Calorimetric Study of Polymorphism in 1-Butyl-3-methylimidazolium Hexafluorophosphate
Yauheni Paulechka, Tatsiana Liavitskaya, Andrey V. Blokhin
Stable and metastable crystal phases of 1-butyl-3-methylimidazolium hexafluorophosphate were obtained in an adiabatic calorimeter providing precise temperature control during crystallization. Heat capacities and temperatures and enthalpies of phase transitions, including fusion, and were determined for three polymorphic sequences (I, II, and III). Structures of the crystal phases were assigned using crystallographic studies from the literature. The standard entropy for each sequence was the same at T = 0 K within the uncertainty of the measurements. This, in combination with the crystallographic results, implies that the lowest-temperature crystal form is ordered for all sequences. The complete pattern of phase transformations in this ionic liquid at ambient pressure is described, and results show that relative stability of sequences II and III invert at T = ~281 K.
, Liavitskaya, T.
and Blokhin, A.
Calorimetric Study of Polymorphism in 1-Butyl-3-methylimidazolium Hexafluorophosphate, Journal of Chemical Thermodynamics, [online], https://doi.org/10.1016/j.jct.2016.07.012
(Accessed December 9, 2023)