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三元体系NaCl-CaCl2-H2O是一种重要的天然水-盐体系。然而,研究人员在过去只研究了低温下该体系的相变,但在高温高压条件下拉曼位移和物理参数之间的定量关系却并没有被报道。利用利用热液金刚石压腔(HDAC)和石英压标,对高温高压下三元体系NaCl-CaCl2-H2O的拉曼光谱特征进行了系统的研究,并获得了水的O—H伸缩振动谱带的拉曼位移、溶质质量分数和压力之间的定量关系。其中盐的质量分数相等(NaCl与CaCl2),分别为4.0mass%,8.0mass%和12.0mass%。实验结果表明,当盐的质量分数和体系的压力保持不变时,O—H伸缩振动的标准拉曼位移差(Δν(O—H))伴随着温度的升高而增大。当温度和压力恒定时,Δν(O—H)随盐的质量分数的增加而增大。对于这个三元体系,其Δν(O—H)与压力近似为线性关系,且不同盐度条件下的关系斜率相近。Δν(O—H)与温度(T)、压力(P)、溶质质量分数(M)之间的定量关系为P=-31.892Δν(O—H)+10.131T+222.816 M-3 183.567,其中该方程的有效PTM范围为200MPa≤P≤1 700MPa,273K≤T≤539K以及M≤12mass%。该公式可以用来作为地质压力计,用于研究等盐度条件下在NaCl-CaCl2-H2O体系流体包裹体。该方法作为一种直观的地质探测技术,具有潜在的应用价值。
Ternary system NaCl-CaCl2-H2O is an important natural water-salt system. However, in the past, researchers have only studied the phase transition of the system at low temperature, but the quantitative relationship between Raman shift and physical parameters under high temperature and high pressure has not been reported yet. The Raman spectra of ternary system NaCl-CaCl2-H2O under high temperature and high pressure were systematically studied by using hydrothermal diamond pressure chamber (HDAC) and quartz pressure gauge, and the O-H stretching vibration band of water was obtained Raman shift, the quantitative relationship between solute mass fraction and pressure. Among them, the mass fraction of salt is equal (NaCl and CaCl2), respectively 4.0mass%, 8.0mass% and12.0mass%. The experimental results show that the standard Raman shift (Δν (O-H)) of O-H stretching vibration increases with the increase of temperature when the mass fraction of salt and the pressure of the system are kept constant. When the temperature and pressure are constant, Δν (O-H) increases with the mass fraction of salt. For this ternary system, its Δν (O-H) is approximately linear with pressure, and its slope is similar under different salinities. The quantitative relationship between Δν (O-H) and temperature (T), pressure (P) and solute mass fraction (M) was P = -31.892Δν (O-H) + 10.131T + 222.816 M-3 183.567 The effective PTM range of this equation is 200MPa≤P≤1 700MPa, 273K≤T≤539K and M≤12mass%. The formula can be used as a geostatometer to study fluid inclusions in NaCl-CaCl2-H2O systems under equal salinity conditions. The method, as an intuitive geological exploration technology, has potential application value.