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Thermally and optically stimulated luminescence in long persistent orthorhombic strontium aluminates doped with Eu, Dy and Eu, Nd

2017; Elsevier BV; Volume: 67; Linguagem: Inglês

10.1016/j.optmat.2017.03.040

1873-1252

N.J. Zúñiga-Rivera, P. Salas, V. Chernov, L.A. Dı́az-Torres, R. Meléndrez, Rafael García, R. C. Carrillo-Torres, M. Barboza‐Flores,

Photorefractive and Nonlinear Optics

The long persistent luminescence, thermoluminescence (TL) and IR stimulated luminescence properties of two orthorhombic strontium aluminates (Sr 4 Al 14 O 25 ) co-doped with Eu 2+ , Dy 3+ and Eu 2+ , Nd 3+ exposed to beta radiation is reported. The phosphors were synthesized by the combustion method followed by a post-annealing treatment under a reductive carbon atmosphere. Photoluminescence emission spectra of both phosphors are typical for emission of Eu 2+ ions with 7-fold and 10-fold coordination in Sr 4 Al 14 0 25 and consist of the main band at 480 nm and a weak band between 390 and 440 nm. After exposure to beta radiation the Sr 4 Al 14 0 25 :Eu 2+ ,Dy 3+ phosphor exhibits two strongly overlapped TL peaks at about 70 and 100 °C while the low temperature TL of the Sr 4 Al 14 0 25 :Eu 2+ ,Nd 3+ phosphor consist of two well separated peaks with maxima at about 60 and 130 °C. Additionally, both phosphors exhibit a weak TL between 180 and 400 °C. The traps responsible for the low temperature TL peaks are the Dy 3+ and Nd 3+ centers situated in two different Sr sites with 7-fold and 10-fold coordination. The thermal emptying of the Dy and Nd filled traps creates ultra-long intense afterglow , which gradually decays with time and remains detectable after 220 h storage in dark. IR stimulation of beta irradiated phosphors creates intense IR stimulated luminescence, which is related to the release of electrons from the filled Dy and Nd traps. • Two long persistent Sr 4 Al 14 O 25 co-doped with Eu 2+ , Dy 3+ and Eu 2+ , Nd 3+ are synthesized by the combustion method. • Afterglow, thermally and IR stimulated luminescence properties of the phosphors exposed to beta radiation are reported. • Phosphors present ultra long intense afterglow with slow decay that remains detectable even after 220 h storage in dark. • The mechanism explaining the observed luminescence phenomena is proposed.