Photoluminescence properties of La super(3+)-doped BaY sub(1.94)Eu sub(0.06)ZnO sub(5) phosphor prepared using a sol-gel method

The La super(3+)-doped BaY sub(1.94)Eu sub(0.06)ZnO sub(5) nano-crystal phosphors were prepared using a sol-gel method. The x-ray diffraction profiles show all of the peaks are attributed to the BaY sub(2)ZnO sub(5) phase when co-doped with the (La super(3+), Eu super(3+)) ions. The broad band cente...

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Bibliographic Details
Published in:Journal of luminescence 2015-01, Vol.157, p.98-103
Main Authors: Chang, Yee-Shin, Shih, Hung-Rung, Tsai, Mu-Tsun, Liu, Kuan-Ting, Teoh, Lay-Gaik
Format: Article
Language:English
Subjects:
Charge
Compressive properties
Emission
Excitation
Lattices
Luminescence
Phosphors
Sol gel process
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Summary:The La super(3+)-doped BaY sub(1.94)Eu sub(0.06)ZnO sub(5) nano-crystal phosphors were prepared using a sol-gel method. The x-ray diffraction profiles show all of the peaks are attributed to the BaY sub(2)ZnO sub(5) phase when co-doped with the (La super(3+), Eu super(3+)) ions. The broad band centered at 301 nm and the sharp peaks from 320 to 410 nm are attributed to the charge transition state (CTS) from O super(2-) to Eu super(3+) ions of the host lattice and the intra-4f forbidden transitions of Eu super(3+) ion, respectively. Under an excitation of 395 nm, the emission spectra of BaY sub(1.94-x)La sub(x)Eu sub(0.06)ZnO sub(5 ) samples exhibit a series of shaped peaks assigned to the super(5)D sub(0) arrow right super(7)F sub(J) (J=0, 1, 2, 3, and 4) transitions. Luminescence from the higher excited states, such as super(5)D sub(1), super(5)D sub(2), and super(5)D sub(3), was also observed, even though the La super(3+) concentration was up to x=0.36. In the BaY sub(1.94-x)La sub(x)Eu sub(0.06)ZnO sub(5 ) system, a different La super(3+) concentration did not change the locations of these excitation and emission peaks, but did change the intensities of them. The intensities of excitation and emission peaks increase and then decrease, when the La super(3+) ion concentrations are increased, and the maximum intensities for both the peaks occur when x is 0.28. This is due to the lattice distortion and induces an increase in the degree of compressive strain, which causes the amount of oxygen vacancies to decrease when La super(3+) substitutes the Y super(3+) ion.
ISSN:0022-2313
DOI:10.1016/j.jlumin.2014.07.024