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Cadmium Telluride (CdTe)
Cadmium Telluride can be used for spectroscopy and where deep IR transmission is required. It is relatively workable and offers transmission to >20 microns. The data is for information only. We cannot supply this material.
| Transmission Range | 0.85 to 28 μm (1)(3) |
| Refractive Index | 2.653 at 10 μm (1) |
| Reflection Loss | 32% at 10 μm (2 surfaces) |
| Absorption Coefficient | n/a |
| Reststrahlen Peak | n/a |
| dn/dT | 50 x 10⁻⁶ K⁻¹ |
| dn/dμ | 0 |
| Density | 6.2 g/cc |
| Melting Point | 1092 °C (4) |
| Thermal Conductivity | 6.2 W m⁻¹ K⁻¹ at 293K |
| Thermal Expansion | 5.9 x 10⁻⁶ K⁻¹ at 293K |
| Hardness | Knoop 54 |
| Specific Heat Capacity | 210 J Kg⁻¹ K⁻¹ @ 293K |
| Dielectric Constant | 11 at 1 MHz |
| Youngs Modulus (E) | 36.52 GPa |
| Shear Modulus (G) | n/a |
| Bulk Modulus (K) | 25 GPa |
| Elastic Coefficients | C11=53.51; C12=36.81; C44=19.94 |
| Apparent Elastic Limit | 5.9 MPa (3) |
| Poisson Ratio | 0.41 |
| Solubility | Insoluble in water |
| Molecular Weight | 249.02 |
| Class/Structure | Cubic ZnS. (110) cleavage |
| μm | No | μm | No | μm | No |
|---|---|---|---|---|---|
| 0.8 | 2.876 | 5.0 | 2.684 | 20.0 | 2.614 |
| 1.0 | 2.840 | 6.0 | 2.681 | 22.2 | 2.601 |
| 2.0 | 2.713 | 7.0 | 2.679 | 24.8 | 2.5801 |
| 2.5 | 2.702 | 8.0 | 2.677 | 26.32 | 2.570 |
| 3.0 | 2.695 | 10.0 | 2.653 | 27.03 | 2.564 |
| 3.5 | 2.691 | 12.5 | 2.646 | ||
| 4.0 | 2.6807 | 15.5 | 2.6407 |
CdTe is rarely used because of its toxicity. The finished optics are not particularly hazardous but should be handled with care. However, difficulties with processing cadmium compounds means that very few optical companies will cut and polish the material. Crystran Ltd does NOT supply CdTe. This data is provided for reference only.
A form of CdTe was originally utilised as the obsolete Kodak designation of IRTRAN-6
CAUTION: Cadmium salts are TOXIC and should be handled with care.
REFERENCES:
(1) Handbook Optical Constants, ed Palik, V1, ISBN 0-12-544420-6
(2) NIST USA data
(3) Hawkins, Sherwood, Djotni: Mid IR Filters for astronomical and remote sensing instrumentation. Invited Paper SPIE Conference Glasgow 2008