Coordination of Eu3+ Activators in ZnAlEu Layered Double Hydroxides Intercalated by Isophthalate and Nitrilotriacetate

Author(s)

Morais, Alysson F. ; Silva, Ivan G. N. ; Lima, Bonifacio C. ; Garcia, Fernando A. ; Mustafa, Danilo

• Document type: Journal article
• Source: ACS OMEGA; v. 5, n. 37, p. 8-pg., 2020-09-22.

Abstract

Luminescent layered double hydroxides (LDH) intercalated by isophthalate (ISO) and nitrilotriacetate (NTA) have been synthesized and characterized by powder X-ray diffraction (PXRD), extended X-ray absorption fine structure (EXAFS), elemental analysis (ICP-OES and CHN), and photoluminescence spectroscopy. While PXRD shows the successful formation of ZnAlEu LDHs, EXAFS reveals that the Eu activators are hosted in the hydroxide layers with an eightfold, oxygen-rich coordination, distinct from the sixfold coordination expected for the octahedral sites of metal cations in LDHs. This kind of coordination should locally distort the brucite-like layers. Additionally, the intercalation of ISO and NTA in the LDHs is shown to change the coordination environment around Eu compared to nitrate-intercalated ZnAlEu LDHs, which suggests that these anions directly interact with the Eu centers and/or strongly affect their coordination geometry. Finally, from the photoluminescence results, analyzed based on the Judd-Ofelt theory, it is determined that Eu is most likely in an environment with no inversion symmetry. (AU)

• FAPESP's process: 15/19210-0 - Nanostructured double layered hydroxides with up e down-conversion properties for applications as sensitizers in solar cells
• Grantee: Danilo Mustafa
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 18/13837-0 - Rare earth spectroscopy as a tool for monitoring controlled release of food additives
• Grantee: Alysson Ferreira Morais
• Support Opportunities: Scholarships in Brazil - Post-Doctoral