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At least 1,171 records · Page 65
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on PrGePd by Materials Project

PrPdGe crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Pr is bonded in a 12-coordinate geometry to six equivalent Pd and six equivalent Ge atoms. There are a spread of Pr–Pd bond distances ranging from 3.08–3.33 Å. There are a spread of Pr–Ge bond distances ranging from 3.18–3.37 Å. Pd is bonded in a 10-coordinate geometry to six equivalent Pr, one Pd, and three equivalent Ge atoms. The Pd–Pd bond length is 2.93 Å. There are two shorter (2.57 Å) and one longer (3.03 Å) Pd–Ge bond lengths. Ge is bonded in a 10-coordinate geometry to six equivalent Pr, three equivalent Pd, and one Ge atom. The Ge–Ge bond length is 2.58 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tm2CdPd2 by Materials Project

Tm2Pd2Cd crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Tm is bonded in a 6-coordinate geometry to six equivalent Pd and four equivalent Cd atoms. There are two shorter (2.83 Å) and four longer (2.98 Å) Tm–Pd bond lengths. All Tm–Cd bond lengths are 3.38 Å. Pd is bonded in a 9-coordinate geometry to six equivalent Tm, one Pd, and two equivalent Cd atoms. The Pd–Pd bond length is 2.80 Å. Both Pd–Cd bond lengths are 3.01 Å. Cd is bonded to eight equivalent Tm and four equivalent Pd atoms to form a mixture of distorted face and corner-sharing CdTm8Pd4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CeGePd by Materials Project

CePdGe crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Ce is bonded in a 12-coordinate geometry to six equivalent Pd and six equivalent Ge atoms. There are a spread of Ce–Pd bond distances ranging from 3.03–3.27 Å. There are a spread of Ce–Ge bond distances ranging from 3.10–3.33 Å. Pd is bonded in a 10-coordinate geometry to six equivalent Ce, one Pd, and three equivalent Ge atoms. The Pd–Pd bond length is 2.81 Å. There are two shorter (2.57 Å) and one longer (2.94 Å) Pd–Ge bond lengths. Ge is bonded in a 10-coordinate geometry to six equivalent Ce, three equivalent Pd, and one Ge atom. The Ge–Ge bond length is 2.56 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho2CdPd2 by Materials Project

Ho2Pd2Cd crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Ho is bonded in a 6-coordinate geometry to six equivalent Pd and four equivalent Cd atoms. There are two shorter (2.85 Å) and four longer (3.01 Å) Ho–Pd bond lengths. All Ho–Cd bond lengths are 3.40 Å. Pd is bonded in a 9-coordinate geometry to six equivalent Ho, one Pd, and two equivalent Cd atoms. The Pd–Pd bond length is 2.77 Å. Both Pd–Cd bond lengths are 3.04 Å. Cd is bonded to eight equivalent Ho and four equivalent Pd atoms to form a mixture of face and corner-sharing CdHo8Pd4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca2GePd3 by Materials Project

Ca2Pd3Ge crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Ca is bonded in a 12-coordinate geometry to nine equivalent Pd and three equivalent Ge atoms. There are three shorter (3.03 Å) and six longer (3.26 Å) Ca–Pd bond lengths. All Ca–Ge bond lengths are 3.30 Å. Pd is bonded to six equivalent Ca, four equivalent Pd, and two equivalent Ge atoms to form distorted PdCa6Ge2Pd4 cuboctahedra that share corners with four equivalent GeCa6Pd6 cuboctahedra, corners with fourteen equivalent PdCa6Ge2Pd4 cuboctahedra, edges with six equivalent PdCa6Ge2Pd4 cuboctahedra, faces with six equivalent GeCa6Pd6 cuboctahedra, and faces with twelve equivalent PdCa6Ge2Pd4 cuboctahedra. All Pd–Pd bond lengths are 2.83 Å. Both Pd–Ge bond lengths are 2.65 Å. Ge is bonded to six equivalent Ca and six equivalent Pd atoms to form GeCa6Pd6 cuboctahedra that share corners with six equivalent GeCa6Pd6 cuboctahedra, corners with twelve equivalent PdCa6Ge2Pd4 cuboctahedra, edges with six equivalent GeCa6Pd6 cuboctahedra, and faces with eighteen equivalent PdCa6Ge2Pd4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ti2H2Pd by Materials Project

Ti2PdH2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ti is bonded to four equivalent Pd and five equivalent H atoms to form distorted TiH5Pd4 square pyramids that share corners with four equivalent TiH5Pd4 square pyramids, corners with eight equivalent HTi5Pd square pyramids, edges with twelve equivalent TiH5Pd4 square pyramids, and faces with five equivalent TiH5Pd4 square pyramids. All Ti–Pd bond lengths are 2.84 Å. There is one shorter (1.93 Å) and four longer (2.05 Å) Ti–H bond length. Pd is bonded in a 10-coordinate geometry to eight equivalent Ti, four equivalent Pd, and two equivalent H atoms. All Pd–Pd bond lengths are 2.86 Å. Both Pd–H bond lengths are 2.33 Å. H is bonded to five equivalent Ti and one Pd atom to form distorted HTi5Pd square pyramids that share corners with five equivalent HTi5Pd square pyramids, corners with eight equivalent TiH5Pd4 square pyramids, and edges with eight equivalent HTi5Pd square pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HoGePd by Materials Project

HoPdGe crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Ho is bonded in a 12-coordinate geometry to six equivalent Pd and six equivalent Ge atoms. There are a spread of Ho–Pd bond distances ranging from 3.05–3.20 Å. There are a spread of Ho–Ge bond distances ranging from 3.06–3.25 Å. Pd is bonded in a 10-coordinate geometry to six equivalent Ho, one Pd, and three equivalent Ge atoms. The Pd–Pd bond length is 2.83 Å. There are two shorter (2.53 Å) and one longer (2.78 Å) Pd–Ge bond lengths. Ge is bonded in a 10-coordinate geometry to six equivalent Ho, three equivalent Pd, and one Ge atom. The Ge–Ge bond length is 2.59 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MoPdRuRh by Materials Project

MoRuRhPd is beta-derived structured and crystallizes in the trigonal P3m1 space group. The structure is three-dimensional. Mo is bonded to six equivalent Mo, three equivalent Ru, and three equivalent Rh atoms to form MoMo6Ru3Rh3 cuboctahedra that share corners with six equivalent MoMo6Ru3Rh3 cuboctahedra, corners with twelve equivalent PdPd6Ru3Rh3 cuboctahedra, edges with six equivalent MoMo6Ru3Rh3 cuboctahedra, edges with six equivalent RuMo3Pd3Ru6 cuboctahedra, edges with six equivalent RhMo3Pd3Rh6 cuboctahedra, faces with two equivalent PdPd6Ru3Rh3 cuboctahedra, faces with six equivalent MoMo6Ru3Rh3 cuboctahedra, faces with six equivalent RuMo3Pd3Ru6 cuboctahedra, and faces with six equivalent RhMo3Pd3Rh6 cuboctahedra. All Mo–Mo bond lengths are 2.78 Å. All Mo–Ru bond lengths are 2.67 Å. All Mo–Rh bond lengths are 2.69 Å. Ru is bonded to three equivalent Mo, six equivalent Ru, and three equivalent Pd atoms to form RuMo3Pd3Ru6 cuboctahedra that share corners with six equivalent RuMo3Pd3Ru6 cuboctahedra, corners with twelve equivalent RhMo3Pd3Rh6 cuboctahedra, edges with six equivalent MoMo6Ru3Rh3 cuboctahedra, edges with six equivalent RuMo3Pd3Ru6 cuboctahedra, edges with six equivalent PdPd6Ru3Rh3 cuboctahedra, faces with two equivalent RhMo3Pd3Rh6 cuboctahedra, faces with six equivalent MoMo6Ru3Rh3 cuboctahedra, faces with six equivalent RuMo3Pd3Ru6 cuboctahedra, and faces with six equivalent PdPd6Ru3Rh3 cuboctahedra. All Ru–Ru bond lengths are 2.78 Å. All Ru–Pd bond lengths are 2.79 Å. Rh is bonded to three equivalent Mo, six equivalent Rh, and three equivalent Pd atoms to form RhMo3Pd3Rh6 cuboctahedra that share corners with six equivalent RhMo3Pd3Rh6 cuboctahedra, corners with twelve equivalent RuMo3Pd3Ru6 cuboctahedra, edges with six equivalent MoMo6Ru3Rh3 cuboctahedra, edges with six equivalent RhMo3Pd3Rh6 cuboctahedra, edges with six equivalent PdPd6Ru3Rh3 cuboctahedra, faces with two equivalent RuMo3Pd3Ru6 cuboctahedra, faces with six equivalent MoMo6Ru3Rh3 cuboctahedra, faces with six equivalent RhMo3Pd3Rh6 cuboctahedra, and faces with six equivalent PdPd6Ru3Rh3 cuboctahedra. All Rh–Rh bond lengths are 2.78 Å. All Rh–Pd bond lengths are 2.83 Å. Pd is bonded to three equivalent Ru, three equivalent Rh, and six equivalent Pd atoms to form PdPd6Ru3Rh3 cuboctahedra that share corners with six equivalent PdPd6Ru3Rh3 cuboctahedra, corners with twelve equivalent MoMo6Ru3Rh3 cuboctahedra, edges with six equivalent RuMo3Pd3Ru6 cuboctahedra, edges with six equivalent RhMo3Pd3Rh6 cuboctahedra, edges with six equivalent PdPd6Ru3Rh3 cuboctahedra, faces with two equivalent MoMo6Ru3Rh3 cuboctahedra, faces with six equivalent RuMo3Pd3Ru6 cuboctahedra, faces with six equivalent RhMo3Pd3Rh6 cuboctahedra, and faces with six equivalent PdPd6Ru3Rh3 cuboctahedra. All Pd–Pd bond lengths are 2.78 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Dy(PPd)2 by Materials Project

Dy(PdP)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Dy is bonded in a 8-coordinate geometry to eight equivalent Pd and eight equivalent P atoms. All Dy–Pd bond lengths are 3.22 Å. All Dy–P bond lengths are 3.10 Å. Pd is bonded to four equivalent Dy, four equivalent Pd, and four equivalent P atoms to form a mixture of distorted corner, edge, and face-sharing PdDy4P4Pd4 cuboctahedra. All Pd–Pd bond lengths are 2.89 Å. All Pd–P bond lengths are 2.47 Å. P is bonded in a 9-coordinate geometry to four equivalent Dy, four equivalent Pd, and one P atom. The P–P bond length is 2.20 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TmPPd by Materials Project

TmPdP crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Tm is bonded in a 5-coordinate geometry to six equivalent Pd and five equivalent P atoms. There are a spread of Tm–Pd bond distances ranging from 3.01–3.25 Å. There are a spread of Tm–P bond distances ranging from 2.81–2.89 Å. Pd is bonded to six equivalent Tm, two equivalent Pd, and four equivalent P atoms to form a mixture of distorted face, edge, and corner-sharing PdTm6P4Pd2 cuboctahedra. Both Pd–Pd bond lengths are 2.99 Å. There are a spread of Pd–P bond distances ranging from 2.53–2.76 Å. P is bonded in a 9-coordinate geometry to five equivalent Tm and four equivalent Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ErSiPd by Materials Project

ErPdSi crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Er is bonded in a 11-coordinate geometry to six equivalent Pd and six equivalent Si atoms. There are a spread of Er–Pd bond distances ranging from 3.02–3.14 Å. There are a spread of Er–Si bond distances ranging from 2.99–3.30 Å. Pd is bonded in a 10-coordinate geometry to six equivalent Er, one Pd, and three equivalent Si atoms. The Pd–Pd bond length is 2.92 Å. There are two shorter (2.47 Å) and one longer (2.71 Å) Pd–Si bond lengths. Si is bonded in a 10-coordinate geometry to six equivalent Er, three equivalent Pd, and one Si atom. The Si–Si bond length is 2.44 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La2CdPd2 by Materials Project

La2Pd2Cd crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. La is bonded in a 6-coordinate geometry to six equivalent Pd and four equivalent Cd atoms. There are two shorter (2.98 Å) and four longer (3.15 Å) La–Pd bond lengths. All La–Cd bond lengths are 3.53 Å. Pd is bonded in a 9-coordinate geometry to six equivalent La, one Pd, and two equivalent Cd atoms. The Pd–Pd bond length is 2.80 Å. Both Pd–Cd bond lengths are 3.12 Å. Cd is bonded to eight equivalent La and four equivalent Pd atoms to form a mixture of corner and face-sharing CdLa8Pd4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BaPdO5 by Materials Project

BaPdO5 crystallizes in the monoclinic P2 space group. The structure is three-dimensional. there are two inequivalent Ba sites. In the first Ba site, Ba is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Ba–O bond distances ranging from 2.65–2.88 Å. In the second Ba site, Ba is bonded in a 8-coordinate geometry to ten O atoms. There are a spread of Ba–O bond distances ranging from 2.66–3.40 Å. Pd is bonded to six O atoms to form corner-sharing PdO6 octahedra. The corner-sharing octahedral tilt angles are 59°. There are a spread of Pd–O bond distances ranging from 2.06–2.09 Å. There are six inequivalent O sites. In the first O site, O is bonded in a 3-coordinate geometry to one Ba, one Pd, and one O atom. The O–O bond length is 1.40 Å. In the second O site, O is bonded in a 3-coordinate geometry to one Ba, one Pd, and one O atom. The O–O bond length is 1.40 Å. In the third O site, O is bonded in a 1-coordinate geometry to two Ba, one Pd, and one O atom. The O–O bond length is 1.46 Å. In the fourth O site, O is bonded in a 1-coordinate geometry to three Ba, one Pd, and one O atom. In the fifth O site, O is bonded to two equivalent Ba and two equivalent Pd atoms to form distorted corner-sharing OBa2Pd2 tetrahedra. In the sixth O site, O is bonded to two equivalent Ba and two equivalent Pd atoms to form distorted corner-sharing OBa2Pd2 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

The superior hydrothermal stability of Pd/SSZ-39 in low temperature passive NOx adsorption (PNA) and methane combustion

We successfully synthesized uniform SSZ-39 with an average crystal size of about a micron. Pd (0.7 - 3 wt%) was supported on SSZ-39 with Si/Al ratio ~12. The as-synthesized materials were characterized by FTIR, XRD, Helium Ion Microscopy, HAADF-STEM imaging, 27 Al, 29 Si and H solid state NMR spectroscopic techniques. FTIR studies with CO and NO probe molecules reveal that the 0.7 wt% Pd/SSZ-39 material with Si/Al ~12 has the majority of Pd dispersed atomically as isolated Pd(II) and Pd(II)-OH centers, and thus can be used as a low-temperature passive NOx adsorber. Pd(II)-NO, Pd(II)(OH)(NO) and Pd(II)(CO)(NO) complexes form during PNA in this material. We compare this PNA material directly with the Pd/SSZ-13 system (with Si/Al ratio ~12) and show its superior hydrothermal stability. Remarkably, Pd/SSZ-39 with Si/Al ratio ~12 survives hydrothermal aging up to 815 ºC in 10% H 2 O/Air vapor for 16 hours without significant loss in activity. The SSZ-39 crystal structure remains intact during hydrothermal aging up to 1,000 ºC as we elucidate it with XRD and HAADF-STEM imaging/EDS mapping. However, changes to the framework during such harsh hydrothermal treatment significantly change the NOx release profiles during PNA as evidenced by high-field 27 Al NMR on fresh and aged Pd/SSZ-39 samples as well as PNA performance measurements. Besides PNA application, these hydrothermally very stable materials (3 wt% Pd on SSZ-39 with Si/Al ratio ~12) can be used as a robust methane combustion catalyst under industrially relevant conditions (GHSV~600,000hr -1 ). This catalyst shows minimal deactivation after both harsh hydrothermal aging at 750 and 800 ºC, and prolonged time on stream (105 hrs) at 425 °C. In contrast, both 3wt% Pd/alumina and 3wt% SSZ-13 supported samples lose a significant portion of their activity. Our study opens new avenues to prepare the most hydrothermally stable known Pd/zeolite materials with applications for adsorption and catalytic hydrocarbon combustion under industrially relevant conditions.

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

Catalytic influence of light element incorporation in the lattice of palladium

The alloying of metals with foreign elements is a common approach for manipulating catalytic properties of active sites. For palladium-based catalysts, incorporation of light elements receives far less attention than Pd-metal alloys even though incorporated light element are catalytically significant. Due to their small size, light elements (H, B, C, and O) can occupy octahedral sites in Pd to form an interstitial phase, while palladium adjusts its lattice to accommodate the incorporation of larger light elements (S and P) to form distinct phases. The incorporated light element modifies the electronic structure of palladium, influencing the binding energy of substrates and reactive intermediates. Pd hydride and oxide often form in situ during hydrogenation or oxidation reactions, respectively, representing the (more, less) active phase of the catalyst. Further, the reactive interstitial hydrogen dissolved in Pd tends to hydrogenate reactants completely and unselectively. Pd oxide can be the active phase for oxidation reactions, and the incorporated oxygen or oxygen vacancies may participate in the reaction directly. Incorporated light elements change geometric aspects of Pd ensembles, serving the role of site blocking, ensemble isolation, or serve as an additional active site, endowing Pd with bifunctional character. We review the synthetic approaches for incorporating light elements into the palladium lattice. We summarize the catalytic influence of light element incorporation into the palladium lattice with respect to electronic and geometric modification, in situ incorporated hydrogen and oxygen, and discuss the influence of light element incorporation into Pd on specific reactions (i.e., selective hydrogenation, oxidation, electrocatalysis, and C—C cross coupling).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

A hybrid meshfree discretization to improve the numerical performance of peridynamic models

Efficient and accurate calculation of spatial integrals is of major interest in the numerical implementation of peridynamics (PD). The standard way to perform this calculation is a particle-based approach that discretizes the strong form of the PD governing equation. This approach has rapidly been adopted by the PD community since it offers some advantages. Additionally, it is computationally cheaper than other available schemes, can conveniently handle material separation, and effectively deals with nonlinear PD models. Nevertheless, PD models are still computationally very expensive compared with those based on the classical continuum mechanics theory, particularly for large-scale problems in three dimensions. This results from the nonlocal nature of the PD theory which leads to interactions of each node of a discretized body with multiple surrounding nodes. Here, we propose a new approach to significantly boost the numerical efficiency of PD models. We propose a discretization scheme that employs a simple collocation procedure and is truly meshfree; i.e., it does not depend on any background integration cells. In contrast to the standard scheme, the proposed scheme requires a much smaller set of neighboring nodes (keeping the same physical length scale) to achieve a specific accuracy and is thus computationally more efficient. Our new scheme is applicable to the case of linear PD models and within neighborhoods where the solution can be approximated by smooth basis functions. Therefore, to fully exploit the advantages of both the standard and the proposed schemes, a hybrid discretization is presented that combines both approaches within an adaptive framework. The high performance of the developed framework is illustrated by several numerical examples, including brittle fracture and corrosion problems in two and three dimensions.

42 ENGINEERING↗
DOE OSTI2021

Influence of Hydrogen Isotopes on Vacancy Formation and Antisite Defect Diffusion in Palladium and Vanadium Metals

Density functional theory calculations are performed to study the interaction between hydrogen isotopes, vacancy, and antisite defects in Pd and V. Various defect configurations and defect-defect distances are systematically explored. Binding energies and migration energy barriers are calculated and tabulated. The study provides atomistic data for subsequent mesoscale simulations of tritium, vacancy, and antisite diffusion. In Pd, a strong binding is found between a vacancy and tritium (0.16 eV). This tritium binding increases the thermal concentration of vacancies by a factor of ~10 at 500 ?C. The increase in vacancy concentration enhances V antisite diffusion in Pd by a factor of ~6 at 500 ?C. The influence of tritium is even stronger in V, with a tritium and vacancy binding energy of 0.38 eV. Such a strong binding increases the thermal concentration of vacancies by a factor of ~300 at 500 ?C. The increase in vacancy concentration enhances Pd antisite diffusion in V by a factor of ~640 at 500 ?C. Vanadium and Pd exhibit a strong driving force to intermix with a formation energy of -1.57 eV for V antisite in Pd and -1.05 eV for Pd antisite in V. The results suggest vanadium diffusion into Pd is energetically stronger than the reverse. Zero-point-energy corrections are taken into account and calculations for hydrogen and tritium are presented.

Setyawan, Wahyu↗
DOE OSTI2021

Highly Active and Stable Palladium Catalysts on Novel Ceria–Alumina Supports for Efficient Oxidation of Carbon Monoxide and Hydrocarbons

Precious metal catalysts with superior low-temperature activity and excellent thermal stability are highly needed in environmental catalysis field. In this study, a novel two-step incipient wetness impregnation (T-IWI) method was developed for the fabrication of a unique and highly stable CeO 2 /Al 2 O 3 support (CA-T). Pd anchored on CA-T exhibited a much higher low-temperature catalytic activity and superior thermal stability in carbon monoxide (CO) and hydrocarbon (HC) oxidations, compared to Pd anchored on conventional CeO 2 /Al 2 O 3 (CA), which was prepared by a one-step IWI method. After aging treatment at 800 °C, the CO oxidation rate on Pd/CA-T (1.69 mmol/(g Pd s)) at 120 °C was 4.1 and 84.5 times of those on Pd/CA (0.41 mmol/(g Pd s)) and Pd/Al 2 O 3 (0.02 mmol/(g Pd s)), respectively. It was revealed that the CA-T support with well-controlled small CeO 2 particles (ca. 12 nm) possessed abundant defects for Pd anchoring, which created rich Pd-CeO 2 interfaces with strengthened interaction between Pd and CeO 2 where oxygen could be efficiently activated. This resulted in the significantly improved oxidation activity and thermal stability of Pd/CA-T catalysts. The T-IWI method developed herein can be applied as a universal approach to prepare highly stable metal oxide-alumina-based supports, which have broad application in environmental catalyst design, especially for automobile exhaust aftertreatment.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗