Sapphire properties
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Crystal structure:
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Chemical composition:
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Al2O3
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Molecular weight:
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101.96
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Purity
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99.996%
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Crystal system:
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Rhombohedral systems(R3c)
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Lattice constant:
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a=4.765A/c=13.001A*
A=10 nm
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Density (specific gravity):
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3.98 g/cm3
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Cleavability:
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(1011), (1120), imperfect
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Mechanical properties:
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Hardness:
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[Mohs] 9(*Diamond=10, quartz=7)
[Knoop] 15.0 to 16.3GPa (perpendicular to the c axis)
16.4 to 19.6GPa (parallel to the c axis)
[Vickers] 2300
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Young's modulus:
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300 to 400 GPa
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Crushing strength:
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2000 Mpa
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Tensile strength:
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2250 Mpa
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Compression strength:
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2950 Mpa
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Bending strength:
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450 to 690 Mpa
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Destruction coefficient:
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490 to 690 Mpa
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Bulk modulus of elasticity:
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250 GPa
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Shearing modulus:
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140 Gpa
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Optical Properties
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OpticalTransmissionRange, (80%):
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350-5500
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Refractive index:
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1.83 at 0.26 mm
1.76 at 0.63 mm
1.58 at 5.57 mm
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Thermal Coefficient of Refractive Index:
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bo=(0.88...1.28) x 10 -5
bc= (0.99...1.39) x 10 -5
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sapphire application
Micro-electronics
For Substrates, mainly for SOS circuits, and high-speed digitally information systems.
Blue LED's (BLED's) - sapphire is the substrate for the growth of III-V and II-VI compounds such as GaN for LED's.
IR Detectors - sapphire provides the substrate for the growth of mercury cadmium tellurium (HgCdTe)
GaAs wafer carriers microwave integrated circuits.
Aerospace: Sapphire is used for its durability and erosion/corrosion resistance, often in combination with the ability to withstand high heat while having a very broad transmission range. Applications include:
Windows - FLIR (Forward Looking Infra Red) windows for sensors and other optics. Optical clarity over a broad spectral range combines with durability in this application.
Windows - for erosion resistance in salt and blowing sand environments, sapphire is used in conventional windows and dome shapes in replacement of softer, more fragile IR transmitting materials.
Countermeasures lamps - sapphire flash lamps are used in IRCM's (Infra red countermeasures). The high temperature performance of sapphire combines with broad spectral range in this application.
Analytical applications: Sapphire is used in analytical applications where combinations of high temperature, pressure, and hydrofluoric acid species are encountered. These applications need the survivability of sapphire, while often needing other properties such as favourable UV (ultraviolet) or IR (infrared) transmission.
NMR (Nuclear Magnetic Resonance) tubes. Sapphire is used for very high-pressure applications in replacement of glass or quartz tubes.
Sample preparation - sapphire is used in digestion cells as sheaths and liners. When hydrofluoric acid is used, sapphire replaces quartz components.
Analytical chemistry - for mass spectroscopy, ICAP, and other systems, sapphire replaces quartware to improve durability and reduce contamination while offering good UV transmission.
Medical applications: Sapphire is used in surgical systems for laser transmission and in contact with body fluids.
Surgical tips - sapphire is used in contact tips for various surgical laser applications, especially sapphire tips for dental laser.
Sapphire waveguides-For high thermal conductivity, wearing-resistance and good transmission at the broad-band wavelength, sapphire waveguide mainly be used in laser hair removal and other aesthetics applications.
Endoscope lenses - sapphire is often used in endoscope lenses due to its durability in contact with tissues and in sterilisation environments such as autoclaving.
Sapphire knives - with a sapphire knife, thinner sections are possible. The near perfect cutting edge of this knife / blade gives distortion-free sections down to 10 microns thick.
Optical applications: Sapphire is used for short and long wavelength applications UV and IR) beyond the range where conventional optics performs adequately. High temperatures and hostile environments also necessitate the use of sapphire optics.
Illumination windows - for very high brightness illumination, sapphire windows survive the very high heat while providing the broadest spectral transmission.
Sapphire lightguides - sapphire rods and used in high temperature thermometry beyond the range of quartz optics.
Optical components: lenses, prisms and other laser and infrared optics are fabricated from high optical quality sapphire.
Instruments
Watch industry: Sapphire is widely used for the watch glasses. The world demand in watch industry centres on scratchproof sapphire watch crystals. However, besides traditional flat shapes, crystals with spherical and cylindrical curves are also in great demand.
Bearing industry: For good mechanical properties and hardness( Mohs 9), it is used for the bearing of many meters, clocks, parts of abrasion-resistance. V-shape and U-shape bearing are widely used in flowmeters, ammeters, water meters.
Sapphire substrate with ZnO coating has been made to be 4.4 KGHz Sound surface Filter, which is using for the new-type sound surface systems with high work efficiency and now the applications are widely for civial and military instruments. Surface wave TV IF filters are widely used in TV, which simplizes TV adjustment, and imaging, color of TV improve a lot.
