Reversible firsthyphen;order transition between two H2O amorphs at sim;0.2 GPa and sim;135 K

摘要

Transition between the lowhyphen; and highhyphen;density amorphous H2O was observed with a pistonhyphen;cylinder apparatus from 77 K to 140 K, almost the glasshyphen;transition temperature of the amorphs. The transition was found to occur reversibly and abruptly at sim;135 K and sim;0.2 GPa with a volume change of 0.20plusmn;sim;0.01 cm3/g and some hysteresis. This confirmed the transition to be first order. Absence of intermediate amorphous states between the lowhyphen;density and highhyphen;density amorphs suggested existence of two substantially different liquid phases near the glasshyphen;transition temperature. thinsp;