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Eu-Doped Y2O3-SiO2 Nanocomposite Obtained by a Sol-Gel Method
| Content Provider | Semantic Scholar |
|---|---|
| Author | Casua, Mariano Licheri, Roberta Musinua, Anna Piccalugaa, Giorgio Speghinib, Adolfo Bettinellib, Marco |
| Copyright Year | 2001 |
| Abstract | A Y2O3-SiO2 nanocomposite doped with Eu 3+ was obtained by a sol-gel method and characterized by X-ray diffraction, IR, Si NMR and laser-excited luminescence spectroscopy. It was found that small (2-3 nm) yttria nanoparticles are homogeneously dispersed in, and interacting with, the amorphous silica matrix. Luminescence spectroscopy indicates that the Eu ion is preferentially located inside or at the surface of highly disordered Y2O3 nanoparticles. These luminescent nanocomposites form a class of materials which could find applications in the field of phosphors. INTRODUCTION Lanthanide ions in insulating host matrix find uses in a wide variety of applications, such as phosphors for fluorescent lighting, display monitors, X-ray imaging, laser and amplifiers for fiber–optic communication. Preparing nanoscale host materials can change the physical properties, which affect the luminescence and dynamics of the optically active dopant. Nanocrystalline Y2O3 has been investigated as a host, due to its interesting applications in the field of the phosphors for lighting and for cathode ray tubes . In the present work, we decided to investigate the optical properties of Eu doped Y2O3 nanoparticles dispersed in a transparent medium such as amorphous SiO2, which can stabilize and protect the nanoparticles from aggregation . The Eu ion was chosen on the basis of its high emission quantum yield, its relatively simple energy level scheme, its applications as structural probe for the sites occupied by the Ln in a given material, 4 and the technological importance of Y2O3:Eu 3+ as a phosphor . The present study focuses on the preparation, the characterization of structural and optical properties of a Eu-doped Y2O3-SiO2 nanocomposite, containing 10 wt% of Y2O3, obtained by a sol-gel method which involves the use of the nitrate salt as precursor . This procedure in principle favors the formation of metal oxide nanoparticles hampering the embedding of metal ions in the silica matrix amorphous network. This work may also lead to an easy, effective preparation method for these materials. EXPERIMENTAL An Eu-doped Y2O3-SiO2 nanocomposite containing 9.8 wt% of Y2O3 and 0.2 wt% of Eu2O3 (corresponding to an Eu/Si atomic ratio of 7.6⋅10) was prepared by a sol-gel method following the procedure described elsewhere . An aqueous solution of weighted amounts of yttrium and europium nitrate (Y(NO3)3·6H2O and anhydrous Eu(NO3)3, Aldrich 99%) was mixed with an ethanolic solution of tetraethoxysilane (EtOH 95%, TEOS, Aldrich 98%) and acidified with nitric acid up to pH<1. The TEOS/EtOH/water molar ratio was 1/3/10. The clear sol was stirred for one hour and then poured into a Teflon beaker and allowed to gel at room temperature. The same procedure was used to prepare the silica matrix as reference sample. In order to minimize the presence of defects typical of sol-gel silica in the samples Mat. Res. Soc. Symp. Proc. Vol. 676 © 2001 Materials Research Society |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://profs.sci.univr.it/~bettinel/anna.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
