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Luminescent Properties of Near UV Excitable Phosphors Based on Broates or Chlorobroates

Author: DingXu
Tutor: GuoChongFeng
School: Huazhong University of Science and Technology
Course: Inorganic Chemistry
Keywords: phosphor energy transfer broates
CLC: O611.3
Type: Master's thesis
Year: 2011
Downloads: 39
Quote: 2
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Abstract


Phosphors based on broates or chlorobroates have a rapidly development in recent years for their diversification structures, stable characters with chemical and thermal, lower synthesis temperature and so on. In this paper, we synthesized several phosphors which are activated by Eu2+、Ce3+、Mn2+ and Tb3+ based on Sr2B5O9Cl, LiCaBO3 and RSr4（BO3）3（R=Li, Na）,a further analysis of their luminescent properties, energy transfer and chromaticity have been carried out and the following results are achieved:（1） Sr2B5O9Cl:Eu2+ exhibits strong blue emission band upon the excitation of 365nm ultraviolet light. The PL intensity of the phosphors varied with the dopant concentration. As the Eu2+ concentration increases, the PL intensity first increases and reaches the maximum at 0.08. Beyond the critical concentration, the emission intensity begins to decrease due to the concentration quenching of the activators. A red shift has been observed in the emission when Sr atoms are partly or entirely replaced by Ca atoms.（2） Sr2B5O9Cl:Tb3+ exhibits a green emission centered at 545nm under the excitation of 254nm ultraviolet light. The intensity of Tb3+ can be remarkablely enhanced by co-doped Ce3+, which is attributed to the resonance-type energy transfer from Ce3+ to Tb3+. The intensity of phosphor Sr2B5O9Cl:8%Ce3+,yTb3+ varied with the dopant concentration. As the Tb3+ concentration increases, the PL intensity first increases and reaches the maximum at 0.10. Beyond the critical concentration, the emission intensity begins to decrease due to the concentration quenching of the Tb3+. （2） In LiCaBO3, Ce3+ occupied two Ca2+ crystal lattices and fromed two luminescence centers [Ce3+（1）] and Ca2+[Ce3+（2）], respectively. Energy transfer processes of Ce（1）3+→Ce（2）3+ and Ce3+→Mn2+ have been observed. Phosphors with dual-emitting of blue and red under excitation of 357nm near-ultraviolet light can be obtained by adjusting the concentration of Ce3+ and Mn2+.（3） RSr4（BO3）3:Tb3+（R=Li, Na） exhibits a green emission centered at 545nm under the excitation of 237nm ultraviolet light. The intensity of Tb3+ can be enhanced by co-doped Ce3+ which is attributed to the energy transfer from Ce3+→Tb3+.

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CLC: > Mathematical sciences and chemical > Chemistry > Inorganic Chemistry > Chemical elements and inorganic compounds > Nature
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