IR Active Phonon Spectra of B–C–Al Compounds with Boron Carbide Structure

✍ Scribed by R. Schmechel; H. Werheit; K. Robberding; T. Lundström; H. Bolmgren

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 255 KB
• Volume: 133
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1997.7451

✦ Synopsis

The IR spectra of boron carbide containing up to about 1.5 at.% aluminum atoms are determined between 80 and 5000 cm ؊1 for temperatures between 70 and 450 K. While the essential features of the boron carbide phonon spectrum remain largely unchanged, there are several new low energy absorption bands at about 190 and 290 cm ؊1 obviously induced by the aluminum atoms. The band at 190 cm ؊1 is attributed to the bending mode of Al 2 chains, which are assumed to be formed in otherwise chain-free unit cells of boron-rich boron carbide. The dynamical conductivity of aluminum-doped boron carbide decreases with increasing aluminum content, while the Seebeck coefficient showing p-type behavior for all compounds increases. This makes evident that doping with aluminum atoms changes the electronic properties of boron carbide.