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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Improving the performance for direct electrolysis of CO 2 in solid oxide electrolysis cells with a Sr 1.9 Fe 1.5 Mo 0.5 O 6– δ electrode via infiltration of Pr 6 O 11 nanoparticles

Direct CO 2 electrolysis using solid oxide electrolysis cells (CO 2 -SOECs) holds promise to efficiently convert carbon dioxide to carbon monoxide and oxygen. Cathodes with desirable catalytic activity and chemical stability play a critical role in the development of direct CO 2 -SOECs. Although Sr 2 Fe 1.5 Mo 0.5 O 6–δ (SFM) has exhibited promise for direct CO 2 -SOECs due to its redox stability, it suffers from insufficient activity for the CO 2 reduction reaction (CO 2 RR). Here we report interface engineering of nanosized Pr 6 O 11 on the SFM cathode obtained through infiltration to promote the CO 2 RR performance for direct CO 2 -SOECs. The effect of Pr 6 O 11 loading on the performance of the CO 2 RR is systematically investigated. At 800 °C, the current density of the Pr 6 O 11 infiltrated SFM cathode with an optimum Pr 6 O 11 loading of 14.8 wt% reaches 1.61 A cm –2 at 1.5 V, more than double that of the SFM cathode (0.76 A cm –2 ) under the same operating conditions. X-ray photoelectron spectroscopy (XPS) characterization and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis indicate that the adsorption ability of CO 2 on the SFM cathode has been significantly improved by the formation of Pr 6 O 11 . Temperature-programmed desorption (TPD) of CO 2 measurements further manifest that a 14.8 wt% Pr 6 O 11 -SFM cathode has better CO desorption capacity. In addition, polarization resistance of the SFM cathode has significantly decreased with the addition of Pr 6 O 11 . Three-electrode measurement was used to analyze the improved electrode kinetics. Finally, these results demonstrate that the formation of Pr 6 O 11 in the SFM cathode through infiltration is a promising approach for increasing CO 2 RR activity for CO 2 -SOECs.

03 NATURAL GAS↗
DOE OSTI2020

Materials Data on Pr(Al2Cu)4 by Materials Project

Pr(CuAl2)4 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Pr is bonded in a 12-coordinate geometry to eight equivalent Cu and twelve Al atoms. All Pr–Cu bond lengths are 3.41 Å. There are four shorter (3.11 Å) and eight longer (3.27 Å) Pr–Al bond lengths. Cu is bonded to two equivalent Pr, two equivalent Cu, and eight Al atoms to form a mixture of distorted face, edge, and corner-sharing CuPr2Al8Cu2 cuboctahedra. Both Cu–Cu bond lengths are 2.60 Å. There are four shorter (2.59 Å) and four longer (2.73 Å) Cu–Al bond lengths. There are two inequivalent Al sites. In the first Al site, Al is bonded in a 12-coordinate geometry to two equivalent Pr, four equivalent Cu, and six Al atoms. There are a spread of Al–Al bond distances ranging from 2.80–2.84 Å. In the second Al site, Al is bonded in a 10-coordinate geometry to one Pr, four equivalent Cu, and five Al atoms. The Al–Al bond length is 2.69 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(FeO3)2 by Materials Project

Pr(FeO3)2 crystallizes in the orthorhombic Pmn2_1 space group. The structure is three-dimensional. Pr is bonded in a 12-coordinate geometry to twelve O atoms. There are a spread of Pr–O bond distances ranging from 2.47–3.07 Å. Fe is bonded to six O atoms to form corner-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 11–17°. There are a spread of Fe–O bond distances ranging from 1.91–1.95 Å. There are four inequivalent O sites. In the first O site, O is bonded in a 3-coordinate geometry to two equivalent Pr and two equivalent Fe atoms. In the second O site, O is bonded in a 3-coordinate geometry to two equivalent Pr and two equivalent Fe atoms. In the third O site, O is bonded in a distorted rectangular see-saw-like geometry to two equivalent Pr and two equivalent Fe atoms. In the fourth O site, O is bonded in a 4-coordinate geometry to two equivalent Pr and two equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(Re2Si)2 by Materials Project

Pr(Re2Si)2 crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. Pr is bonded in a 12-coordinate geometry to eight Re and eight equivalent Si atoms. There are four shorter (3.37 Å) and four longer (3.47 Å) Pr–Re bond lengths. All Pr–Si bond lengths are 3.20 Å. There are two inequivalent Re sites. In the first Re site, Re is bonded in a 12-coordinate geometry to two equivalent Pr, eight Re, and two equivalent Si atoms. There are a spread of Re–Re bond distances ranging from 2.62–2.94 Å. Both Re–Si bond lengths are 2.52 Å. In the second Re site, Re is bonded to two equivalent Pr, eight Re, and two equivalent Si atoms to form a mixture of distorted edge, face, and corner-sharing RePr2Re8Si2 cuboctahedra. Both Re–Re bond lengths are 2.58 Å. Both Re–Si bond lengths are 2.56 Å. Si is bonded in a 9-coordinate geometry to four equivalent Pr, four Re, and one Si atom. The Si–Si bond length is 2.52 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(Ga5Mo)8 by Materials Project

Pr(MoGa5)8 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. Pr is bonded in a 6-coordinate geometry to two equivalent Mo and twelve Ga atoms. Both Pr–Mo bond lengths are 3.26 Å. There are six shorter (3.08 Å) and six longer (3.73 Å) Pr–Ga bond lengths. There are two inequivalent Mo sites. In the first Mo site, Mo is bonded in a 10-coordinate geometry to one Pr and nine Ga atoms. There are a spread of Mo–Ga bond distances ranging from 2.61–2.65 Å. In the second Mo site, Mo is bonded in a distorted q6 geometry to ten Ga atoms. There are a spread of Mo–Ga bond distances ranging from 2.57–2.70 Å. There are eight inequivalent Ga sites. In the first Ga site, Ga is bonded in a cuboctahedral geometry to twelve Ga atoms. There are six shorter (2.91 Å) and six longer (3.02 Å) Ga–Ga bond lengths. In the second Ga site, Ga is bonded in a distorted linear geometry to two equivalent Mo atoms. In the third Ga site, Ga is bonded in a 2-coordinate geometry to one Pr, two equivalent Mo, and two equivalent Ga atoms. There are one shorter (2.77 Å) and one longer (3.00 Å) Ga–Ga bond lengths. In the fourth Ga site, Ga is bonded in a distorted bent 150 degrees geometry to two equivalent Mo and one Ga atom. In the fifth Ga site, Ga is bonded in a distorted bent 150 degrees geometry to two Mo and one Ga atom. In the sixth Ga site, Ga is bonded in a 2-coordinate geometry to two equivalent Mo and one Ga atom. The Ga–Ga bond length is 2.68 Å. In the seventh Ga site, Ga is bonded in a 2-coordinate geometry to two Mo and two equivalent Ga atoms. There are one shorter (2.75 Å) and one longer (2.90 Å) Ga–Ga bond lengths. In the eighth Ga site, Ga is bonded in a 8-coordinate geometry to one Pr, two Mo, and five Ga atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(ClO2)3 by Materials Project

Pr(O2Cl)3 crystallizes in the monoclinic P2/c space group. The structure is two-dimensional and consists of one Pr(O2Cl)3 sheet oriented in the (0, 1, 0) direction. Pr is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Pr–O bond distances ranging from 2.31–2.65 Å. There are three inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to one Pr and one Cl atom. The O–Cl bond length is 1.54 Å. In the second O site, O is bonded in a bent 120 degrees geometry to one Pr and one Cl atom. The O–Cl bond length is 1.65 Å. In the third O site, O is bonded in a bent 120 degrees geometry to one Pr and one O atom. The O–O bond length is 1.30 Å. There are two inequivalent Cl sites. In the first Cl site, Cl is bonded in a single-bond geometry to one O atom. In the second Cl site, Cl is bonded in a water-like geometry to two equivalent O atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(GeIr)2 by Materials Project

PrIr2Ge2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Pr is bonded in a 8-coordinate geometry to eight Ir and eight Ge atoms. There are four shorter (3.27 Å) and four longer (3.36 Å) Pr–Ir bond lengths. There are four shorter (3.28 Å) and four longer (3.31 Å) Pr–Ge bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 9-coordinate geometry to four equivalent Pr and five Ge atoms. There are one shorter (2.46 Å) and four longer (2.51 Å) Ir–Ge bond lengths. In the second Ir site, Ir is bonded in a 4-coordinate geometry to four equivalent Pr and four equivalent Ge atoms. All Ir–Ge bond lengths are 2.53 Å. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent Pr and five Ir atoms. In the second Ge site, Ge is bonded in a 4-coordinate geometry to four equivalent Pr and four equivalent Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(CuSn)2 by Materials Project

PrCu2Sn2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Pr is bonded in a 12-coordinate geometry to eight Cu and eight Sn atoms. There are four shorter (3.38 Å) and four longer (3.45 Å) Pr–Cu bond lengths. There are four shorter (3.38 Å) and four longer (3.59 Å) Pr–Sn bond lengths. There are two inequivalent Cu sites. In the first Cu site, Cu is bonded in a 12-coordinate geometry to four equivalent Pr and four equivalent Sn atoms. All Cu–Sn bond lengths are 2.62 Å. In the second Cu site, Cu is bonded in a 9-coordinate geometry to four equivalent Pr and five Sn atoms. There are one shorter (2.54 Å) and four longer (2.67 Å) Cu–Sn bond lengths. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 4-coordinate geometry to four equivalent Pr and four equivalent Cu atoms. In the second Sn site, Sn is bonded in a 9-coordinate geometry to four equivalent Pr and five Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Improved 140 Nd Production for the 140 Nd/ 140 Pr In Vivo Generator through Target Recycling and Radiochemical Optimization

Theranostic strategies that utilize f-block therapeutic radionuclides, including 161 Tb, 177 Lu, 225 Ac, and 227 Th, suffer from a shortage of positron emission tomography (PET) imaging counterparts in the same chemical space and often rely on 68 Ga as a surrogate. The 140 Nd/ 140 Pr in vivo PET generator, which belongs to the f-block, may address this issue and can be produced via the 141 Pr(p,2n) 140 Nd production route by using medium-energy cyclotrons. However, impurities in the target material, including stable Nd, and the inherent difficulty of adjacent lanthanide separations limit the achievable radionuclidic and chemical purity of 140 Nd. In this work, we address these challenges through the purification and recycling of praseodymium target material and optimization of Nd/Pr separation. The resulting purified 140Nd was evaluated using DOTA and Macropa chelators via radiolabeling and in vitro stability studies. A target material purification and recycling method was developed for the monoisotopic 141 Pr starting material to remove stable Nd impurities, yielding 90.3 ± 4.7% (n = 3) recovery. The purified 141 Pr was isolated as Pr 6 O 11 and irradiated with 24 MeV protons (20.07 MeV at the target surface) at 20 μA for 4 h, which produced 1417.0 ± 83.4 MBq (38.3 ± 2.2 mCi) of 140 Nd at the end of bombardment (EOB). The produced 140 Nd was purified through an optimized DGA normal method to recover 71.6 ± 6.3% pure 140 Nd. The amount of stable Nd reduced progressively in each target purification cycle from >340 ppm without purification to <250 ppb after three cycles, while other measured metallic impurities were below 30 ppb. This improvement in target purity was reflected in the direct increase of apparent molar activity (AMA), when purified 140 Nd was evaluated with DOTA and Macropa chelators. AMA of [ 140 Nd]Nd-DOTA and [ 140 Nd]Nd-Macropa increased from 70.3 MBq/μmol (1.9 mCi/μmol) and 74 MBq/μmol (2.0 mCi/μmol) to 8025.3 MBq/μmol (216.9 mCi/μmol) and 8473.0 MBq/μmol (229.0 mCi/μmol), respectively, after the third target purification cycle. Further evaluation of chelator-labeled 140 Nd showed that [ 140 Nd]Nd-DOTA was stable in phosphate-buffered saline (PBS), saline, human serum, and mouse serum, whereas [140Nd]Nd-Macropa was stable in all except human serum. This work established a practical methodological advance for the production of 140 Nd/ 140 Pr in vivo PET generators, combining optimized target recycling and radiochemical separation to enable scaled-up and high-molar activity 140 Nd suitable for preclinical imaging. These advances support broader development of 140 Nd/ 140 Pr as a robust PET analogue, especially for f-block therapeutics.

Irradiation↗
DOE OSTI2025

Production and radiochemistry of the in vivo PET generator 140 Nd/ 140 Pr as an imaging surrogate for F-block therapeutic radionuclides

Theranostics, a combined approach of diagnostics and therapeutics, often employs F-block therapeutic radionuclides including 225 Ac, 177 Lu, and 161 Tb. While there is a lack of F-block PET imaging radionuclides, the in vivo PET generator pair 140 Nd/ 140 Pr can act as a theranostic imaging counterpart to the F-block therapeutic radionuclides. In this study, we explored the production and separation of high purity 140 Nd via the 141 Pr(p,2n) 140 Nd reaction route. Monoisotopic 141 Pr targets irradiated with 20 MeV protons for 10 min with 10 µA beam current yielded 21.45 ± 0.82 MBq (580 ± 22 µCi) of 140 Nd. A two-step separation method was developed for the purification of 140 Nd from the 141 Pr target material. Recoveries of 27.4 ± 2.1% 140Nd were obtained upon separation with < 20 ppb of 141 Pr target material in the final product. Radiolabeling of Macropa and DOTA chelators with 140 Nd resulted in [ 140 Nd]Nd-Macropa with a molar activity of 74.0 MBq/µmol (2.0 mCi/µmol) and [ 140 Nd]Nd-DOTA with a molar activity of 70.3 MBq/µmol (1.9 mCi/µmol). An imaging study with a phantom indicated the PET spatial resolution of 140 Nd/ 140 Pr was distinguishable down to 2.4 mm. This study sets the stage for the 140 Nd/ 140 Pr in vivo PET generator to be explored in radiopharmaceutical applications.

F-block↗
DOE OSTI2020

Materials Data on Pr(AlZn)2 by Materials Project

Pr(ZnAl)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Pr is bonded in a 8-coordinate geometry to eight equivalent Zn and eight equivalent Al atoms. All Pr–Zn bond lengths are 3.23 Å. All Pr–Al bond lengths are 3.47 Å. Zn is bonded in a 9-coordinate geometry to four equivalent Pr, one Zn, and four equivalent Al atoms. The Zn–Zn bond length is 2.47 Å. All Zn–Al bond lengths are 2.60 Å. Al is bonded to four equivalent Pr and four equivalent Zn atoms to form a mixture of distorted corner, edge, and face-sharing AlPr4Zn4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(CoGe)2 by Materials Project

Pr(CoGe)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Pr is bonded in a 8-coordinate geometry to eight equivalent Co and eight equivalent Ge atoms. All Pr–Co bond lengths are 3.29 Å. All Pr–Ge bond lengths are 3.17 Å. Co is bonded to four equivalent Pr and four equivalent Ge atoms to form a mixture of distorted edge, face, and corner-sharing CoPr4Ge4 tetrahedra. All Co–Ge bond lengths are 2.36 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Pr, four equivalent Co, and one Ge atom. The Ge–Ge bond length is 2.76 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(NiSn)2 by Materials Project

Pr(NiSn)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Pr is bonded in a 8-coordinate geometry to eight equivalent Ni and eight equivalent Sn atoms. All Pr–Ni bond lengths are 3.45 Å. All Pr–Sn bond lengths are 3.45 Å. Ni is bonded in a 4-coordinate geometry to four equivalent Pr and four equivalent Sn atoms. All Ni–Sn bond lengths are 2.52 Å. Sn is bonded in a 9-coordinate geometry to four equivalent Pr, four equivalent Ni, and one Sn atom. The Sn–Sn bond length is 2.87 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(AsPd)2 by Materials Project

Pr(PdAs)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Pr is bonded in a 8-coordinate geometry to eight equivalent Pd and eight equivalent As atoms. All Pr–Pd bond lengths are 3.40 Å. All Pr–As bond lengths are 3.32 Å. Pd is bonded in a 12-coordinate geometry to four equivalent Pr and four equivalent As atoms. All Pd–As bond lengths are 2.56 Å. As is bonded in a 9-coordinate geometry to four equivalent Pr, four equivalent Pd, and one As atom. The As–As bond length is 2.54 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(BRu)2 by Materials Project

Pr(RuB)2 crystallizes in the orthorhombic Fddd space group. The structure is three-dimensional. Pr is bonded in a 10-coordinate geometry to four equivalent Ru and six equivalent B atoms. All Pr–Ru bond lengths are 3.04 Å. There are two shorter (2.93 Å) and four longer (3.07 Å) Pr–B bond lengths. Ru is bonded in a 4-coordinate geometry to two equivalent Pr and four equivalent B atoms. There are two shorter (2.09 Å) and two longer (2.16 Å) Ru–B bond lengths. B is bonded in a 7-coordinate geometry to three equivalent Pr and four equivalent Ru atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(Al2Fe)4 by Materials Project

PrFe4Al8 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Pr is bonded in a 12-coordinate geometry to eight equivalent Fe and twelve Al atoms. All Pr–Fe bond lengths are 3.35 Å. There are four shorter (3.02 Å) and eight longer (3.20 Å) Pr–Al bond lengths. Fe is bonded to two equivalent Pr, two equivalent Fe, and eight Al atoms to form a mixture of distorted corner, edge, and face-sharing FePr2Al8Fe2 cuboctahedra. Both Fe–Fe bond lengths are 2.52 Å. There are four shorter (2.54 Å) and four longer (2.66 Å) Fe–Al bond lengths. There are two inequivalent Al sites. In the first Al site, Al is bonded in a 12-coordinate geometry to two equivalent Pr, four equivalent Fe, and six Al atoms. There are a spread of Al–Al bond distances ranging from 2.73–2.79 Å. In the second Al site, Al is bonded in a 10-coordinate geometry to one Pr, four equivalent Fe, and five Al atoms. The Al–Al bond length is 2.76 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(ClO2)3 by Materials Project

Pr(O2Cl)3 crystallizes in the monoclinic P2/c space group. The structure is three-dimensional. Pr is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Pr–O bond distances ranging from 2.41–2.62 Å. There are three inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to one Pr and one Cl atom. The O–Cl bond length is 1.58 Å. In the second O site, O is bonded in a distorted bent 150 degrees geometry to one Pr and one Cl atom. The O–Cl bond length is 1.56 Å. In the third O site, O is bonded in a trigonal planar geometry to two equivalent Pr and one Cl atom. The O–Cl bond length is 1.63 Å. There are two inequivalent Cl sites. In the first Cl site, Cl is bonded in a water-like geometry to two O atoms. In the second Cl site, Cl is bonded in a water-like geometry to two equivalent O atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(BIr)2 by Materials Project

Pr(IrB)2 is alpha Pu-derived structured and crystallizes in the orthorhombic Fddd space group. The structure is three-dimensional. Pr is bonded in a 10-coordinate geometry to eight equivalent Ir and six equivalent B atoms. There are four shorter (3.09 Å) and four longer (3.32 Å) Pr–Ir bond lengths. There are two shorter (3.05 Å) and four longer (3.16 Å) Pr–B bond lengths. Ir is bonded in a 4-coordinate geometry to four equivalent Pr and four equivalent B atoms. There are two shorter (2.10 Å) and two longer (2.18 Å) Ir–B bond lengths. B is bonded in a 4-coordinate geometry to three equivalent Pr and four equivalent Ir atoms.

36 MATERIALS SCIENCE↗