Abstract – Publication

Structural and luminescence characterization of europium-doped niobium germanate glasses and glass-ceramics: novel insights from 93Nb solid-state NMR spectroscopy.
MARCONDES, Lia Mara; BRADTMÜLLER, Henrik; SANTOS, Sabrina Nicoleti Carvalho dos; NOLASCO, Lucas Konaka; MENDONÇA, Cleber Renato; SANTAGNELI, Silvia Helena; POIRIER, Gael Yves; NALIN, Marcelo.
Abstract: A thorough understanding of network former roles in optical glasses and glass-ceramics, as well as structural environments of luminescent rare-earth atoms, is paramount to assessing their suitability and effectiveness as components for fully-optical integrated devices. The present contribution sheds light on the overall poorly un- derstood structural role of Nb2O5 in oxide glasses and offers a rationale for the luminescence changes concomitant to the heat-treatment induced glass-to-crystal transition in niobium germanate glasses. To this end, results from 93Nb nuclear magnetic resonance (NMR), Raman, and Eu3+ion based luminescence spectroscopies as well as 3D micromanufacturing are reported for glasses and glass-ceramics in system (89.9-x)GeO2-xNb2O5- 10K2O-0.1Eu2O3. Thanks to very-fast 93Nb magic-angle spinning (MAS) and a novel excitation scheme for Triple- quantum (TQ)MAS solid-state NMR spectroscopy distinct Nb(OGe)6-y(ONb)y species were identified for the first time: at low Nb concentrations structural units with rather low y-values are formed, reaching down to isolated Nb (OGe)6 units ? next to units bearing non-bridging oxygen atoms; at intermediate Nb contents and beyond, structural units with increasingly higher y-values up to Nb(ONb)6 are found, resembling the local environments found in crystalline Nb2O5. After the glass-to-crystal transition the Nb local environment maintains a high degree of disorder while some residual glass remains. Moreover, photoluminescence spectroscopy of the europium probes suggests the rare-earth ions are preferentially incorporated into high y-value Nb(OGe)6-y(ONb)y polyhedra based on spectral features such as the phonon sideband, the 5D0 ? 7F2/7F1 ratio, and split 4f bands. Finally, femtosecond laser microfabrication of waveguides was successful in the presented europium-doped niobium germanate glasses, making them promising candidates for further studies as photonic devices.
Ceramics International
v. 48, n. 14, p. 20801-20808 - Ano: 2022
Fator de Impacto: 5,532
    @article={003080436,author = {MARCONDES, Lia Mara; BRADTMÜLLER, Henrik; SANTOS, Sabrina Nicoleti Carvalho dos; NOLASCO, Lucas Konaka; MENDONÇA, Cleber Renato; SANTAGNELI, Silvia Helena; POIRIER, Gael Yves; NALIN, Marcelo.},title={Structural and luminescence characterization of europium-doped niobium germanate glasses and glass-ceramics: novel insights from 93Nb solid-state NMR spectroscopy},journal={Ceramics International},note={v. 48, n. 14, p. 20801-20808},year={2022}}

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