Preparation of nanosized CoAl2O4 powders by sol–gel and sol–gel-hydrothermal methods

Synthesis, structure and optical properties of CoAl2O4 spinel nanocrystals

“…In recent years, much work has been done on the preparation and the optical properties of CoAl 2 O 4 spinel materials [13][14][15][16][17][18][19]. A variety of techniques such as combustion [13], Pechini [14], sol-gel [15,17], and reverse microemulsion [16] have been successfully used for the preparation of cobalt aluminate oxide. Previous studies have shown that the color of CoAl 2 O 4 is strongly affected by the synthesis temperature [17][18][19].…”

Evolution of structural and optical properties in the course of thermal evolution of sol–gel derived cobalt-doped gahnite

“…The influence of preparation route on temperature at which the color of the samples changes from green to blue has also been observed [9,12]. The oxidizing environment produced during thermal decomposition of the nitrates could promote oxidation of cobalt to Co 3+ ion [6,13] and the existence of Co 3+ ions in octahedral coordination may lead to a development of green coloration [14].…”

“…Partial oxidation of Co 2+ ions to the Co 3+ ions, caused by the thermal decomposition of nitrate ions at temperatures between 180 and 300 • C, [13] leads to the appearance of the Co 3+ absorption bands in the DRS spectra of samples (band in the wavelength range 320-420 nm and band at 660 nm, Fig. 5).…”

Production of Copper and Cobalt Aluminate Spinels and Their Application As Supports for Inulinase Immobilization

“…Copper 53 , freeze-drying 54 , sol-gelhydrothermal method 55 , ultrasonic-assisted-hydrothermal method 56 , polymerized complex technique 57 , chemical vapor deposition 58 , and via supercritical water conditions 59 . In this work, both copper and cobalt aluminates were prepared by route using chitosan as template.…”