Magnetic properties of electrodeposited amorphous nickel–phosphorus alloys

The influence of the sodium hypophosphite concentration in a sulfate–citrate electrolyte of nickel plating on the phosphorus content in electrodeposited amorphous Ni–P alloys was analyzed. The effect of the thermal treatment on the magnetic properties (coercive force and specific magnetization) of the obtained Ni–P alloys was considered; the Curie temperatures of the alloys were determined.     

Effect of TMAB concentration on structural,mechanical and corrosion properties of electrodeposited Ni–B alloys

The influence of trimethylamine borane (TMAB) concentration as a boron (B) source on the structural and corrosive properties of Ni–B alloy coatings produced by electrodeposition was investigated. The crystal structure of the Ni–B coatings is influenced by the B content in the coating, having a slight (220) preferred orientation. The B content in the coating increased from 16 to 34 at.% with the corresponding increase in the concentration of TMAB from 1 to 20 g/L, while interestingly retaining a crystal structure. The hardness of the coatings increased with increasing B content owing to the formation of smaller crystallites. An increase in B content in the alloy coatings, led to a shift in the E_corr values to more anodic potentials, indicating increase corrosion protection for the Ni–B coatings. This study achieved to reach 34 at.% B content in Ni–B alloy coatings produced by electrodeposition while preventing amorphization of the coating layer.     

Synthesis of Organophosphorus Compounds with ‒P˭P≡ and ‒P˭S˭ Units

Abstract

The lithium phosphide tetrahydrofurane complexes 1 react with phosphinic acid chlorides (2) to yield diphosphenes (4), possessing a tri- and a quinquevalent phosphorus atom; the diphosphane oxides 3 are regarded to be intermediate steps of the transformation.     

Spontaneous near-substrate composition modulation in electrodeposited Fe–Co–Ni alloys

Conventional and reverse depth profile analysis of electrodeposited Fe–Co–Ni alloys was performed by secondary neutral mass spectrometry (SNMS). It was found that the reverse sputtering method gave a much better depth resolution at the vicinity of the substrate. The reverse SNMS spectra showed that the deposition of Fe–Co–Ni alloys starts with the formation of an Fe-rich zone followed by an increase in Co concentration, then the nickel content increases and a steady-state alloy composition is achieved. At high current density, the initial depth pattern reproduces itself twice before the composition becomes stable. It was concluded that the varying depth profile is a consequence of the anomalous nature of the codeposition of the alloy components, the depletion of the electrolyte with respect to the metal salts, and the dependence of the intensity of the hydrogen evolution on the deposit surface composition.     

Preparation of carbon supported Pd–P catalyst with high content of element phosphorus and its electrocatalytic performance for formic acid oxidation

The carbon supported Pd–P (Pd–P/C) anodic catalyst in direct formic acid fuel cell (DFAFC) was prepared with a novel phosphorus reduction method. The Pd–P/C catalyst obtained possesses the high content of P⁰ in the alloying state. Because alloying P⁰ could decrease the 3d electron density of Pd and the adsorption affinity of CO and H on Pd, alloying P⁰ would promote the formic acid (FA) oxidation through the direct pathway. Therefore, the electrocatalytic performance of the Pd–P/C catalyst for the FA oxidation is much better than that of the Pd/C catalyst.     

Electrodeposition Mechanism of Zn‒Ni‒Mn Alloy at Different Time Intervals

Russian Journal of Applied Chemistry - Mechanism of electrodeposition and stripping of Zn?Ni?Mn alloys deposited at different time intervals from aqueous sulfate media were...     

Magnetic properties of UFe12−xSix

The homogeneity range of the system UFe_12−xSi_x with tetragonal ThMn₁₂ structure was determined to extend from x = 1 to x = 3. The Curie temperature and magnetic moment depend on the silicon content with maximum values T_c = 653 K and μ_m = 17.5 μ_B per formula unit reached at x = 2.0. The thermal expansion of UFe₁₀Si₂ was investigated by X-ray diffractometry. A volume magnetostriction of ω_s = 1% at T = 5 K was found. The hysteresis properties of powdered, sintered and melt-spun samples of UFe₁₀Si₂ were studied.     

Effect of nano-Al2O3 particles and of the Co concentration on the corrosion behavior of electrodeposited Ni–Co alloys

Incorporation of nano-Al₂O₃ particles into a Ni–Co alloy by electrodeposition influences the corrosion properties, morphology, and structure of the layers. The resistance against corrosion of Ni–Co/Al₂O₃ composite films deposited on stainless steel was investigated in a 0.1-M NaCl solution by potentiodynamic polarization. The presence of nanoparticles improves the corrosion resistance of Ni–Co/nano-Al₂O₃ deposits when compared to pure Ni–Co alloy. Moreover, by increasing the pH of the electrodeposition bath and the content of Co in the alloy, the resistance against corrosion is furthermore improved. The morphology of the deposits before and after their corrosion was analyzed by scanning electron microscopy. The presence of the embedded alumina particles in the Ni–Co alloys was one of the key factors that limited further propagation of corrosion on the metallic surface. Preferential corrosion attack, in the form of a pitting corrosion, was located mainly at the grain boundaries.     

Magnetic and electronic properties of α-graphyne nanoribbons

Based on the first-principles calculations, we investigate the magnetic and electronic properties of α-graphyne nanoribbons (NRs). We show that all the armchair α-graphyne NRs are nonmagnetic semiconductors with band gaps as a function of ribbon widths. The zigzag α-graphyne NRs are found to have magnetic semiconducting ground state with ferromagnetic ordering at each edge and opposite spin orientation between the two edges. Under the application of transverse electric field, we further predict the existence of half-metallicity in the zigzag NRs which strongly depends on the width of the ribbon.     

Magnetic properties of TlFe2−xSe2

Mössbauer studies on a mosaic of single crystals of the layered compound TlFe_2−xSe₂ have been carried out at various temperatures between 100 and 460 K. A magnetic transition occurs at ∼450 K. The magnetic ordering within the FeSe layers is antiferromagnetic with the spins oriented along the tetragonal axis. X-Ray diffraction data indicated ordering of the iron vacancies at the chosen composition (x ∼ 0.3) yielding a supercell with a volume five times that of the ThCr₂Si₂ type subcell, the cell parameters being a = 8.6909(5) Å and c = 14.005(1) Å.     

Thermodynamic properties of liquid copper–lanthanum alloys

Mixing enthalpies of alloys in the Cu–La system are measured using isoperibolic calorimetry method over the ranges 0 < x _La < 0.185 at 1400–1430 K and 0.659 < x _La < 1 at 1370 K. They have moderate exothermic values over the whole concentration range and agree with literature data. Activities of the components, enthalpies and entropies of formation of intermetallics in this system, and its phase diagram are optimized using an ideal associated solution (IAS) model, and agree with most literature data. The updated thermodynamic properties can be used in further investigation of multicomponent systems based on the binary Cu–La.     

Effects of Ta content on the phase stability and elastic properties of β Ti–Ta alloys from first-principles calculations

The effects of Ta content on the phase stability, the elastic property and the electronic structure of β type Ti–Ta alloys were studied from first-principles calculations based on the density functional theory. It is found that the phase stability, tetragonal shear constant C′, bulk modulus, elastic modulus and shear modulus of β type Ti–Ta alloys increase with the Ta content increasing monotonously. The lowest elastic modulus of the alloys is realized when the valence electron number (e/a) is around 4.25. Moreover, the phase stability of the alloys was discussed based on the calculated density of state (DOS).     

Relationship between the Cu content and thermal properties of Al–Cu alloys for latent heat energy storage

Current Al alloys still have shortcomings in their volumetric latent heat (LHV), compatibility and high-temperature inoxidizability, which limit their applications in the field of latent heat energy storage (LHES). The performance of aluminum alloys can be improved by the addition of Cu. The effects of the Cu content on the phase change temperature, mass latent heat (LHM), LHV, supercooling degree and microstructure of Al–Cu alloys were first studied by means of power-compensated differential scanning calorimetry, density, composition analysis and metallographic analysis. The measured values of the latent heat of Al–Cu alloys have been compared with the theoretically predicted values. The results show that for Al–Cu alloys with 7.3–52.8% Cu, the melting/freezing temperature is 540–655 °C/510–637 °C; the LHM and the LHV are 290–340 J g^?1 and 877–1224 J cm^?3, respectively; and the degree of supercooling is within 10 °C. The LHM and LHV of Al–Cu alloys decrease with the increase in the Cu content; when the content of Cu is over 16.6%, the difference between the theoretical value of the LHM and the measured average of the Al–Cu alloys is within 5%. The LHES phases in Al–Cu alloys are the α-Al and theta phases. Quantitative relationships of the Cu content and metallurgical microstructure with the LHM and LHV of Al–Cu alloys are established, and both theoretical and empirical equations are obtained for the estimation of the latent heat for Al–Cu alloys.     

Influence of Fe concentration on the properties of the electrodeposited Zn–Fe coatings

Electrodeposition of Zn–Fe alloys on a copper substrate from a sulfate bath with different Fe²⁺ concentration (0.05, 0.10 and 0.20 mol L^?1) at room temperature was investigated using cyclic voltammetry. The influence of the Fe²⁺ content in the plating bath on the surface morphology, structural and magnetic properties of the coatings were characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Vibrating Sample Magnetometer (VSM). The results show that the morphology of Zn–Fe films changes with different Fe²⁺ concentration. The EDS analysis demonstrated that the Fe content of the coatings increased with increasing the Fe concentration in the bath. XRD measurements shows the presence of ?Zn (hcp), δ1ZnFe (hcp) and the ΓZnFe (bcc) phases with a (101) preferential orientation in all the electrodeposited films. The magnetic analysis of Zn–Fe films indicated that the saturation magnetization was largely enhanced in comparison to pure Zn, especially with 0.2 at. % Fe, while the coercivity decreased.     

Thermodynamic properties of alloys of the binary In–La system

The thermochemical properties of melts of the binary In–La system were studied by the calorimetry method at 1250–1480 K over the whole concentration interval. It was shown that significant negative heat effects of mixing are characteristic features for these melts. Using the ideal associated solution (IAS) model, the activities of components, Gibbs energies and the entropies of mixing in the alloys, and the phase diagram of this system were calculated. They agree with the data from literature.     

Modeling of the thermodynamic properties of lead–tellurium liquid alloys

Application of the Redlich–Kister polynomial with varied number of parameters for describing the concentration dependence of thermodynamic systems of liquid metallic systems with a strong interaction between their components is considered for the example of the lead–tellurium system. Particular attention is given to the range of dilute solutions of tellurium in liquid lead.