Network Structure and Rare-Earth Ion Local Environments in Fluoride Phosphate Photonic Glasses Studied by Solid-State NMR and Electron Paramagnetic Resonance Spectroscopies

Autor(es)

de Oliveira, Jr., Marcos ^[1] ; Uesbeck, Tobias ^[2] ; Goncalves, Tassia S. ^[1] ; Magon, Claudio Jose ^[1] ; Pizani, Paulo S. ^[3] ; de Camargo, Andrea S. S. ^[1] ; Eckert, Hellmut ^{[2, 1]}

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Fis Sao Carlos, BR-13566590 Sao Carlos, SP - Brazil

^[2] Univ Munster, Inst Phys Chem, D-48149 Munster - Germany

^[3] Univ Fed Sao Carlos, Dept Fis, BR-13566590 Sao Carlos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of Physical Chemistry C; v. 119, n. 43, p. 24574-24587, OCT 29 2015.
• Citações Web of Science: 17

Resumo

A detailed structural investigation of a series of fluoride phosphate laser glasses with nominal composition 25BaF(2)-25SrF(2)-(30 - x)Al(PO3)(3)-xAlF(3)-(20-z)YF3:zREF(3) with x = 25, 20, 15 and 10, RE = Yb and Eu, and 0 <= z <= 1.0 has been conducted using Raman, solid-state nuclear magnetic resonance (NMR), and electron paramagnetic resonance (EPR) spectroscopies. The network structure is dominated by the preferred formation of aluminum-to-phosphorus linkages, which have been quantified by means of Al-27/P-31 NMR double-resonance techniques. The fluoride ions are found in mixed Al/Y/Ba/Sr environments accommodating the luminescent dopant species as well. The local environments of the rare-earth species have been studied by pulsed EPR spectroscopy of the Yb3+ spin probe (S = 1/2), revealing composition-dependent echo-detected lineshapes and strong hyperfme coupling with F-19 nuclei in hyperfine sublevel correlation (HYSCORE) spectra consistent with the formation of Yb3+-F bonds. In addition, photoluminescence spectra of Eu3+-doped samples reveal that the D-5(0) -> F-7(2)/D-5(0) -> F-7(1) transitions intensity ratio, the normalized phonon sideband intensities in the excitation spectra, and excited state D-5(0) lifetime values are systematically dependent on fluoride content. Altogether, these results indicate that the rare-earth ions are found in a mixed fluoride/phosphate environment, to which the fluoride ions make the dominant contribution. Nevertheless, even at the highest fluoride levels (x = 25), the data suggest residual rare-earth phosphate coordination. (AU)

• 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: 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