Fig. 7: Second-order phase transition in vaterite.
From: Unlocking the mysterious polytypic features within vaterite CaCO3
a Temperature and order parameter Q as a function of simulation time. Tc represents the critical temperature with the value of approximately 190 K. b Schematic illustration of the carbonate group orientations in high-symmetry (HS) and low-symmetry (LS) states. The carbonate group is shown in stick model, where carbon and oxygen atoms are colored with blue and yellow, respectively. c Two-dimensional free energy surface of vaterite as functions of order parameter Q and temperature. d Landau parameters as a function of temperature. Inset: Ginzburg-Landau free energy surface below, at, and above the critical temperature Tc of vaterite.
