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Abstract

Abstract: Changes in frequency and line width of the 206 and 464 cm^-1 Raman modes of quartz were determined over temperatures from 23 to 800 degr. C and simultaneously at pressures ranging between 0.1 MPa and 2.1 GPa using a hydrothermal diamond-anvil cell (HDAC). The frequency shift of the 464 cm^-1 peak can be used as a secondary pressure standard for SiO2-saturated systems in HDAC experiments at temperatures up to 560 degr. C. The frequency of this peak depends quasilinearly on pressure in the studied pressure range. The global slope (partial V_464/partial P)_T is 9 plus minus 0.5 cm^-1/GPa. A significant variation of this slope with temperature was not observed. Including literature data, the temperature induced frequency shift of the 464 cm^-1 mode is described by (delta T)_(464, P = 0.1 MPa) (cm^-1) = 2.50136*10^-11*T^4 + 1.46454*10^-8*T^3 + 1.801*10^-5*T^2 - 0.01216*T + 0.29 where -196 <= T (degr. C) <= 560. The pressure dependence of the line width of the 464 cm^-1 line increases with temperature. The frequency shifts and line widths for the 206 cm^-1 mode indicate that this line can be used as an alternative to the ruby fluorescence technique as a pressure sensor to about 5 GPa for experiments at room temperature. Both the frequency and line width of this mode show significant cross-derivatives (partial^2 V_206/partialP*partial) and (partial^2 FWHM_206/partialP*partial).