Institut des Sciences de la Terre d'Orléans (ISTO), UMR7327 Université d'Orléans, CNRS-INSU, Bureau de Recherches Géologiques et Minières (BRGM), 45071 Orléans, France.
CEMHTI-CNRS UPR3079, 45071 Orléans, France.
Phys Chem Chem Phys. 2019 Sep 21;21(35):19554-19566. doi: 10.1039/c9cp03647d. Epub 2019 Aug 29.
Microthermometric measurements of a synthetic high-density (984 kg m) water inclusion in quartz revealed that only part of the super-cooled liquid water (L) transforms to solid ice I upon ice nucleation (L → ice I + L). While ice nucleation occurs in the ice I stability field at -41 °C and 28 MPa the pressure increases instantaneously to 315 MPa into the ice II stability field. At this point, both phases, liquid water and ice I are metastable. The coexistence of these two phases was confirmed by Raman spectroscopy and could be traced down to -80 °C. The pressure along this low-temperature metastable extension of the ice I melting curve was determined by means of the frequency shift of the ice I peak position using both the O-H stretching band around 3100 cm and the lattice translational band around 220 cm. At -80 °C and 466 MPa the super-cooled ice I melting curve encounters the homogeneous nucleation limit (T) and the remaining liquid water transformed either to metastable ice IV (ice I + L → ice I + ice IV) or occasionally to metastable ice III (ice I + L → ice I + ice III). The nucleation of ice IV resulted in a pressure drop of about 180 MPa. Upon subsequent heating the pressure develops along a slightly negatively sloped ice I-ice IV equilibrium line terminating in a triple point at -32.7 °C and 273 MPa, where ice IV melts to liquid water (ice I + ice IV → ice I + L). Hitherto existing experimental data of the ice IV melting curve (ice IV → L) were found to be in line with the observed ice I-ice IV-liquid triple point. If, on the other hand, ice III nucleated at -80 °C (instead of ice IV) the associated pressure drop was about 260 MPa. The ice I-ice III-liquid triple point was determined at -22.0 °C and 207 MPa (ice I + ice III → ice I + L), which is in agreement with previous experimental data.
对在石英中形成的一种高密度（984kg/m）过冷水包裹体进行的微量热测量表明，只有部分过冷液态水（L）在冰核形成时转变为固态冰 I（L→冰 I+L）。虽然冰核在-41°C 和 28MPa 时形成于冰 I 稳定区内，但压力会立即增加到 315MPa，进入冰 II 稳定区。此时，液态水和冰 I 都处于亚稳状态。拉曼光谱证实了这两种相的共存，并可追踪到-80°C。通过使用 3100cm 左右的 O-H 伸缩带和 220cm 左右的晶格平移带，根据冰 I 峰位的频率移动，确定了沿冰 I 熔融曲线低温亚稳延伸段的压力。在-80°C 和 466MPa 时，过冷冰 I 熔融曲线遇到均相成核极限（T），剩余的液态水要么转变为亚稳冰 IV（冰 I+L→冰 I+冰 IV），要么偶尔转变为亚稳冰 III（冰 I+L→冰 I+冰 III）。冰 IV 的成核导致压力下降约 180MPa。随后加热时，压力沿略呈负斜率的冰 I-冰 IV 平衡线发展，在-32.7°C 和 273MPa 的三相点终止，此时冰 IV 熔化成液态水（冰 I+冰 IV→冰 I+L）。迄今已有的冰 IV 熔融曲线（冰 IV→L）实验数据与观察到的冰 I-冰 IV-液态三相点一致。另一方面，如果在-80°C 时冰 III 成核（而不是冰 IV），则相关的压力下降约为 260MPa。冰 I-冰 III-液态三相点在-22.0°C 和 207MPa 处确定（冰 I+冰 III→冰 I+L），与以前的实验数据一致。
