Sapphire (Al2O3)

Crystallographic

Syngony	Tetragon
Symmetry Class	3m
Lattice Constants	a = 4.758 Å c = 12.991 Å
Cleavability	(1011), (1120) imperfect

 

Optical

Refractive Index at ne	1.7771
Refractive Index at nF' - nC'	0.0107
Thermal Coefficient of Refractive Index at 3.39 microns for ±60 °C	bo = (0.88 ... 1.28) x 10-5 be = (0.99 ... 1.39) x 10-5
Spectral Range, microns	0.17 - 5.0

 

Thermal

Thermal Linear Expansion, °C-1 for ±60 °C
^ to c-axis	(3.24 ... 5.66) x 10-6
Thermal Conductivity, W/(m * °C) at 46 °C
^ to c-axis	25.2
|| to c-axis	23.1
Specific Heat Capacity, J/(kg * °C)	0.7610 x 103
Thermal Stability, °C	162 ±8
Melting Point, °C	2030

 

Mechanical

Density, g/cm3 at 20 °C	3.98
Mohs Hardness	9
Vickers Microhardness, Pa
^ to c-axis	2200
|| to c-axis	1940
Constants of Elastic Compliance, Pa-1	S11 = 2.3 x 10-12 S12 = -0.7 x 10-12 S13 = 0.4 x 10-12 S33 = 2.2 x 10-12 S44 = -6.8 x 10-12 S14 = 0.5 x 10-12
Young Modulus (E), Pa
^ to c-axis	46.26 x 1010
|| to c-axis	42.64 x 1010
Shear Modulus (G), Pa
^ to c-axis	14.43 x 1010
|| to c-axis	16.29 x 1010
Poisson Ratio || to c-axis	0.309

 

Chemical

Molecular Weight	101.96
Solubility
in water, gram/100 cm3	98 x 1010

 

Ref. Index vs. Wavelength l

Wavelength, Microns	Refractive Index no	Refractive Index ne
1.0	1.7545	1.7460
2.0	1.7374	1.7299
3.0	1.7015	1.6920
4.0	1.6748	1.6679

 

Internal Transmittance t i (l) vs. Wavelength l

Wavelength, Microns	Internal Transmittance
0.2	0.79
0.5	0.97
1.0	0.97
3.0	0.97
5.0	0.45

Custom sizes and specifications are available on request.