Magnesium Aluminate, Spinel, MgAl2O4 substrate

MgAl2O4 Substrate (Spinel)

Magnesium Aluminate (MgAl2O4 or spinel) single crystalsare widely used for bulk acoustic wave and microwave devices and fast IC epitaxial substrates. MgAl2O4 is an attractive material for uses in a wide range of optical, electronic and structural applications including windows and lenses, which require excellent transmission from the visible through to the mid IR. Theoretical transmission is very uniform and approaches 87% between 0.3 to 5 microns. Transmission characteristics rival that of ALON and sapphire in the mid-wave IR, making it especially attractive for the ever-increasing performance requirements of current and next-generation IR imaging systems. MgAl2O4 is a relatively low-cost substrate material, which has been successfully applied to the growth of high quality GaN films. MgAl2O4 is cleaved on the (100) plane. GaN LD cavities have been obtained by simply cleaving MgAl2O4 substrates along the (100) direction, which will also work well for ZnO. MgAl2O4 crystal is very difficult to grow, due to the difficulty in maintaining a single phase structure.


1 ) Good optical, chemical and thermal properties

2 ) Good high temperature properties

3 ) Stable physical performance


1 ) Bulk acoustic wave devices

2 ) Microwave devices

3 ) Fast IC epitaxial substrates



MgAl2O4 (Spinel)


[100] or [100] or [111] < ±0.5°

Surface Finish

Single side polished (SSP) or Double sides polished (DSP)

Polished Side Roughness

< 0.5 nm

Typical Size

10 x 10 x 0.5 mm, φ50.8 x 0.5 mm etc.

Dimension Tolerance

±0.1 mm or better

Thickness Tolerance

±0.05 mm or better

Maximum Size

Diameter 2 inches


Chemical Formula


Crystal Structure


Lattice Parameters

a = 8.083 Å  

Melting Point

2130 ℃


3.60 g/cm3

Transmission Range

0.21~5.3 µm  

Refractive Index



7.5~8 Mohs

Thermal Expansion Coefficient

7.45 × 10^-6/K 

Phase Velocity

6500 m/s at (100) shear wave

Propagation Loss

6.5 dB/ms

Specific Heat

0.59 W.s/g/K

Dielectric Constants