Bismuth telluride

Bismuth telluride (Bi₂Te₃) is a grey powder that is a compound of bismuth and tellurium also known as Bismuth(III) telluride. It is a semiconductor which is an efficient thermoelectric material for refrigeration or portable power generation. The CAS registry number is [1304-82-1]. The density is 7700 kg.m^-3. It has a melting point of 573 C.

Additional recommended knowledge

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The properties relevant to thermoelectric efficiency are:

• A high Seebeck coefficient (voltage per unit temperature difference). The Seebeck coefficient of N-type bismuth telluride is -287 μV/K^[1] Seebeck coefficient of P-type Bismuth Telluride is 81μV/K^[2]
• A high electrical conductivity. The electrical conductivity of N-type bismuth telluride is 1.1 × 10⁵ Siemens per meter.^[3]
• Low thermal conductivity. The thermal conductivity of bismuth telluride is 1.20W/(m*K) giving the compound a thermal insulation value similar to ordinary glass.^[4]

Toxicity

Although generally a low risk compound, it can be toxic; fatal if large doses are ingested. Avoid breathing the dust. A reaction with water may release toxic fumes. Material safety data sheets should be consulted.

References

1. ^ [1],
2. ^ [2]
3. ^ [3]
4. ^ [4] (dead link as of Oct 9, 2007)

• The performance of bismuth telluride thermojunctions, H. J. Goldsmid, A. R. Sheard and D. A. Wright, Br. J. Appl. Phys. vol. 9 pp. 365-370 (1958) doi:10.1088/0508-3443/9/9/306