|
This run features an aqueous solution that is approximately 15.5 wt.% Na2SO4. Initially, the pressure was about 78 MPa. 11/08/07 17:30:06: The run started all liquid and was cooled. 11/08/07 20:53:02: After supercooling to 268 K, crystals (presumably mirabilite) grow rapidly. 11/08/07 23:33:02: After further supercooling below the eutectic to 252.8 K, the remaining material freezes and the volume increases, since this is in the Ice Ih regime. The screen darkens due to the light scattered by all the small crystals, but increasing the light intensity allows some light to pass through the sample. 11/08/08 12:03:02: With the material frozen in the connecting tubing, the pressure and volume sensors do not reflect the conditions inside the cell. The pressure inside is likely higher than indicated. As the system warms, some material inside the system melts, but the connecting tubing remains frozen, so the pressure and volume sensors do not reflect the transition. 11/08/10 16:53:02: Several temperature cycles do not produce a clear transition, but this is the start of a eutectic melting transition where there is a significant visual change in the image accompanied by large pressure and volume changes. 11/08/11 20:13:02: At high temperature, when everything is melted, there are still water droplets condensed on the lenses in the optical system,
|