Abstract
As potential candidates for high temperature piezoelectric materials, alpha-quartz-type Ge1-xSixO2 (0 < x <= 0.067) single crystals grown by the flux method were structurally and thermally characterized. When compared to pure alpha-GeO2, room temperature polarized Raman spectra contained additional lines which have been assigned from density functional theory on a alpha-Ge0.833Si0.167O2 solid solution. The results highlight that Si-O-Ge bridges were involved. Moreover, a linear relationship between the wavenumber position of the main A(1) Raman lines and the SiO2 substitution rate x was also observed. The analysis of the temperature dependence of unpolarized Raman signals of an alpha-Ge1-xSixO2 phase with x = 0.067 pointed out the high-thermal stability up to 1000 degrees C of the alpha-quartz-like structure related to the lack of a libration mode and to the absence of a softening mode with temperature.