Material Characteristics of Gemstone
Ruby, Sapphire, and White Sapphire crystals are typical series of the corundum gems. They have excellent thermal conductivity (the conductivity is 0.86 cal/degree.cm.sec at 25℃), high electrical insulation, high transmittance and good mechanical performance. As an excellent infrared transmission material, it can be used made as windows of infrared detectors to ensure the transmission and collection of infrared light, to realize the best photoelectric conversion. It can be used in infrared analyzers, night vision devices and guidance instruments.
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Physical property |
Crystal structure |
Hexagonal crystal system |
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Chemical component |
Al2O3 |
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Purity |
100.00% |
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Density |
3.99—9.98 |
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Thermal light performance |
Melting point |
2320 K |
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Pyroconductivity |
40W/m·K ┷ at 300K |
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Coefficient of thermal expansion |
6.2·10-6/K∥ C-axis |
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|
6.2·10-6/K∥ C-axis |
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Mechanical property |
Hardness |
Mohs9 |
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Knoop 2200 face∥C—axis |
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Knoop 1800 face ┷C—axis |
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Young’s modulus |
4.4·1011 Pa at 300 K |
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Compression strength |
2.1·109 Pa at 300 K |
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Flexure strength |
1.9·108 Pa at 300 K |
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Chemical property |
No Acid-base reaction in normal temperature |
0 at570K |
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Electrical property |
Dielectric constant |
7.4~10.6 |
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Specific resistance |
109Ω·m at 770 K |
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104 Ω·m at 1270 K |
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10Ω·m at2270K |
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Optical property |
Refractive index |
1.760faceC-axis |
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Nd = 0.589μm |
1.760faceC-axis |
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Light transmission scope |
0.15~5.5μm |