Descrição
While niobium-containing oxide glass are used in several technological applications, especially for high-resolution augmented reality devices, the exact structural role of niobium (Nb), which can serve either as a network modifier or as a network former, in these glasses is still ill-understood. Solid-state nuclear magnetic resonance (NMR) has been proven to be a powerful tool for structural elucidation of glasses, due to its element-selectivity, inherently quantitative character, and its focus on local order. (1) From the NMR point of view, Nb features one of the most NMR-sensitive nuclei ($^{93}$Nb) which is 100% natural abundant. Nevertheless, it suffers from a large nuclear quadrupolar moment, and the $^{93}$Nb NMR spectra are dominated by strong quadrupolar interactions, resulting in excessive line broadening and poor resolution. These challenges can be addressed by techniques involving fast Magic angle spinning (MAS), wideband excitation methods and dipolar recoupling techniques. (2) Here, we report results on glasses from the structurally more simple niobium phosphate glasses in the system $xNb_{2}O_{5}-(1-x)NaPO_{3}$. Advanced NMR experiments have been used to characterize the local environments of sodium, phosphorus and niobium with the aim of obtaining new structural insight towards the development of new structure function correlations. As first results, $^{93}$Nb MAS NMR and Raman spectroscopy suggest that Nb is pentavalent and six-coordinated.
Referências
1 ZHANG, R. et al. Structural studies of Bi2O3-NaPO3 glasses by solid state nuclear magnetic resonance and x-ray photoelectron spectroscopy. Journal of Physical Chemistry C, v. 121, n. 18, p. 10087-10094, 2017.
2 KOPPE, J.; HANSEN, M. R. Minimizing lineshape distortions in static ultra-wideline nuclear magnetic resonance of half-integer spin quadrupolar nuclei. Journal of Physical Chemistry A, v. 124, n. 21, p. 4314-4321, 2020.
| Certifico que os nomes citados como autor e coautor estão cientes de suas nomeações. | Sim |
|---|---|
| Palavras-chave | NMR. Phosphate glass. Niobium. |
| Orientador e coorientador | Hellmut Eckert |
| Subárea 1 | Física da Matéria Condensada |
| Subárea 2 (opcional) | Ressonância Magnética Nuclear |
| Agência de Fomento | FAPESP |
| Número de Processo | 2022/01937-5 |
| Modalidade | DOUTORADO |
| Concessão de Direitos Autorais | Sim |
