In situ and homogeneous hydrolysis of urea was utilized to design a homogeneous precipitation method to synthesize the ZnCr2O4 functional material. The as‐prepared nanospinel was systematically studied in terms of crystal structure, morphology, texture, and light absorption. A well‐crystalline single phase of ZnCr2O4 nanospinel with a spongy network structure was obtained. Transmission electron microscopy and X‐ray diffraction observations confirmed the formation of monocrystalline nanoparticles of ZnCr2O4 with the nanosize of 13 nm. The synthesized nanospinel showed a low direct band gap value of 1.8 eV with appropriate absorption in the visible light region, which was a remarkable result for this route.
The effect of different alumina precursors (aluminum nitride, aluminum hydroxide, and aluminum oxide) on morphology and the structural properties of ZnO-Al 2 O 3 nanocomposite prepared via chemical precipitation using urea hydrolysis was studied. The synthesized nanocomposites were systematically characterized by X-ray diffraction, thermal gravimetric, field-emission scanning electron microscopy, surface area analysis, and UV-vis absorption. In the case of aluminum hydroxide and aluminum oxide, a core-shell structure consisting of the ZnO nanoflakes on Al 2 O 3 particles was obtained. Aluminum nitrate precursor resulted in the ZnAl 2 O 4 spinel as the only crystalline phase. The characteristics of the synthesized nanocomposites strongly depend on the alumina sources. *hamid_tjz@yahoo.com
The present work deals with the preparation and characterization of Al 2 O 3 -SiO 2 -ZnO composite under mid-temperature conditions via sol-gel method. The structural features of all the samples were assessed by X-ray diffraction (XRD), specific surface area (BET) and scanning electron microscopy (SEM). The changes in the morphology and particle size of the as prepared composites were investigated. Al 2 O 3 -SiO 2 -ZnO composites with different amount of ZnO were prepared. The effect of temperature on the crystallization of Al 2 O 3 -SiO 2 -ZnO composites containing 70% ZnO was investigated. When the calcinations temperature increases up to 850 °C, broad peaks of ZnAl 2 O 4 with some impurities of Zn 2 SiO 4 was appeared. From SEM images it was revealed that Naiad structure is formed when the calcinations temperature is 500 °C.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.