Optimising synthesis conditions for long lasting SrAl₂O₄phosphor

Abstract

PurposeTo evaluate the effect of flux, activator and co‐activator on solid state synthesis of SrAl2O4: Eu2 + , Dy3 + phosphor, where boric oxide, europium oxide and dispersium oxide were used, respectively.Design/methodology/approachTo optimise synthesis condition of long lasting phosphorescence SrAl2O4 phosphor, boric oxide was used as a flux. To improve relative intensity of SrAl2O4: Eu2 + phosphor, the critical concentration of Eu2 + was determined. The effect of various concentration of co‐activator on afterglow properties, the effect of Dy3 + ion on the emission and excitation spectra were examined.FindingsThe SrAl2O4: Eu2 + , Dy3 + phosphor powders have been synthesised by solid state reaction method. The result of XRD patterns indicated that, addition of 5 mol% B2O3 enhanced the formation of SrAl2O4 at 1,200°C. Investigation on the variation of emission intensity of different phosphors containing different amounts of Eu2 + revealed that after 6 mol% of Eu2 + concentration, quenching process occurred. Dy3 + formed trap levels and results demonstrated that increasing concentration of Dy3 + up to 5 mol% reduced the relative intensity and increased the decay time.Originality/valueUsing B2O3 as a flux and solid state reaction method for preparation of this phosphor is in good agreement with industrial production and make it economic, because of reduced sintering temperature.

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

“…It can be seen that the PL intensity of emission from Eu 2+ ions initially increases with the increase of dopant and co-dopant concentration. After it reaches the maximum value, a further increase in concentration makes the intensity decrease, because of the concentration quenching effect [21,72,80,81]. When considering the possible origin of the trap-ping centres, it can not be excluded that similar defects to those in α-Al2O3 could be present in the strontium aluminate -F centres ( , that is close to impossible to get rid of in the synthesis process, and intrinsic defects -F-centres and F2-centres luminescence.…”

Persistent Luminescence in Strontium Aluminate: A Roadmap to a Brighter Future

“…[74,76,77] The green emission is characterized by a much higher quenching temperature of 440 K [4] and concentration quenching only sets in at Eu concentrations around 6%. [77][78][79] At low temperature, both emission bands have a comparable intensity in samples with a low activator concentration from which Poort et al [74] concluded that Eu 2+ is equally likely incorporated on both Sr sites. However, one should be careful when interpreting this statement as the intensity ratio of both emission bands is highly temperature-, concentration-, and excitation-wavelength-dependent.…”

“…The green emission is characterized by a much higher quenching temperature of 440 K [ 4 ] and concentration quenching only sets in at Eu concentrations around 6%. [ 77–79 ] At low temperature, both emission bands have a comparable intensity in samples with a low activator concentration from which Poort et al. [ 74 ] concluded that Eu 2+ is equally likely incorporated on both Sr sites.…”

Improved anti‐sedimentation for acrylic resin containing long afterglow phosphors by in situ polymerisation

“…The alkaline earth aluminates based long afterglow phosphors as luminescent pigments are being actively explored nowadays because of their "glow-in-the-dark" and no radiation (Sharma et al, 2008;Li et al, 2008;Faridnia et al, 2007). When used in luminescent paint, it can be applied in emergency escape route guidance system, glow signs, display devices, toys, golf balls, etc.…”