In-situ Cr-doped Alumina Nanorods Powder Prepared by Hydrothermal Method

Abstract:

Cr-doped ammonium aluminum carbonate hydroxide nanorods were successfully prepared by hydrothermal method, using Al(NO3)3?9H2O, Cr(NO3)3?9H2O, and urea as raw materials and PEG-20000 as surfactant. In-situ Cr-doped alumina nanorods powder can be obtained through calcinations at 1200 ℃. The crystal composition, structure and morphology of the as-prepared products were characterized by XRD, SEM and FTIR. Besides, the color performances of the products were analyzed by UV/Vis/NIR spectrometer and automatic color measurement. Results showed that the precursors of Cr-doped alumina nanorods powder prepared by the hydrothermal method were composed of uniform nanorods. After calcinations at 1200 ℃, the in-situ doping of Cr in the alumina substrate was achieved. In Cr-doped alumina nanorods powder, a continuous solid solution of Cr2O3 and Al2O3 was formed, which had a corundum crystal structure. With increasing Cr content, Cr-doped ammonium aluminum carbonate hydroxide nanorods gradually became short, and the melting phenomenon occurred in calcined products. UV-Vis spectroscopy analysis showed that Cr-doped alumina nanorods powder had three strong absorption bands at 562 nm, 406 nm and 372 nm, respectively, thus leading to a pink color for samples in agreement with chromatic data. In the study, Cr-doped alumina nanorods powder prepared by the hydrothermal method can reduce the formation temperature of corundum crystal structures and resolve the problem of mixing homogeneity of Al2O3 and Cr2O3, which will contribute to preparation and application of alumina-chrome refractory, pink corundum abrasive and ceramic pigment.

Key words:chromium doped; alumina; hydrothermal method