Recently

because of the requirement of plasma display panels (PDPs) and a possible new generation of Hg-free lamps

much attention has been paid to phosphors for vacuum ultraviolet (VUV) excitation. BaMgAl

10

O

17

:Eu(BAM) is widely used as a blue emitting commercial phosphor for plasma display panels (PDP) and used in Hg-free lamp due to its high efficiency and good chromaticity. However

BAM suffers a thermal degradation during the manufacturing of PDP and a lifetime degradation during PDP operation. Thus the application of BAM in PDP is hindered. In Hg-free lamps

the degradation of BAM is mainly caused by thermal treatment during lamp manufacturing. One of the options to enhanced thermal stability and ion resis-tance for BAM is the application of a closed particle coating. Among the coating materials

MgF

2

is preferable for its high secondary electron emission coefficient and low refractive index in the range from 130 nm to 7400 nm. In this work

a sol-gel process was applied to coat BAM phosphors with MgF

2

which is low apparatus-dependent compared with other processes

using trifluoroacetic acid (TFA) and magnesium acetate as precursors. The coatings were characterized by XPS and SEM. Their anti-thermal degradation and photoluminescence properties were investigated under UV and VUV excitation. The results indicated that BAM phosphors were successfully coated with MgF

2

-coatings and the coated BAM was much more stable than the uncoated when both fired at 600℃ for 30 min in the air. The optimum anti-thermal degradation properties were obtained at the mass ratio 0.2% under 254 nm excitation and 0.5% under 147 nm excitation

respectively. As a conclusion

the sol-gel coating process is a promising method to protect the phosphor powders

and improves the phosphors anti-thermal degradation properties under UV and VUV excitation for application in displays and lamps.