ABSTRACT
This chapter addresses the synthesis of single-crystal materials at high pressures. High pressures are also required when the material to be grown has a high vapor pressure, or when it decomposes below its melting point at atmospheric pressure. The Czochralski method of crystal growth represents a way for pulling single crystals from the surface of their melts. The significant differences between the hydrothermal process and the flux process are the relatively low temperatures at which crystallization occurs the extreme solubility of the solute in the aqueous solution at the higher pressure and the high rate of convection which promotes rapid crystal growth. Reaction rates at high pressures also have a great effect upon the size of crystals that can be obtained. The effects of seed orientation can make the difference between success and failure in the hydrothermal process. The synthesis of materials at still higher pressure involves mainly the study of polymorphic transitions and chemical reactions.
