The phosphor CaSO

4

:Eu is a interesting material because of its very high sensitivity to ionizing radiations

negligible fading rate and high chemical stability.It has been used in the thermoluminescent(TL) dosimetry of -ray

-ray

X-ray

neutrons and highenergy cosmic rays.In CaSO

4

:Eu the chemical valence of the incorporated Eu ions can be +3 and/or +2 valence depending on the preparing methods.Most of the published papers about this phosphor were concerned with the thermoluminescent characteristics.Recently its photoluminescent properties attract more and more attentions.In this work the main attention was paid to its near ultra-violet(AUV) emission of the Eu

2+

ions in the phosphor CaSO

4

:Eu.The luminescence spectra of the CaSO

4

:Eu samples prepared with different methods were measured at room temperature in order to examine the effects of the preparing method on their luminescent properties.Experiments showed that the Ca and Eu sulphate codeposition method is a better one for the AUV emission of the Eu

2+

ions in these phosphors.In the concrete

a proportional amount of pure CaCl

2

and EuCl

3

was solved in deionized water and the co-precipitate was obtained by adding some sulfuric acid to the mixed aqueous solution.After washing by deionized water and drying the co-precipitate was fired at 650

7

50℃ for one hour under a weak reducing atmosphere.In the phosphors CaSO

4

:Eu prepared with this method the Eu

2+

ions are predominant over the Eu

3+

ions.In the phosphor the emission comes from the 5d-4f transition of the Eu

2+

ions.Its emission peak is at about 386

3

90 nm and its FWHM is about 16 nm.The UV excitation spectrum is composed of two bands peaking at about 274 nm and 323 nm

respectively.They are attributed to the absorption of the 5f-4d transitions of the Eu

2+

(ions.) When the content x is between 0.003 and 0.024 the phosphor gives a stronger AUV emission

the(strongest) emission occurs when the

x

is at about 0.02.The increase of the concentration of the incorporated Eu

2+

ions makes the emission band shift slightly to the longer wavelength.The results showed that CaSO

4

:Eu

2+

is a good candidate as the phosphors used in the backlight source of PLLCD.