| Abstract
| - Organically functionalized Ni(II) phyllosilicates, in which the nickel atoms are arranged in a triangular 36 net, are self-reduced under mild conditions in an inert atmosphere to produce the rare metastable hexagonal (hcp) Ni(0), which is then transformed into the more stable cubic (fcc) Ni(0) nanoparticles (20 nm) at high temperature.
- We report on the formation of air-stable fcc Ni nanoparticles via the rarely observed metastable hcpNi from two organically modified layered Ni(II) phyllosilicates at a moderately low temperature of lessthan 573 K in an inert atmosphere. The presence of hcp Ni as an intermediate is related to the organizationof the nickel atoms within the layers of the phyllosilicates, which is a triangular network with Ni−Nidistances of 3.2 Å protected by a strong covalent Si−O network on each surface. Characterizations ofthe products were performed by TG-DTA coupled to mass spectroscopy, in situ X-ray diffraction, electronmicroscopy, infrared, and in situ magnetization measurements. TEM shows that the fcc Ni particles arespherical and that the size (average of ca. 20 nm) depends on the starting phyllosilicate. Given that theamount of reduced Ni is proportional to the organic content and not to the Ni content of the phyllosilicateswhen the atmosphere is inert, we propose that the reduction takes place by the gases produced during thedecomposition of the organic moiety. The stabilization of the hcp Ni phase depends on the percentageof Si−O coverage of the surface.
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