Aluminium Oxide
Al2O3
Chemical name
Aluminium Oxide |
Mineral name
Sapphire, Corundum |
Chemical formula
Al2O3 |
Melting point [°C]
2072 |
Crystal system
hexagonal, rhomboedric |
Unit cell
a [Å]:4.758 b [Å]:4.758 c [Å]:12.991; a : c = 1 : 2.734 |
Molecular weight [g/mol]
101.96 |
Twinning
twinfree |
Mohs hardness
9 |
Density [g/cm3]
3.95 |
Color
colourless |
Refractive Index
nd=1.8336 (at 265 nm); nd = 1.58638 (at 5.6 mm) |
Piezoelectric crystals |
Thermal expansation coefficient [(10^(-5))/K]
0.54 || c-axis RT; 6.2 ^c-axis RT |
Crystal growth method
Czochralski, HEM, Verneuil |
Crystal growth orientation
(0001), (1102), (1012), (1010) |
Maximum size
7 inch in diameter |
Variations
doped crystals (Fe, Nb, Ti, W, Ta, V, Cr), other dopands on request |
Dielectric constant
9.4 || c-axis RT; 11.5 ^c-axis RT |
Dielectric loss tangent (10 GHz)
3.0*10^(-5) || c-axis RT; 8.6*10^(-5) ^c-axis RT |
Specific resistivity [W/cm]
10^16 |
Transmission range
0.2 - 6.0 mm |
Orientation
(0001), (1102), (1012), (1010) |
Dispersion
0.011 |