[Study on Raman spectrum of nanophase anatase]

The nanophase anatase of different sizes (2-40 nm) were synthesized with chemical precipitation method. Nanophase anatase (2-40 nm), anatase (micron) and natural anatase were investigated by Raman spectrum. The spectra indicate: when the crystalline particles sizes decreased, obvious Raman shifts towards higher frequencies were observed and the intensity of Raman scattering decreased markedly. The shift towards higher frequencies reached max (10 cm-1) at 143 cm-1 comparing 2 nm anatase and natural anatase; when the crystalline particles sizes decreased; the shifts at 515 and 637 cm-1 towards higher frequencies reached max, but while the crystalline particles sizes became smaller, the shifts reached towards lower frequencies; There was no obvious shift at 396 cm-1 with the decreasing of the crystalline particle sizes. These reflect the complexity of nanophase materials structure, that may be caused by flexibility distortion of crystal.