Some former researches revealed that the composition of Eu

Dy co-doped alkaline earth aluminate plays an important role on the persistent luminescence.However

the researches about the effect of composition on luminescence of phosphors was not systemically carried out up to now

and the relevant mechanisms were not clearly given out.In this paper

Eu

Dy co-doped strontium aluminate phosphors with different composition were synthesized by solid-state reaction

crystal phase composition of phosphors was investigated by XRD technology

emission and excitation spectra and afterglow decay curve were measured via fluorescent photometer.The influence of strontium aluminate composition on phosphorescent properties was studied.The results of XRD and persistent luminescent properties showed that three crystal phases(SrAl

2

O

4

:Eu

2+

Dy

3+

;Sr

4

Al

14

O

25

:Eu

2+

Dy

3+

and SrAl

4

O

7

:Eu

2+

Dy

3+

) with good persistent luminescent properties could be formed by changing Al

2

O

3

/SrO ratio.From excitation and emission spectra and afterglow decay properties

it can be concluded that with the decreasing of Sr/Al ratio

excitation spectra extend to short wavenumber side

emission peaks take blue-shift

initial afterglow luminance is increased and afterglow life is prolonged.The effect mechanisms were investigated and discussed.There are more O

2-

ions around the Eu

2+

ions in Sr

2+

-poor phases so the effect of crystal field on electron levels of Eu

2+

ions is bigger(maybe due to the high electro-negativity of oxygen)

the electron levels are split more.It is this reason that makes emission peaks blue-shift.Thermoluminescence results showed there were bigger trap depth and higher trap density in Sr

2+

-poor phases so that the Sr

2+

-poor phosphors showed better persistent luminescence.