Stimulated emission of Co2+-doped glass–ceramics

Recycling of solid wastes in the synthesis of Co-bearing calcium hexaluminate pigment

“…The general aspect was similar for all the pigments insofar as a wide band was obtained that was composed of three emissions in the NIR region, at w1200, 1300 and 1500 nm. These seem to be attributable to spin forbidden transitions of tetrahedrally coordinated Co 2þ ions from 4 A 2 (F) ground state to the excited 4 T 1 (F) state [19][20][21][22][23]. In the visible region, four bands of distinct intensities are noticed.…”

“…In the visible region, four bands of distinct intensities are noticed. This multiple excitation reflected at 471, 544, 580 and 610 nm is assigned to 4 A 2 (F) / 4 T 1 (P) forbidden d-d transitions of Co 2þ (3d 7 ) in a tetrahedral field (T d ) [19][20][21][22][23]. The exhibited colour is interpreted by the first reflected band at 471 nm in the range of blue visible light interval (490-450 nm) [23].…”

Spectroscopic properties of Co2+ ions in La2O3–MgO–Al2O3–SiO2 glass-ceramics

“…The luminescence peak of 666 nm was slightly red shifted compared to 660 nm for MgO-Al 2 O 3 -SiO 2 GCs doped with 0.1 wt.% CoO [15], but blue shifted compared with 685 nm, 694 nm, and 703 nm for MgO-Al 2 O 3 -SiO 2 GCs respectively containing 0.24 wt.%, 0.48 wt.%, and 1.22 wt.% CoO [25]. According to crystal field theory, the crystal field strength, D q , depends on the bonding distance between cations and anions [6].…”

“…During the past few years, transparent GCs with tetrahedral Co 2+ ions containing spinel nanocrystals have been used successfully as saturable absorbers [9,12,13]. Meanwhile, stimulated emission from 600 nm to 700 nm of Co 2+ -doped GCs has also been observed [14], and the peak value of effective stimulated emission cross-sections for Co 2+ ions was found to be higher than that in spinel single crystals [15].…”

Synthesis and Spectroscopic Properties of ZnAl2O4:Co2+ via a Hydrothermal Process

“…It is known that divalent cobalt ions occupy tetrahedrally coordinated sites in spinel crystals and demonstrate a bright red luminescence [5]. The crystal-field splitting of energy levels of Co 2+ (3d 7 ) in a tetrahedral field is similar to that of Cr 3+ (3d 3 ) in an octahedral field, but the value of crystal field parameter is significantly smaller in the octahedral case [6].…”