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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Eu(CoGe)2 by Materials Project

EuCo2Ge2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Eu is bonded in a 8-coordinate geometry to eight equivalent Co and eight equivalent Ge atoms. All Eu–Co bond lengths are 3.30 Å. All Eu–Ge bond lengths are 3.16 Å. Co is bonded to four equivalent Eu and four equivalent Ge atoms to form a mixture of distorted face, edge, and corner-sharing CoEu4Ge4 tetrahedra. All Co–Ge bond lengths are 2.34 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Eu, four equivalent Co, and one Ge atom. The Ge–Ge bond length is 2.83 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu by Materials Project

Eu is Tungsten structured and crystallizes in the cubic Im-3m space group. The structure is three-dimensional. Eu is bonded in a body-centered cubic geometry to eight equivalent Eu atoms. All Eu–Eu bond lengths are 4.02 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu by Materials Project

Eu is Magnesium structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Eu is bonded to twelve equivalent Eu atoms to form a mixture of face, edge, and corner-sharing EuEu12 cuboctahedra. There are six shorter (4.01 Å) and six longer (4.05 Å) Eu–Eu bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu by Materials Project

Eu is Copper structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Eu is bonded to twelve equivalent Eu atoms to form a mixture of edge, face, and corner-sharing EuEu12 cuboctahedra. All Eu–Eu bond lengths are 3.90 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu by Materials Project

Eu is Protactinium-like structured and crystallizes in the trigonal R-3c space group. The structure is three-dimensional. Eu is bonded in a 10-coordinate geometry to ten equivalent Eu atoms. There are a spread of Eu–Eu bond distances ranging from 3.74–4.00 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu by Materials Project

Eu is Magnesium structured and crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Eu is bonded to twelve equivalent Eu atoms to form a mixture of face, edge, and corner-sharing EuEu12 cuboctahedra. There are a spread of Eu–Eu bond distances ranging from 3.80–3.97 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Uncertainty improvement of 22 Na based radioactive tracer dilution for determining total mass of pyroprocessing molten salt systems by 154 Eu removal

To determine the total salt mass of the molten salt systems for pyroprocessing spent nuclear fuels, a 22 Na based radioactive tracer dilution was studied in Idaho National Laboratory in recent years. This 22 Na based RTD technique was deemed feasible, but due to the gamma energy peak of 22 Na coinciding with one of the energy peaks of 154 Eu radioisotope in the molten salt, the uncertainty of the 22 Na radioactivity in the 22 Na-spiked salt samples was quite high. To improve the uncertainty of the 22 Na based RTD technique, we proposed to chemically remove the 154 Eu of the salt samples by DGA resin for gamma spectroscopy. The effectiveness of removing 154 Eu on uncertainty improvement was evaluated. Furthermore, it was found that (1) the 154 Eu fission product effect on the uncertainty and detection limit can be effectively eliminated by chemically removing the 154 Eu during the salt sample preparation and (2) the uncertainty of 22 Na radioactivity in the salt samples for electrorefining was significantly improved from 13% to 2%, showing the potential of practical engineering application of 22 Na based RTD as a safeguards technique for molten salt systems for pyroprocessing spent nuclear fuels.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2021

Crystal structure, magnetic properties and bonding analysis of M 3 Pt 23 Ge 11 (M=Ca, Sr, Ba and Eu)

The properties of Pt-based materials can be intriguing due to the importance of spin-orbit coupling for Pt. Herein, we report four new phases with formulas M 3 Pt 23 Ge 11 (M ​= ​Ca, Sr, Ba and Eu), which adopt the same structure type as Ce3Pt23Si11. Magnetic susceptibility measurements indicate that none of the phases is superconducting above 1.8 ​K, while for Eu 3 Pt 23 Ge 11 ferromagnetic ordering is observed at ~ 3 ​K. The low Curie temperature for that material compared to that of Eu 3 Pt 23 Si 11 may be due to its larger Eu–Eu distance. One potential factor that destabilizes the structure of other rare-earth based M 3 Pt 23 Ge 11 is demonstrated through COHP calculations.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Crystal Growth Scale-Up and Stability of RbSr 2 X 5 :Eu Scintillators

The discovery and development of new scintillation materials support national security needs. In these applications, large volumes of scintillator crystals are needed to achieve efficient screening for contraband. Therefore, one important step in the discovery of new scintillator compositions is testing their feasibility for scale-up and their stability. In this work, high-quality Ø22 mm crystals of two new scintillators RbSr 2 Br 5 :Eu and RbSr 2 I 5 :Eu were grown via the Vertical Bridgman method, and their scintillation properties were characterized. Here, the Ø22 mm RbSr 2 I 5 :Eu crystals could be grown with fast translation rates up to 3.5 mm/h. Both RbSr 2 Br 5 :Eu and RbSr 2 I 5 :Eu had high scintillation performance, including light yields of 46,000 and 61,000 ph/MeV, respectively, for Ø22 × 35 mm crystals. Additionally, properties related to physical stability were investigated, including the coefficients of thermal expansion via high-temperature X-ray diffraction (HTXRD) as well as moisture sensitivity. HTXRD confirmed the absence of solid–solid phase transitions and showed that RbSr 2 Br 5 had minimal thermal expansion anisotropy compared to RbSr 2 I 5 and some other inorganic metal halide scintillators, which favors the growth of large-sized crystals.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Pressure effect on magnetism and valence in ferromagnetic superconductor Eu(Fe 0.75 Ru 0.25 ) 2 As 2

Eu(Fe 0.75 Ru 0.25 ) 2 As 2 is an intriguing system with unusual coexistence of superconductivity and ferromagnetism, providing a unique platform to study the nature of such coexistence. To establish a magnetic phase diagram, time-domain synchrotron Mössbauer experiments in 151 Eu have been performed on a single crystalline Eu(Fe 0.75 Ru 0.25 ) 2 As 2 sample under hydrostatic pressures and at low temperatures. Upon compression the magnetic ordering temperature increases sharply from 20 K at ambient pressure, reaching ~49 K at 10.1GPa. With further compression, the magnetic order is suppressed and eventually collapses. Isomer shift values from Mössbauer measurements and x-ray absorption spectroscopy data at Eu L 3 edge show that pressure drives Eu ions to a homogeneous intermediate valence state with mean valence of ~2.4 at 27.4 GPa, possibly responsible for the suppression of magnetism. Synchrotron powder x-ray diffraction experiment reveals a tetragonal to collapsed-tetragonal structural transition around 5 GPa, a lower transition pressure than in the parent compound. Furthermore, these results provide guidance to further work investigating the interplay of superconductivity and magnetism.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Magnetism in EuAlSi and the Eu 1−𝑥 ⁢Sr 𝑥 ⁢ AlSi solid solution solid solution

The magnetic properties of EuAlSi, a compound comprising a honeycomb lattice of Al/Si atoms and a triangular lattice of Eu atoms, are presented. By means of single-crystal x-ray diffraction, we find that EuAlSi crystallizes in an AlB 2 -type structure with space group 𝑃⁢6/mmm and unit cell parameters 𝑎 = 4.2229⁢ (10) ⁢Å and 𝑐 = 4.5268 ⁢(12)⁢ Å. Our magnetic measurements indicate that EuAlSi is a soft ferromagnetic material with 𝑇 Curie = 25.8 K. The susceptibility follows the Curie-Weiss law at high temperatures, which allowed us to determine the paramagnetic Curie temperature 𝜃 𝑃 = 36.2 ⁢(1) ⁢K and an effective magnetic moment 𝜇 eff = 8.07 ⁢(1)⁢ µ 𝐵 /Eu. This value is in agreement with the theoretical value of 7.9 µ 𝐵 for Eu 2+ free ion. Moreover, we have prepared the Eu 1−𝑥 ⁢Sr 𝑥 ⁢ AlSi solid solution, where the atoms in the triangular lattice were systematically exchanged, in order to study the evolution of the collective quantum properties from the ferromagnetic EuAlSi toward the superconducting SrAlSi. Across the Eu 1−𝑥 ⁢Sr 𝑥 AlSi solid solution, the unit cell parameters change linearly, following Vegard’s law, and making the system reliable for studying composition dependence of the interplay between the crystal structure and physical properties. As the Sr content increases, i.e., 𝑥 increases, we note a consistent reduction of 𝜇 eff and 𝑇 Curie . Long-range magnetic order in Eu 1−𝑥 ⁢Sr 𝑥 ⁢ AlSi persists up to 𝑥 = 0.95, whereas superconductivity is only observed for samples with 𝑥 > 0.97.

Walicka, Dorota I. [University of Geneva (Switzerl↗
DOE OSTI2025

Crystal Growth, Optical and Scintillation Properties of Eu 2+ -doped TlSr 2 Br 5

Crystals of undoped and Eu 2+ -doped TlSr 2 Br 5 of up to 16 mm in diameter and 50 mm in length were grown by the Vertical Bridgman technique. TlSr 2 Br 5 has the monoclinic crystal structure with space group P21/c. Its density and Z eff are 5.03 g/cm 3 and 58.6, respectively. Radioluminescence spectra of undoped and Eu 2+ -doped TlSr 2 Br 5 feature a broad emission band peaking at about 440 nm for undoped and 520 nm for Eu 2+ -doped crystals. The light yield of undoped TlSr 2 Br 5 is 42,000 ph/MeV, which increases to 55,000 ph/MeV for Eu 2+ -doped crystals. The energy resolution at 662 keV ( 137 Cs) is about 5 – 6% (FWHM). As a result, the scintillation decay of undoped and Eu 2+ -doped TlSr 2 Br 5 is of the order of 100s of nanoseconds.

Bridgman technique↗
DOE OSTI2026

Synthesis, Structure, and Properties of the Complex Zintl Phase Eu 9 Zn 4.5 As 9 : A Candidate Topological Insulator and Thermoelectric Material

Reported are the synthesis and detailed analysis of the crystal and electronic structure of the novel Zintl phase Eu 9 Zn 4.5 As 9 . This material was identified in the densely populated Eu–Zn–As compositional space. For structure determination and for property measurements, suitable single crystals of this compound were grown from either Sn- or Pb-flux. Single-crystal X-ray diffraction methods indicate that Eu 9 Zn 4.5 As 9 crystallizes in the orthorhombic crystal system with the space group Pnma (a = 12.1953(7) Å, b = 4.3730(2) Å, c = 42.674(2) Å) and is formally isostructural to Ca 9 Mn 4+x Sb 9 , the less common “9–4–9” type. The structure is heavily disordered, with multiple partially occupied sites, yet, according to the Zintl-Klemm formalism, a charge-balanced composition (Eu 2+ ) 9 (Zn 2+ ) 4.5 (As 3− ) 9 is attained. Electronic structure calculations for a model, disorder-free structure indicate no energy gap between the valence and the conduction bands and suggest (semi)metallic behavior. Preliminary susceptibility measurements confirm the expected divalent nature of Eu 2+ ([Xe] 4 f 7 ground state).

Zintl phases↗
NASA NTRS1998

Anisotropic Optical-Response of Eu-doped Yttrium Orthosilicate

Eu-doped yttrium orthosilicate (Eu(3+) : Y2SiO5) had been a subject being investigated for coherent time-domain optical memory and information processing applications since its ultraslow optical dephasing was discovered several years ago. In this crystal the weakly allowed (7)F0 - (5)D0 transition of europium ions exhibits a sufficient long dephasing time and no spectral difli.usion on a time scale of several hours at low temperature, thus an information pattern or data can be stored as a population grating in the ground state hyperfine levels. On the other hand, the study on photon-echo relaxation shows that the dephasing time T2 of Eu (3+) and other rare-earth ions doped YAG, YAlO3 strongly depends on the intensity of the excitation pulses. In Eu (3+) :YAlO3, an exponential decay of photon-echo with T2 = 53 microseconds if the excitation pulses are weak (5 vJ/pulse) was observed. However, when the excitation pulses are strong (80 pJ/pulse) they observed a much shortened T2 with a highly nonexponential decay pattern. The conclusion they derived is that the intensity-dependent dephasing rate effects are quite general, and it depends on how much the excitation intensity varies. In this paper we use transient grating formation technique showing that a temporal lattice distortion may only occur along crystal c axis, caused by EU (3+) excitation. At high excitation level the produced exciton in conduction band may also couple to the dynamical lattice relaxation process, giving rise to an apparently much shortened dephasing time.

Liu, Huimin↗
DOE OSTI2020

Materials Data on Eu(BIr)4 by Materials Project

Eu(IrB)4 is alpha Pu-derived structured and crystallizes in the tetragonal P4_2/n space group. The structure is three-dimensional. Eu is bonded in a 4-coordinate geometry to four equivalent B atoms. All Eu–B bond lengths are 2.92 Å. Ir is bonded in a 4-coordinate geometry to four equivalent B atoms. There are a spread of Ir–B bond distances ranging from 2.11–2.17 Å. B is bonded in a 6-coordinate geometry to one Eu, four equivalent Ir, and one B atom. The B–B bond length is 1.87 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(Al10V)2 by Materials Project

Al20V2Eu crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Eu is bonded in a 4-coordinate geometry to sixteen Al atoms. There are four shorter (3.15 Å) and twelve longer (3.22 Å) Eu–Al bond lengths. V is bonded to twelve Al atoms to form VAl12 cuboctahedra that share corners with six equivalent VAl12 cuboctahedra, edges with eighteen equivalent AlEuAl10V cuboctahedra, and faces with six equivalent AlEuAl10V cuboctahedra. There are six shorter (2.58 Å) and six longer (2.81 Å) V–Al bond lengths. There are three inequivalent Al sites. In the first Al site, Al is bonded in a distorted linear geometry to two equivalent Eu and twelve equivalent Al atoms. All Al–Al bond lengths are 3.11 Å. In the second Al site, Al is bonded to one Eu, one V, and ten Al atoms to form distorted AlEuAl10V cuboctahedra that share corners with fifteen equivalent AlEuAl10V cuboctahedra, edges with two equivalent AlEuAl10V cuboctahedra, edges with three equivalent VAl12 cuboctahedra, a faceface with one VAl12 cuboctahedra, and faces with fifteen equivalent AlEuAl10V cuboctahedra. There are a spread of Al–Al bond distances ranging from 2.70–2.93 Å. In the third Al site, Al is bonded in a 12-coordinate geometry to two equivalent V and ten Al atoms. All Al–Al bond lengths are 2.86 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(GaSb)2 by Materials Project

EuGa2Sb2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Eu2+ sites. In the first Eu2+ site, Eu2+ is bonded in a 6-coordinate geometry to six Sb3- atoms. There are a spread of Eu–Sb bond distances ranging from 3.39–3.47 Å. In the second Eu2+ site, Eu2+ is bonded in a 6-coordinate geometry to six Sb3- atoms. There are a spread of Eu–Sb bond distances ranging from 3.41–3.48 Å. In the third Eu2+ site, Eu2+ is bonded in a 6-coordinate geometry to six Sb3- atoms. There are a spread of Eu–Sb bond distances ranging from 3.39–3.47 Å. In the fourth Eu2+ site, Eu2+ is bonded in a 6-coordinate geometry to six Sb3- atoms. There are a spread of Eu–Sb bond distances ranging from 3.40–3.47 Å. There are eight inequivalent Ga2+ sites. In the first Ga2+ site, Ga2+ is bonded in a trigonal non-coplanar geometry to three Sb3- atoms. All Ga–Sb bond lengths are 2.72 Å. In the second Ga2+ site, Ga2+ is bonded in a trigonal non-coplanar geometry to three Sb3- atoms. All Ga–Sb bond lengths are 2.72 Å. In the third Ga2+ site, Ga2+ is bonded in a trigonal non-coplanar geometry to three Sb3- atoms. All Ga–Sb bond lengths are 2.72 Å. In the fourth Ga2+ site, Ga2+ is bonded in a trigonal non-coplanar geometry to three Sb3- atoms. All Ga–Sb bond lengths are 2.72 Å. In the fifth Ga2+ site, Ga2+ is bonded in a trigonal non-coplanar geometry to three Sb3- atoms. There are two shorter (2.73 Å) and one longer (2.86 Å) Ga–Sb bond lengths. In the sixth Ga2+ site, Ga2+ is bonded in a trigonal non-coplanar geometry to three Sb3- atoms. There are a spread of Ga–Sb bond distances ranging from 2.72–2.86 Å. In the seventh Ga2+ site, Ga2+ is bonded in a trigonal non-coplanar geometry to three Sb3- atoms. There are two shorter (2.73 Å) and one longer (2.87 Å) Ga–Sb bond lengths. In the eighth Ga2+ site, Ga2+ is bonded in a trigonal non-coplanar geometry to three Sb3- atoms. There are a spread of Ga–Sb bond distances ranging from 2.72–2.87 Å. There are eight inequivalent Sb3- sites. In the first Sb3- site, Sb3- is bonded in a 6-coordinate geometry to three Eu2+ and three Ga2+ atoms. In the second Sb3- site, Sb3- is bonded in a 6-coordinate geometry to three Eu2+ and three Ga2+ atoms. In the third Sb3- site, Sb3- is bonded in a 6-coordinate geometry to three Eu2+ and three Ga2+ atoms. In the fourth Sb3- site, Sb3- is bonded in a 6-coordinate geometry to three Eu2+ and three Ga2+ atoms. In the fifth Sb3- site, Sb3- is bonded in a 6-coordinate geometry to three Eu2+ and three Ga2+ atoms. In the sixth Sb3- site, Sb3- is bonded in a 6-coordinate geometry to three Eu2+ and three Ga2+ atoms. In the seventh Sb3- site, Sb3- is bonded in a 6-coordinate geometry to three Eu2+ and three Ga2+ atoms. In the eighth Sb3- site, Sb3- is bonded in a 6-coordinate geometry to three Eu2+ and three Ga2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(Ge3Pt)4 by Materials Project

Eu(PtGe3)4 crystallizes in the cubic Im-3 space group. The structure is three-dimensional. Eu is bonded to twelve equivalent Ge atoms to form EuGe12 cuboctahedra that share faces with eight equivalent PtGe6 octahedra. All Eu–Ge bond lengths are 3.39 Å. Pt is bonded to six equivalent Ge atoms to form PtGe6 octahedra that share corners with six equivalent PtGe6 octahedra and faces with two equivalent EuGe12 cuboctahedra. The corner-sharing octahedral tilt angles are 60°. All Pt–Ge bond lengths are 2.54 Å. Ge is bonded in a 2-coordinate geometry to one Eu, two equivalent Pt, and two equivalent Ge atoms. There are one shorter (2.58 Å) and one longer (2.66 Å) Ge–Ge bond lengths.

36 MATERIALS SCIENCE↗