Investigation of the structure-luminescence relationship in ZnAlEu layered double hydroxides intercalated with nitrate and benzenecarboxylates

Autor(es)

Nunes Silva, Ivan Guide ^[1] ; Morais, Alysson Ferreira ^[1] ; Lima, Bonifacio Coelho ^[1] ; Garcia, Fernando Assis ^[1] ; Mustafa, Danilo ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Fis, BR-05508090 Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: APPLIED CLAY SCIENCE; v. 199, DEC 1 2020.
• Citações Web of Science: 0

Resumo

Rare Earth-containing materials exhibit interesting luminescence properties, such as a spectral profile with narrow emission lines and a well understood crystal field dependence. These features make them appealing materials for molecular probing. Here, the structural properties governing the luminescence of Eu3+ ions hosted in layered double hydroxides (LDH) are investigated. Eu3+-substituted LDH have been shown to present photoluminescence properties dependent on the anionic species intercalated between the hydroxide layers. This feature is shown by the characterization and comparison between LDH intercalated with NO3- and a set of benzenecarboxylates: trimesate (benzene-1,3,5-tricarboxylate, BTC), trimellitate (benzene-1,2,4-tricarboxylate, TLA) and terephthalate (benzene-1,4-dicarboxylate, TERE). Successful LDH formation and intercalation with the respective anion was confirmed by powder X-ray diffraction (PXRD). The coordination structure of Eu3+ has been investigated by Extended X-ray Absorption Fine Structure (EXAFS) experiments, showing the incorporation of this activator in the hydroxide layers of the LDH in an 7/8-fold Oxygen-rich environment. The systems here investigated present very similar coordination, except for the presence of a water related Oxygen at around 3.0 angstrom in the nitrate-intercalated LDH, absent in the benzenecarboxylate-intercalated materials. The photoluminescence properties of all samples were analysed on the basis of the Judd-Ofelt theory, showing that the polycarboxylateand NO3--intercalated LDH can be grouped into two distinct classes with different sets of Judd-Ofelt intensity parameters (Omega(2) and Omega(4)). This has been rationalized based on the EXAFS results. Symmetry distortions in the first coordination shell of Eu are also expected from the observed changes in Omega(2) and Omega(4). This distinctive feature allows one to probe interlayer modifications in LDH through changes in the luminescence properties of lanthanide activators hosted in their hydroxide layers, opening up new opportunities for in-situ investigation of anion exchange reactions in these materials. (AU)

• Processo FAPESP: 18/13837-0 - Espectroscopia de terras raras como uma ferramenta para monitorar a liberação controlada de aditivos alimentares
• Beneficiário: Alysson Ferreira Morais
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 15/19210-0 - Hidróxidos duplos lamelares (LDH) nanoestruturados com propriedades de up e down-conversion para aplicações como sensibilizadores em células solares
• Beneficiário: Danilo Mustafa
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores