Sapphire growth by Stepanov.
Sapphire growth by the Stepanov method allows to grow the sapphire crystals of any desired cross-sectional shape and profile (tube, filament, plate, thin tape, etc.)
Sapphire growth by the Stepanov method based on the use of different effects (surface tension, gravity, electromagnetic interaction, hydrodynamic phenomena, etc.) forming a meniscus of the melt in the process of pulling the crystal.
A. V. Stepanov came from the fact that the liquid (melt) can take a certain form not only through the walls of the vessel but outside the vessel, in a free state. The form or form element, which is preferably to be created in the liquid state due to the different effectsto allow fluid to retain the shape. Formed the volume of liquid is transferred into the solid state result in the selection of specific crystallization conditions.
A. V. Stepanov suggested, for example, to form a meniscus with the help of special formoobrazovateli (dies) that is placed in the melt so that a meniscus of the melt is raised above the slit in the float lying on the surface of the melt in the crucible and is made of a material, wetted by the melt.
A forming device (die) in this case represents a rather complex elements. It allows you to control the shape, the geometry, the thermal condition of the column of melt and pulling the crystal and a distribution of an impurity in the crystal. Solid shaper (die) is characterized by the physical properties of the materialfrom which it is made (its wettability, density, conductivity, heat capacity), and configuration (shape of holes or slits, the depth of the hole, the hole shape depth) that controls and determines the cross section of the crystal (meniscus).
– possibility of control of both shape and orientation of the crystal during its growth
– growing sapphire crystals of any desired cross-sectional shape (tube, filament, plate, thin tape,etc.)
– receiving predetermined articles of various profiles and complex shapes, which kristallizuetsya directly from the melt,
– minimization of the machining of finished products. It is either minimal or not required at all,
– the sustainability of the growth process of a crystal to mechanical stress and temperature fluctuations that lead to the displacement of the crystallization front height of the melt column, without disturbing the shape of the cross section of the crystal,
– the possibility of growing on priming with different crystallographic orientations,
– growth conditions that promote good dissipation of heat of crystallization to provide a high rate of crystallization of the crystal,
– the method is well suited for growing profiled monocrystals of various materials (sapphire, tantalate of barium and magnesium, lithium fluoride, copper alloy-gold, and various eutectic materials with anisotropic properties).
Equipment for sapphire growing by Stepanov method represented by the setting of growing profiled sapphire crystals “RANGE-DM2”.
|A method of heating||resistive|
|The power to the heater||rectified current|
|Internal dimensions of chamber, mm|
|Thermal management by regulating power to the heater. The deviation of power from established value in stabilization mode, %||± 0,2|
|The maximum temperature in the working space, ° C||2100|
|Working stroke, mm, not less||600|
|Working environment in the chamber:|
|– vacuum, PA (mm Hg.St.), to||Of 6.65 (5·10-2)|
|– inert argon with excess pressure, kPa (kgf/cm2)||29,4 (0,3)|
|A system of remote observation with a magnification of within||5…10|
|The power supply unit from the system power supply TN-S:||three-phase five-wire (with zero defensive and zero working PE N wires) network
AC with earthed neutral voltage (400 ± 24), frequency (50 ± 0,5) Hz.
|Maximum consumed power, kVA||65|
|Consumption of cooling water with a temperature of 20 ± 5 º C and a pressure of 3 kgf/cm2,
necessary for cooling the installation, m3/h, not more
|Footprint, taking into account the service area, m2||12|
|Weight, kg, not more||2700|
Note: the description of technology on the example of setting “SPECTRUM-DM2”.