Ti3+/Eu2+3+ - DOPED LSCAS GLASS PHOSPHORUS FOR WHITE LIGHT DEVICES
SIMONE FINOTO1; CLAUDIO YAMAMOTO MORASSUTI1; LUIS HUMBERTO DA CUNHA
ANDRADE1; SANDRO MARCIO LIMA1.
1 Grupo de Espectroscopia Óptica e Fototérmica - GEOF, Centro de Estudos em Recursos NaturaisCERNA, Universidade Estadual de Mato Grosso do Sul - UEMS, Dourados, MS, Brazil.
Introduction: Rare-earth-doped aluminosilicate glasses have attracted greater attention due their potencial
application as phosphorus for white light LEDs [1]. One of the most interesting result reported was concerned
to Ti3+ or Eu2+,3+ - doped low calcium aluminosilicate glasses (LSCAS) [2,3]. Aim: Here we report at the first
time the use of LSCAS co-doping samples with titanium and europium ions for white light LEDs application
with the possibility of tunable color temperature. Material and methods: The glass composition in wt% was
39.5-x Al2O3 (5N), 47.4 CaO (5N), 7 SiO2 (5N), 2.0 TiO2 (5N), 4.1-x MgO (5N), x Eu2O3 (4N) where x = 0.1
and 0.5. The mixture was melted under vacuum atmosphere at 1600 ºC for two hours. All emission spectra
were collected by a HR4000 Ocean optics spectrometer. Results and discussion: Figure 1a) show a broad
visible emission band around 525 nm for all samples are attributed to Eu2+ and Ti4+,3+. The peak centered at
613nm from Eu3+ increase with the concentration of Eu2O3 as a red shift the broad emission band from Ti3+.
This result indicate that the addition of Eu2O3 in LSCAS:Ti induces the reduction of Ti4+ and an increase of
Ti3+. Figure 1b show the changes of emission with change in excitation wavelength, by CIE1931 x-y
chromatic diagram, to sample with 0.1 wt% Eu2O3, presenting tunable color according to excitation
wavelength. 0.1 wt% Eu2O3 sample present high color retendering index (CRI Ra of 88%) and variable
correlated color temperature (CCT) from 6300 to 8800 K when excited with ultraviolet LEDs. Conclusions:
The addition of Eu2O3 in LSCAS:Ti promotes the increase the ratio Ti3+/Ti4+ resulting in a red shift of the
emission band that is interesting effect for the development of phosphorous materials.
a)
b)
1.2
Norm. Intensity (a. u.)
ex: 280 nm
Eu2O3 (%)
0.1
0.5
0.9
0.6
0.3
0.0
400
450
500
550
600
650
700
750
Wavelength (nm)
Figure 1. a): Emission band 0.1% and 0.5% Eu samples at 280 nm excitation. b) CIE 1931
color diagram from LSCAS glass sample doped with 2.0 wt.% of TiO 2 an 0.1 wt.% of Eu2O3.
References:
[1] A. C. P. Rocha, L. H. C. Andrade, S. M. Lima, A. M. Farias, A. C. Bento, M. L. Baesso, Y. Guyot, and G.
Boulon, Optics Express 20 (2012) 10034-10041.
[2] L. H. C. Andrade, S. M. Lima, A. Novastski, P. T. Udo, N. G. C. Astrath, A. N. Medina, A. C. Bento, M. L.
Baesso, Y. Guyot, and G. Boulon, Physical Review Letters, 100 (2008) 1- 4.
[3] J. A. Sampaio, M. C. Filadelpho, A. A. Andrade, J. H. Rohling, A. N. Medina, A. C. Bento, L. M. da Silva,
F. C. G. Gandra, L. A. O. Nunes and M. L. Baesso, J. Phys.: Condens. Matter 22 (2010) 1-5.
Keywords: LSCAS; earth-rare; white light generation.
Acknowledgment: FUNDECT/MS.
Promoção/Realização:
Apoio: