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Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations
EuCu2Sn2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Eu is bonded in a 10-coordinate geometry to six equivalent Cu and four equivalent Sn atoms. There are two shorter (3.19 Å) and four longer (3.33 Å) Eu–Cu bond lengths. All Eu–Sn bond lengths are 3.47 Å. Cu is bonded in a 9-coordinate geometry to three equivalent Eu, two equivalent Cu, and four equivalent Sn atoms. Both Cu–Cu bond lengths are 2.60 Å. There are a spread of Cu–Sn bond distances ranging from 2.61–2.68 Å. Sn is bonded in a 9-coordinate geometry to two equivalent Eu, four equivalent Cu, and one Sn atom. The Sn–Sn bond length is 3.05 Å.
UCu2Sn2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. U is bonded in a 12-coordinate geometry to eight Cu and eight Sn atoms. There are four shorter (3.35 Å) and four longer (3.38 Å) U–Cu bond lengths. There are four shorter (3.32 Å) and four longer (3.50 Å) U–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 U and four equivalent Sn atoms. All Cu–Sn bond lengths are 2.59 Å. In the second Cu site, Cu is bonded in a 9-coordinate geometry to four equivalent U and five Sn atoms. There are one shorter (2.47 Å) and four longer (2.61 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 U and four equivalent Cu atoms. In the second Sn site, Sn is bonded in a 9-coordinate geometry to four equivalent U and five Cu atoms.
CeCu2Sn2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Ce is bonded in a 12-coordinate geometry to eight Cu and eight Sn atoms. There are four shorter (3.36 Å) and four longer (3.44 Å) Ce–Cu bond lengths. There are four shorter (3.37 Å) and four longer (3.56 Å) Ce–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 Ce and four equivalent Sn atoms. All Cu–Sn bond lengths are 2.61 Å. In the second Cu site, Cu is bonded in a 9-coordinate geometry to four equivalent Ce and five Sn atoms. There are one shorter (2.52 Å) and four longer (2.65 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 Ce and four equivalent Cu atoms. In the second Sn site, Sn is bonded in a 9-coordinate geometry to four equivalent Ce and five Cu atoms.
GdCu2Sn2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Gd is bonded in a 12-coordinate geometry to eight Cu and eight Sn atoms. There are four shorter (3.34 Å) and four longer (3.39 Å) Gd–Cu bond lengths. There are four shorter (3.32 Å) and four longer (3.55 Å) Gd–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 Gd and four equivalent Sn atoms. All Cu–Sn bond lengths are 2.58 Å. In the second Cu site, Cu is bonded in a 9-coordinate geometry to four equivalent Gd and five Sn atoms. There are one shorter (2.50 Å) and four longer (2.63 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 Gd and four equivalent Cu atoms. In the second Sn site, Sn is bonded in a 9-coordinate geometry to four equivalent Gd and five Cu atoms.
Er3Cu4Sn4 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. there are two inequivalent Er sites. In the first Er site, Er is bonded to six Sn atoms to form distorted edge-sharing ErSn6 octahedra. There are four shorter (3.03 Å) and two longer (3.17 Å) Er–Sn bond lengths. In the second Er site, Er is bonded in a 12-coordinate geometry to six equivalent Cu and six Sn atoms. There are four shorter (3.15 Å) and two longer (3.20 Å) Er–Cu bond lengths. There are two shorter (3.16 Å) and four longer (3.26 Å) Er–Sn bond lengths. Cu is bonded in a 8-coordinate geometry to three equivalent Er, one Cu, and four Sn atoms. The Cu–Cu bond length is 2.60 Å. There are a spread of Cu–Sn bond distances ranging from 2.60–2.74 Å. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 9-coordinate geometry to three Er and six equivalent Cu atoms. In the second Sn site, Sn is bonded in a 9-coordinate geometry to six Er, two equivalent Cu, and one Sn atom. The Sn–Sn bond length is 2.81 Å.
Tm3Cu4Sn4 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. there are two inequivalent Tm sites. In the first Tm site, Tm is bonded to six Sn atoms to form distorted edge-sharing TmSn6 octahedra. There are four shorter (3.02 Å) and two longer (3.14 Å) Tm–Sn bond lengths. In the second Tm site, Tm is bonded in a 12-coordinate geometry to six equivalent Cu and six Sn atoms. There are two shorter (3.14 Å) and four longer (3.17 Å) Tm–Cu bond lengths. There are two shorter (3.15 Å) and four longer (3.24 Å) Tm–Sn bond lengths. Cu is bonded in a 12-coordinate geometry to three equivalent Tm, one Cu, and four Sn atoms. The Cu–Cu bond length is 2.60 Å. There are a spread of Cu–Sn bond distances ranging from 2.62–2.69 Å. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 9-coordinate geometry to three Tm and six equivalent Cu atoms. In the second Sn site, Sn is bonded in a 9-coordinate geometry to six Tm, two equivalent Cu, and one Sn atom. The Sn–Sn bond length is 2.84 Å.
Tm3Cu4Sn4 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Tm sites. In the first Tm site, Tm is bonded to four equivalent Cu and six Sn atoms to form distorted face-sharing TmCu4Sn6 octahedra. All Tm–Cu bond lengths are 3.45 Å. There are four shorter (3.02 Å) and two longer (3.15 Å) Tm–Sn bond lengths. In the second Tm site, Tm is bonded in a 12-coordinate geometry to six Cu and seven Sn atoms. There are a spread of Tm–Cu bond distances ranging from 3.06–3.30 Å. There are a spread of Tm–Sn bond distances ranging from 3.16–3.50 Å. There are two inequivalent Cu sites. In the first Cu site, Cu is bonded in a 12-coordinate geometry to three equivalent Tm, one Cu, and four Sn atoms. The Cu–Cu bond length is 2.65 Å. There are one shorter (2.62 Å) and three longer (2.69 Å) Cu–Sn bond lengths. In the second Cu site, Cu is bonded in a 10-coordinate geometry to five Tm, one Cu, and four Sn atoms. There are a spread of Cu–Sn bond distances ranging from 2.60–2.73 Å. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 9-coordinate geometry to four Tm and six Cu atoms. In the second Sn site, Sn is bonded in a 9-coordinate geometry to six Tm, two Cu, and one Sn atom. The Sn–Sn bond length is 2.82 Å.
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.
Er3Cu4Sn4 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Er sites. In the first Er site, Er is bonded to four equivalent Cu and six Sn atoms to form distorted face-sharing ErCu4Sn6 octahedra. All Er–Cu bond lengths are 3.50 Å. There are four shorter (3.03 Å) and two longer (3.19 Å) Er–Sn bond lengths. In the second Er site, Er is bonded in a 12-coordinate geometry to six Cu and six Sn atoms. There are a spread of Er–Cu bond distances ranging from 3.11–3.27 Å. There are a spread of Er–Sn bond distances ranging from 3.15–3.28 Å. There are two inequivalent Cu sites. In the first Cu site, Cu is bonded in a 10-coordinate geometry to five Er, one Cu, and four Sn atoms. The Cu–Cu bond length is 2.60 Å. There are a spread of Cu–Sn bond distances ranging from 2.61–2.74 Å. In the second Cu site, Cu is bonded in a 12-coordinate geometry to three equivalent Er, one Cu, and four Sn atoms. There are a spread of Cu–Sn bond distances ranging from 2.62–2.70 Å. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 9-coordinate geometry to three Er and six Cu atoms. In the second Sn site, Sn is bonded in a 9-coordinate geometry to six Er, two Cu, and one Sn atom. The Sn–Sn bond length is 2.82 Å.
SrCu2Sn2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Sr is bonded in a 10-coordinate geometry to six equivalent Cu and eight equivalent Sn atoms. There are two shorter (3.22 Å) and four longer (3.38 Å) Sr–Cu bond lengths. There are four shorter (3.53 Å) and four longer (3.72 Å) Sr–Sn bond lengths. Cu is bonded in a 9-coordinate geometry to three equivalent Sr, two equivalent Cu, and four equivalent Sn atoms. Both Cu–Cu bond lengths are 2.59 Å. There are a spread of Cu–Sn bond distances ranging from 2.64–2.70 Å. Sn is bonded in a 9-coordinate geometry to four equivalent Sr, four equivalent Cu, and one Sn atom. The Sn–Sn bond length is 3.15 Å.
Y3Cu4Sn4 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. there are two inequivalent Y sites. In the first Y site, Y is bonded to six Sn atoms to form distorted edge-sharing YSn6 octahedra. There are four shorter (3.05 Å) and two longer (3.18 Å) Y–Sn bond lengths. In the second Y site, Y is bonded in a 12-coordinate geometry to six equivalent Cu and six Sn atoms. All Y–Cu bond lengths are 3.19 Å. There are two shorter (3.19 Å) and four longer (3.28 Å) Y–Sn bond lengths. Cu is bonded in a 8-coordinate geometry to three equivalent Y, one Cu, and four Sn atoms. The Cu–Cu bond length is 2.62 Å. There are a spread of Cu–Sn bond distances ranging from 2.64–2.73 Å. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 9-coordinate geometry to three Y and six equivalent Cu atoms. In the second Sn site, Sn is bonded in a 9-coordinate geometry to six Y, two equivalent Cu, and one Sn atom. The Sn–Sn bond length is 2.84 Å.
In operando 2D X-ray absorption near edge structure (XANES) imaging was performed near the Cu K-edge during cycling of Cu 6 Sn 5 composite anodes for lithium ion batteries. Galvanostatic lithiation and delithiation with intermittent constant voltage holds near reaction plateaus show evolution of absorption spectra for active material particles. XANES spectra obtained from images taken during cycling were compared to standard spectra for Cu, Cu 6 Sn 5 , and Li 2 CuSn. Chemical composition was assessed for Cu-containing phases. Distinct Cu, Cu 6 Sn 5 , and Li 2 CuSn regions were identified for each voltage plateau. Mechanical degradation, electrode particle fracture and expansion were observed during delithiation. Furthermore, movement of particles during cycling suggests that expansion also impacts the supporting secondary phases and the transport networks therein. These results demonstrate that spectroscopic X-ray imaging methods can clearly distinguish chemically distinct phases in alloy electrodes and have the versatility to observe the evolution of these phases during lithiation and delithiation.
Electrochemical reduction of carbon dioxide and carbon monoxide offers an electricity‐powered route to make multicarbon liquid products. However, in conventional systems employing anion exchange membranes (AEMs), significant liquid product crossover leads to dilute product streams, increasing separation costs; and also produces unwanted anodic oxidation, further decreasing overall efficiency. Here, we report a forward‐biased bipolar membrane (FB‐BPM) system that achieves <10% liquid product crossover while sustaining a highly alkaline environment near the cathode, suppressing ethylene and hydrogen and favoring liquid products. By tuning catalyst composition to modulate the adsorption of *H and *OH, we steer selectivity toward acetate and alcohols. Using the FB‐BPM system, we achieve >25 wt% acetate on CuZn and >15 wt% alcohols on CuSn directly from the cathode outlet stream.
Currently available Cu–Nb–Sn phase diagrams lack the recently discovered nausite phase (Cu,Nb)Sn 2 , which is an important intermediate in the course of thermal processing of superconducting Nb 3 Sn wires. Processing decisively determines the resulting microstructure of Nb 3 Sn and, thus, its superconducting properties. Lack of suitable and complete phase diagrams, however, obstructs rational design of such thermal processing procedures. To close this gap and to obtain valid knowledge of homogeneity and stability range of nausite, various Cu–Nb–Sn samples, which are heat-treated between 300 °C and 500 °C, are investigated. By means of energy-dispersive X-ray spectroscopy (EDX), a temperature-dependent homogeneity range of nausite is observed, which covers average mole fractions of Cu between 0.09 and 0.15. This is correlated with a change in the mean atomic volume and can be seen in the lattice parameters determined by X-ray diffraction (XRD). Additionally performed first-principles calculations on different CuSn 2 and NbSn 2 model structures confirm this trend. Furthermore, the peritectic decomposition of nausite to NbSn 2 and liquid at 586 °C is determined by means of in situ XRD and differential scanning calorimetry (DSC). By using the CALPHAD (CALculation of PHase Diagrams) approach, all these findings are used to extend a previous thermodynamic description of the Cu–Nb–Sn system by including the nausite as an additional phase. Finally, with this noteworthy integration, the updated modelling of the Cu–Nb–Sn system can be used for optimizing the multistage heat-treatment steps during processing superconducting Nb 3 Sn wires.
Heterometallic clusters have attracted broad interests in the synthetic chemistry due to their various coordination modes and potential applications in heterogeneous catalysis. Here we report the synthesis, experimental, and theoretical characterizations of four ternary clusters ([M 2 (CO) 6 Sn 2 Sb 5 ] 3- (M = Cr, Mo), and [(MSn 2 Sb 5 ) 2 ] 4- , (M = Cu, Ag)) in the process of capturing the hypho - [Sn 2 Sb 5 ] 3- in ethylenediamine (en) solution. We show that the coordination of the binary anion to transition-metal ions or fragments provides additional stabilization due to the formation of locally σ-aromatic units, producing a spherical aromatic shielding region in the cages. While in the case of [Mo 2 (CO) 6 Sn 2 Sb 5 ] 3- stabilization arises from locally σ-aromatic three-centre and five-centre two-electron bonds, aromatic islands in [(AgSn 2 Sb 5 ) 2 ] 4- and [(CuSn 2 Sb 5 ) 2 ] 4- render them globally antiaromatic. This work describes the coordination chemistry of the versatile building block [Sn 2 Sb 5 ] 3- , thus providing conceptual advances in the field of metal-metal bonding in clusters.
The development of next-generation quaternary chalcogenides, such as Cu2ZnSnS4 (CZTS) and Cu2ZnGeS4 (CZGS), for solar energy and thermoelectric applications hinges upon both careful experimentation and accurate quantum mechanical modeling. To address the latter, many have turned to density functional theory (DFT), which offers several choices for the approximate treatment of electron exchange and correlation (XC). Popular XC functionals include the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) and the recently developed strongly constrained and appropriately normed (SCAN) meta-GGA. Extensions of DFT functionals, such as adding a Hubbard U correction and introducing a fraction of the Fock exchange (hybrid functionals), have been used widely to model systems containing 3d metal ions. However, no studies yet have compared comprehensively PBE(+U) and SCAN(+U) in the quality of their predictions of the bulk and defect thermodynamics of quaternary chalcogenides, which play a critical role in device fabrication and performance. Hence, here we calculate the (i) 0 K formation energies of bulk Ge compounds and (ii) neutral defect formation energies including charge-balanced (e.g., CuZn + ZnCu) and charge-imbalanced (e.g., CuSn) combinations of antisites and vacancies in CZTS and CZGS using the PBE, PBE +U, SCAN, SCAN +U, and the hybrid Heyd-Scuseria-Ernzerhof XC frameworks. We find that the formation energies of charge-imbalanced defects are more sensitive to the choice of the XC functional than those of charge-balanced defects, which can be explained by the differences in the extent of penalization of defect-generated delocalized electrons/holes by PBE, PBE +U, SCAN, and SCAN +U. Additionally, our results show that SCAN systematically underbinds Ge-containing compounds, thus highlighting the need for even further improvement of XC functionals. Based on our findings, we recommend the use of SCAN for modeling quaternary chalcogenides because its errors are systematic, and it has the firmest theoretical underpinning. Our work provides guidance for future modeling of quaternary chalcogenides.