Produção Nacional
Revisado por pares
Photoluminescence behavior of Eu3+ ion doped into γ- and α-alumina systems prepared by combustion, ceramic and Pechini methods
2007; Elsevier BV; Volume: 108; Issue: 1-3 Linguagem: Inglês
10.1016/j.micromeso.2007.03.045
ISSN1873-3093
AutoresMarcela Monteiro, Hermi F. Brito, M.C.F.C. Felinto, G.E.S. Brito, Ercules E. S. Teotônio, Flávio Maron Vichi, R. Stefani,
Tópico(s)Microwave Dielectric Ceramics Synthesis
ResumoAl2O3:Eu3+(1%) samples were prepared by combustion, ceramic, and Pechini methods annealed from 400 to 1400 °C. XRD patterns indicate that samples heated up to 1000 °C present disordered character of activated alumina (γ-Al2O3). However, α-Al2O3 phase showed high crystallinity and thermostability at 1200–1400 °C. The sample characterizations were also carried out by means of infrared spectroscopy (IR), scanning electron microscopy (SEM) and specific surface areas analysis (BET method). Excitation spectra of Al2O3:Eu3+ samples present broaden bands attributed to defects of Al2O3 matrices and to LMCT state of O → Eu3+, however, the narrow bands are assigned to 7F0 → 5DJ,5HJ and 5LJ transitions of Eu3+ ion. Emission spectra of samples calcined up to 1000 °C show broaden bands for 5D0 → 7FJ transitions of Eu3+ ion suggesting that the rare earth ion is in different symmetry sites showed by inhomogeneous line broadening of bands, confirming the predominance of the γ-alumina phase. For all samples heated from 1200 to 1400 °C the spectra exhibit narrow 5D0 → 7FJ transitions of Eu3+ ion indicating the conversion of γ to α-Al2O3 phases, a high intensity narrow peak around 695 nm assigned to R lines of Cr3+ ion is shown. Al2O3:Eu3+ heated up to 1100 °C presents an increase in the Ω2 intensity parameter with the increase of temperatures enhancing the covalent character of metal–donor interaction. The disordered structural systems present the highest values of emission quantum efficiencies (η). CIE coordinates of Al2O3:Eu3+ are also discussed.
Referência(s)