Dynamically slow solid-to-solid phase transition induced by thermal treatment of DimimFeCl4 magnetic ionic liquid

Area of Science:

• Materials Science
• Solid-State Chemistry
• Magnetism

Background:

• Magnetic ionic liquids (MILs) are a class of materials with potential applications in various fields.
• Understanding their phase behavior is crucial for controlling their properties.
• Solid-state transitions in MILs have been largely unexplored experimentally.

Purpose of the Study:

• To provide the first direct experimental evidence of solid-to-solid phase transitions in MILs induced by thermal treatment.
• To characterize the phase transitions of 1,3-dimethylimidazolium tetrachloroferrate (DimimFeCl4) and their dependence on thermal history.
• To elucidate the structural and magnetic properties associated with these phase transitions.

Main Methods:

• Synchrotron and neutron powder diffraction
• Density Functional Theory (DFT) calculations
• Magnetometry
• Mössbauer spectroscopy
• Muon spectroscopy

Main Results:

• Observed two series of solid-to-solid phase transitions in DimimFeCl4.
• Phase transitions are dependent on cooling rates and prolonged heating above 180 K.
• Identified slow translational and reorientational dynamics of ions during phase transitions.
• Observed modifications in super-exchange pathways correlating with antiferromagnetic behavior.

Conclusions:

• Thermal history critically influences the solid-phase behavior of DimimFeCl4.
• The observed phase transitions involve complex ionic dynamics and affect magnetic interactions.
• These findings offer new insights into the structure-property relationships of MILs.