Impex HighTech offers a wide range of products of synthetic sapphire. This material is used among others to manufacture precision optics, domes, high pressure components, and other optics.
Some of our main products
Synthetic single crystalline Sapphire (Al2O3)
is the most requested material for optical high-tech applications due to its unique combination of excellent physical and chemical properties. Sapphire is transparent over a large wavelength range from Vacuum-UV up to middle infrared (0.18µm up to nearly 6µm). Because of its rhombic, hexagonal crystal structure, sapphire shows anisotropic behavior in many of its optical and physical properties. Therefore, the exact behavior optical components made of sapphire is strongly dependent on the crystallographic alignment relative to the optical axis (c-axis, 0001). Sapphire shows slight birefringence in all crystal directions except parallel to the c-axis. As sapphire is the hardest material among the oxidic single crystals, sapphire can be processed by only a few materials (e.g., diamond or boron carbide) due to its extreme hardness. It therefor is "scratch resistant" to other materials. Thanks to its high strength, sapphire windows, for example, can be made much thinner than comparable windows made of other optical materials while maintaining the same performance. That is one more reason to use sapphire also at wavelengths close to the transmission limit. The resistivity towards most chemicals, its high temperature resistivity and biocompatibility open many other application possibilities besides optics in the fields of industry, medicine & Healthcare, aerospace etc.
We deliver preferably - but not only - sapphire materials produced via the following methods:
This growth method results in very big crystal bulbs with nearly cylindric shape, diameters between 70mm and 300mm and a length up to 600mm. Kyropoulus crystals stand out in their high homogeneity and very low dislocation density (crystal defects) and can be cut in any orientation. This method is economically efficient to produce substrates for LED and SOS technology.
Stepanov (EFG) Method
This method allows the crystal growth with geometries near the final product and minimizes the processing effort. This results in a significant cost reduction diversely. These include tubes, rods (also single- or multi-hole rods), plates or, e.g., unilaterally closed crucibles. Such plates can reach dimensions of 80mm width and over 1000mm length. Rods and tubes can be larger depending on the diameter. These crystals can grow according to different crystallographic orientations and can be applied wherever the optical requirements are not so high.
Optical and spectral properties
Transmission range in µm (minimum 10%)
0.15-5.4 (parallel to c-axis)
Transmission range in µm (minimum 50%)
Refractive index @633nm
Reflection losses in % at 1 surface
Reflection losses, % for two surfaces
dN/dT in 1/K
13.6 · 10-6
Density in g/cm3
Melting point in °C
Specific heat capacity in J/(kg · K)
Thermal conductivity in W/(m · K)
32.5 (parallel to c-axis)
30.3 (perpendicular to c-axis)
Thermal expansion in 1/K
6.6 · 10-6 (parallel to c-axis)
5 · 10-6 (perpendicular to c-axis)
11.5 (parallel c-axis)
9.3 (perpendicular to c-axis)
Solubility in water in g/100g
Knoop hardness in kg/mm²
2200 (parallel to c-axis)
1900 (perpendicular to c-axis)
single crystalline, synthetic
Lattice constant in Å
a = 4.785
c = 12.991
Elastic coefficient in GPa
C11 = 497
C12 = 164
C33 = 498
C44 = 147
C13 = 111
C14 = 24
Young's Modulus (E) in Gpa
Shear Modulus (G) in GPa
Bulk Modulus (K) in GPa
Rupture Modulus in MPa
Apparent elastic limit in MPa
|sample thickness: 2 mm|
Main application areas of synthetic sapphire
Sapphire is the excellent material for most demanding optical applications due to its high transparency in the wavelength area of approximately 180nm to 6µm and, because it is harder than glass in order of magnitudes. The high optical transmission in combination with the nearly 100% chemical resistivity, mechanical friction resistance and high temperature tolerance makes sapphire to the leading material in the optical sensor technology, spectroscopy, interferometry etc.
High temperature and high pressure
Due to the high and stable dielectric constants of sapphire, it is widely applied as electronic substrate material besides typical application as isolation and thermal conductivity. By exploiting the anisotropic properties, sapphire wafer are the bases for different products from the semiconductor industry and therefore, they are the most widely used substrate material for the epitaxial layer deposition for LEDs based on GaN.
Sapphire is a common window material for medical (and also technical) endoscopes. In addition to biocompatibility, this is based on high resistance in contact with biological tissue and medical fluids and easy sterilizability in autoclaves. The use of scalpels or tips made of sapphire for the laser surgery is common today. In the field Beauty Care / dermatology, sapphire light guides form the contact between high energy sources and human skin, e.g., to treat pigment disorders, hair and tattoo removal etc.