Physical Properties of Sapphire

Crystal Structure

Hexagonal.   a =4.758 Å   c= 12.992 Å

Crystallographic D spacing 

(1120 ) - a plane:  2.379 Å      (1102) - r plane:  1.740 Å

(1010) - m plane:  1.375 Å      (1123) - n plane: 1.147 ů

(0001) - c plane:   2.165 Å      (1011) - s plane:  1.961 Å

Crystal Purity 

> 99.99% 

Melt Point

2040 oC         

Density

3.98  g/cm3  

Hardness

9 (mohs)

Thermal Expansion 

7.5 (x10-6/ oC)

Specific Heat

0.10 (cal / oC)

Thermal Conductivity, 

46.06 @ 0°C  25.12 @ 100°C, 12.56 @ 400°C  ( W/(m.K) )

Dielectric Constant

~ 9.4 @300K at A axis    ~ 11.58@ 300K at C axis 

Loss Tangent at 10 GHz

< 2x10-5 at A axis ,     <5 x10-5 at C axis

Standard Products

As - grown boules

<0001> ori.± 0.5o

3" dia x 50 ~ 70 mm length

2" dia x 50 ~ 70 mm length 

30 mm dia  x 150 mm  length 

As-cut blanks

<0001> ori.± 0.5o

2" dia x 0.7 mm thickness

1" dia x 0.7 mm thickness

Epi -polished substrates 

C, R, A plane: ori.± 0.5o

1 or 2 sides polished

Ra< 10 Å

3" dia. x 0.5 mm   

2" dia. x 0.33 mm,   2"dia x 0.5 mm

1" dia  x 0.5 mm

0.5" x 0.5" x 0.5 mm

10x10x0.5 mm