scholarly journals Spotlight on Alkali Metals: The Structural Chemistry of Alkali Metal Thallides

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1013
Author(s):  
Stefanie Gärtner
Keyword(s):  
Crystal Structure ◽  
Alkali Metal ◽  
Crystal Structures ◽  
Alkali Metals ◽  
Valence Electron ◽  
Oxidation States ◽  
Valence Electron Concentration ◽  
Base Metals ◽  
Charge Balancing

Alkali metal thallides go back to the investigative works of Eduard Zintl about base metals in negative oxidation states. In 1932, he described the crystal structure of NaTl as the first representative for this class of compounds. Since then, a bunch of versatile crystal structures has been reported for thallium as electronegative element in intermetallic solid state compounds. For combinations of thallium with alkali metals as electropositive counterparts, a broad range of different unique structure types has been observed. Interestingly, various thallium substructures at the same or very similar valence electron concentration (VEC) are obtained. This in return emphasizes that the role of the alkali metals on structure formation goes far beyond ancillary filling atoms, which are present only due to charge balancing reasons. In this review, the alkali metals are in focus and the local surroundings of the latter are discussed in terms of their crystallographic sites in the corresponding crystal structures.

Thermoelectric Properties of Ru2Si3-Based Chimney-Ladder Phases

2007 ◽  
Vol 561-565 ◽  
pp. 463-466 ◽  
Author(s):  
Kyosuke Kishida ◽  
Akira Ishida ◽  
Katsushi Tanaka ◽  
Haruyuki Inui
Keyword(s):  
Crystal Structures ◽  
Thermoelectric Properties ◽  
Electron Concentration ◽  
Valence Electron ◽  
Valence Electron Concentration ◽  
Compositional Range ◽  
Wide Compositional Range ◽  
P Type ◽  
Semiconducting Behavior

The variations of the crystal structures and thermoelectric properties of the Ru1-xRexSiy chimney-ladder phases were studied as a function of the Re concentration. A series of chimney-ladder phases with a compositional formula of Ru1-xRexSi1.539+0.178x are formed in a wide compositional range, 0.14 ≤ x ≤ 0.76. The composition of the chimney-ladder phase is systematically deviated from the idealized composition satisfying the valence electron concentration rule: VEC=14. Measurements of thermoelectric properties reveal that the chimney-ladder phases exhibit n-type semiconducting behavior at low Re concentrations and p-type semiconducting behavior at high Re concentrations, which are well consistent with the prediction based on the deviation of the composition of the chimney-ladder phase from the idealized composition.

On the charge transfer between conventional cations: the structures of ternary oxides and chalcogenides of alkali metals

2012 ◽  
Vol 68 (4) ◽  
pp. 364-377
Author(s):  
Angel Vegas
Keyword(s):  
Charge Transfer ◽  
Alkali Metal ◽  
Crystal Structures ◽  
Alkali Metals ◽  
Group 14 ◽  
Zintl Phases ◽  
Partial Structures ◽  
Alkali Atoms ◽  
Group 14 Elements ◽  
Ternary Oxides

The structures of ternary oxides and chalcogenides of alkali metals are dissected in light of the extended Zintl–Klemm concept. This model, which has been successfully extended to other compounds different to the Zintl phases, assumes that crystal structures can be better understood if the cation substructures are contemplated as Zintl polyanions. This implies the occurrence of charge transfer between cations, even if they are of the same kind. In this article, the charge transfer between cations is even more illustrative because the two alkali atoms have different electronegativity, so that the less electropositive alkali metal and the O/S atom always form skeletons characteristic of the group 14 elements. Thus, partial structures of the zincblende-, wurtzite-, PbO- and SrAl2-type are found in the oxides/sulfides. In this work, such an interpretation of the structures remains at a topological level. The analysis also shows that this interpretation is complementary to the model developed by Andersson and Hyde which contemplates the structures as the intergrowth of structural slabs of more simple compounds.

scholarly journals Distinct effects of Q925 mutation on intracellular and extracellular Na+ and K+ binding to the Na+, K+-ATPase

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Hang N. Nielsen ◽  
Kerri Spontarelli ◽  
Rikke Holm ◽  
Jens Peter Andersen ◽  
Anja P. Einholm ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Binding Sites ◽  
Functional Role ◽  
Transmembrane Helix ◽  
Binding Properties ◽  
Ion Translocation ◽  
Extracellular Side ◽  
Insight Into

Abstract Three Na+ sites are defined in the Na+-bound crystal structure of Na+, K+-ATPase. Sites I and II overlap with two K+ sites in the K+-bound structure, whereas site III is unique and Na+ specific. A glutamine in transmembrane helix M8 (Q925) appears from the crystal structures to coordinate Na+ at site III, but does not contribute to K+ coordination at sites I and II. Here we address the functional role of Q925 in the various conformational states of Na+, K+-ATPase by examining the mutants Q925A/G/E/N/L/I/Y. We characterized these mutants both enzymatically and electrophysiologically, thereby revealing their Na+ and K+ binding properties. Remarkably, Q925 substitutions had minor effects on Na+ binding from the intracellular side of the membrane – in fact, mutations Q925A and Q925G increased the apparent Na+ affinity – but caused dramatic reductions of the binding of K+ as well as Na+ from the extracellular side of the membrane. These results provide insight into the changes taking place in the Na+-binding sites, when they are transformed from intracellular- to extracellular-facing orientation in relation to the ion translocation process, and demonstrate the interaction between sites III and I and a possible gating function of Q925 in the release of Na+ at the extracellular side.

Electrochemical and 1H NMR studies of proton behavior of ImCl and LiCl solution in acetonitrile

1997 ◽  
Vol 75 (11) ◽  
pp. 1730-1735 ◽  
Author(s):  
Ping He ◽  
Keith E. Johnson
Keyword(s):  
Alkali Metal ◽  
Alkali Metals ◽  
Passive Layer ◽  
Acetonitrile Solution ◽  
Nmr Studies ◽  
Imidazolium Chloride ◽  
Electrochemical Window ◽  
Lithium Chloride Solution ◽  
Stripping Efficiency

The role of the proton in extending the electrochemical window and promoting the stripping efficiency of alkali metals has been studied in acetonitrile solution. The platinum hydride surface generated in the hydrogen evolution was considered responsible for the potential shift of 1-ethyl-3-methyl-1H-imidazolium (Im+) reduction in the absence of lithium. In lithium chloride solution, the lithium layer deposited on the electrode may be the main cause for the stretch of the solvent electrochemical window because of the high overpotential of Im+ reduction on that surface. The proton may affect the properties of the passive layer on newly deposited alkali metal surfaces and then improve the performance of the alkali metal anodes. Keywords: 1-ethyl-3-methyl-1H-imidazolium chloride, protons, acetonitrile, lithium reduction.

scholarly journals Superconductivity in Cubic A15-type V–Nb–Mo–Ir–Pt High-Entropy Alloys

2021 ◽  
Vol 9 ◽  
Author(s):  
Bin Liu ◽  
Jifeng Wu ◽  
Yanwei Cui ◽  
Qinqing Zhu ◽  
Guorui Xiao ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Valence Electron ◽  
Upper Critical Field ◽  
Valence Electron Concentration ◽  
High Entropy Alloys ◽  
Zero Temperature ◽  
Superconducting Properties ◽  
High Entropy ◽  
Weakly Coupled ◽  
Type V

We report the crystal structure and superconducting properties of new V5+2xNb35−xMo35−xIr10Pt15 high-entropy alloys (HEAs) for x in the range of 0 ≤x≤ 10. These HEAs are found to crystallize in a cubic A15-type structure and have a weakly coupled, fully gapped superconducting state. A maximum Tc of 5.18 K and zero-temperature upper critical field Bc2(0) of 6.4 T are observed at x = 0, and both quantities decrease monotonically with the increase of V content x. In addition, Tc shows an increase with increasing valence electron concentration from 6.4 to 6.5, which is compared with other A15-type HEA and binary superconductors.

Van der Waals and repulsive interactions in the crystal structure of heavy alkali metals

1980 ◽  
Vol 58 (6) ◽  
pp. 905-911 ◽  
Author(s):  
J. C. Upadhyaya ◽  
S. Wang ◽  
R. A. Moore
Keyword(s):  
Crystal Structure ◽  
Binding Energy ◽  
Alkali Metal ◽  
Alkali Metals ◽  
High Pressures ◽  
Van Der Waals ◽  
Energy Difference ◽  
Repulsive Interactions

The present work deals with the calculation of a screened van der Waals contribution to the binding energy of heavy alkali metals, namely K, Rb, and Cs. Our calculations show that the van der Waals contribution is of the order of energy difference between different phases for a heavy alkali metal. Further we study the effect of the Born–Mayer type repulsive interactions on the crystal structure for heavy alkalis. It appears from this study that these repulsive interactions are important in the determination of the crystal structure, particularly for a heavy alkali metal under high pressures.

scholarly journals Necessary Thermodynamics Factors to Obtain Simple Solid Solutions in High-Entropy Alloys from the Al-Ti-Co-Ni-Fe System

2017 ◽  
Vol 62 (4) ◽  
pp. 2141-2145 ◽  
Author(s):  
K. Górecki ◽  
P. Bała ◽  
T. Kozieł ◽  
G. Cios
Keyword(s):  
Crystal Structure ◽  
Electron Concentration ◽  
Valence Electron ◽  
Intermetallic Phases ◽  
Mixing Enthalpy ◽  
Valence Electron Concentration ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Mixing Entropy ◽  
Design And Synthesis

AbstractIn this paper findings regarding the design and synthesis of High-Entropy Alloys based on mixing enthalpy, mixing entropy,δparameter, Ω parameter and valence electron concentration are presented. Four alloys were synthesised with different predicted crystalline structures. Results of the microstructure and crystal structure studies are presented. It was shown that predicted structures as well as complex intermetallic phases exist in the material. The validity of valence electron concentration as well as additional parameters such as mixing enthalpy, mixing entropy and others necessary to obtain only the solid solution in High-Entropy Alloys were examined.

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