Study of the Raman spectrum of nanometer SnO2

Abstract

The Raman spectra of nanometer-sized particles of SnO2 (3–90 nm) at room temperature are reported. In the Raman spectra of the particles of SnO2, which are quite different from that of single-crystal SnO2, there appear two new characteristic peaks, and their intensities decrease gradually with the increase of crystal size. It is concluded that the new peaks can be explained by the surface phonon modes of nanometer SnO2, consequently there is a relation between the structures of surface layers and bulk. It is believed that it is possible to determine the exact positions of atoms in surface layers of some nanometer crystals from their laser Raman spectra.

The complete Raman spectrum of nanometric SnO2 particles

“…34 Despite the number of publications related to SnO 2 and Raman spectroscopy, however, they have not generally been reported for SnO 2 . [12][13][14][15] An exception to this is our previous paper 11 in which we demonstrated them to be an effective way of evaluating not only the average nanoparticle size, but also the whole size distribution.…”

“…Low frequency bands have been observed previously in SnO 2 , 11 and several authors have reported the existence of bands not observed in single-crystal or polycrystalline SnO 2 which have been found to be closely related to grain size. [12][13][14][15] However, some of these reports do not adequately explain the origin of the abnormal spectrum.…”

“…The calculated value of d corresponds to an average of the surface region thickness for all particles forming the size distribution, assuming that this thickness is similar for all samples. Although not exact, this would seem to give a better approximation than considering the existence of only one monolayer of atoms in the surface of the nanoparticles, 12,15 especially for the smaller ones.…”

High oxygen vacancy tin oxide synthesized by combustion chemical vapor deposition (CCVD)

“…are not observed for bulk SnO 2 might be due to the shape of the SnO 2 nanostructure [39] because it will affect the surface phonon modes. [40] In fact, a diffused peak at ∼622 cm −1 has been reported for nanocrystalline SnO 2 material [41] present on the surface of ancient Chinese black mirrors. It is well known that in an infinitely perfect crystal only the phonons near the center of the BZ contribute to the scattering of incident radiation because of the momentum conservation rule between phonons and incident light.…”

Surface-enhanced Raman scattering of SnO2bulk material and colloidal solutions

“…Tin dioxide in the rutile form belongs to the symmetry space group D 4h [21][22][23][24][25][26] . The 6 units cell atoms give rise to 18 vibrational modes.…”