Facile Ionic Liquid‐Assisted Strategy for Direct Precipitation of Eu2+‐Activated Nanophosphors under Ambient Conditions. Issue 17 (24th March 2018)

• Record Type: Journal Article
• Authors: Terraschke, Huayna; Olchowka, Jacob; Geringer, Eugenie; Rodrigues, Aline Varella; Wickleder, Claudia
• Is Part Of: Small. Volume 14:Issue 17(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-03-24
• Subjects: divalent europium -- ionic liquids -- microwave chemistry -- nanoparticles -- sonochemistry; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.201703707
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: This work describes a novel ionic liquid (IL)‐assisted synthesis strategy for a direct and easy production of Eu 2+ ‐doped nanoparticles (NPs), where ILs are also used as fluoride sources to avoid the use of elemental fluorine or toxic hydrofluoric acid. Up to now, the direct synthesis of Eu 2+ ‐doped nanophosphors consisted of an enormous challenge, due to the oxidation to Eu 3+ observed in hydrous solution, which is commonly used for the preparation of NPs, generating lattice defects and undesired particle growth or agglomeration by additional reducing steps at high temperatures. In contrast, ILs, unless containing ClO4 – or NO3 – anions, do not present an oxidizing character, allowing the direct precipitation of NPs, e.g., using Eu 2+ containing starting materials. Here, the undoped and Eu 2+ ‐doped BaFCl NPs have been prepared under atmospheric conditions for the first time using ILs as solvents and also as fluoride source, applying sonochemical and microwave‐assisted approaches. In general, this method bears an enormous potential for an easy synthesis of fluoride materials compared to inconvenient solid‐state methods. In addition, the IL plays the role of a strongly attached protecting shell which represents ≈7–8% of the total NPs weight. Abstract : Here, the formation of Eu 3+ during the synthesis of Eu 2+ phosphors is prevented in the relative redox stable ionic liquid BmimBF4 and allows the direct precipitation of nanoparticles (NPs) from Eu 2+ starting materials. Eu 2+ NPs, e.g., BaFCl:Eu 2+, have been prepared by means of two different synthetic routes in ionic liquids, in air for the first time.