Structure-Property Relations in Fluorophosphate Glasses: An Integrated Spectroscopic Strategy

Autor(es)

de Oliveira, Jr., Marcos ; Goncalves, Tassia S. ; Ferrari, Cynthia ; Magon, Claudio Jose ; Pizani, Paulo S. ; de Camargo, Andrea S. S. ; Eckert, Hellmut

• Tipo de documento: Artigo Científico
• Fonte: Journal of Physical Chemistry C; v. 121, n. 5, p. 2968-2986, FEB 9 2017.
• Citações Web of Science: 12

Resumo

A detailed structural investigation of a series of fluoride phosphate glasses with nominal compositions 25BaF(2)-25SrF(2)-(30-x)Al(PO3)(3)-xAlF(3)- (20-z)ScF3:zREF(3) with x = 25, 20, and 15, RE = Yb and Eu, and 0 <= z <= 1.0, and of a Sc-free set Of glasses with compositions w{[}80(Ba/Sr)F-2-20AlF(3)]-(1-w){[}80Ba(PO3)(2)-20Al(PO3)(3)] (w = 25, 50, 75), doped with 0.2 mol % Yb3+ or Eu3+, has been conducted. As indicated by Raman scattering and solid state NMR, the network structure is dominated by aluminum-oxygen-phosphorus linkages, which can be quantified by means of Al-27/P-31 NMR double resonance techniques. The ligand environment of the rare-earth ions is studied by (1) Sc-45 NMR of the diamagnetic mimic Sc3+, (2) pulsed X-band EPR spectroscopy of Yb3+ spin probes, and (3) excitation and emission spectroscopy of Eu3+ dopants. The rare-earth ions are found in a mixed environment of fluoride and phosphate ions, which changes systematically as a function of glass composition. In the Sc-containing glasses the quantitative makeup of this ligand environment has been determined by Sc-45[F-19] and Sc-45[P-31] rotational echo double resonance (RED OR). Comparison of the P- to F-ligand ratio with the batch composition indicates that the Sc3+ ions show a clear preference for phosphate over fluoride ion ligation. These REDOR results were correlated with Yb3+ EPR data, the intensity ratio of Eu3+ transitions D-5(0) -> F-7(2) to D-5(0) -> F-7(1), and the lifetime values of the Eu3+ emitting level D-5(0). As a result, it was possible to obtain a global interpretation in terms of the associated quantitative ligand distribution (fluoride versus phosphate) in the first coordination sphere of the rare earth ions. The calibration of EPR and luminescence spectra on the basis of such solid state NMR data defines a new spectroscopic strategy for characterizing the rare-earth local environments in promising laser glasses. (AU)

• Processo FAPESP: 13/23490-3 - Técnicas de ressonância magnética empregadas no estudo da correlação estrutura/propriedades em vidros e vitrocerâmicas fotônicos
• Beneficiário: Marcos de Oliveira Junior
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 13/07793-6 - CEPIV - Centro de Ensino, Pesquisa e Inovação em Vidros
• Beneficiário: Edgar Dutra Zanotto
• Modalidade de apoio: Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs
• Processo FAPESP: 15/04063-2 - Ambientes de coordenação de íons terra-rara em vidros fotônicos analisados por técnicas de ressonância paramagnética eletrônica pulsada
• Beneficiário: Marcos de Oliveira Junior
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Pós-Doutorado