Recent progress in understanding the persistent luminescence in SrAl₂O₄:Eu,Dy

Abstract

Ever since the discovery of SrAl2O4:Eu,Dy persistent afterglow material, that can intensively glow up to 20 h, the mechanism of long-lasting luminescence has been a popular area of research. The research is focused on discovering the mechanism of persistent luminescence in order to prolong the duration and intensity of afterglow in a controlled way. Although most researchers agree on the general things, there are still many unclarities and ambiguities to discuss upon. This review paper briefly sketches in the highlights of past research on the luminescence mechanism in SrAl2O4:Eu,Dy, mainly focusing on the research conducted in the past decade dedicated to clearing these ambiguities. This paper provides an overview of the latest persistent luminescence mechanisms offered by researchers.

The boron effect on low temperature luminescence of SrAl2O4:Eu, Dy

“…There is strong evidence confirming the fact that Eu 2+ is the luminescence center in SrAl 2 O 4 responsible for the blue/green emission [8]. The Eu 2+ changes its charge state during excitation, the electron from Eu 2+ is transferred to some unidentified trap [2] and a number of traps are filled. The gradual thermally stimulated release of electrons from traps takes place at room temperature (RT).…”

“…The released electrons recombine with Eu 3+ ion, thus resulting in excited Eu 2+ creation. The following radiative transition to the Eu 2+ ground state is the origin of the green luminescence observed [2]. However, in addition to thermally stimulated process, the creation of excited Eu 2+ luminescence centre via electron tunnelling was observed recently as well [9][10][11].…”

“…SrAl 2 O 4 :Eu,Dy is a very efficient green-emitting phosphor, its longlasting afterglow can be observed for hours after the termination of excitation [1][2][3]. Therefore, SrAl 2 O 4 :Eu,Dy is widely used in many applicationsemergency signs, watch dials, luminous paints, luminescent coatings, in vivo imaging [2][3][4][5][6]. The problem that will be highlighted in this publication, is the temperature dependence of the afterglow of this material.…”

“…The problem that will be highlighted in this publication, is the temperature dependence of the afterglow of this material. Due to the shape and position of thermally stimulated luminescence (TSL) peak, SrAl 2 O 4 :Eu,Dy loses a lot of its afterglow efficiency in temperatures below zero Celsius, that is a major problem for material outdoor use [2,7]. However, there might be a solution for this problem, that is worth looking in to.…”

Recent Developments in Lanthanide-Doped Alkaline Earth Aluminate Phosphors with Enhanced and Long-Persistent Luminescence

“…The incorporation of Eu 2+ ions in these different sites leads to a variation in the luminescent properties from both sites because of their different symmetries and orientations. The incorporated dopant ions are thought to introduce localized states of the bandgap in the host matrix, which facilitate the luminescent properties that arise from the various dopant-incorporated sites in the SrAl 2 O 4 host material [ 56 ]. The doping sites in the host material are known to be determined by the host lattice components and the ionic radii of the dopants.…”