Calibration of zircon as a Raman spectroscopic pressure sensor to high temperatures and application to water-silicate melt systems
Calibration of zircon as a Raman spectroscopic pressure sensor to high temperatures and application to water-silicate melt systems
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DOI：
10.2138/am.2013.4143
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发表时间：
2013-04
影响因子：
3.1
通讯作者：
C. Schmidt;M. Steele‐MacInnis;A. Watenphul;M. Wilke
中科院分区：
文献类型：
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作者：
C. Schmidt;M. Steele‐MacInnis;A. Watenphul;M. Wilke
本文对全晶态合成锆石的ν_3(SiO_4)(~1008 cm~(-1))拉曼光谱谱带的波数随压力(P)和温度(T)的变化进行了标定，使其作为拉曼光谱压力传感器应用于光学小室，温度为10 Gpa，温度为1000℃左右。该波段的波数(ν)与温度之间的关系为：ν(cm-1)=7.5 4·10−9·T3-1.6 1·10−5·T2-2.89·10−2·T+1008.9，其中T以°C为单位.在研究的P波段内，压力与压力的关系几乎是线性的.在~2 5°C时，∂ν/∂P斜率为5.6 9 cm-1/Gpa，2 Gpa斜率为5.77 cm-1/Gpa.∂ν/∂P斜率不会随着温度的变化而显著变化，这是从沿等温线到700°C的实验确定的。因此，这种压力传感器的优点是，恒定的∂ν/∂P斜率为5.8±0.1 cm-1/Gpa，可以在至少约6.6 Gpa的压力下进行实验，而不会引入明显的误差。压力传感器在803°C和1.65 GPaH2O+Na2Si3O7和H2O+NaAlSi3O8流体的实验中被测试以确定等温线。在同一实验中，将这些压力与根据测量的蒸汽溶解或冰融化温度的H2O状态方程(Eos)计算的压力进行比较。在NaAlSi3O8熔体溶解于水溶液中的运行中，由锆石传感器测定的压力接近或低于使用蒸汽溶解或冰融温度计算的H2O的Eos的压力。然而，在H2O+Na2O+SiO_2流体的实验中，从锆石的拉曼光谱获得的压力往往比由H2O的状态方程估计的压力高得多。这表明，沿水-硅酸盐熔体准二元系某些临界曲线的压力应予以修正。
Abstract The shifts in wavenumber of the ν3(SiO4) (~1008 cm-1) Raman band of fully crystalline synthetic zircon with changing pressure (P) and temperature (T) were calibrated for application as a Raman spectroscopic pressure sensor in optical cells to about 1000 °C and 10 GPa. The relationship between wavenumber (ν) of this band and T from 22 to 950 °C is described by the equation ν (cm-1) = 7.54·10−9·T3 - 1.61·10−5·T2 - 2.89·10−2·T + 1008.9, where T is given in °C. The pressure dependence is nearly linear over the studied range in P. At ~25 °C, the ∂ν/∂P slope to 6.6 GPa is 5.69 cm-1/GPa, and that to 2 GPa is 5.77 cm-1/GPa. The ∂ν/∂P slope does not significantly change with temperature, as determined from experiments conducted along isotherms up to 700 °C. Therefore, this pressure sensor has the advantage that a constant ∂ν/∂P slope of 5.8 ± 0.1 cm-1/GPa can be applied in experiments to pressures of at least about 6.6 GPa without introducing a significant error. The pressure sensor was tested to determine isochores in experiments with H2O+Na2Si3O7 and H2O+NaAlSi3O8 fluids to 803 °C and 1.65 GPa. These pressures were compared to pressures calculated from the equation of state (EoS) of H2O based on the measured vapor dissolution or ice melting temperature for the same experiment. Pressures determined from the zircon sensor in runs in which NaAlSi3O8 melt dissolved in aqueous fluid were close to or lower than the pressure calculated from the EoS of H2O using the vapor dissolution or ice melting temperature. In experiments with H2O+Na2O+SiO2 fluids, however, the pressure obtained from the Raman spectrum of zircon was often significantly higher than that estimated from the EoS of H2O. This suggests that the pressures along some critical curves of water-silicate melt pseudobinary systems should be revised.