Synthesis and Photoluminescence Properties of Hierarchical Zinc Germanate Nanostructures

Novel hierarchical zinc germanate nanostructures have been successfully synthesized by the simple thermal evaporation method without the presence of catalyst at 1100 degrees C. Its morphology and microstructures were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction, high-resolution transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and photoluminescence spectroscopy (PL). SEM shows that the synthesized product displays interesting firefly-like morphology, in which numerous secondary branches (ZnGeO3 nanowires) are grown randomly around the main stems (Zn2GeO4 microrods). TEM indicates that Zn2GeO4 micorods are 2-3 mu m in diameters and several tens of micrometers in length. However, ZnGeO3 nanowires have diameters of about 15 nm and range from ten to several hundred micrometers in lengths with the growth direction of [110]. A broad emission band from 350 to 550 nm is obtained in the photoluminescence (PL) spectrum of these nanostructures at room temperature. There are three emission peaks: an UV emission peak at 395 nm, a strong green emission peak at 455 nm and a blue emission peak at 532 nm.