title: Spontaneous liquifaction of isomerizable molecular crystals.
abstract: A lattice vacancy raises the energy of the neighboring (flexible) molecule in a crystal, which may be enough to isomerize it to a tautomer that does not fit the lattice site, thus creating a liquidlike local region embedding the vacancy. Similar regions may appear elsewhere in the lattice and the regions may ultimately merge. Thus a crystal may spontaneously liquefy over a period of hours to years at a temperature below its normal melting point. Simultaneous heat capacity and heat absorption measurements of several such molecular crystals show that they spontaneously liquefy at a temperature far below their reputed melting point, according to a non-exponential rate kinetics and a temperature dependent rate constant, and do not crystallize on cooling.
authors.affiliation: Istituto per i Processi Chimico-Fisici del CNR, 56124 Pisa, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Tombari
authors.forename: C
authors.initials: C
authors.lastname: Ferrari
authors.forename: G
authors.initials: G
authors.lastname: Salvetti
authors.forename: G P
authors.initials: GP
authors.lastname: Johari