OPTICAL-ABSORPTION OF NANOSTRUCTURED AL2O3

Optical absorption of nanostructured Al2O3 was investigated. Results a re as follows: (1) when the annealing temperature, Ta < 800 degrees C, two broad absorption bands are observed in the reflection spectrum; ( 2) when Ta > 1100 degrees C, six absorption bands appear in the reflec tion spectrum. The appearance of the pronounced absorption bands with peak energies of 6.0 ev, similar to 5.5 ev, 4.8 ev, 3.75 ev and 3.05 e v, respectively, demonstrates that a large number of color centers exi st in nanostructured Al2O3, including the F+ center, the v-type center (V2-, V- and V-OH- centers) and the Cr3+ impurity center and others.