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

Autor(es)

de Oliveira Jr, Marcos ; Amjad, Raja Junaid ^{[1, 2]} ; de Camargo, Andrea S. S. ^[2] ; Eckert, Hellmut ^{[3, 2]}

Afiliação do(s) autor(es)

^[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

• Tipo de documento: Artigo Científico
• Fonte: Journal of Physical Chemistry C; v. 122, n. 41, p. 23698-23711, OCT 18 2018.
• Citações Web of Science: 1

Resumo

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)

• 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: 15/08434-5 - Vidros fluoroindatos e telúritos dopados com íons terras raras e nanopartículas metálicas para melhor eficiência de células solares por redução e conversão ascendente de energia solar
• Beneficiário: Andrea Simone Stucchi de Camargo Alvarez Bernardez
• Modalidade de apoio: Auxílio à Pesquisa - Pesquisador Visitante - Internacional
• 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