Volume 86 Issue 40 | p. 47 | Concentrates
Issue Date: October 6, 2008

Improved Fabrication Of Crystalline Films

Department: Science & Technology
Credit: Chem. Commun.
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Credit: Chem. Commun.

Researchers in Japan have developed a simple method for preparing rare-earth hydroxide films by trapping crystallites of one such material at a solvent interface and then uniformly transferring them to a substrate (Chem. Commun., DOI: 10.1039/b812111g). The resulting films are of much better quality in terms of orientation and coverage than crystalline films prepared by traditional methods, such as solvent evaporation or spin-coating. Takayoshi Sasaki of the National Institute for Materials Science and coworkers had previously synthesized Eu(OH)2.5Cl0.50.9H2O, which forms micrometer-sized platelike crystals. The team's film-fabrication method begins by dispersing the crystallites in water and then adding hexane, which results in a two-phase system. When a few drops of ethanol are added, the crystallites form a monolayer at the water-hexane interface. When a pretreated substrate is dipped into the solution, the crystallites adhere to the substrate, forming a monolayer film; multiple layers are deposited by repeatedly dunking the substrate. Subjecting the film to ultrasound treatment serves to create uniform layers of the large crystallites. Well-organized films of the type made by the Japanese team, which are photoluminescent and readily undergo anion exchange for further modification, have potential applications in optical devices and chemical sensing.

 
 
Chemical & Engineering News
ISSN 0009-2347
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