Abstract:The optical properties of BaAl 2 S 4 doped with Eu 2+ were investigated. The synthesis was performed in evacuated and sealed quartz ampul at 1000°C during 1 h, then at 840°C during 20 h. With absorption, excitation, and emission spectra we have determined the crystal-field splitting, the redshift, the influence of the lattice vibration properties, and the thermal quenching of the luminescence. The crystal-field splitting of Eu 2+ in BaAl 2 S 4 was estimated on the order of 8000 to 10 000 cm −1 and the Huang-Rh… Show more
“…Nevertheless, the 5d state is assumed to separate basically to two energy levels according to two broad bands located at 320 and 460 nm. Such similarity in the excitation spectrum is also observed in the Ca-a-SiAlON:Eu 2+ [15] and MAl 2 S 4 :Eu 2+ [16] phosphors. The excitation shoulder in the spectrum at 270 nm is due to the transition between the valence and conduction bands of the host, which is in agreement with the optical band gap of 4.5 eV [17].…”
“…Nevertheless, the 5d state is assumed to separate basically to two energy levels according to two broad bands located at 320 and 460 nm. Such similarity in the excitation spectrum is also observed in the Ca-a-SiAlON:Eu 2+ [15] and MAl 2 S 4 :Eu 2+ [16] phosphors. The excitation shoulder in the spectrum at 270 nm is due to the transition between the valence and conduction bands of the host, which is in agreement with the optical band gap of 4.5 eV [17].…”
“…The main part of the decay curve is characterized by a single exponential decay, with a time constant of 0.40 ms. During the first 0.3 ms after excitation, the decay is slightly faster, an effect which is enhanced at room temperature. The main decay constant of 0.40 ms is comparable to other Eu-doped thiogallates and thioaluminates [30].…”
Section: Influence Of the Temperaturesupporting
confidence: 61%
“…Barthou et al [30] determined the phonon energy of BaAl 2 S 4 , using two separate methods, namely optical methods and Raman spectroscopy. With optical methods, similar to ours, a value of 3172 meV was obtained.…”
“…These Raman spectra are in good agreement with those reported in Refs. [27,28] and could be used in fitting of the emission bands. The emission spectra are shown in Fig.…”
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