Ionic liquids are salts that exist in a liquid state at, or near, room temperature. Due to their extremely low vapour pressure, high electrochemical stability, and powerful solvation properties, ionic liquids are viewed as green solvents which play an important role as electrolytes in many electrochemical applications such as lithium ion batteries, solar cells, fuel cells, electrodeposition and electroplating. Research into the structures and properties of ionic liquids has intensified in the last decade. It is apparent that fundamental studies on the structure-property relationships of pure ionic liquids and ionic liquid solutions may provide breakthrough results in the choice of ionic liquids for specific applications.

An intensive study of ionic liquids and their possible applications in minerals and metals processing is being undertaken by CSIRO Minerals, Australia. One of the ionic liquids under investigation is 1-butyl-1-methylpyrrolidinium methanesulfonate (P₁₄MeS) which has a melting point of 65 °C. Synchrotron powder diffraction studies were undertaken in order to examine the crystalline phase transformations at solid and solid-liquid state temperatures for pure P₁₄MeS and impure P₁₄MeS containing AlCl₃ and water. 

Powder diffraction data were collected at the Australian Synchrotron powder diffraction beamline primary end station from samples loaded in 2.0 mm capillaries. These were mounted concentrically to the rotation axis of the 3-circle diffractometer. Monochromatic X-rays of wavelength 1.0054 Å were used. The Mythen X-ray detector was used to collect data in a continuous mode throughout the temperature programme; data were collected over the angular range 0.0≤2Θ≤80.0º with each histogram being collected for 10 s. The temperature of the sample was maintained by an Oxford Cryosystems cryostream set to a constant ramp rate of 6 ºC/min throughout the temperature cycle; the temperature programme used was a cycle between +25 to -80 to +100 to -80 to +100 to +25 °C. 

During these measurements the phase transitions and hysteresis in the phase transformations was able to be observed. Such transformations give useful information about the behaviour of the ionic liquid near its melting point and also indicate the nature of aluminium speciation present in the solid phases. Further analyses are expected to reveal some information about how water affects the structure of the ionic liquid and its solutions.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/15307 must be provided.

1. Industrial applications of in-situ diffraction