Bismuth(III) Telluride

Bismuth(III) telluride is a compound composed of bismuth and tellurium atoms with a 3:5 stoichiometric ratio, represented by the chemical formula Bi2Te3. It belongs to the family of IV-VI semiconductors and exhibits interesting properties such as high thermoelectric efficiency and topological insulator behavior.

In terms of its crystal structure, Bi2Te3 has a rhombohedral lattice with a space group of R-3m. The unit cell contains 25 atoms, with 6 bismuth atoms located at the corners of a trigonal prism and 18 tellurium atoms forming a close-packed hexagonal array around the prism. The layers of bismuth atoms alternate with layers of tellurium atoms, forming a van der Waals gap between them.

The electronic band structure of Bi2Te3 is characterized by a direct bandgap of about 0.15 eV at the gamma point. The valence band maximum is predominantly composed of tellurium p-orbitals, while the conduction band minimum is dominated by bismuth p-orbitals. This gives rise to the unique thermoelectric properties of Bi2Te3, where the transport of electrons and holes occurs in opposite directions.

Bismuth(III) telluride can be synthesized by several methods, including melting and casting, chemical vapor deposition, and electrodeposition. It is commonly used in applications such as thermoelectric generators, coolers, and infrared sensors due to its high Seebeck coefficient, low thermal conductivity, and good electrical conductivity. In addition, its topological insulator behavior makes it a promising material for spintronics and quantum computing.