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At least 991 records · Page 55
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Effect of disorder on thermodynamic instability of binary Rare-earth – Nickel – Palladium compounds

In this work, we have investigated the thermodynamic stability of disordered rare-earth phases SmX 2 and Sm 10 X 21 (X=Ni, Pd) using machine-learning based analytical descriptor and first-principles density functional theory methods. The absence of Laves phase compounds in R-Pd binary systems is a longstanding problem of rare earth science: even though Ni and Pd belong to the same group of the periodic table and have similar electronic structure, the Pd compound crystallizes in a monoclinic (C2/m) phase with 10:21 stoichiometry, i.e., Sm 10 Pd 21 , while the Ni compound adopts a cubic Laves phase (MgCu 2 ) structure. To understand this contrasting phase stability, we performed thermodynamic convex hull analysis of Sm x Ni 1-x and Sm x Pd 1-x binary systems, which is experimentally validated using powder X-ray diffraction (PXRD) analyzes of polycrystalline Sm(Ni x Pd 1-x ) 2 samples with x=0, 0.5, and 1. A detailed electronic-structure (band-structure, charge density, and Fermi-surface) analysis of the differences between SmNi 2 /SmPd 2 and Sm 10 Ni 21 /Sm 10 Pd 21 compounds provides the quantum mechanical origin of the unfavorable mixing of Pd with Ni in cubic Laves phase. We show that the stability of Sm-Pd in 10:21 stoichiometry arises from improved intra-/inter-layer 5d-4d bonding compared to the 1:2 stoichiometry. Our work emphasizes the importance of ab-initio methods and computationally inexpensive analytical descriptors for the detailed analysis of thermodynamic and electronic properties of hard-to-prepare rare-earth compounds.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Azo(xy) vs Aniline Selectivity in Catalytic Nitroarene Reduction by Intermetallics: Experiments and Simulations

Intermetallic nanoparticles are promising catalysts in hydrogenation and fuel cell technologies. Much is known about the ability of intermetallic nanoparticles to selectively reduce nitro vs alkene, alcohol, or halide functional groups; less is known about their selectivity toward aniline vs azo or azoxy condensation products that result from the reduction of a nitro group alone. Because azo(xy)arenes bear promise as dyes, chemical stabilizers, and building blocks to functional materials but can be difficult to isolate, developing high surface area nanoparticle catalysts that display azo(xy) selectivity is desirable. To address this question, we studied a family of nanocrystalline group 10 metal (Pd, Pt)- and group 14 metal (Ge, Sn, Pb)-containing intermetallics-Pd 2 Ge, Pd 2 Sn, Pd 3 Sn 2 , Pd 3 Pb, and PtSn-in the catalytic reduction of nitroarenes. In contrast to monometallic Au, Pt, and Pd nanoparticles and "random" PdxSn1 – x nanoalloys, which are selective for aniline, nanoparticles of atomically precise intermetallic Pd 2 Ge, Pd 2 Sn, Pd 3 Sn 2 , and PtSn prefer an indirect condensation pathway and have a high selectivity for the azo(xy) products. The only exception is Pd 3 Pb, the most active among the intermetallic nanoparticles studied here, which is instead selective for aniline. Employing a novel application of molecular dynamics-based on machine learned potentials within a DeePMD framework-to heterogeneous catalysis, we are able to identify key reaction species on the different types of catalysts employed, furthering our understanding of the unique selectivity of these materials. By demonstrating how intermetallic nanoparticles can be as active yet more selective than other more traditional catalysts, this work provides new physical insights and opens new opportunities in the use of these materials in other important chemical transformations and applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Xylem-dwelling pathogen unaffected by local xylem vessel network properties in grapevines ( Vitis spp.)

Abstract Background and aims Xylella fastidiosa (Xf) is the xylem-dwelling bacterium associated with Pierce’s disease (PD), which causes mortality in agriculturally important species, such as grapevine (Vitis vinifera). The development of PD symptoms in grapevines depends on the ability of Xf to produce cell-wall-degrading enzymes to break up intervessel pit membranes and systematically spread through the xylem vessel network. Our objective here was to investigate whether PD resistance could be mechanistically linked to xylem vessel network local connectivity. Methods We used high-resolution X-ray micro-computed tomography (microCT) imaging to identify and describe the type, area and spatial distribution of intervessel connections for six different grapevine genotypes from three genetic backgrounds, with varying resistance to PD (four PD resistant and two PD susceptible). Key results Our results suggest that PD resistance is unlikely to derive from local xylem network connectivity. The intervessel pit area (Ai) varied from 0.07 ± 0.01 mm2 mm−3 in Lenoir to 0.17 ± 0.03 mm2 mm−3 in Blanc do Bois, both PD resistant. Intervessel contact fraction (Cp) was not statically significant, but the two PD-susceptible genotypes, Syrah (0.056 ± 0.015) and Chardonnay (0.041 ± 0.013), were among the most highly connected vessel networks. Neither Ai nor Cp explained differences in PD resistance among the six genotypes. Bayesian re-analysis of our data shows moderate evidence against the effects of the traits analysed: Ai (BF01 = 4.88), mean vessel density (4.86), relay diameter (4.30), relay density (3.31) and solitary vessel proportion (3.19). Conclusions Our results show that radial and tangential xylem network connectivity is highly conserved within the six different Vitis genotypes we sampled. The way that Xf traverses the vessel network may limit the importance of local network properties to its spread and may confer greater importance on host biochemical responses.

Plant Sciences↗
DOE OSTI2023

Mixed Oxygenate Conversion to Sustainable Aviation Fuel via Ketones Intermediate

This report describes our effort in developing Pd based bimetallic catalysts during Tandem ketone condensation-hydrogenation reaction. We have synthesized a series of bimetallic catalysts containing equimolar amount of Pd with various other 3d, 4d and 5d transition and coinage metals. The activity of theses bimetallic catalysts towards C=C and C=O hydrogenation was evaluated using mesityl oxide and 2-heptanone as model compounds. All these catalysts show much higher activity towards C=C hydrogenation compared to C=O hydrogenation at a given temperature and at different H2 pressure, indicated the higher intrinsic activity of Pd based bimetallic catalysts towards C=C hydrogenation. Alloy catalysts with Pd and other 4d and 5d metals such as PdRu, PdRh, PdPt and PdIr shows higher activity towards both C=C and C=O hydrogenation compared to baseline Pd catalyst as well as alloy catalysts containing Pd and 3d transition metals. Among the different Pd-3d metal alloy catalysts, the activity of the bimetallic catalysts depends on alloying transition metals. Although, PdRu, PdRh, PdPt and PdIr catalysts shows very high activity towards C=O hydrogenation of 2-heptanone, the same catalysts didn’t show any C=O hydrogenation when ?,?-unsaturated carbonyl compound such as mesityl oxide was used as the model substrate. Based on these results, it is evident that Pd based bimetallic catalysts are very selective to the C=C hydrogenation and their activity could be tuned by the judicious choice of the alloying elements. Although alloying with Ru, Rh and Pt shows significant rate enhancement in case of C=C hydrogenation reaction, higher cost of those metals prevents their usage in industry as it significantly increases the cost of the catalyst. Considering all the factors, we have identified PdZn as one of promising alternative of Pd catalyst as it shows comparable activity towards C=C hydrogenation and reduces the activity for C=O hydrogenation. Based on the electrochemical CO stripping, we unambiguously established the weaker bonding CO on the PdZn surface compared to pristine Pd and highlight the benefits of its usage due to higher CO tolerance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Data for: Climatic Imprint on Interfacially-Controlled Platinum-Palladium Resources

Data package for manuscript "Climatic Imprint on Interfacially-Controlled Platinum-Palladium Resources" by Emily G. Wright, Ivey Wang, Yihang Fang, Elaine D. Flynn, and Jeffrey G. Catalano. This dataset contains adsorption results from experiments designed to investigate the effect of chloride on Pd(II) adsorption to goethite and Pt(II) adsorption to hematite and goethite, including lab experiments, X-ray absorption fine structure spectroscopy, and models of retention within a laterite. See the associated manuscript for full methods information. The file "Wright2025_PtAds_data.csv" contains the target starting Pt concentration (uM), final aqueous Pt and associated error (in uM), calculated adsorbed Pt and associated error (in umol/m2), target and measured aqueous chloride (mM), target aqueous nitrate (mM), final pH, and mineral concentration/loading (g/L). Associated mineral-free controls (mineral loading = 0 g/L) are included; the aqueous Pd error was not calculated and chloride was not measured in every sample. These data appear in Figures 1, S3, S4, S5, S20, and S22 in the associated manuscript. The file "Wright2025_PdAds_data.csv" contains the target starting Pd concentration (uM), final aqueous Pd and associated error (in uM), calculated adsorbed Pd and associated error (in umol/m2), target and measured aqueous chloride (mM), and mineral concentration/loading (g/L). Associated mineral-free controls (mineral loading = 0 g/L) are included; the aqueous Pd error was not calculated and chloride was not measured in every sample. These data appear in Figures 1, S3, S4, S5, and S20 in the associated manuscript. The file "Wright2025_MineralBatches_data.csv" contains the mineral identity and BET specific surface area (m2/g) for every mineral batch synthesized and used in experiments. The annealing time used is listed for hydrothermally annealed goethite. These data appear in Table S2 in the associated manuscript. The file "Wright2025_XRD_data.csv" contains the XRD patterns for every mineral batch synthesized as the counts as a function of two theta (in degrees). See "Wright2025_MineralBatches_data.csv" for more details on specific mineral batches. These data appear in Figure S2 in the associated manuscript. The file "Wright 2025_ZetaPotential_data.csv" contains the measured zeta potentials for samples of goethite (batch G2) at pH 4 the presence of varying amounts of sodium chloride. These data appear in Table S3 in the associated manuscript. The file "Wright2025_XAFSSamples_data.csv" contains the specific mineral batch, measured final aqueous Pd or Pt (uM), measured final aqueous chloride (mM), and estimated adsorbed Pd or Pt (umol/m2) of all XAFS samples. These data appear in Tables S4, S7, S8, and S10 in the associated manuscript. The files "Wright2025_PdXAFS_data.csv" and "Wright2025_PtXAFS_data.csv" contain the normalized spectra of Pd and Pt, respectively, adsorbed to minerals at varying chloride concentrations. See "Wright2025_XAFSSamples_data.csv" for a guide to sample names. Note that "05" in a sample name is equivalent to "0.5". These data appear in Figures 2, S6, S7, S8, S12, S13, and S14 in the associated manuscript. The file "Wright2025_LateriteProfileProfileModelParameters_data.csv" include the ratio of hematite to hematite and goethite in two synthetic, modeled profiles, as well as the modeled surface areas of goethite and hematite as a function of relative depth within the modeled weathering zone. These data were used, in conjunction with equations presented in the paper, to calculate the theoretical concentrations of Pd and Pt (and the resulting Pt/Pd ratio) within the profiles. These data appear in Figure 3 in the associated manuscript. The file "Wright2025_Imagery_data.zip" is a zipped folder containing the TEM and STEM images appear in Figures S18 and S19. Individual files are labeled as either STEM (Fig. S18) or TEM (Fig. S19) with a letter representing the part of the multipart figure.

58 GEOSCIENCES↗
DOE OSTI2020

Materials Data on HfPd3 by Materials Project

Pd3Hf is Uranium Silicide-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Hf sites. In the first Hf site, Hf is bonded to twelve Pd atoms to form a mixture of face and corner-sharing HfPd12 cuboctahedra. All Hf–Pd bond lengths are 2.84 Å. In the second Hf site, Hf is bonded to twelve Pd atoms to form a mixture of face and corner-sharing HfPd12 cuboctahedra. There are six shorter (2.84 Å) and six longer (2.86 Å) Hf–Pd bond lengths. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a distorted square co-planar geometry to four Hf atoms. In the second Pd site, Pd is bonded in a distorted see-saw-like geometry to four Hf atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YMgPd by Materials Project

MgYPd crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Mg is bonded in a 4-coordinate geometry to four Pd atoms. There are two shorter (2.74 Å) and two longer (2.88 Å) Mg–Pd bond lengths. Y is bonded in a 5-coordinate geometry to five Pd atoms. There are four shorter (3.05 Å) and one longer (3.08 Å) Y–Pd bond lengths. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 9-coordinate geometry to six equivalent Mg and three equivalent Y atoms. In the second Pd site, Pd is bonded in a 9-coordinate geometry to three equivalent Mg and six equivalent Y atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zr3Pd4 by Materials Project

Zr3Pd4 is delta Molybdenum Boride-like structured and crystallizes in the trigonal R-3 space group. The structure is three-dimensional. Zr is bonded in a 9-coordinate geometry to nine Pd atoms. There are a spread of Zr–Pd bond distances ranging from 2.73–3.09 Å. There are three inequivalent Pd sites. In the first Pd site, Pd is bonded in a 8-coordinate geometry to six equivalent Zr atoms. In the second Pd site, Pd is bonded in a 6-coordinate geometry to six equivalent Zr atoms. In the third Pd site, Pd is bonded in a 7-coordinate geometry to seven equivalent Zr atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgPd3 by Materials Project

MgPd3 is Uranium Silicide-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Mg is bonded to twelve Pd atoms to form a mixture of edge, face, and corner-sharing MgPd12 cuboctahedra. There are a spread of Mg–Pd bond distances ranging from 2.80–2.83 Å. There are three inequivalent Pd sites. In the first Pd site, Pd is bonded in a distorted rectangular see-saw-like geometry to four equivalent Mg atoms. In the second Pd site, Pd is bonded in a distorted square co-planar geometry to four equivalent Mg atoms. In the third Pd site, Pd is bonded to four equivalent Mg atoms to form a mixture of distorted edge and corner-sharing PdMg4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PdF3 by Materials Project

PdF3 crystallizes in the trigonal P321 space group. The structure is three-dimensional. there are two inequivalent Pd sites. In the first Pd site, Pd is bonded to six F atoms to form corner-sharing PdF6 octahedra. The corner-sharing octahedra tilt angles range from 26–35°. There are three shorter (1.99 Å) and three longer (2.04 Å) Pd–F bond lengths. In the second Pd site, Pd is bonded to six equivalent F atoms to form distorted corner-sharing PdF6 octahedra. The corner-sharing octahedral tilt angles are 26°. All Pd–F bond lengths are 2.10 Å. There are two inequivalent F sites. In the first F site, F is bonded in a bent 150 degrees geometry to two Pd atoms. In the second F site, F is bonded in a bent 150 degrees geometry to two equivalent Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg3Pd by Materials Project

Mg3Pd crystallizes in the hexagonal P6_3cm space group. The structure is three-dimensional. there are four inequivalent Mg sites. In the first Mg site, Mg is bonded in a distorted trigonal non-coplanar geometry to three equivalent Pd atoms. All Mg–Pd bond lengths are 2.70 Å. In the second Mg site, Mg is bonded in a trigonal planar geometry to three equivalent Pd atoms. All Mg–Pd bond lengths are 2.73 Å. In the third Mg site, Mg is bonded in a 2-coordinate geometry to two equivalent Pd atoms. There are one shorter (2.78 Å) and one longer (2.79 Å) Mg–Pd bond lengths. In the fourth Mg site, Mg is bonded in a distorted trigonal planar geometry to three equivalent Pd atoms. There are one shorter (2.79 Å) and two longer (2.86 Å) Mg–Pd bond lengths. Pd is bonded in a 10-coordinate geometry to eight Mg atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CeMgPd by Materials Project

MgCePd crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Mg is bonded in a 4-coordinate geometry to four Pd atoms. There are two shorter (2.73 Å) and two longer (2.97 Å) Mg–Pd bond lengths. Ce is bonded in a 5-coordinate geometry to five Pd atoms. There are four shorter (3.07 Å) and one longer (3.18 Å) Ce–Pd bond lengths. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 9-coordinate geometry to six equivalent Mg and three equivalent Ce atoms. In the second Pd site, Pd is bonded in a 9-coordinate geometry to three equivalent Mg and six equivalent Ce atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GdMgPd by Materials Project

GdPdMg crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Mg is bonded in a 4-coordinate geometry to four Pd atoms. There are two shorter (2.75 Å) and two longer (2.91 Å) Mg–Pd bond lengths. Gd is bonded in a 5-coordinate geometry to five Pd atoms. There are four shorter (3.06 Å) and one longer (3.11 Å) Gd–Pd bond lengths. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 9-coordinate geometry to six equivalent Mg and three equivalent Gd atoms. In the second Pd site, Pd is bonded in a 9-coordinate geometry to three equivalent Mg and six equivalent Gd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu4Pd by Materials Project

Cu4Pd crystallizes in the tetragonal P4_2/m space group. The structure is three-dimensional. Pd is bonded to one Pd and eleven Cu atoms to form distorted PdCu11Pd cuboctahedra that share corners with five equivalent PdCu11Pd cuboctahedra, corners with seven CuCu10Pd2 cuboctahedra, edges with four equivalent PdCu11Pd cuboctahedra, edges with twenty CuCu10Pd2 cuboctahedra, faces with two equivalent PdCu11Pd cuboctahedra, and faces with sixteen CuCu10Pd2 cuboctahedra. The Pd–Pd bond length is 2.73 Å. There are a spread of Pd–Cu bond distances ranging from 2.57–2.67 Å. There are four inequivalent Cu sites. In the first Cu site, Cu is bonded to two equivalent Pd and ten Cu atoms to form CuCu10Pd2 cuboctahedra that share corners with six equivalent PdCu11Pd cuboctahedra, corners with six equivalent CuCu10Pd2 cuboctahedra, edges with four equivalent PdCu11Pd cuboctahedra, edges with twenty CuCu9Pd3 cuboctahedra, faces with four equivalent PdCu11Pd cuboctahedra, and faces with fourteen CuCu10Pd2 cuboctahedra. There are a spread of Cu–Cu bond distances ranging from 2.58–2.60 Å. In the second Cu site, Cu is bonded to four equivalent Pd and eight Cu atoms to form distorted CuCu8Pd4 cuboctahedra that share corners with twelve equivalent CuCu9Pd3 cuboctahedra, edges with four equivalent PdCu11Pd cuboctahedra, edges with twenty CuCu9Pd3 cuboctahedra, faces with four equivalent PdCu11Pd cuboctahedra, and faces with fourteen CuCu9Pd3 cuboctahedra. There are four shorter (2.64 Å) and four longer (2.67 Å) Cu–Cu bond lengths. In the third Cu site, Cu is bonded to two equivalent Pd and ten Cu atoms to form CuCu10Pd2 cuboctahedra that share corners with four equivalent PdCu11Pd cuboctahedra, corners with eight CuCu10Pd2 cuboctahedra, edges with two equivalent PdCu11Pd cuboctahedra, edges with twenty-two CuCu10Pd2 cuboctahedra, faces with six equivalent PdCu11Pd cuboctahedra, and faces with twelve CuCu10Pd2 cuboctahedra. There are a spread of Cu–Cu bond distances ranging from 2.55–2.62 Å. In the fourth Cu site, Cu is bonded to three equivalent Pd and nine Cu atoms to form distorted CuCu9Pd3 cuboctahedra that share corners with twelve CuCu9Pd3 cuboctahedra, edges with seven equivalent PdCu11Pd cuboctahedra, edges with seventeen CuCu10Pd2 cuboctahedra, faces with three equivalent PdCu11Pd cuboctahedra, and faces with fifteen CuCu10Pd2 cuboctahedra. There are two shorter (2.61 Å) and one longer (2.66 Å) Cu–Cu bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZrPd3 by Materials Project

Pd3Zr is Uranium Silicide-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Zr sites. In the first Zr site, Zr is bonded to twelve Pd atoms to form a mixture of corner and face-sharing ZrPd12 cuboctahedra. There are six shorter (2.86 Å) and six longer (2.88 Å) Zr–Pd bond lengths. In the second Zr site, Zr is bonded to twelve Pd atoms to form a mixture of corner and face-sharing ZrPd12 cuboctahedra. All Zr–Pd bond lengths are 2.86 Å. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a distorted see-saw-like geometry to four Zr atoms. In the second Pd site, Pd is bonded in a distorted square co-planar geometry to four Zr atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TbGe2Pd by Materials Project

TbPdGe2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. there are two inequivalent Tb sites. In the first Tb site, Tb is bonded in a 12-coordinate geometry to four equivalent Pd and ten Ge atoms. All Tb–Pd bond lengths are 3.27 Å. There are a spread of Tb–Ge bond distances ranging from 3.27–3.41 Å. In the second Tb site, Tb is bonded in a 12-coordinate geometry to six equivalent Pd and eight Ge atoms. There are four shorter (3.22 Å) and two longer (3.33 Å) Tb–Pd bond lengths. There are six shorter (3.03 Å) and two longer (3.09 Å) Tb–Ge bond lengths. Pd is bonded in a 10-coordinate geometry to five Tb and five Ge atoms. There are a spread of Pd–Ge bond distances ranging from 2.49–2.70 Å. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded in a 8-coordinate geometry to four Tb, three equivalent Pd, and one Ge atom. The Ge–Ge bond length is 2.64 Å. In the second Ge site, Ge is bonded in a 9-coordinate geometry to six Tb, two equivalent Pd, and one Ge atom. The Ge–Ge bond length is 2.45 Å. In the third Ge site, Ge is bonded in a 2-coordinate geometry to four equivalent Tb, two equivalent Pd, and one Ge atom. The Ge–Ge bond length is 2.47 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pd16S7 by Materials Project

Pd16S7 crystallizes in the cubic I-43m space group. The structure is three-dimensional and consists of two Pd16S7 frameworks. there are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a linear geometry to two S atoms. There are one shorter (2.29 Å) and one longer (2.34 Å) Pd–S bond lengths. In the second Pd site, Pd is bonded in a distorted trigonal non-coplanar geometry to three equivalent S atoms. All Pd–S bond lengths are 2.51 Å. There are two inequivalent S sites. In the first S site, S is bonded to four equivalent Pd atoms to form distorted corner-sharing SPd4 trigonal pyramids. In the second S site, S is bonded to six Pd atoms to form distorted SPd6 pentagonal pyramids that share corners with three equivalent SPd4 trigonal pyramids and edges with three equivalent SPd6 pentagonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GePd2 by Materials Project

Pd2Ge crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. there are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 5-coordinate geometry to five Ge atoms. There are one shorter (2.66 Å) and four longer (2.73 Å) Pd–Ge bond lengths. In the second Pd site, Pd is bonded to four Ge atoms to form a mixture of distorted edge and corner-sharing PdGe4 tetrahedra. There are two shorter (2.51 Å) and two longer (2.53 Å) Pd–Ge bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 9-coordinate geometry to nine Pd atoms. In the second Ge site, Ge is bonded in a 9-coordinate geometry to nine Pd atoms.

36 MATERIALS SCIENCE↗