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Belonging to hexagonal system, the Sapphire crystal is a simple oxide crystal with coordination type and a refractory oxide crystal with high melting point. With high mechanical strength, high temperature refractoriness and excellent chemical stability, it is an excellent laser host material, window material for various optical components, infrared devices, and high-intensity laser, and the most commonly used LED semiconductor lighting substrate material. It is also the most widely used synthetic single crystal material so far.