Aquino, Felipe ThomazPereira, Rafael R.Ferrari, Jefferson LuisRibeiro, Sidney Jose Lima [UNESP]Ferrier, AlbanGoldner, PhilippeGoncalves, Rogeria Rocha2015-03-182015-03-182014-10-15Materials Chemistry And Physics. Lausanne: Elsevier Science Sa, v. 147, n. 3, p. 751-760, 2014.0254-0584http://hdl.handle.net/11449/116650This paper reports on the preparation of novel sol-gel erbium-doped SiO2-based nanocomposites embedded with Nb2O5 nanocrystals fabricated using a bottom-up method and describes their structural, morphological, and luminescence characterization. To prepare the glass ceramics, we synthesized xerogels containing Si/Nb molar ratios of 90:10 up to 50:50 at room temperature, followed by annealing at 900, 1000, or 1100 degrees C for 10 h. We identified crystallization accompanying host densification in all the nanocomposites with orthorhombic (T-phase) or monoclinic (M-phase) Nb2O5 nanocrystals dispersed in the amorphous SiO2 phase, depending on the niobium content and annealing temperature. A high-intensity broadband emission in the near-infrared region assigned to the I-4(13/2) --> I-4(15/2) transition of the Er3+ ions was registered for all the nanocomposites. The shape and the bandwidth changed with the Nb2O5 crystalline phase, with values achieving up to 81 nm. Er3+ ions were located mainly in Nb2O5-rich regions, and the complex structure of the different Nb2O5 polymorphs accounted for the broadening in the emission spectra. The materials containing the T-phase, displayed higher luminescence intensity, longer I-4(13/2) lifetime and broader bandwidth. In conclusion, these nanostructured materials are potential candidates for photonic applications like optical amplifiers and WDM devices operating in the S, C, and L telecommunication bands. (C) 2014 Elsevier B.V. All rights reserved.751-760engOxidesOptical materialsLuminescencePhotoluminescence spectroscopySol-gel growthArtigo10.1016/j.matchemphys.2014.06.016WOS:000340975900056Acesso restrito