Hydrothermal Synthesis Of The ZnO Crystal And Sapphire Crystal

ZnO single crystals about one millimeter in dimension are grown by the hydrothermal method at 430℃ and 40Mpa conditions without temperature gradient. The effects of various growth conditions (temperature, mineralizer consistence and different mineralizer) on the morphology and quality of ZnO crystals are investigated. When KOH and NaOH are used as mineralizer, at the lower mineralizer consistence (<1M) conditions, only small ZnO crystals (with the magnitude of several microns) are obtained; but at the higher mineralizer consistence, ZnO crystals with size ranging from several microns to several hundred microns are obtained, which have integrity crystal facets. The growth behavior of ZnO crystal is investigated and the growth mechanism of bipyramid crystal was explained. Furthermore, the decay process of photoelectrons from ZnO crystals prepared by hydrothermal synthesis method is measured by microwave absorption method, which demonstrated obvious difference of photoelectron lifetime between nano- ZnO and micro-ZnO crystals. The pure a -A1203 crystals are also synthesized by hydrothermal method, and the morphology of a -A1203 crystal prepared under different growth conditions is studied using scanning electron microscopy. The Al203:Ti crystals are synthesized when the Ti irons are added into the reaction medium and orange color sapphire crystals are obtained when the Mn irons were added. The studies in this dissertation pave the way to the investigation and production of the ZnO, a-Al203and sapphire crystal.