We offer precision spinel spheres starting 0.20 mm. Due to its monocubic structure, spinel has almost no refringence. It supports high temperature and has a good shock resistance. Spinel is a very interesting material for optical applications.
Physical properties | crystalline structure | Cubic monocrystal |
---|---|---|
composition | MgO · 3.5 Al2O3 | |
purity | 99,99 % | |
density | 3.61 | |
dislocation density | 109 – 108 /m2 | |
Thermal properties | melting point | 2300-2330 K |
softening point | 2070 K | |
specific heat | 7.9 · 102 j/kg ·K at 300 K | |
thermal expansion | 5.9 · 10-6 /K | |
Mechanical properties | hardness | Mohs 8 |
Knoop 1175-1380 | ||
young’s modulus | 4.4 · 1011 Pa at 300 K | |
modulus of rupture | 4.0 · 108 Pa at 300 K | |
compressive strenght | 2.1 · 109 Pa at 300 K | |
tensile strength | 1.9 · 108 Pa at 300 K | |
poisson’s constant | 0.30 | |
Chemical properties | acids and alkalis attack | 0 at ambiant temperature |
porosity | 0 | |
Electrical properties | dielectric constant | 8-9 |
Optical properties | refractive index Nd at 0.5893 µm | 1.727 |
chromatic dispersion (nf – nc) | 0.012 | |
Transmission, disc thickness 1 mm : | ||
- infrared | 85% 1µm |