Abstract
The system for the crystal growth in supercritical fluid at ultra-high pressure and temperature using a diamond anvil cell and infra-red laser-heating (Laser-DAC) is described. Well crystalline fine crystals of GaN in the wultzite-type structure have been grown from gallium/aluminium and supercritical nitrogen fluid at about 10GPa and 3000K. They have hexagonal platelet or prismatic morphology, indicating a solution growth using supercritical nitrogen fluid as a solvent. Rectangular hollow tube single crystals of the rutile-type GeO_2 having a structure equivalent to that of TiO_2, a well-known photocatalyst, have been grown for the first time in supercritical oxygen fluid at about 5GPa and 3000K within 1sec. They are in submicron sizes (cross section with sides of 500nm, wall thickness of 20nm, and longitudinal length of 5μm) and grown along the c-axis surrounded by the (110) faces. These results open us a new way of synthesis and crystal growth of various kinds of nitrides and oxides in supercritical fluid in ultra-high pressures and temperatures using diamond anvil cell and infra-red laser heating.
