Synthesis and study of the phase composition of Ni-Pt particles used in carbon composite materials
N. S. ZAKHAROV1, E. S. PARSHKOVA1, A. N. PRIGORODOVA (POPOVA)1, V. G. DODONOV1, D. M. RUSSAKOV2, V. I. KRASHENIN1
1Federal Research Center for Coal and Coal Chemistry, Kemerovo, Russia
2Kemerovo State University, Kemerovo, Russia
Keywords: nanoalloys, solid solution, intermetallic compounds, Ni-Pt, phase composition, X-ray diffraction, small-angle X-ray scattering, transmission electron microscopy
Abstract
As a result of studying the phase composition of Ni-Pt nanoalloy particles using X-ray diffraction (XRD) analysis, it has been established that during the synthesis of Ni-Pt nanoalloy particles by co-reduction of the aqueous metal precursor solutions (Ni2+ and [PtCl6]2-) with an alkaline hydrazine hydrate solution, the formation of fcc-type Ni-Pt solid solution particles occurs, with an average Ni content of 13 at%. These particles have ellipsoid shape with the equatorial and lateral size 6-13 and 10-28 nm, respectively. By comparing the XRD results with data obtained from high-resolution transmission electron microscopy (HRTEM) and small-angle X-ray scattering (SAXS), it has been shown that, in addition to the aforementioned Ni-Pt solid solution particles, the synthesised samples contain ultrafine Ni-rich particles: the phases of Ni-Pt intermetallides and the fcc-phase of individual Ni. As a result of heating the sample with total nickel content 20 at% in high vacuum to a temperature of 390 °C, the phase transformation takes place, leading to the formation of fcc-type Ni-Pt solid solution particles with Ni content 23 at% and average size ≈26 nm, as well as the particles of practically pure platinum with the average size ≈55 nm.
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