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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Network Former Mixing Effects in Heavy Metal Oxide Glasses: Structural Characterization of Lead Zinc Phosphotellurite Glasses Using NMR and EPR Spectroscopies

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de Oliveira Jr, Marcos ; Amjad, Raja Junaid [1, 2] ; de Camargo, Andrea S. S. [2] ; Eckert, Hellmut [3, 2]
Total Authors: 4
[1] COMSATS Inst Informat Technol, Dept Phys, Lahore 54000 - Pakistan
[2] de Oliveira Jr, Jr., Marcos, Univ Sao Paulo, Sao Carlos Inst Phys, CP 369, BR-13566590 Sao Carlos, SP - Brazil
[3] WWU Munster, Inst Phys Chem, Corrensstr 30, D-48149 Munster - Germany
Total Affiliations: 3
Document type: Journal article
Source: Journal of Physical Chemistry C; v. 122, n. 41, p. 23698-23711, OCT 18 2018.
Web of Science Citations: 1

Network former mixing effects in Yb3+-doped glasses in the system {[}(2TeO(2))(x)(P2O5)(1-x) ](0.6) {[}(PbO)(0.5)-(ZnO)(0.5)](0.4) have been investigated using a comprehensive strategy involving complementary NMR ((31)p,Te-125,Pb- 207) and EPR (of Yb3+ probe ions) spectroscopies. Phosphate local environments and connectivities are extracted from detailed 31P MAS NMR line shape analyses with assignments to distinct P `'(mTe) sites supported by recoupling of homonuclear spin-spin interactions (refocused-INADEQUATE experiments). These results suggest a preference for P-O-Te over P-O-P and Te-O-Te connectivities for x < 0.5, consistent with nonlinear compositional trends of glass transition temperatures. While sharing of the network modifiers PbO and ZnO between the phosphate and the tellurite networks is close to proportional, the NMR data indicate subtle deviations favoring phosphate ligation at x > 0.6, where the anionic fraction of phosphate exceeds the expected fraction (67%) based on composition. On a local scale, nonlinear trends in Pb-207 chemical shift parameters suggest the preferred formation of a ligand environment with approximately equal numbers of phosphate and tellurite ligands near x = 0.5, which persists over a wide composition range. While electron spin echo envelope modulation (ESEEM) experiments suggest that the overall elemental distribution appears to be homogeneous on a 1 nm distance scale, the EPR lineshapes suggest significant changes (and possibly inhomogeneous distributions) of the local Yb3+ environments. (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 type: Scholarships in Brazil - Post-Doctorate
FAPESP's process: 13/07793-6 - CEPIV - Center for Teaching, Research and Innovation in Glass
Grantee:Edgar Dutra Zanotto
Support type: Research Grants - Research, Innovation and Dissemination Centers - RIDC
FAPESP's process: 15/08434-5 - Fluoroindate and tellurite glasses doped with rare earth ions and metallic nanoparticles for enhanced solar cell efficiency by sunlight down-shifting and upconversion
Grantee:Andrea Simone Stucchi de Camargo Alvarez Bernardez
Support type: Research Grants - Visiting Researcher Grant - International