Directional growth technology of sapphire crystal

                                                         Directional growth technology of sapphire crystal

At present, the widely used and studied sapphire crystal growth technology in the world is the melt method, which specifically involves horizontal directional crystallization method, bubble growth method, czochralski method, heat exchange method, guided mold method, crucible drop method, temperature gradient method and other methods. These methods are used to indirectly control the temperature of sapphire crystal growth interface by controlling the power input to the crystal growth furnace. This method can not realize the control of sapphire crystal growth interface temperature, that is, it can not timely respond to and feedback the fluctuation of sapphire crystal growth interface temperature, resulting in slow growth rate, poor consistency and low yield of sapphire crystal. Therefore, the existing sapphire growth method or control method or sapphire crystal growth furnace needs to be improved or innovated. The sapphire crystal is oriented to improve the utilization rate of sapphire single crystals, reduce the subsequent processing and cutting costs, further reduce the preparation cycle of sapphire single crystals, improve the quality and yield of the prepared sapphire crystals, and reduce the preparation cost of sapphire crystals.

If sapphire crystal oriented gem grade corundum is cut perpendicular to the optical axis of the corundum during processing, six radial star lines may appear, showing starlight effect, so it is called starlight sapphire. The reason for the starlight effect is that the sapphire contains rutile silk inclusion, which is processed into a high arc shape. Under the irradiation of a point light source, this optical effect will appear. Starlight sapphires are generally expensive. Generally speaking, the advantages and disadvantages of sapphires are violet, blue, light blue, and gray blue in order. For sapphires of other colors, their trade names are different; White sapphire, green sapphire, yellow sapphire, yellow green sapphire, purple sapphire, etc.

Sapphire crystal has excellent optical, mechanical, thermal, dielectric, corrosion resistance and other properties, and has a wider transmission band and higher transmittance in the ultraviolet, visible and infrared bands. Compared with many other optical window materials, it has more stable chemical and thermodynamic properties, such as acid and alkali corrosion resistance, high temperature resistance, high hardness, high tensile strength, high thermal conductivity and significant thermal shock resistance.