Fig. 3: Theoretical and experimental analysis of thermodynamic properties of water in different electrolytes.

a In situ optical microscopic observations of four electrolytes (5 m) before and after freezing. Black scale bar, 1 mm. b The probability distributions of the tetrahedral order parameter Q_tet for water molecules in different electrolytes at 25 °C. Inset shows the schematic models of liquid-like and ice-like water. c Fraction of ice-like water (tetrahedrality above 0.8) for four electrolytes at 25 °C. d Tetrahedral entropy of water molecules in the four electrolytes, which follows the order SO₄^2- < Cl^-<Br^-<ClO₄^- over the temperature range −80 to 40 °C.