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 |
