Self-assembling synthesis of alpha -Al sub(2)O sub(3)-carbon composites and a method to increase their photoluminescence

alpha -alumina-carbon composites were synthesized and characterized by X-ray powder diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and fluorescence spectrophotometry. The results indicate that the sample morphology depends on the choice of chelating agent. Photoluminescence spectra show that a major emission band around 420 nm and two weaker side bands located around 440 and 470 nm are observed when the excitation wavelength is 360 nm. Interestingly, the intensity of emission peak located at 420 nm decreases with the increase in calcination temperature. But quite on the contrary, the emission intensity at 420 nm increases with the increase of full width at half-maximum of X-ray powder diffraction lines. The carbon doping improved the luminescence properties of alpha -alumina and did not change the rhombohedral structure of the host. The carbon dopant also improved the surface morphology. The highest luminescence intensity was observed for a composition of 0.4C/0.6 alpha -Al sub(2)O sub(3). The as-prepared alumina - carbon composites exhibit a pronounced blue light emission when the excitation wavelength is 360 nm, which is expected to widen the potential applications for blue light-emitting materials.