Thermoelectric properties and crystal structure of ternary compounds in the Ge(Sn,Pb)Te–Bi2Te3 systems

✍ Scribed by L.A. Kuznetsova; V.L. Kuznetsov; D.M. Rowe

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 143 KB
• Volume: 61
• Category: Article
• ISSN: 0022-3697
• DOI: 10.1016/s0022-3697(99)00423-0

✦ Synopsis

Polycrystalline samples of stoichiometric ternary compounds in the quasi-binary systems GeTe-Bi 2 Te 3 , SnTe-Bi 2 Te 3 and PbTe-Bi 2 Te 3 have been prepared and characterised by X-ray powder diffraction analysis. Lattice parameters have been determined and compared with literature data. At room temperature all the samples exhibit a high carrier concentration in the range 3:4 × 10 19 -2:6 × 10 20 cm Ϫ3 : All A IV Bi 4 Te 7 and PbBi 2 Te 4 compounds possess negative type of conductivity, while for other compounds it is positive. The Seebeck coefficient and electrical resistivity have been measured over the temperature range 100-800 K. The calculated values of the energy band gap of Ge(Sn)Bi 4 Te 7 and Ge(Sn)Bi 2 Te 4 compounds were 0.19-0.22 eV as determined from the temperature dependence of electrical resistivity in the intrinsic region. The density of state effective masses m ‫ء‬ have been estimated for Ge-and Pb-based ternary compounds and are in the range 0.6-1.1m 0 . An assessment of the potential of these materials for thermoelectric application has also been made.