Luminescence studies of MBrCl: Eu2+ (M=Ca, Sr, Ba)

Europium doped MBrCl (M=Ca, Sr, and Ba) phosphors were prepared by solid state reaction in reductive atmosphere. Photoluminescence (PL), photostimulated luminescence (PSL) after X-ray irradiation and optical absorption studies of MBrCl:Eu2+ (M=Ca, Sr, and Ba) revealed that: (1) blue light emission, under the excitation of 300 nm, was observed in all these phosphors; (2) the shape of the emission spectra in CaBrCl:Eu2+ could be changed by varying the bromine/chlorine ratio during synthesis, while that in SrBrCl:Eu2+ and BaBrCl:Eu2+ showed no change; and (3) PSL was observed in SrBrCl:Eu2+ and BaBrCl:Eu2+ after X-ray irradiation. Difference absorption spectrum (DAS) in SrBrCl:Eu2+ showed two broad bands centered at about 470 and 570 nm, and DAS in BaBrCl:Eu2+ showed two bands at about 550 and 675 nm, respectively. This enabled the use of He-Ne laser (633 nm) or even semiconductor light-emitting diodes (LED) instead of gas lasers for photostimulation.