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

Author(s)

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

• Document type: Journal article
• Source: Journal of Physical Chemistry C; v. 121, n. 5, p. 2968-2986, FEB 9 2017.
• Web of Science Citations: 12

Abstract

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)

• FAPESP's process: 13/23490-3 - Magnetic Resonance Techniques for the Study of Structure/Property Correlations in Photonic Glassy and Glass Ceramic Materials
• Grantee: Marcos de Oliveira Junior
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 13/07793-6 - CEPIV - Center for Teaching, Research and Innovation in Glass
• Grantee: Edgar Dutra Zanotto
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 15/04063-2 - Coordination environments of rare-earth ions in photonic glasses analyzed by pulsed electron paramagnetic resonance techniques
• Grantee: Marcos de Oliveira Junior
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor