Study of the structure, particle morphology and optical properties of mixed metal oxides

The structure, morphology and optical properties of metal oxides (ZnO, MgO and SrO), their composites (MgO-ZnO, SrO-ZnO) and systems with different x molar concentration values (0.2, 0.4, 0.5, 0.6, 0.7, 0.8) of MgxZn1-xO and SrxZn1-xO, were synthesized via solution combustion method at initial reaction temperature of 600 ˚C for 15 minutes. These properties of the synthesized nanostructures were investigated using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), High resolution transmission electron microscope (HR-TEM) and Photoluminescence (PL) spectroscopy. The ZnO, MgO and SrO phosphors were successfully synthesized via solution combustion method and their crystallization was confirmed by XRD analysis. The ZnO powder crystallized in the hexagonal phase. The diffraction patterns of the ZnO samples became sharper and more intense when synthesis temperature was increased from 600 ˚C to 700 ˚C indicating improvement of crystallinity and an increase in crystallite sizes from 23.3 nm to 30.06 nm of the as-prepared undoped ZnO phosphor powder. The MgO powder had cubic crystal structure with Fm-3m space group and crystallized in rocksalt/sodium chloride (NaCl) type cubic structure and the SrO sample indicated the presence of three well-defined crystalline phases which are SrO, Sr(OH)2 and Sr(CO3)2, with Sr(OH)2 appearing as the most prominent phase. With respect to the following systems: MgxZn1-xO and SrxZn1-,xO and their composites, their XRD patterns revealed the presence of two well-defined crystalline phases, namely MgO or SrO and ZnO, the most prominent phase being ZnO. The SEM images of ZnO showed agglomeration of small particles and flower-like morphology. The HR-TEM images showed that the nanoparticles (NPs) were hexagonally shaped and aggregated into clusters. The SEM images of MgO showed spherical cube-like morphology with the appearance of closely-packed or attached particles in all the SEM micrographs. The HR-TEM images show that the NPs were cubic
National Research Foundation (NRF)
University of the Free State