Based on the variation of solution pH and precipitation particle size during the precipitation and crystallization process of lanthanum carbonate,which precipitated with ammonium bicarbonate,the spontaneous crystallization characteristics were investigated.

In the present dissertation,the study is on fabricating high quality hydrothermal ZnO crystals,is on influences on crystal s appearances and quality under growing conditions of spontaneous crystallizations,is on manufacturing autoclave with lining for growing large size ZnO crystals,is on crystal s quality under varied growing conditions with seeds.

The result shows: the critical temperature that austenite grain size abruptly coarsens is 1200℃;the minimum temperature of austenite spontaneity recrystallization is 850℃,the recrystallization austenite is needle austenite and spher austenite at 850～900℃ ; there is structure inheritance at the temperature under 900℃and there is no structure inheritance at the temperat.

Application of self-cooled crystallization process in production of chlorates;