Cathodoluminescent Properties and Energy Transfer in Red Calcium Sulfide Phosphors (CaS:Eu, Mn)

Abstract

Red and orange calcium sulfide phosphors (CaS:Eu and CaS:Mn) were prepared by the flux method. Eu2+ and Mn2+ show strong concentration quenching at 0.1 and 0.8% respectively. Use of the potassium polysulfide flux leads to efficient phosphors; their efficiency reaches 60 and 100% of Y2O2S:Eu, respectively. Calcium sulfide codoped with Eu and Mn shows a strong increase of Eu2+ in addition to Mn2+ emission. The colour obtained varies between red and orange depending on the concentration rates of Mn and Eu. A luminous efficiency of about 86% was reached for CaS:Eu(0.08%), Mn(0.3%). The decay characteristics of Mn2+ in CaS:Mn, Eu show that the fast part depends on the Eu2+ content. On the other hand, the Eu2+ decay became slower in the presence of Mn2+. These observations support the resonant mechanism of the energy transfer from Mn2+ to Eu2+.

Luminescent properties of novel Ca2.89Mg0.11(PO4)2:Eu2+ single-phase white light-emitting phosphor for white LEDs

“…The experimental decay curves of Ca 2.89 Mg 0.11 (PO 4 ) 2 :0.02Eu 2 þ can be best fitted with a single exponential equation: I¼ A 1 exp(À t/τ 1 ), while Ca 2.89 Mg 0.11 -(PO 4 ) 2 :0.06Eu 2 þ with a double exponential equation: I¼ A 1 exp (À t/τ 1 )þ A 2 exp(À t/τ 2 ), where I is the luminescence intensity, A 1 and A 2 are constants, t is the time, τ 1 and τ 2 are the decay times for the exponential components. The average decay times (τ n ) can be estimated by the following relation [23]:…”

Luminescent properties of red-emitting LiSr4B3O(9−3x/2)Nx:Eu2+ phosphor for white-LEDs

“…The decay times can be determined using a curve fitting technique based on the following equation: I¼A 1 exp(À t/t 1 )þ A 2 exp(À t/t 2 ), where I is phosphorescence intensity, A 1 and A 2 are constants, t is time, t 1 and t 2 are decay times for exponential components, respectively. The average decay times (t) can be calculated by the following formula [17]:…”

A blue-emitting Sc silicate phosphor for ultraviolet excited light-emitting diodes

“…The excitation band monitored by 426 nm is made up of a strong band centered at 360 nm and a weak one peaked at 257 nm. The two 30 excitation bands centered at 360 nm and 257 nm can be associated with the 1 A 1 -1 T 1 and 1 A 1 -1 T 2 charge transfer of SiO 4 4-, respectively. 22 Under the excitation of 360 nm, the emission spectrum exhibits a broad change transfer band range from 380 to 550 nm located at 420 nm, as shown in Fig.…”

“…The temperature-dependent photoluminescent property was tested using a heating apparatus (TAP-02) in combination with PL equipment. 25 The powder XRD of our prepared samples was performed to 30 detect the phase purity. Figure 1 Table 1.…”

“…26 The Eu 2+ content dependent PL intensities are drawn in Fig. 4 30 mainly caused by the non-radiative energy migration among the activators due to the exchange interaction or multipole-multipole interaction. 27 It is well-known that the interaction type between activators can be calculated by the following equation: 28…”