For BAM

a serious thermal degradation takes place after annealing in air.The same BAM phosphors may exhibit a large difference in different annealing processes.It is known that thermal degradation of BAM is relevant to annealing process. Since in PDP and fluorescent lamp manufacturing processes the phosphor is heated in air or oxygen containing gas at 600℃ to make phosphor layer

it is important to show effect of oxygen concentration in gas and mechanism of thermal degradation of BAM. In this paper a model of thermal degradation of the blue emitting BaMgAl

10

O

17

:Eu(BAM)phosphor is presented to disclose effect of oxygen concentration on luminance decrease

Z

in BAM after annealing in oxygen containing gas. According to the model

Z

is proportional to one sixth power of oxygen partial pressure

(P

O

2

)

1/6

and satisfies the following equation:

Z

=(P

O

2

)

1/6

+ There

is a temperature dependent parameter and increases with temperature

and has the value of

Z

as P

O

2

=0.The experimental results of thermal degradation of BAM in gas with different oxygen concentrations at different temperatures were simulated by using the above equation.We got the formulae of

Z

at 600℃

615℃

675℃ as follow:600℃:

Z

=0.85(P

O

2

)

1/6

+6.35 615℃:

Z

=1.05(P

O

2

)

1/6

+6.06 675℃:

Z

=1.62(P

O

2

)

1/6

+5.28 This stiumlation results indicate that 1) when O

2

%

<

10%

P

O

2

has much effect on

Z

; and however

when O

2

%

>

10%

P

O

2

has little effect on

Z

finally

Z

approaches to 12% at 600℃

13.5% at 615℃ and 17% at 675℃;2)with increasing temperature

the temperature dependent parameter increases and the thermal degradation of BAM increases.