Impurity optical absorption of Co2+-doped MgAl2S4 and CaAl2S4 single crystals

Luminescent properties of cobalt-doped α-ZnAl2S4 spinel type single crystals

“…The E A2 absorption lines are ascribed to the spin and electric dipole allowed transitions 4 A 2 ( 4 F)-4 T 1 ( 4 P). Indeed, in MgAl 2 S 4 :Co 2 þ , CaAl 2 S 4 :Co 2 þ [9] as well as in ZnS:Co 2 þ , where the impurity replaces only the tetrahedral coordinated Zn 2 þ ion [13], similar absorption lines are located almost at the same energies. In conformity with the crystal field theory [14], the 4 T 1 ( 4 P) state of the Co 2 þ ion sited in T d symmetry splits into three sublevels G 6 , G 8 and G 7 þG 8 due to the first order of the spin-orbit coupling effects.…”

“…Optical properties of the tetrahedral Co 2 þ in the sulphur surrounding have been studied in Refs. [9,10] and references therein, however, there are no papers on spectroscopic investigations of the cobalt doped sulphide spinels.…”

Luminescent characterization of CaAl2S4:Eu powder

“…The synthesis reactions were performed in silica tubes sealed under vacuum. Oh et al [20] prepared CaAl 2 S 4 single crystals by a chemical transport reaction method in a closed system using high-purity iodine as a transport agent. Sealed quartz ampules, containing the starting materials under vacuum, were placed in a furnace for a process of 12 days to obtain single crystals.…”

Optical properties of Sn‐doped and Sn:Ce‐codoped CaAl2S4 and application to white light emitting phosphor

“…The spectrum was attributed to Tl + -type Sn 2+ ions. Ternary compounds CaGa 2 S 4 and CaAl 2 S 4 with a band gap of 4.2 and 4.8 eV [2], respectively, are potential candidates as host material to be applied in optoelectronic devices. CaGa 2 S 4 and CaAl 2 S 4 were applied to blue or green emission EL devices with the rare earth elements doping such as Ce and Eu [3,4].…”