Bimetallic nanoparticles like Cu–Ni are particularly attractive due to their magnetic and catalytic properties; however, their properties depend strongly on the structure of the alloy i.e. mixed, core–shell or Janus. To predict the alloy structure, this paper investigates the size and shape effects as well as the surface segregation effect on the Cu–Ni phase diagram. Phase maps have been plotted to determine the mixing/demixing behavior of this alloy according the particle shape. Cu–Ni nanoalloy can form a mixed particle or a Janus one depending on the synthesis temperature. Surface segregation is also considered and reveals a nickel surface-enrichment. Finally, this paper provides a useful roadmap for experimentalists.

Mn ²⁺ and Cd ²⁺ form a family of isostructural hexacyanoferrates(II,III). Their crystal structures, including those of mixed compositions containing K ⁺ and Cs ⁺ as charge balance cations, were resolved and refined from XRD powder patterns. The crystal structures of M ₃ [Fe(CN) ₆ ] ₂ ⋅xH ₂ O and MCs ₂ [Fe(CN) ₆ ] (where M=Mn, Cd) were refined in the space group Fm3m. The mixed salts, MK ₂ [Fe(CN) ₆ ]⋅2H ₂ O, were found to be orthorhombic (space group Pmn2 ₁ ). The orthorhombic structure results from a local distortion due to monohydrated potassium ions located in interstitial sites. On ionic exchange in an aqueous solution containing Cs ⁺ , the orthorhombic distortion disappears and the cubic cell is obtained. Cs ⁺ is a large ion, which practically fills the available interstitial voids stabilizing the cubic structure. In solutions of K ⁺ and Cs ⁺ the single salts, M ₂ [Fe(CN) ₆ ]⋅8H ₂ O (monoclinic P2 ₁ /n) also transform, in this case liberating M ²⁺ ions and forming the corresponding mixed salts. An analogous but slow structural transformation was also observed in the anhydrous forms of these single salts. These structural transformations could be relevant to the use of these compounds as ion exchangers and particularly for the sorption of ¹³⁷ Cs ⁺ from radioactive waste solutions. The XRD data were complemented with structural information from infrared (IR), Mössbauer and water vapor adsorption techniques. © 2004 International Centre for Diffraction Data.

In the last decade, the urgent need to environmental protection has promoted the development of new materials with potential applications to remediate air and polluted water. In this work, the effect of the TiO₂ thin layer over MoS₂ material in photocatalytic activity is reported. We prepared different heterostructures, using a combination of electrospinning, solvothermal, and spin-coating techniques. The properties of the samples were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD), nitrogen adsorption-desorption isotherms, UV-Vis diffuse reflectance spectroscopy (UV-Vis-DRS), and X-ray photoelectron spectroscopy (XPS). The adsorption and photocatalytic activity were evaluated by discoloration of rhodamine B solution. The TiO₂-MoS₂/TiO₂ heterostructure presented three optical absorption edges at 1.3 eV, 2.28 eV, and 3.23 eV. The high adsorption capacity of MoS₂ was eliminated with the addition of TiO₂ thin film. The samples show high photocatalytic activity in the visible-IR light spectrum.