 |
|
Sapphire (Al2O3)
Synthetic sapphire is an anisotropic crystalline material with many unique optical and physical properties which make it a material of choice for many optical applications:
- Sapphire transmits over a very broad spectrum, 150nm to 6.0µm
- Extreme surface hardness. Sapphire may only be scratched by diamond, boron nitride and of course, itself
- High mechanical strength
- Extremely high melting temperature
- Excellent electrical properties. Low dielectric constant
- Sapphire is chemically inert and insoluble in virtually everything up to very high temperatures
- Very high thermal conductivity. Sapphire can be effectively force heated or cooled very quickly
- High refractive index. n = 1.8337 @ 265.2nm to n = 1.5863 @ 5577nm
- Sapphire is water clear
Main Properties
| Chemical formula | Al2O3 | | Crystal symmetry | Hexagonal
a=b=4.758Å
c=12.991Å
| | Density | 3.98g/cm³ at 25˚C
| | Reflection loss, % per surface at 3µm | 5 | | Mohs hardness | 9 mohs (std) | | Coefficient of thermal expansion | 8.4x10-6 | | Melting point | 2040˚C | | | | | | | | | |
Indices of Refraction
| Wavelength, nm | Sapphire | | 265.20 | 1.83360 | | 280.35 | 1.82427 | | 302.15 | 1.81351 | | 334.15 | 1.80184 | | 346.62 | 1.79815 | | 365.02 | 1.79358 | | 404.66 | 1.78582 | | 435.84 | 1.78120 | | 546.07 | 1.77078 | | 706.52 | 1.76303 | | 852.11 | 1.75885 | | 1013.98 | 1.75547 | | 1529.52 | 1.74660 | | 1970.09 | 1.73833 | | 2325.42 | 1.73055 | | 3243.90 | 1.70437 | | 3507.00 | 1.69504 | | 4954.00 | 1.62665 | | 5577.00 | 1.58638 |
|
|
|
|
|
|
|
