On BaMgAl10O17:Eu2+ phosphor degradation mechanism by vacuum-ultraviolet excitation

• Published in: Journal of applied physics Vol. 98; no. 11
• Main Authors: Bizarri, G., Moine, B.
• Format: Journal Article
• Language: English
• Published: 01.12.2005
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.2132094

Additional to a correct color and a high efficiency, phosphors for plasma display panels must maintain their light output for thousands of hours. Often the degradation is the restricting factor in using phosphors. In this article, the mechanism of luminance decrease in blue-emitting BaMgAl10O17:Eu2+ phosphor during the operation of the PDPs has been studied. It is shown experimentally that the aging process is mainly due to the vacuum-ultraviolet excitation (VUV). It is demonstrated that the degradation mechanism can be accelerated by using a 193nm laser excitation. Based on excitation, reflectance, thermoluminescence spectra, and aging or annealing processes by laser excitation, the main causes of the degradation are demonstrated. The aging process can be separated in two different processes according to the temperature: a first one, at low temperature, corresponding to the autoionization of luminescent centers (Eu2+→Eu3+); and a second one, at high temperature, linked to the formation of traps in the phosphor. These traps induce a perturbation of the energy migration in the phosphor. In addition, the relevant parameters of trap formation are highlighted: density of the VUV excitation, temperature, and atmosphere/pressure surrounding the phosphor. A model of BaMgAl10O17:Eu2+ phosphor degradation mechanism is proposed.