Competing roles of defects in SrAl₂O₄:Eu²⁺,Dy³⁺ phosphors detected by luminescence techniques

Abstract

Thermoluminescence (TL) and radioluminescence (RL) spectra of the long-lasting phosphorescence of SrA1 2 O 4 :Eu 21 ,Dy 31 with A1N addition and commercially used SrA1 2 O 4 :Eu 21 ,Dy 31 were compared. Their spectra were slowly recorded over the temperature range from 25 to 673 K (400°C). A1N offers a higher temperature TL peak, which should lengthen the phosphor lifetime. However, both TL and RL, especially that below room temperature, reveal that there are additional decay paths for the samples of SrA1 2 O 4 :Eu 21 ,Dy 31 with A1N additions. These new defect sites reduce the phosphor efficiency. Some speculative models of potential sites are proposed and discussed. In addition, discontinuous intensity changes have been observed for both sample types in TL and RL spectra, which are assigned to the transitions of embedded impurity phases. The justification for this model is explained. Suggestions for future experimentation are also considered.

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

“…In this research SrAl 2 O 4 :Dy material is studied through TSL, X-ray excited luminescence (Figure 10) and kinetics analysis and this gives rise to a claim that Dy might act as a hole trapping centre. There is quite a strong argument in favour of this claim – Dy 3+ emission spectrum is observable also in afterglow [64] and TSL spectrum [84,88,93]. The Dy 3+ characteristic lines, that are observable under X-ray irradiation SrAl 2 O 4 :Dy 3+ are said to be created by electron returning to Dy 4+ ion, thus creating an excited Dy 3+ centre.…”

Novel cementitious materials with mechanoluminescence for the application of visible stress monitoring and recording

“…Figure 4 a shows the PL spectrum, which displays a broad green emission peak, located at 522 nm, The green emission responds to the transition of 5d-4f. for Eu 2+ 37 , 38 , and the CIE coordinate is (0.2876, 0.5690) (Fig. 4 b).…”