Cu-Cr-O and Cu-Cr-O, Zn-Cr-O Nano-Composites: Synthesis and Study of Different Parameters on the Composition and Morphology of Them

In this research, the synthesis of Cu-Cr-O and Cu-Cr-O.Zn-Cr-O nano-composite was done by the co-precipitation method at pH=9. The effect of some materials such as Al(NO3)3.9H2O and Zn(NO3)2, two polymeric surfactants, PEG-400 and PEG-600, and different calcination conditions of precursor on the structure, crystal phase, and morphology of nanocomposite was investigated. All samples were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray (EDX) spectroscopy analysis. According to the results of XRD, the structure of nano-composite is a function of the salts used as reactants and surfactants. When the salts used are Cu(NO3)2.3H2O and (NH4)2Cr2O7 in the absence of surfactants, the nano-composite is composed of CuO and CuCr2O4. While, within the presence of PEG-400 and PEG-600, the nano-composite consists of CuO and CuCr2O4, in addition, a small amount of Cu2Cr2O4 is also found. The presence of Cu2Cr2O4 can be due to the reduction of some Cu2+ ion to Cu+ in spinel in the presence of a little remaining surfactant. When Zn(NO3)2 is added to the reactants the nano-composite is composed of CuCr2O4 and ZnCr2O4 spinels and CuO is not seen in the crystal structure of nano-composite. Adding of Al(NO3)3.9H2O to the reactants will cause Al2O3 to enter the structure of the nano-composite. CuAl2O4 doesn’t form here because the CuAl2O4 (which contains Al3+ (d0) ions) is less sustainable than CuCr2O4 based on Crystal Field Stabilization Energy (CFST). SEM images of nano-composites revealed that different calcination conditions and calcination temperature and surfactants affect the morphology and uniformity and the sizes of nano-composites. The best nano-composite according to the uniformity of morphology and small particle size is formed when the reactants are Cu(NO3)2.3H2O, (NH4)2Cr2O7, and Zn(NO3)2. and the precursor is calcined 2h at 400˚C and 2h at 600˚C. The morphology of the Nano-composite is almost like a small nano-sheet with a thickness of about 15 nm.