Nizhankovsky S. The growth of the optiсal sapphire crystals by the horizontal directional crystallization using reducing gaseous media

Object of investigation - the sapphire grown by the horizontal directional crystallization (HDC) in the redusing gaseous media from the metallurgical alumina-based raw material. Aim of investigation: to study the pecularities of the formation of the optical and ctructure properties of the sapphire. Methods of investigations: fotospectroscopy, X-ray diffraction method, spectral analysis, electron-probe microanalysis, scanning electronic microscopy, optical microscopy, electron-paramagnetic spectroscopy. Theoretical and practical results, novelty : the conditions of the purification of the alumina in the reducing medium CO+H2 is established. The technology of obtaining raw material from the metallurgical alumina was found. It is shown, that the optical properties of the sapphire grown in the reducing medium CO+H2 are determinated by the content of impurity of titanium and by the reducing potential of the growth atmoshere. It is establishied, that the annealing in the medium with different redusing potential allows to obtain sapphire with simultaneosly high UV-radiation resistance and high UV-range transmission. It is shown, that sapphire growth in reducing media don't leads to the significant change of the microstructure parametries of the crystals. It is shown, that the microinclusions in the sapphire grown in reducing media Ar+(CO,H2) appeare in the melt due to anionic non-stochiometry. It is shown, that growth of the sapphire without the microinclusions possibly with supporting partial pressure of the reducing components below the critical level. Field of application: the sapphire crystal growth technology.