scholarly journals Thermodynamics of the Atomic Distribution in Pt3Pd2, Pt2Pd3 and their Corresponding (111) Surfaces

2021 ◽  
Vol 74 ◽  
Author(s):  
Kyle Meerholz ◽  
David Santos-Carballal ◽  
Umberto Terranova ◽  
Anzel Falch ◽  
Cornelia G.C.E. van Sittert ◽  
...  
Keyword(s):  
Solid State ◽  
Bimetallic Catalysts ◽  
Computational Study ◽  
Interatomic Potentials ◽  
Site Occupation ◽  
Surface Energies ◽  
General Utility ◽  
Production Of Hydrogen ◽  
Surface Models ◽  
State Models

ABSTRACT In this study, we have developed solid-state models of platinum and palladium bimetallic catalysts, Pt3Pd2 and Pt2Pd3, which are rapidly thermally annealed at 800 °C. These models were constructed by determining all the unique atomic configurations in a 2x2x1 supercell, using the program Site-Occupation Disorder (SOD), and optimized with the General Utility Lattice Program (GULP) using Sutton-Chen interatomic potentials. Each catalyst had 101 unique bulk models that were developed into surface models, which were constructed using the two-region surface technique before the surface energies were determined. The planes and compositions with lowest surface energies were chosen as the representative models for the surface structure of the bimetallic catalysts. These representative models will now be used in a computational study of the HyS process for the production of hydrogen. Keywords: HyS process, platinum, palladium, solid-state, catalyst, Site-Occupation Disorder.

Synthesis of New Chalcogenide Materials. The Novel One-Dimensional Semiconductor K4 Ti3 S14

1987 ◽  
Vol 97 ◽  
Author(s):  
Steven A. Sunshine ◽  
Doris Kang ◽  
James A. Ibers
Keyword(s):  
Electrical Conductivity ◽  
Solid State ◽  
Alkali Metal ◽  
The Novel ◽  
Conductivity Measurements ◽  
One Dimensional ◽  
General Utility ◽  
Solid State Materials ◽  
Chalcogenide Materials

ABSTRACTThe use of A2 Q/Q melts (A - alkali metal, Q - S or Se) for the synthesis of new one-dimensional solid-state materials is found to be of general utility and is illustrated here for the synthesis of K4 Ti3 SI4. Reaction of Ti metal with a K2 S/S melt at 375°C for 50 h affords K4 Ti3 SI4. The structure possesses one-dimensional chains of seven and eightcoordinate Ti atoms with each chain isolated from all others by surrounding K atoms. There are six S-S pairs (dave - 2.069(3) Å) so that the compound is one of TiIV and may be described as K4 [Ti3 (S)2 (S2)6]. Electrical conductivity measurements indicate that this material is a semiconductor.

scholarly journals Development of Solid-state Models for the Gears of Different Geometry

2015 ◽  
Vol 129 ◽  
pp. 369-373 ◽  
Author(s):  
V.V. Bruzhas ◽  
B.A. Lopatin
Keyword(s):  
Solid State ◽  
State Models

Are the amide bonds in N-acyl imidazoles twisted? A combined solid-state 17O NMR, crystallographic, and computational study

2015 ◽  
Vol 93 (4) ◽  
pp. 451-458 ◽  
Author(s):  
Xianqi Kong ◽  
Aaron Tang ◽  
Ruiyao Wang ◽  
Eric Ye ◽  
Victor Terskikh ◽  
...  
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Crystal Structures ◽  
Computational Study ◽  
Chemical Shifts ◽  
Amide Bond ◽  
Chemical Shift Tensors ◽  
Amide Bonds ◽  
Bond Rotation ◽  
Quadrupole Coupling

We report synthesis of 17O-labeling and solid-state 17O NMR measurements of three N-acyl imidazoles of the type R-C(17O)-Im: R = p-methoxycinnamoyl (MCA-Im), R = 4-(dimethylamino)benzoyl (DAB-Im), and R = 2,4,6-trimethylbenzoyl (TMB-Im). Solid-state 17O NMR experiments allowed us to determine for the first time the 17O quadrupole coupling and chemical shift tensors in this class of organic compounds. We also determined the crystal structures of these compounds using single-crystal X-ray diffraction. The crystal structures show that, while the C(O)–N amide bond in DAB-Im exhibits a small twist, those in MCA-Im and TMB-Im are essentially planar. We found that, in these N-acyl imidazoles, the 17O quadrupole coupling and chemical shift tensors depend critically on the torsion angle between the conjugated acyl group and the C(O)–N amide plane. The computational results from a plane-wave DFT approach, which takes into consideration the entire crystal lattice, are in excellent agreement with the experimental solid-state 17O NMR results. Quantum chemical computations also show that the dependence of 17O NMR parameters on the Ar–C(O) bond rotation is very similar to that previously observed for the C(O)–N bond rotation in twisted amides. We conclude that one should be cautious in linking the observed NMR chemical shifts only to the twist of the C(O)–N amide bond.

scholarly journals Моделирование твердых растворов NaGd(MoO-=SUB=-4-=/SUB=-)-=SUB=-2-=/SUB=-- NaEu(MoO-=SUB=-4-=/SUB=-)-=SUB=-2-=/SUB=- и Na-=SUB=-2-=/SUB=-Gd-=SUB=-4-=/SUB=-(MoO-=SUB=-4-=/SUB=-)-=SUB=-7-=/SUB=--Na-=SUB=-2-=/SUB=-Eu-=SUB=-4-=/SUB=-(MoO-=SUB=-4-=/SUB=-)-=SUB=-7-=/SUB=- методом межатомных потенциалов

2019 ◽  
Vol 61 (4) ◽  
pp. 678
Author(s):  
В.Б. Дудникова ◽  
Е.В. Жариков ◽  
Н.Н. Еремин
Keyword(s):  
Solid Solutions ◽  
Atomistic Simulation ◽  
Statistical Distribution ◽  
Partial Ordering ◽  
Interatomic Potentials ◽  
Vibrational Entropy ◽  
Solid State Lasers ◽  
General Utility ◽  
Gadolinium Molybdate

AbstractSimulation of the solid solutions in the system of double sodium–gadolinium and sodium–europium molybdates, which are promising matrices for solid state lasers and phosphors has been carried out by the method of interatomic potentials. Two types of solid solutions have been studied, one of which contains finite components corresponding to the stoichiometric NaGd(MoO_4)_2–NaEu(MoO_4)_2 compositions with statistical distribution of cations in the crystal lattice. Another object is a cation-deficient Na_2Gd_4(MoO_4)_7–Na_2Eu_4(MoO_4)_7 system, in which we have examined the variants of statistical distribution and partial ordering of cations over structural positions. Atomistic simulation has been performed using the GULP 4.0.1 software package (General Utility Lattice Program). It is shown that when we pass from sodium-gadolinium molybdate to sodium-europium molybdate, both of stoichiometric and cation-deficient compositions, an increase in the unit cell volume is observed, while the density of the crystal, the energy of interatomic interactions in the structure, the vibrational entropy and the heat capacity decrease along with increasing europium content. The energy of interatomic interactions in the structure for cation-deficient solid solutions is less than for stoichiometric ones. Other aforementioned characteristics for cation-deficient solid solutions have greater values than for stoichiometric ones. The role of cluster europium centers in concentration quenching in NaGd(MoO_4)_2–NaEu(MoO_4)_2 solid solutions has been examined.

scholarly journals Ionic Conduction Through Reaction Products at the Electrolyte/electrode Interface in All-Solid-State Li⁺ Batteries

2020 ◽  
Author(s):  
Chuhong Wang ◽  
Koutarou Aoyagi ◽  
Muratahan Aykol ◽  
Tim Mueller
Keyword(s):  
Solid State ◽  
Lithium Ion Batteries ◽  
Ionic Conduction ◽  
Lithium Ion ◽  
Interatomic Potentials ◽  
Reaction Products ◽  
Ion Diffusion ◽  
Ion Conductivities ◽  
Common Electrode ◽  
Growth Limits

The development of all-solid-state lithium ion batteries has been hindered by the formation of a poorly conductive interphase at the interface between electrode and electrolyte materials. In the manuscript, we shed light on this problem by computationally evaluating potential lithium ion diffusion pathways through metastable arrangements of product phases that can form at 56 interfaces between common electrode and electrolyte materials. The evaluation of lithium-ion conductivities in the product phases is made possible by the use of machine-learned interatomic potentials trained on the fly. We identify likely reasons for the degradation of solid-state battery performance and discuss how these problems could be mitigated. These results provide enhanced understanding of how interface impedance growth limits the performance of all-solid-state lithium-ion batteries.

scholarly journals High-Speed 3d Modelling from Premium Rebuilding of Solid State Models

2017 ◽  
Vol 10 (28) ◽  
pp. 1-12
Author(s):  
Aykut Zongur ◽  
M. Fatih Talu ◽  
Ali Ozdes ◽  
◽  
◽  
...  
Keyword(s):  
Solid State ◽  
High Speed ◽  
3D Modelling ◽  
State Models

A tale of hydrogen abstraction, initially detectedviaX-ray diffraction

2014 ◽  
Vol 70 (3) ◽  
pp. 250-255 ◽  
Author(s):  
Alice K. Hui ◽  
Chun-Hsing Chen ◽  
Adam M. Terwilliger ◽  
Richard L. Lord ◽  
Kenneth G. Caulton
Keyword(s):  
Solid State ◽  
Density Functional ◽  
Computational Study ◽  
Hydrogen Abstraction ◽  
Open Shell ◽  
X Ray Diffraction ◽  
Neutral Radical ◽  
X Ray ◽  
Chloride Ligand ◽  
Synthetic Reaction

Reaction of a bis-tetrazinyl pyridine pincer ligand, btzp, with a vanadium(III) reagent gives not a simple adduct but dichlorido{3-methyl-6-[6-(6-methyl-1,2,4,5-tetrazin-3-yl-κN2)pyridin-2-yl-κN]-1,4-dihydro-1,2,4,5-tetrazin-1-yl-κN1}oxidovanadium(IV) acetonitrile 2.5-solvate, [V(C11H10N9)Cl2O]·2.5CH3CN, a species which X-ray diffraction reveals to have one H atom added to one of the two tetrazinyl rings. This H atom was first revealed by a short intermolecular N...Cl contact in the unit cell and subsequently established, from difference maps, to be associated with a hydrogen bond. One chloride ligand has also been replaced by an oxide ligand in this synthetic reaction. This formula for the complex, [V(Hbtzp)Cl2O], leaves open the question of both ligand oxidation state and spin state. A computational study of all isomeric locations of the H atom shows the similarity of their energies, which is subject to perturbation by intermolecular hydrogen bonding found in X-ray work on the solid state. These density functional calculations reveal that the isomer with the H atom located as found in the solid state contains a neutral radical Hbtzp ligand and tetravalentd1V center, but that these two unpaired electrons are more stable as an open-shell singlet and hence antiferromagnetically coupled.

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