Infrared and Raman spectroscopy study of Si 1-x Ge x O 2 solid solutions with α-quartz structures.

Single crystals of α-quartz-type Si1−xGexO2 (x < 0.12), grown under hydrothermal conditions in NH4F solutions, were investigated using infrared (IR) and Raman spectroscopy. Compositional dependencies of the IR absorption spectra were found both for the fundamental and combination vibrations. With an increase in Ge content in the crystals, new absorption bands, corresponding to the vibrations of OGeO in the GeO4 tetrahedra (670, 930, 1010, 2125 cm−1), appeared, and the intensities of the absorption bands of OSiO in the SiO4 tetrahedra (263, 695, 2137, doublet at 2326 and 2333, 2499, 2599, 2673 cm−1) decreased. The shifts in the absorption bands at 354, 511, 2499 and 2673 cm−1 to lower wavenumbers linearly depends on the Ge content and are characteristic of vibrations in the SiOGe chains. The origin of some combinational vibrations is also clarified. A combination vibration that caused the band at 1395 cm−1 was formed by vibrations with wavenumbers of 263 (type E) and 1170 cm−1 (type E). The bands at 2499 and 2673 cm−1 were composed of the band at 354 cm−1 and two vibrations at 1083 cm−1 (type E) and by two vibrations at 1170 cm−1 (type E), respectively.