Predicting glass-to-glass and liquid-to-liquid phase transitions in supercooled water using classical nucleation theory

Glass-to-glass and liquid-to-liquid phase transitions are observed in bulk and confined water, with or without applied pressure. They result from the competition of two liquid phases separated by an enthalpy difference depending on temperature. The classical nucleation equation of these phases is completed by this quantity existing at all temperatures, a pressure contribution, and an enthalpy excess. This equation leads to two homogeneous nucleation temperatures in each liquid phase; the first one (Tn- below T-m) being the formation temperature of an "ordered" liquid phase and the second one corresponding to the overheating temperature (Tn+ above T-m). Thermodynamic properties, double glass transition temperatures, sharp enthalpy and volume changes are predicted in agreement with experimental results. The first-order transition line at T-LL = 0.833 x T-m between fragile and strong liquids joins two critical points. Glass phase above T-g becomes "ordered" liquid phase disappearing at T-LL at low pressure and at Tn+ = 1.302 x T-m at high pressure. (C) 2017 Elsevier B.V. All rights reserved.