Leuco Sapphire Boules Manufactured by the Verneuil process

The Verneuil process is a common method of growing leuco sapphire monocrystals of smaller diameter and is based on melting powder aluminum oxide in a hydrogen fire created by vertical burners. A batch comes on a thin crystalline rod of sapphire (seed) from above in small portions administered by a special device. On a crystal seed, melted batch particles create a thin film that solidifies as it descends. The synchronization of batch, hydrogen and oxygen consumption with the rate of seed lowering provides the required level of crystallization. The absence of a container for melt simplifies the whole process by eliminating the problem of interaction between the container and the melt, though the purity of crystals grown this way relies on the presence of reliable control over impurities coming from the atmosphere and furnace ceramics.

RHT offers mono-crystalline feed grown by the Vereuil method for manufacturing larger crystals. The quality of our mono-crystals is no worse than that of well-known Czech crystalline feedstock grown using the same method. The content of Al2O3 is no less than 99.998%, and it contains impurities as follows.
  • Si – < 4 ppm
  • Fe – < 3 ppm
  • Cu – < 1 ppm
  • Ca – < 1 ppm
  • Ti – < 1 ppm
  • Mg – < 1 ppm
  • Na – < 1 ppm
  • K – < 1 ppm