Preparation and characterisation of Si nanocrystallites embedded in a silica matrix

Raman scattering of acoustical modes of silicon nanoparticles embedded in silica matrix

“…Our results are in agreement with those of Fujii et al 12 in that case also, the sizes estimated from the wavenumbers of the acoustic modes of Si crystallites were much larger than those observed by TEM. Similar observation was also made by Pauthe et al 26 Fujii et al 12 ascribed this phenomenon to the large anisotropy of the elastic constants and to the matrix effects. On the basis of the present results, one can rule out that the disagreement is due to a matrix effect, which was considered in the calculation.…”

“…34 The recent Raman scattering results on acoustic modes in silicon nanoparticles doped with erbium 29 are quite different from those of the present work and of other previous studies. 12,26 It seems that when erbium atoms are placed on the surface of nc-Si, the observed wavenumber of the symmetrical mode is in agreement with Eqn (1), and that there is no need for invoking resonance effects. However, it seems unlikely that the presence of Er can change the mechanism of inelastic light scattering, and the origin of the observed difference is not clear.…”

Vibrations of free and embedded anisotropic elastic spheres: Application to low-frequency Raman scattering of silicon nanoparticles in silica

“…Results are most often successfully explained with the free sphere model described above. However, calculated frequencies are much too high in silicon nanoparticles embedded in a silica matrix 16,17 . In this work, we want to see if the situation can be improved by taking into account the presence of the matrix and the elastic anisotropy of silicon.…”

Magnetic resonances of Fe and Ni nanoparticles in films of silicon suboxide produced by ion irradiation of triethoxysilane gels containing Fe or Ni solute atoms

“…1 On the other hand, the side group R 0 of alkoxides may display a reduction ability for some of the M 0 X molecules. This possibility is used in present study, knowing that the hydrido group in triethoxysilane HSi(OC 2 H 5 ) 3 (referred to with the abbreviation TH) is very reactive. Gels from this ethoxide have a stoichiometry close to SiO 1:5 H 1 and are converted into silica embedding Si nanoclusters by heat treatments [1][2][3].…”

“…This possibility is used in present study, knowing that the hydrido group in triethoxysilane HSi(OC 2 H 5 ) 3 (referred to with the abbreviation TH) is very reactive. Gels from this ethoxide have a stoichiometry close to SiO 1:5 H 1 and are converted into silica embedding Si nanoclusters by heat treatments [1][2][3]. A reduction of various metals M 0 (Cu, Ni, Co, Pt) has been observed either in TH gelling solutions or in dried monoliths after treatments at moderate temperatures [4,5].…”