Nanoparticles of metal alloys have been in the focus of considerable attention for displaying many interesting properties, such as depression of melting point, surface plasmon resonance, enhanced catalytic activity, and variable morphology. A challenging task is to calculate nanoalloy phase diagrams in dependence on the particles size for complex systems. Nanoalloys could be synthesized by various routes but the solvothermal synthesis with the hot-injection step in oleylamine is quite advantageous as it ensures homogeneous conditions for nanoparticle nucleation and growth. We synthesized binary metal alloy nanoparticles (AgNi, CuNi, AgCu, NiSn, NiSb) by injection of suitable molecular metal precursors into a mixture of oleylamine and octadecene at 230 °C. The type and nature of the precursors have a decisive effect on nanoparticle formation and their morphology and properties. In case of AgCu nanoalloy synthesis, we demonstrated their influence on the final nanoalloy elemental distribution, phase composition, particle size distribution, shape, morphology and optical properties. Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM), Elemental analyses (ICP OES), and Small-Angle X-ray Scattering (SAXS) analyses were performed for determination of the chemical composition, average size, size distribution, and shape of the prepared nanoparticles. Plasmon resonances were also observed. Phase separation was followed by High Temperature X-Ray Diffraction (HT-XRD) technique and was confirmed by Scanning Electron Microscopy (SEM) and by measuring of magnetic properties during heating. The combination of CALPHAD approach with the ab initio calculations of surface stresses was used for modelling of size-dependent phase diagrams of binary systems. Temperatures of invariant reactions were obtained by DSC measurements and experimental results were compared to calculated values.

Controlled synthesis and characterization of metal alloy nanoparticles and their size-dependent phase diagrams

256th National Meeting (2018)

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