Kjeldahl Crystal Growth Method

Kjeldahl crystal growth method (Kyropoulos method) referred KY France , mainland

Kjeldahl crystal growth method

Kyropoulos Kyropoulos is first proposed in 1926 and used for the crystal growth , after a long period of time, the methods are used for large size crystals of halogen , hydroxides and carbonates of crystal with . The 1960s and 1970s,the former Soviet Union Musatov improvements, this method is applied to the preparation of sapphire crystal.

The single crystal growth method,the appearance is usually pear-shaped , the crystal can grow to a diameter smaller than the inner diameter of the crucible 10 ~ 30mm in size. The principle and the method of Czochralski crystal pulling (Czochralski method) is similar to the first material is heated to form a molten melt after melting , then the seed crystal (Seed Crystal, also known as the seed crystal bar ) come into contact with molten metal surface, molten crystal species and start to grow on the solid-liquid interface and the same crystal structure as the seed crystal , seed crystal pulled up very slowly , but on the seed crystal pulled up over time to form a crystal neck , to be molten seed interface with the solidification rate is stable, the seed will no longer be pulled up , nor for rotation , only way to control the cooling rate of the single crystal solidification from the top down gradually , and finally solidified into a whole single crystal ingot Figure 10 is Kyropoulos (Kyropoulos method) a schematic representation .

Kyropoulos is the use of temperature control to grow crystals, it Czochralski crystal pulling out the biggest difference is the only crystal neck, crystal body part is relying on the growth of temperature change , pulled and rotated less interference , better control processes and pulling the neck , adjust the heater power , the molten material to achieve the most appropriate length of crystal temperature range , so to achieve the best growth rate of , and thus the best quality sapphire single crystal to grow.Main features of the method :

1)During the entire length of the crystal , the crystal is not made ​​crucible , is still in the hot zone. So that it can accurately control the cooling rate , reduce the thermal stress ;

China called Kyropoulos.
2)Crystal growth , the solid-liquid interface in the melt siege. Such melt surface temperature perturbations and mechanical perturbations before reaching the solid-liquid interface can be reduced resulting in elimination of the melt ;

3)Selection of soft water as the working fluid within the heat exchanger with respect to the use of helium as a coolant heat exchange method can effectively reduce the cost of experiments ;

4)Existing in the crystal during crystal growth and rotational movement , be exposed to mechanical vibration.