- STACKING DISORDER IN NbP, TaP, NbAs AND TaAs.
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Stacking disorder in the monophosphides and arsenides of niobium and tantalum was studied using X-ray diffraction techniques. Special attention was paid to the effects of the composition and the heat treatment of the samples. A metastable WC-type structure is formed during the early stages of the reaction while the sample is heating up. As the temperature increases, the metastable WC-type structure partially transforms into a stable NbAs-type structure, resulting in a disordered structure comprising variable amounts of the WC- and NbAs-type structures which coexist within a common coherent lattice. This transformation appears to be constrained by the presence of the metal phase so that the completeness of the transformation, and thus the amount of stacking disorder, varies with the sample composition.
- Willerstrom
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- Effect of magnetic field on the hydrogen evolution activity using non-magnetic Weyl semimetal catalysts
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An external switch to control the kinetics of the reaction by manipulating the participating electrons could be interesting as it can alter the rate of the reaction without affecting the reaction pathway. The magnetic field, like a switch, is non-invasive
- Felser, Claudia,Gupta, Uttam,Kumar, Nitesh,Li, Guowei,Rajamathi, Catherine R.,Rao, C. N. R.,Shekhar, Chandra,Sun, Yan
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supporting information
p. 3398 - 3402
(2020/04/02)
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- A Series of MAX Phases with MA-Triangular-Prism Bilayers and Elastic Properties
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We report a new type of MAX phase (M=transition metals, A=main group elements, and X=C/N), Nb3As2C, designated as 321 phase. It differs from all the previous Mn+1AXn phases in that it consists of an alternate stacking of one MX layer and two MA layers in its unit cell, while only one MA layer is allowed in usual MAX phases. The new 321 phase exhibits a bulk modulus of Nb3As2C up to 225(3) GPa as determined by high-pressure synchrotron X-ray diffraction, one of the highest values among MAX phases. Isostructural 321 phases V3As2C, Nb3P2C, and Ta3P2C are also found to exist. First-principles calculations reveal the outstanding elastic stiffness in 321 phases. Among all 321 phases, Nb3P2C is predicted to have the highest elastic properties. These 321 phases, represented by a chemical formula Mn+1AnX, were added as new members to the MAX family and their other properties deserve future investigations.
- Chen, Hongxiang,Yang, Dongliang,Zhang, Qinghua,Jin, Shifeng,Guo, Liwei,Deng, Jun,Li, Xiaodong,Chen, Xiaolong
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supporting information
p. 4576 - 4580
(2019/03/13)
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- Evolution of the Fermi surface of Weyl semimetals in the transition metal pnictide family
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Topological Weyl semimetals (TWSs) represent a novel state of topological quantum matter which not only possesses Weyl fermions (massless chiral particles that can be viewed as magnetic monopoles in momentum space) in the bulk and unique Fermi arcs generated by topological surface states, but also exhibits appealing physical properties such as extremely large magnetoresistance and ultra-high carrier mobility. Here, by performing angle-resolved photoemission spectroscopy (ARPES) on NbP and TaP, we directly observed their band structures with characteristic Fermi arcs of TWSs. Furthermore, by systematically investigating NbP, TaP and TaAs from the same transition metal monopnictide family, we discovered their Fermiology evolution with spin-orbit coupling (SOC) strength. Our experimental findings not only reveal the mechanism to realize and fine-tune the electronic structures of TWSs, but also provide a rich material base for exploring many exotic physical phenomena (for example, chiral magnetic effects, negative magnetoresistance, and the quantum anomalous Hall effect) and novel future applications.
- Liu,Yang,Sun,Zhang,Peng,Yang,Chen,Zhang,Guo,Prabhakaran,Schmidt,Hussain,Mo,Felser,Yan,Chen
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- Interaction of Group VB Transition Metals with Uranium Monophosphide
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The character and extent of interaction of Group VB transition metals with uranium monophosphide at 1073-2273 K is studied. The interaction products are solid solutions; VP, NbP. and TaP monophosphides; and at high temperatures, liquid phases of the eutectic type. The kinetic constants for the growth of monophosphide layers are determined. In all cases, small quantities of uranium dissolve in the resulting monophosphides. A comparison of the kinetic constants for phosphidization of the transition metals is made.
- Panov
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p. 490 - 493
(2008/10/08)
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