Compositional Optimization of Emission Properties for Rare-Earth Doped Fluoride Phosphate Glasses: Structural Investigations via NMR, EPR, and Optical Spectroscopies

Author(s)

Galleani, Gustavo ^[1] ; Doerenkamp, Carsten ^[1] ; Santagneli, Silvia ^[2] ; Magon, Claudio Jose ^[1] ; de Camargo, Andrea S. S. ^[1] ; Eckert, Hellmut ^{[1, 3]}

Affiliation

^[1] Univ Sao Paulo, Inst Fis Sao Carlos, Ave Trabalhador Saocarlense 400, BR-13566590 Sao Carlos, SP - Brazil

^[2] Univ Estadual Paulista, Inst Quim, Rua Prof Francisco Degni 55, BR-14800060 Araraquara, SP - Brazil

^[3] Westfalische Wilhelms Univ Munster, Inst Phys Chem, Corrensstr 30, D-48149 Munster - Germany

• Document type: Journal article
• Source: Journal of Physical Chemistry C; v. 123, n. 51, p. 31219-31231, DEC 26 2019.
• Web of Science Citations: 0

Abstract

A detailed structural investigation of two series of fluoride phosphate glasses with nominal compositions 20BaF(2)-20SrF(2)-20ZnF(2)-xIn(PO3)(3)-(40 - x)InF3 (x = 0, 5, 10, and 15) and 20BaF(2)-20SrF(2)-20ZnF(2)-10ScF(3)-xIn(PO3)(3)-(30 - x)InF3 (x = 0, 10, 15, 20), both doped with either 0.2 mol % Yb3+ or 0.S mol % Eu3+, has been conducted. As indicated by Raman scattering and solid- state NMR, the network structure is dominated by six-coordinated In3+, orthophosphate Q((0)()) species, and the (near) absence of P-O-P connectivity. The ligand environment of the rare-earth ions is studied by (1) Sc-45 NMR of the diamagnetic mimic Sc3+, (2) echo-detected field-sweep EPR spectra at the X-band, using Yb3+ spin probes, and (3) excitation and emission spectroscopy of Eu3+ dopants. Sc-45[P-31] rotational echo double resonance (REDOR) results, the ratio of the Eu3+ D-5(0) -> F-7(2) to (5) D-0 -> F-7(1) emission intensities, the lifetime values of the Eu3+ emitting level D-5(0), as well as the g factor measured by EPR spectroscopy consistently indicate that the fluoride ligands strongly dominate in the first coordination sphere of the rare-earth ions. This result stands in contrast to previous studies on aluminofluorophosphate glasses with similar compositions that show mixed ligation of the rare-earth ions by fluoride and phosphate ions. Thus, by substituting aluminum by its homologue indium one can achieve the original design goal of fluoride phosphate glasses, which is the creation of a framework structure dominated by oxide, while the local environment of the RE emitting ion is dominated by fluoride ligands, so as to improve their emissive properties. The results also illustrate the successful use of the previously developed combined NMR/EPR/optical characterization strategy for the design of optimized matrices for rare-earth ion emitters. (AU)

• FAPESP's process: 17/06649-0 - New Optical Materials based on Rare-Earth Doped Oxyfluoride Glasses and Ceramics: Structural Studies by Electron Paramagnetic Resonance Methods
• Grantee: Carsten Doerenkamp
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 18/03931-9 - Preparation of fluoride-phosphate glass and glass-ceramics doped with rare-earth ions for potential use as radiation detectors
• Grantee: Gustavo Galleani
• 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: 18/24735-3 - The correlation between structure and properties as investigated by multinuclear solid state NMR in disordered materials
• Grantee: Silvia Helena Santagneli
• Support Opportunities: Regular Research Grants