A simple way to prepare Co:MgAl2O4 transparent ceramics for saturable absorber

Synthesis, structure and spectroscopy of Fe2+:MgAl2O4 transparent ceramics and glass-ceramics

“…Optical quality of ceramics can be greatly improved by proper adjusting the synthesis procedure. Recently, multiple studies were dedicated to the development of transparent spinel ceramics, such as MgAl2O4 and ZnAl2O4 (gahnite) both undoped and Co 2+ doped [16,[31][32][33][34][35]. For the consolidation of optical-quality spinel ceramics, either hot pressing with a fluoride-based sintering additive [36] or free sintering with a subsequent hot isostatic pressing (HIP) treatment is used [37].…”

Directionally Solidified Cobalt-Doped MgO-MgAl2O4 Eutectic Composites for Selective Emitters

“…Four lines located at around 1300, 1430, 1500 and 1685 nm were found and related to the spin-orbit splitting of the parent 4 F ionic state ( 4 F 9/2 + 4 F 7/2 + 4 F 5/2 + 4 F 3/2 ). The positions of these peaks were red-shifted with respect to the absorption bands measured at room temperature [16,25]. This shift towards low energies of the emission at a high temperature is expected as the thermal expansion of the crystal produces a lengthening of the Co 2+ -O 2ligand distance, which decreases the cubic crystal field intensity.…”

“…The choice of Co 2+ as the selective emitter ion for this eutectic is relevant as, considering that cobalt ions can enter substituting Mg 2+ ions in both MgO and MgAl 2 O 4 eutectic phases, the content of the dopant ion in the composite could be higher than in the case of nickel, increasing the thermal emission of the composite. In addition, Co 2+ ions show a high effective absorption cross section in MgAl 2 O 4 [16,17], which would lead to a higher emission. Finally, recent results in directionally solidified MgO-MgAl 2 O 4 eutectic ceramics show that this eutectic composite is translucent in the medium infrared range under some processing parameters [18], which would make it a suitable matrix for selective emission by reducing the emission out of the TPV convertible wavelength range.…”

Influence of presintering temperature on magnesium aluminate spinel transparent ceramics fabricated by solid‐state reactive sintering

“…In the past 50 years, transparent magnesium aluminate spinel ceramics have been widely studied due to its excellent optical quality, low area density, high mechanical properties, and good corrosion resistance. [1][2][3][4][5][6] High-quality transparent spinel ceramics are commonly used in missile domes, 7 spacecraft windows, 8,9 saturable absorbers in solid-state lighting, 10,11 and other function windows. [12][13][14] Although spinel ceramics with relatively good performance have already been prepared, but reducing costs for better achieving mass production and further improving the comprehensive performance have been the most important issues now.…”