Synthesis and characteristics of ZnGa sub(2)O sub(4) hollow nanostructures via carbon[at]Ga(OH)CO sub(3)[at]Zn(OH) sub(2) by a hydrothermal method

ZnGa sub(2)O sub(4) hollow nanostructures were synthesized by a two step hydrothermal and calcination process using carbon spheres as a template. We observed that the carbon[at]Ga(OH)CO sub(3) core-shell nanostructures were covered by a uniform shell of Zn(OH) sub(2) nanoparticles when prepared using 2.5 mmol of ZnAc, and ZnGa sub(2)O sub(4) hollow nanostructures with diameters of approximately 200 nm and shell thicknesses of around 15 nm could then be obtained. After calcination at 900 degree C for 1 h, the amorphous core-shell-shell nanostructures yielded highly crystalline ZnGa sub(2)O sub(4) hollow nanostructures. The shell possesses a single-crystal structure and a lattice spacing of around 0.253 nm which corresponds to the d spacing of (311) crystal planes of cubic ZnGa sub(2)O sub(4). The composition and surface electron state of the ZnGa sub(2)O sub(4) hollow nanostructures prepared at 900 degree C were confirmed by X-ray photoelectron spectroscopy. UV and blue emissions of the ZnGa sub(2)O sub(4) hollow nanostructures were found to result from self-activation centers of the octahedral Ga-O groups in the spinel structures and symmetry distortion of the octahedral sites by oxygen vacancies, respectively.