Introduction of Sapphire
Sapphire is often used in infrared optical components, high-durability windows and very thin electronic wafers, which are used as the insulating substrates of special-purpose solid-state electronics such as integrated circuits and GaN-based blue LEDs.
Sapphire has a unique combination of physical, chemical and optical properties, which make it resistant to high temperature, thermal shock, water and sand erosion, and scratching. It is a superior IR window material for use under such conditions as high temperature and pressure, thermal shock, corrosion resistance, abrasion resistance or chemical attack. Sapphire exhibits high internal transmittance all the way from 150nm to 6um. It is very hard, second only to diamond. Large sizes are grown by using the heat exchanger method (HEM). It has a hexagonal crystalline structure and exhibits birefringence, a difference of 0.008 (refractive index of e-ray is smaller, negative uniaxial crystal). Besides optical applications, C-plane sapphire substrates are widely used to grow III-V and II-VI compounds such as GaN for blue LED and laser diodes, while R-plane substrates are used for the hetero-epitaxial deposition of silicon for microelectronic IC applications.
Sapphire Unit Cell
Sapphire windows/lenses Properties
Refractive index verse wavelength for O-ray
1-mm thick sapphire external transmittance curve
Thermal and Mechanical Properties
| Coefficient of Linear Thermal Expansion 40~400 °C (/°C) |
Parallel to C Axis 7.7X10-6 Perpendicular to C Axis 7.0X10-6 |
| Thermal Conductivity (40°C W/m·K) | 25.12 |
| Melting Point (°C)
|
2053
|
| Specific Heat (J/(Kg·K)
|
0.75X103 |
| Density (g/cm3)
|
3.99
|
| Young’s Modulus (GPa) | 345 |
| Poisson’s Ratio | 0.18~0.29 (Orientation Dependent) |
| Shear Modulus (GPa) | 146
|
| Mohs Hardness | 9 |
| Structure | Hexagonal-rhombohedral |
| Lattice Constants (Å) | a=4.763 c=13.003 |
| Dielectric Strength (V/m) | 48X106 |
| Dielectric Constant | Parallel to C Axis 11.5 (1MHz) Perpendicular to C Axis 9.3 (1MHz) |
| Volume Resistance (Ω·cm, 20°C) | >1014 |
Sapphire product range in Photonchina
Due to its perfect durability, resistance to both corrosion and high temperature, as well as a very wide range of spectral transmission, sapphire products provided by Photonchina, from windows to lens, are widely used in aerospace, analytical instruments, medical equipment, optical devices, and illumination and even in watches.
With the diameter range between 0.2mm to 300mm,Photonchina manufactures sapphire rectangular windows, T-step windows (round and Rectangular), all-surfaces-polished windows, conical windows, wedges, wafers, rod lenses, plano-convex lenses, tubes etc. Excellent surface quality, high level flatness and parallelism have gained good performance in customer’s applications.
