Abstract: New single crystals of ZnGeP.sub.2 are grown by a chemical vapor transport process from bulk synthesized polycrystalline ZnGeP.sub.2 using the LEK process with a controlled injection of phosphorus. The synthesis of the bulk is based on direct injection of phosphorus through a B.sub.2 O.sub.3 encapsulant and reaction with the zinc germanium melt, resulting in synthesis of a large melt (350 g) of ZnGeP.sub.2. When crystallization is followed by cooling the congruent melt down through the .alpha.-.beta. transition temperature (952.degree. C.) as is typical for bulk growth processes, the result is the growth of partially disordered material. This material is placed in a two zone heated furnace where iodine is used to transport the intermediate product to the growth zone where the single crystals grow, at a temperature below the .alpha.-.beta. phase transition. The resulting crystals produced contained a second cubic phase, which has not been reported previously.

Abstract: The growth of bismuth silicate crystals occurs in a high pressure vessel or autoclave using a hydrothermal growth process. The nutrient material is placed in a sealed container of noble metal, liner, along with a solvent to a selected fill level. A filler fluid is also placed between the liner and the pressure vessel. The oriented seeds are placed in the cooler top seed zone over a baffle that slows the movement of supersaturated liquid from the hotter lower nutrient zone. Using a selected heating schedule for the top and the bottom zones, a plurality of large crystals are grown in the seed zone. The temperature differential is about 5.degree. C.

Abstract: A composite susceptor for a radio frequency (RF) heated crystal growing furnace has a plurality of stacked electrically insulating and electrically conducting elements about the crucible area so that a proper temperature gradient is established and controlled.

Abstract: Ultra high pure quartz is grown by a one step in-situ growth process where the nutrient is high purity silica. A negative temperature gradient is maintained between the nutrient zone and the seed zone until about the start of crystal growth. A sealable container made of silver contains the nutrient and the seed within the autoclave chamber.

Abstract: This invention concerns itself with a method for producing single crystal, seed material for use in growing synthetic quartz crystals. This seed material comprises a Z-faced seed crystal cut or sliced from the X-plus growing region of a synthetic quartz, single crystal boule.