ИСТИНА

Doping of fine crystalline corundum has performed during synthesis in water fluid at T=415°C and P=21.6-31.6 MPa with concentration of cerium in interval 0.001 – 0.25 % in reaction medium. Kinetics and mechanism of corundum (alpha-Al2O3) formation from Al(OH)3 (hydrargillite) in supercritical water fluid (SCWF) in presence of cerium ions were investigated. The hydrargillite was transformed into Ce-doped boehmite, which then into the powder of fine crystalline corundum doped with cerium at 415°С is transformed. An induction period precedes the formation of corundum from boehmite, as in the case of a presence of dopant, so also without it. The size of corundum crystals was growing with an increase of pressure and content of cerium ions. The doping of boehmite and corundum results in appearance of absorption bands of cerium ions in the diffuse reflection spectra. At lighting in the absorption band the luminescence of cerium ions as in samples of boehmite and corundum is observed. The luminescent emission of cerium ions in corundum (at 370 nm) is increased with the fluid pressure during synthesis. The heating in vacuum at 1400°C leads to decrease of the luminescence intensity. It is evidence that in the medium of supercritical water the cerium ions form in the structures of boehmite and corundum a complex with hydroxyl groups, which is a luminescence center of Ce-doped corundum synthesized in supercritical water fluid.