| Full text | |
| Author(s): |
Maia, Alessandra S.
[1]
;
Stefani, Roberval
[1]
;
Kodaira, Claudia A.
[2]
;
Felinto, Maria C. F. C.
[2]
;
Teotonio, Ercules E. S.
[3]
;
Brito, Hermi F.
[1]
Total Authors: 6
|
| Affiliation: | [1] Univ Sao Paulo, Inst Quim, BR-05513970 Sao Paulo - Brazil
[2] IPEN, BR-05508900 Sao Paulo - Brazil
[3] Univ Fed Goias, Dept Quim, BR-75704020 Catalao, Go - Brazil
Total Affiliations: 3
|
| Document type: | Journal article |
| Source: | Optical Materials; v. 31, n. 2, p. 440-444, Oct. 2008. |
| Field of knowledge: | Physical Sciences and Mathematics - Chemistry |
| Web of Science Citations: | 43 |
| Abstract | |
MgAl2O4: Eu, Dy nanoparticles were prepared by citrate sol-gel method and thermally treated at 600, 700, 800 and 900 °C. The trivalent europium ion is partially reduced to the divalent state at 700 and 800 °C. Infrared spectra of the phosphors showed bands around 700 and 520 cm-1 corresponding to the AlO6 groups. X-ray diffraction patterns present sharp reflections of samples heated from 700 to 900 °C indicating the MgAl2O4 spinel phase. Grain size in the range 20-30 nm were observed by measurement of transmission electron microscopy (TEM). The emission spectra of the phosphors show a broadened band at 480 nm assigned to the 4f65d -> 4f7 (8S7/2) transition of Eu2+ ion overlapped to the 4F9/2 -> 6H15/2 transition of the Dy3+ ion. Besides, the 4F9/2 -> 6H13/2 transition (579 nm) of Dy3+ ion is overlapped with the 5D0 -> 7F0 (578 nm) and 5D0 -> 7F1 (595 nm) transitions from the Eu3+ ion. Excitation spectra of the sample heated at 900 °C monitoring the excitation at 615 nm of 5D0 -> 7F2 transition of Eu3+ ion exhibit a broad band assigned to the O -> Eu3+ ligand-to-metal charge-transfer states (LMCT) around 280 nm. The samples present green persistent luminescence after exposure to UV radiation. The chromaticity coordinates were obtained from the luminescence emission spectrum. (AU) | |
| FAPESP's process: | 05/01216-0 - Preparation and photoluminescent study of the afterglow phenomena of materials doped with rare earth ions |
| Grantee: | Hermi Felinto de Brito |
| Support Opportunities: | Regular Research Grants |