title: Dynamically slow solid-to-solid phase transition induced by thermal treatment of DimimFeCl4 magnetic ionic liquid.
abstract: The results reported here represent the first direct experimental observations supporting the existence of a solid-to-solid phase transition induced by thermal treatment in magnetic ionic liquids (MILs). The phase transitions of the solid phases of 1,3-dimethylimidazolium tetrachloroferrate, DimimFeCl4, are closely related to its thermal history. Two series of solid-to-solid phase transitions can be described in this MIL: (i) from room temperature (RT) phase II [space group (s.g.) = P21] to phase I-a [s.g. = P212121] via thermal quenching or via fast cooling at T > 2 K min(-1); (ii) from phase I-a to phase I-b [s.g. = P21/c] when the temperature was kept above 180 K for several minutes. The latter involves a slow translational and reorientational dynamical process of both the imidazolium cation and the tetrachloroferrate anion and has been characterized using synchrotron and neutron powder diffraction and DFT (density functional theory) studies. The transition is also related to the modification of the super-exchange pathways of low-temperature phases which show a overall antiferromagnetic behavior. A combination of several experimental methods such as magnetometry, Mössbauer and muon spectroscopy together with polarized and non-polarized neutron powder diffraction has been used in order to characterize the different features observed in these phases.
authors.affiliation: CITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander, Spain. depedrovm@unican.es.
authors.forename: Imanol
authors.initials: I
authors.lastname: de Pedro
authors.affiliation: Institut Laue-Langevin, BP 156X, F-38042 Grenoble Cedex, France. fabelo@ill.fr.
authors.forename: Oscar
authors.initials: O
authors.lastname: Fabelo
authors.affiliation: CITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander, Spain. depedrovm@unican.es.
authors.forename: Abel
authors.initials: A
authors.lastname: García-Saiz
authors.affiliation: ALBA Synchrotron Light Source, Cerdanyola del Vallés, Barcelona, Spain.
authors.forename: Oriol
authors.initials: O
authors.lastname: Vallcorba
authors.affiliation: CITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander, Spain. depedrovm@unican.es.
authors.forename: Javier
authors.initials: J
authors.lastname: Junquera
authors.affiliation: Departamento de Física, Universidad de Oviedo, 33007 Oviedo, Spain.
authors.forename: Jesús Angel
authors.initials: JA
authors.lastname: Blanco
authors.affiliation: Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, 2695-066 Bobadela LRS, Portugal.
authors.forename: João Carlos
authors.initials: JC
authors.lastname: Waerenborgh
authors.affiliation: Faculty of Physics, Babes-Bolyai University, 400084 Cluj-Napoca, Romania.
authors.forename: D
authors.initials: D
authors.lastname: Andreica
authors.affiliation: Institut Laue-Langevin, BP 156X, F-38042 Grenoble Cedex, France. fabelo@ill.fr.
authors.forename: Andrew
authors.initials: A
authors.lastname: Wildes
authors.affiliation: Institut Laue-Langevin, BP 156X, F-38042 Grenoble Cedex, France. fabelo@ill.fr.
authors.forename: María Teresa
authors.initials: MT
authors.lastname: Fernández-Díaz
authors.affiliation: CITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander, Spain. depedrovm@unican.es.
authors.forename: Jesús Rodríguez
authors.initials: JR
authors.lastname: Fernández