Mechanical compression

Abstract

Water and ice respond to mechanical compression unusually with numerous anomalies. Regelation, i.e., ice melts under compression and freezes again when the pressure is relieved, evidences that the O:H–O bond extraordinary recoverability and that quasisolid phase boundary dispersivity. An oxygen atom always finds bonding partners to retain its sp3-orbital hybridization once the O:H breaks, which ensures O:H–O bond recoverability to its original state once the pressure is removed. On the other hand, mechanical compression shortens the O:H nonbond and soften its phonon but the H–O bond responds to compression oppositely, lowering the H–O phonon frequency, which offsets the Debye temperature and the boundaries of the quasisolid phase outwardly, which elevates the freezing point and depresses the melting point, so regelation takes place. Reproduction of the Tm(P) profile clarifies that the H–O bond energy EH determines the Tm with derivative of EH = 3.97 eV for bulk water and ice.