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Herein we report, for the first time, on the synthesis and structural characterization of the Zr-based MAX phase, Zr 3 AlC 2 , fabricated by reactive hot pressing of ZrH 2 , Al, and C powders. The crystal structure of Zr 3 AlC 2 was determined by X-ray diffraction and high resolution transmission electron microscopy to be the hexagonal space group P63/mmc . The a and c lattice parameters are 3.33308(6) Å and 19.9507(3) Å, respectively. The samples include the secondary phases ZrC and Zr–Al intermetallics as confirmed by quantitative electron probe microanalysis. The Vickers hardness, using a force of 30 N, was measured to be 4.4 ± 0.4 GPa. [ABSTRACT FROM AUTHOR]

We report on the electrical characterization of single MXene Ti3C2Tx flakes (where T is a surface termination) and demonstrate the metallic nature of their conductivities. We also show that the carrier density can be modulated by an external gate voltage. The density of free carriers is estimated to be 8 ± 3 x 1021 cm-3 while their mobility is estimated to be 0.7 ± 0.2 cm²/V s. Electrical measurements, in the presence of a magnetic field, show a small, but clearly discernable, quadratic increase in conductance at 2.5K. [ABSTRACT FROM AUTHOR]

Abstract: Ni–Mo nanocomposite coatings (18–32nm) were prepared by electrodeposition of nickel from a nickel salt bath containing suspended Mo nanoparticles. All the coatings have been deposited under galvanostatic conditions using current densities in the range 5–80mA/cm2. According to structural investigation carried out by X-ray diffraction, the obtained coatings consisted of crystalline Mo phase incorporated into Ni matrix. The molybdenum content diminished with increasing the deposition current density and ranged between ∼6 and ∼17% Mo. The crystallite size and the surface roughness increased by raising the current density. A remarkable deterioration in the corrosion resistance of Ni–Mo composites was observed with the increase of Mo content due to crystallite size-refining and surface roughness effect. Electrocatalytic effect for hydrogen production was improved mainly as a result of increasing the surface roughness and thus providing more accessible surface area. [Copyright &y& Elsevier]

Ni-Mo nanocrystalline deposits (7-43 nm) with a nodular morphology were prepared by electrodeposition using direct current from citrate-ammonia solutions. They exhibited a single Ni-Mo solid solution phase. The size of the nodules increased as electroplating current density increased. The molybdenum content―estimated using EDX analysis―in the deposits decreased from about 31 to 11wt% as the current density increased from 5 to 80mA·cm-2. The highest microhardness value (285 Hv) corresponded to nanodeposits with 23%Mo. The highest corrosion resistance accompanied by relatively high hardness was detected for electrodeposits containing 15%Mo. Mo content values between 11 and 15% are recommended for obtaining better electrocatalytic activity for HER. [ABSTRACT FROM AUTHOR]

Here, we report, for the first time, on the first-order Raman spectra of the layered Mo-based ternaries: MoAlB, Mo2Ga2C and Mo2GaC. Polycrystalline samples were fabricated, and well-defined Raman spectra were recorded. When the experimental peak positions were compared with those predicted from density functional theory, good agreement was obtained, indirectly validating both. Furthermore, all modes in the three compounds were symmetry assigned. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This study reports on the first experimental evidence of the existence of the Zr 2 AlC MAX phase, synthesised by means of reactive hot pressing of a ZrH 2 , Al and C powder mixture. The crystal structure of this compound was investigated by X-ray and neutron diffraction. The lattice parameters were determined and confirmed by high-resolution transmission electron microscopy. The effect of varying the synthesis temperature was investigated, indicating a relatively narrow temperature window for the synthesis of Zr 2 AlC. ZrC was always present as a secondary phase by hot pressing in the 1475–1575 °C range. [ABSTRACT FROM AUTHOR]

We report the discovery of a new hexagonal Mo2Ga2C phase, wherein two Ga layers – instead of one – are stacked in a simple hexagonal arrangement in between Mo2C layers. It is reasonable to assume this compound is the first of a larger family. [ABSTRACT FROM AUTHOR]