Optical Properties
Transmission range in µm 0,16 - 3,5
Refractive Index @486nm nf = 1.4632
Refractive Index @588nm nd = 1.4586
Refractive index @656nm nc =1.4565
Reflection losses in % at 1 surface 7.9 @3µm
dn/dT in 1/K 9.1· 10-6 @1064nm
Physical Properties
Density in g/cm³ 2.203
Crystal Structure Amorpheus
Bubbles / Inclusions None
Total metallic impurities in ppm 25 - 30
OH Content in ppm 400 - 500
Thermal Conductivity in W/(m · K) 1.38
Specific Heat Capacity in J/(Kg · K) 703
Thermal Expansion in 1/K 0.55 · 10-6
Softening Point in °C 1730
Annealing Point in °C 1180
Strain Point in °C 1075
Max. Service Temperature (continuous) 1150°C
Max. Service Temperature (limited time) 1300°C
Dielectric Constant @1kHz a = 10
Dielectric Strength in kV/cm @20°C 250 - 400
Young’s Modulus (E) in GPa @25°C 73
Shear Modulus (G) in GPa @25°C 31
Bulk Modulus (K) in GPa @25°C 36.9
Rupture Modulus in MPa @25°C 50
Apparent Elastic Limitin MPa 55
Poisson Ratio @25°C 0.17
Compressive Strengthin GPa 1.1
Tensile Strength in MPa 50
Knoop Hardness in kg/mm² 500
Spectral Properties