Properties

Sapphire properties	Benefits
Resistant to high temperatures	Does not melt at the temperature below 2050°C. Retains purity in high-temperature environments
Rigid and durable	Resistant to scratching by a majority of materials Resistant to high pressure Enduring
Chemically inert, insoluble in the majority of conventional industrial solutions and corrosion-resistant	Can be used in aggressive environment Easily washed Long-life performance Possess high purity In some environments operating life of sapphire up to 5 times more than of quartz
Wide transmittance spectrum in UV, visible IR and microwave ranges	Continuous and stable transmittance of infra-red rays Outstanding light transmittance at 0.25 – 4.50 μm
High thermal conductivity	Enables rapid heating and cooling

Sapphire characteristics

General
Chemical formula:	Al2O3
Growing method:	Kyropoulos, Stepanov (EFG)
Structure:	hexagonal a = b = 4.77 A c = 13.04 A
Thermal
Melting temperature:	2040 °C
Linear expansion coefficient:	6.7 x 10-6 / °C parallel to С axis 5.0 x 10-6 / °C perpendicular to С axis
Thermal conductivity:	46.06 W/m °K (0°C)
Mechanical
Density:	3.98 g/cm3
Hardness:	Mohs: 9 Knoop: 1800 daN/mm2 parallel to С axis 2200 daN/mm2 perpendicular to С axis
Tensile strength:	400 MPa/mm2 (25°C) 275 MPa/mm2 (500°C) 345 MPa/mm2 (1000°C)
Flexural strength:	35 to 39 daN/mm2
Compression stress:	2.0 GPa
Young's modulus	3.6 x 104 to 4.4 x 104 daN/mm2
Electric
Dielectric permeability:	9.3 (103 - 109 Hz, 25°C) perpendicular to С axis 11.5 (1033 - 109 Hz, 25°C) parallel to С axis
Specific resistivity:	1016 Ω/cm (25°C) 1011 Ω/cm (500°C) 106 Ω/cm (1000°C)