner and edge-sharing AsEu3Mg4 pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(AlSe2)2 by Materials Project

Eu(AlSe2)2 crystallizes in the orthorhombic Cccm space group. The structure is three-dimensional. Eu2+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are four shorter (3.25 Å) and four longer (3.28 Å) Eu–Se bond lengths. Al3+ is bonded to four Se2- atoms to form edge-sharing AlSe4 tetrahedra. There are a spread of Al–Se bond distances ranging from 2.41–2.44 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 4-coordinate geometry to two equivalent Eu2+ and two equivalent Al3+ atoms. In the second Se2- site, Se2- is bonded to two equivalent Eu2+ and two equivalent Al3+ atoms to form a mixture of distorted edge and corner-sharing SeEu2Al2 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(BC)2 by Materials Project

Eu(BC)2 crystallizes in the tetragonal P4_2/mmc space group. The structure is three-dimensional. Eu2+ is bonded in a 8-coordinate geometry to eight equivalent C4- atoms. All Eu–C bond lengths are 2.82 Å. B3+ is bonded in an L-shaped geometry to two equivalent C4- atoms. Both B–C bond lengths are 1.61 Å. C4- is bonded in a 2-coordinate geometry to four equivalent Eu2+, two equivalent B3+, and one C4- atom. The C–C bond length is 1.41 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(HoS2)2 by Materials Project

Eu(HoS2)2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded to six S2- atoms to form a mixture of corner and edge-sharing HoS6 octahedra. The corner-sharing octahedra tilt angles range from 48–65°. There are a spread of Ho–S bond distances ranging from 2.69–2.75 Å. In the second Ho3+ site, Ho3+ is bonded to six S2- atoms to form a mixture of corner and edge-sharing HoS6 octahedra. The corner-sharing octahedra tilt angles range from 48–65°. There are a spread of Ho–S bond distances ranging from 2.67–2.76 Å. Eu2+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Eu–S bond distances ranging from 3.04–3.29 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a 5-coordinate geometry to three Ho3+ and two equivalent Eu2+ atoms. In the second S2- site, S2- is bonded to three equivalent Ho3+ and two equivalent Eu2+ atoms to form a mixture of distorted corner and edge-sharing SEu2Ho3 square pyramids. In the third S2- site, S2- is bonded in a 5-coordinate geometry to three Ho3+ and two equivalent Eu2+ atoms. In the fourth S2- site, S2- is bonded to three equivalent Ho3+ and two equivalent Eu2+ atoms to form a mixture of distorted corner and edge-sharing SEu2Ho3 trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(BiS2)2 by Materials Project

Eu(BiS2)2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Eu2+ is bonded in a 7-coordinate geometry to eight S2- atoms. There are a spread of Eu–S bond distances ranging from 3.00–3.54 Å. There are two inequivalent Bi3+ sites. In the first Bi3+ site, Bi3+ is bonded to six S2- atoms to form BiS6 octahedra that share corners with three equivalent BiS7 pentagonal bipyramids, edges with four equivalent BiS6 octahedra, and edges with two equivalent BiS7 pentagonal bipyramids. There are a spread of Bi–S bond distances ranging from 2.67–3.07 Å. In the second Bi3+ site, Bi3+ is bonded to seven S2- atoms to form distorted BiS7 pentagonal bipyramids that share corners with three equivalent BiS6 octahedra, edges with two equivalent BiS6 octahedra, and edges with four equivalent BiS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 6–49°. There are a spread of Bi–S bond distances ranging from 2.82–3.14 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded to two equivalent Eu2+ and four Bi3+ atoms to form distorted SEu2Bi4 octahedra that share corners with four equivalent SEu2Bi3 square pyramids, corners with three equivalent SEu2Bi3 trigonal bipyramids, edges with four equivalent SEu2Bi4 octahedra, edges with three equivalent SEu2Bi3 trigonal bipyramids, and a faceface with one SEu2Bi3 square pyramid. In the second S2- site, S2- is bonded to two equivalent Eu2+ and three Bi3+ atoms to form distorted SEu2Bi3 trigonal bipyramids that share corners with three equivalent SEu2Bi4 octahedra, corners with six equivalent SEu2Bi3 square pyramids, edges with three equivalent SEu2Bi4 octahedra, edges with two equivalent SEu2Bi3 square pyramids, and edges with two equivalent SEu2Bi3 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 4–27°. In the third S2- site, S2- is bonded to two equivalent Eu2+ and three equivalent Bi3+ atoms to form distorted SEu2Bi3 square pyramids that share corners with four equivalent SEu2Bi4 octahedra, corners with six equivalent SEu2Bi3 trigonal bipyramids, edges with four equivalent SEu2Bi3 square pyramids, edges with two equivalent SEu2Bi3 trigonal bipyramids, and a faceface with one SEu2Bi4 octahedra. The corner-sharing octahedra tilt angles range from 57–61°. In the fourth S2- site, S2- is bonded in a 5-coordinate geometry to two equivalent Eu2+ and three Bi3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(CrAs)2 by Materials Project

Eu(CrAs)2 is alpha bismuth trifluoride-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Eu2+ is bonded in a body-centered cubic geometry to eight equivalent As3- atoms. All Eu–As bond lengths are 3.27 Å. Cr2+ is bonded to four equivalent As3- atoms to form a mixture of corner and edge-sharing CrAs4 tetrahedra. All Cr–As bond lengths are 2.44 Å. As3- is bonded in a 4-coordinate geometry to four equivalent Eu2+ and four equivalent Cr2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(BRu)4 by Materials Project

Eu(RuB)4 crystallizes in the tetragonal I4_1/acd space group. The structure is three-dimensional. Eu2+ is bonded in a 12-coordinate geometry to twelve equivalent B3- atoms. There are a spread of Eu–B bond distances ranging from 2.96–3.25 Å. Ru+2.50+ is bonded to five equivalent B3- atoms to form a mixture of distorted edge and corner-sharing RuB5 trigonal bipyramids. There are a spread of Ru–B bond distances ranging from 2.15–2.31 Å. B3- is bonded in a 6-coordinate geometry to three equivalent Eu2+, five equivalent Ru+2.50+, and one B3- atom. The B–B bond length is 1.80 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(PO3)3 by Materials Project

Eu(PO3)3 crystallizes in the orthorhombic C222_1 space group. The structure is three-dimensional. Eu3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Eu–O bond distances ranging from 2.41–2.73 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.62 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There is two shorter (1.51 Å) and two longer (1.60 Å) P–O bond length. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Eu3+ and one P5+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent P5+ atoms. In the third O2- site, O2- is bonded in a distorted linear geometry to one Eu3+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Eu3+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(ZnP)2 by Materials Project

Eu(ZnP)2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Eu2+ is bonded to six equivalent P3- atoms to form EuP6 octahedra that share corners with twelve equivalent ZnP4 tetrahedra, edges with six equivalent EuP6 octahedra, and edges with six equivalent ZnP4 tetrahedra. All Eu–P bond lengths are 3.00 Å. Zn2+ is bonded to four equivalent P3- atoms to form ZnP4 tetrahedra that share corners with six equivalent EuP6 octahedra, corners with six equivalent ZnP4 tetrahedra, edges with three equivalent EuP6 octahedra, and edges with three equivalent ZnP4 tetrahedra. The corner-sharing octahedra tilt angles range from 22–52°. There are three shorter (2.46 Å) and one longer (2.54 Å) Zn–P bond lengths. P3- is bonded in a 7-coordinate geometry to three equivalent Eu2+ and four equivalent Zn2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Realizing Wide-Gamut Human-Centric Display Lighting with K 3 AlP 3 O 9 N:Eu 2+

Abstract Computers, televisions, and smartphones are revolutionized by the invention of InGaN blue light-emitting diode (LED) backlighting. Yet, continual exposure to the intense blue LED emission from these modern displays can cause insomnia and mood disorders. Developing “human-centric” backlighting that uses a violet-emitting LED chip and a trichromatic phosphor mixture to generate color images is one approach that addresses this problem. The challenge is finding a blue-emitting phosphor that possesses a sufficiently small Stokes’ shift to efficiently down-convert violet LED light and produce a narrow blue emission. This work reports a new oxynitride phosphor that meets this demand. K 3 AlP 3 O 9 N:Eu 2+ exhibits an unexpectedly narrow (45 nm, 2206 cm -1 ), thermally robust, and efficient blue photoluminescence upon violet excitation. Computational modeling and temperature-dependent optical property measurements reveal that the narrow emission arises from a rare combination of preferential excitation and site-selective quenching. The resulting chromaticity coordinates of K 3 AlP 3 O 9 N:Eu 2+ lie closer to the vertex of the Rec. 2020 than a blue LED chip and provides access to ≈10% more colors than a commercial tablet when combined with commercial red- and green-emitting phosphors. Alongside the wide gamut, tuning the emission from the violet LED and phosphor blend can reduce blue light emissions to produce next-generation, human-centric displays.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Stabilization Of The CN 3 5− Anion In Recoverable High‐pressure Ln 3 O 2 (CN 3 ) (Ln=La, Eu, Gd, Tb, Ho, Yb) Oxoguanidinates

Abstract A series of isostructural Ln 3 O 2 (CN 3 ) (Ln=La, Eu, Gd, Tb, Ho, Yb) oxoguanidinates was synthesized under high‐pressure (25–54 GPa) high‐temperature (2000–3000 K) conditions in laser‐heated diamond anvil cells. The crystal structure of this novel class of compounds was determined via synchrotron single‐crystal X‐ray diffraction (SCXRD) as well as corroborated by X‐ray absorption near edge structure (XANES) measurements and density functional theory (DFT) calculations. The Ln 3 O 2 (CN 3 ) solids are composed of the hitherto unknown CN 3 5− guanidinate anion—deprotonated guanidine. Changes in unit cell volumes and compressibility of Ln 3 O 2 (CN 3 ) (Ln=La, Eu, Gd, Tb, Ho, Yb) compounds are found to be dictated by the lanthanide contraction phenomenon. Decompression experiments show that Ln 3 O 2 (CN 3 ) compounds are recoverable to ambient conditions. The stabilization of the CN 3 5− guanidinate anion at ambient conditions provides new opportunities in inorganic and organic synthetic chemistry.

Chemistry↗
DOE OSTI2024

Extraction of 88 Y, 152 Eu, 228 Ac, 241 Am, and 244 Cm with 2-thenoyltrifluoroacetone (TTA) resin

In this report the behavior of 88 Y, 152 Eu, 228 Ac, 241 Am, and 244 Cm was studied with 2-thenoyltrifluoroacetone resin with batch uptake, kinetics and column studies. Studies were performed in acetate buffer solutions (pH ~ 2 to ~ 6) and there was high uptake of all isotopes, except 228 Ac, at pH > 4.5. The kinetics of uptake were reasonable, although slower for the actinides, and sufficient for column studies. The retention of 88 Y, 152 Eu, and 241 Am on the resin in column studies was demonstrated as well as a reasonable separation of these isotopes from 228 Ac.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

X-ray absorption spectroscopy of trivalent Eu, Gd, Tb, and Dy chlorides and oxychlorides

Growing interest in next generation molten salt nuclear reactors necessitates a fundamental understanding of the chemical and physico-chemical properties of fission products, including elements of the lanthanide series. In this study, we probed coordination environment of Eu, Gd, Tb, and Dy in their chloride salts with both laboratory and synchrotron scale X-ray absorption spectroscopy (XAS). Here the aerobic melting was carried out with LnCl 3 ·nH 2 O, where Ln is Eu, Gd, Tb, and Dy, and yielded predominant formation of oxychlorides (LnOCl), that was confirmed by extended X-ray absorption fine structure (EXAFS) analysis and X-ray diffraction (XRD). Density functional theory (DFT) and time-dependent density functional theory (TDDFT) computations were performed to obtain ground state structures, lattice parameters, and to simulate L 3 -edge XANES (X-ray absorption near edge structure) spectra of the LnCl 3 ·nH 2 O and LnOCl. A blue shift, initially predicted by our calculations, was also observed for the experimental Ln L 3 -edge XANES spectra of the hydrated trichlorides vs oxychlorides, highlighting the power of combining the predictive ability of theory with experiment to elucidate the properties of the compounds of interest. The blue shift is indicative of structural stabilization of LnCl 3 ·nH 2 O due to higher symmetry compared with LnOCl. To the best of knowledge, this is a first study providing the framework for fundamental insights into the structure of Ln trichlorides and oxychlorides in support of future characterization of lanthanides in the molten salt environment.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Catalyzed oxidation of nuclear graphite by simulated fission products Sr, Eu, and I

The influence of three fission products Sr, Eu, and I on the oxidation of IG-110 nuclear graphite was studied in the temperature range of 400 to 1000 °C. Sr and Eu were introduced as chlorides, and I was introduced as NaI. The temperature dependence of both CO 2 and CO production during the graphite oxidation measured with mass spectroscopy and infrared spectrometry shows that the introduction of these three compounds to graphite significantly decreases the onset temperature for the oxidation of graphite. Among the three compounds, NaI is the most active towards the oxidation reaction, characterized by a significant decrease of the onset temperature from approximately 650 to 400 °C before and after its introduction to graphite. Separate measurements of CO 2 and CO concentration at varying temperatures enable the calculation of the activation energy for the formation of CO 2 and CO. The activation energies for the oxidation of pure and fission product-impregnated graphite samples decrease in the following order: standard IG-110 graphite, EuCl 3 -impregnated IG-110, SrCl 2 -impregnated IG-110, and NaI-impregnated IG-110. This trend indicates that the three compounds catalyze the oxidation of graphite at temperatures relevant to the operation of high-temperature gas-cooled reactors. Furthermore, it is found that the three compounds can also affect the molar ratio of reaction products CO 2 and CO, and the rates of the graphite oxidation. At temperatures higher than about 850 °C, the impregnated samples exhibit lower CO 2 : CO ratios than the pure graphite. Different from EuCl 3 and NaI, the introduction of SrCl 2 decreases the graphite oxidation rates at temperatures higher than about 770 °C. Their catalytic mechanism can be understood based on a redox cycle of the intermediate active species, promoting the dissociation of molecular oxygen and transfer to the carbon.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

High-pressure synthesis, crystal structure, and magnetic properties of the Shastry-Sutherland-lattice oxides BaL n 2 ZnO 5 (L n = Pr, Sm, Eu)

BaPr 2 ZnO 5 , BaSm 2 ZnO 5 , and BaEu 2 ZnO 5 – a series of 4f magnetic insulators comprising the Shastry-Sutherland lattice – were synthesized via a solid-state reaction under high-pressure and high-temperature conditions. The magnetic behaviors are well characterized by the localized 4f electrons of each Ln 3+ (= Pr, Sm, Eu) under the influence of the crystal-electric field of the surrounding ions. The magnetic susceptibility and heat capacity measurements of BaPr 2 ZnO 5 (Pr 3+ ; 4f 2 3 H 4 ) indicate the splitting of the ground state J-multiplet due to the crystal-electric field. BaSm 2 ZnO 5 (Sm 3+ ; 4f 5 6 H 5/2 ) is a strong Van Vleck paramagnet, while BaEu 2 ZnO 5 is non-magnetic due to the 7 F 0 ground state (Eu 3+ ; 4f 6 7 F 0 ). The series of new oxides enriches a group of the Shastry-Sutherland lattice materials and helps to develop a range of two-dimensional quantum materials.

36 MATERIALS SCIENCE↗