title: Phase transition of [C(n)-mim][PF6] under high pressure up to 1.0 GPa.
abstract: Behavior of the phase transition of an ionic liquid, [Cn-mim][PF(6)], has been investigated under pressures up to 1.0 GPa by using a high-pressure differential thermal analysis (DTA) apparatus. The T versus P phase diagrams of [BMIM][PF(6)] and [EMIM][PF(6)] are constructed. The DTA curve of [BMIM][PF(6)] shows one endothermal valley in heating course at each given pressure, which indicates that a simple phase transition from solid to liquid has taken place under high pressure and that the melting point is an increase function of pressure. However, the DTA curve of [EMIM] x [PF(6)] shows two endothermal valleys in the heating course within the tested pressure range, implying that there may exist another phase. After treatment of [EMIM][PF(6)] at different temperatures under high pressure, the structures of the recovered samples are also investigated by wide-angle x-ray scattering. By considering the results above, it indicates that another crystalline phase exists between the solid and liquid of [EMIM][PF(6)].
authors.affiliation: Laboratory of High Pressure Physics, Southwest Jiaotong University, Chengdu 610031, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Su
authors.forename: Liangbin
authors.initials: L
authors.lastname: Li
authors.forename: Yun
authors.initials: Y
authors.lastname: Hu
authors.forename: Chaosheng
authors.initials: C
authors.lastname: Yuan
authors.forename: Chunguang
authors.initials: C
authors.lastname: Shao
authors.forename: Shiming
authors.initials: S
authors.lastname: Hong