Manganese Fluoride Nanoparticles Synthesized by Microwave Irradiation Using Ionic Liquid-Ethylene Glycol Mixtures: Room-Temperature Photoluminescence, Crystalline Phase, and Morphology

Abstract

The facile and rapid microwave-assisted method has been demonstrated to be effective in synthesizing manganese fluoride (MnF2) nanoparticles in binary mixtures of ethylene glycol and imidazolium-based ionic liquid containing fluorine, within a minute, without any surfactant and stabilizer. The effect of volume ratio of an ionic liquid in the binary mixtures with ethylene glycol and the length of the alkyl chain of imidazolium on the morphologies and crystalline structures of MnF2 was investigated. Two types of crystalline phases MnF2, P-2/mnm rutile and P (4) over bar 2m space group, were synthesized depending on the volume ratio of EMIM BF4. The morphologies of rutile MnF2 clearly varied depending on what kind of ionic liquid was used in the synthesis. MnF2 nanoparticles and spherical nanoclusters assembled by nanospheres were synthesized when the used ionic liquid was OMIM BF, and EMIM BF4, respectively. Clear room temperature photoluminescence (PL) spectra of MnF2 nanoparticles were observed at ambient pressure. The change of PL spectra depending on the crystalline phase was also observed. In this study, we report that the microwave-assisted method using ethylene glycol-ionic liquid binary mixtures is proper for synthesizing high-quality MnF2 nanoparticles with controllable crystalline phase and morphology.