Author/Authors :
Uk and Chuvaeva، نويسنده , , T.I and Dymshits، نويسنده , , O.S and Petrov، نويسنده , , V.I and Tsenter، نويسنده , , M.Ya and Shashkin، نويسنده , , A.V and Zhilin، نويسنده , , A.A and Golubkov، نويسنده , , V.V، نويسنده ,
Abstract :
The evolution of low-frequency (<100 cm−1) Raman scattering of titania-containing magnesium aluminosilicate (20MgO:20Al2O3:60SiO2 with 10 mol% TiO2) glasses with heat-treatment has been studied. It was found that in spectra of heat-treated glasses the intensity of the boson peak is rapidly diminished. Under certain conditions of heat-treatment schedules the boson peak disappears while the sample remains amorphous. It implies that sometimes the boson peak is missing from spectra of amorphous materials. In Raman spectra of heat-treated glasses that show the disappearance of the boson peak a new narrow highly polarized low-frequency band appears and increases in intensity. This band has been associated with a spheroidal mode of elastic vibrations in nanometer sized particles of aluminomagnesium phase formed upon phase decomposition of the glass. Its frequency changes with heat-treatment in the temperature range 750–950°C, from 50 to 17 cm−1 reflecting an increase in the sizes of corresponding nanometer particles. The composition and structure of amorphous and crystalline phases formed upon heat-treatment and also of residual glass as well were analyzed using the Raman scattering data, small angle X-ray scattering (SAXS) and X-ray diffraction (XRD) analysis.
