Luminescent properties of blue-emitting long afterglow phosphors Sr2−xCax MgSi2O7:Eu2+, Dy3+ (, 1)

Abstract

The luminescence of two newly developed blue-emitting long afterglow phosphors, Sr 2Àx Ca x MgSi 2 O 7 :Eu 2+ , Dy 3+ (x ¼ 0, 1), has been studied. The emission under VUV-UV excitation from a synchrotron radiation source, along with the long afterglow spectra have been measured at different temperatures ranging from 7 to 300 K. While the emission spectra under 170 nm excitation exhibit both the 5d-4f transitions of Eu 2+ and 4f-4f transitions of Dy 3+ , only the blue band corresponding to the 5d-4f transitions of Eu 2+ is observed in the long afterglow spectra. Emission of Sr 2 MgSi 2 O 7 :Eu 2+ , Dy 3+ excited by an intense VUV laser source (157.6 nm) is also reported. The rich line structures in the laser-excited emission spectra partly result from 4f-4f transitions of Eu 3+ , indicating an efficient photon-induced process, which promotes Eu 2+ to Eu 3+ . The thermoluminescence covering the temperature range from 50 to 450 K for both samples has been measured as well and the depth of the traps responsible for the long afterglow emission was estimated. The mechanism of the persistent luminescence and the origin of the traps are discussed in the light of these results. r

Photoionization behavior of Eu2+-doped BaMgSiO4 long-persisting phosphor upon UV irradiation

“…First, the actual photoionization of Eu 2+ to Eu 3+ is not at all clear and needs identification of the different Eu n+ species present in the material during UV-visible illumination (or during the trapping process) [16]. Up to now, the photoionization of Eu 2+ to Eu 3+ in Eu 2+ -containing phosphorescent material, Sr 2 MgSi 2 O 7 , has been observed by X-rays or VUV irradiation [16,17], but, as far as the present authors know, no direct experimental evidence has been advanced to support such photoionization behavior upon UV irradiation. Based on this, Hassinen et al [18] suggested that the creation of Eu 2+ -h + pairs upon UV irradiation was a more sophisticated choice.…”

Photochromic properties of rare-earth strontium aluminate luminescent fiber

“…The typical spectrum of Eu 2+ ions is attributed to transition from the excited state 4f 6 5d to the ground state 4f 7 [4][5][6]. The emission spectra of yellow and blue luminescent fiber are similar with SrAl 2 O 4 : Eu 2+ , Dy 3+ .…”

Optical Properties of Afterglow Nanoparticles : , Capped with Polyethylene Glycol

“…However, it is water soluble. Sr 2 MgSi 2 O 7 : Eu 2+ , Dy 3+ , a water-insoluble afterglow material, was recently proposed by numerous research groups [15][16][17][18]. If these afterglow materials can be nanosized, they would be very useful in many fields.…”