Aluminium Oxide

Crystal properties

Crystal growth method

Czochralski, HEM,Verneuil

Crystal growth orientation

(0 001),(1102),(1012),(1010)

Maximum size

7 inch diameter

Variations

Doped crystals (Fe, Nb, Ti, W,Ta,V,Cr)
Other dopands on request 

Crystallographic properties

Hexagonal / Rhombohedric

Crystallographic structure

a = 4.77 A
c = 13.04 A
a : c = 1 : 2.734

a =   4.758 Å
c = 12.991 Å

Mineralogical synonyms

 Sapphire, Corundum

Twinning structure

Twinfree

Colour

 Colourless

Density

3.98 g/cm³

Melting point

2052  °C

Hardnes

9   (Mohs)

Thermal  expansion coefficient

5.4 * 10^_6 K^_1 
6.2 * 10^_6 K_1

|| c-axis
^ c-axis 

RT
RT

Dielectric  constant

9.4
11.5

| c-axis
^ c-axis

RT
RT

Physical properties cont.

Dielectric loss tangent (10GHz)

3.0 * 10^_5
8.6 * 10_5

| | c-axis
^ c-axis

RT
RT

Dielectric constant:

10¹⁶ W/cm

RT

Optical properties

Transmission range

0.2 to 6.0 mm

Refraction index:

n_d = 1.8336 
n_d = 1.58638 

at 265 nm
 at 5.6 mm

Dispersion

 0.011

Standard orientations

(0001),(1102),(1012),(1010)

Other orientations on request

List of  Refractive index, ordinary ray at 24 °C (Al₂O₃)

Optical properties  refraction index Aluminium oxide

Wavelength (µm)

Refractive index 

0,28035

1,8243

0,289036

1,8195

0,29673

1,8159

0,30215

1,8135

0,31300

1,8091

0,33415

1,8018

0,34662

1,7981

0,36105

1,7945

0,36501

1,7936

0,39064

1,7883

0,40466

1,7858

0,43583

1,7812

0,54607

1,7708

0,57696

1,7688

0,57907

1,7687

0,64385

1,7655

0,70652

1,7630

0,85212

1,7588

0,89440

1,7579

1,01398

1,7555

1,12866

1,7534

1,36728

1,7494

1,39506

1,7489

1,52952

1,7466

1,69320

1,7437

1,70913

1,7434

1.81307

1,7414

1.97010

1,7383

2,15260

1,7344

2,24929

1,7323

2,32542

1,7306

2,43740

1,7278

3,24320

1,7044

3,26660

1,7036

3,30300

1,7023

3,29300

1,7015

3,41880

1,6982

3,50780

1,6950

3,70000

1,6875

4,25800

1,6637

4,95400

1,6266

5,14560

1,6151

5,34900

1,6020

5,41900

1,5973

5,577

1,5864