Thermoelectric Power of (GeTe)1−x(Bi2Te3)x Solid Solutions (0 ≦x ≦ 0.05) in the Temperature Interval 80 to 350 K

Abstract

The thermoelectric power S of GeTe‐rich (GeTe)1‐x(Bi2Te3)x solid solutions (0 ≦ x ≦ 0.05) is investigated as a function of composition x and temperature T in the range from 80 to 350 K, where the materials have the crystal and band structure of the rhombohedral α‐phase of GeTe. On the basis of the non‐parabolic two‐band Kane model of IV‐VI compounds information on the Fermi energy F (reduced Fermi energy F* = F/k0T, where k0 is the Boltzmann constant) and the degeneracy of the alloys is deduced. A qualitative interpretation of the temperature and composition dependences of S is made. It is assumed that there are two types of carriers (light and heavy holes) and redistribution among the valence bands with the change of temperature.

Thermoelectric efficiency of (1 − x)(GeTe) x(Bi2Se0.2Te2.8) and implementation into highly performing thermoelectric power generators

“…50.4-51.5 at%) and the corresponding high carrier concentration (up to 2.2 × 10 21 cm −3 ). 54,63 These vacancies can be eliminated by adding small amounts of Bi 2 Te 3 . Thus, the thermoelectric properties are enhanced due to the reduction of the carrier concentration and improvement of the Seebeck coefficient 63 In addition alloying also reduces the thermal conductivity due to enhanced point defect scattering.…”

“…54,63 These vacancies can be eliminated by adding small amounts of Bi 2 Te 3 . Thus, the thermoelectric properties are enhanced due to the reduction of the carrier concentration and improvement of the Seebeck coefficient 63 In addition alloying also reduces the thermal conductivity due to enhanced point defect scattering. Thus, alloying of GeTe with Bi 2 Se 0.2 Te 2.8 to form (1 − x)(GeTe) x(Bi 2 Se 0.2 Te 2.8 ) should further improve the thermoelectric properties compared to (1 − x)(GeTe) x(Bi 2 Te 3 ).…”

Low Thermal Conductivity and High Thermoelectric Performance in (GeTe)1–2x(GeSe)x(GeS)x: Competition between Solid Solution and Phase Separation

“…In the IV–VI semiconductor chalcogenide family, PbTe and its solid solutions with PbSe and PbS are highly recognized thermoelectric materials with outstanding performances. ,,− In spite of the high performance, PbTe-based thermoelectric materials may not be used for mass-market applications because of the high toxicity of Pb. GeTe is one of the interesting members in the IV–VI semiconductor family, and it can be a good choice as an alternative to PbTe. , GeTe undergoes a ferroelectric transition at ∼700 K from paraelectric cubic phase (β phase, Fm 3 ̅m ) to ferroelectric rhombohedral phase (α phase, R 3 m ). , Intrinsic Ge vacancies lead to a high carrier density of ∼10 21 /cm 3 in GeTe, which gives rise to a high electrical thermal conductivity and a low Seebeck coefficient, making GeTe less attractive to the thermoelectric community. − Recently, different strategies have been adopted to decrease the thermal conductivity of GeTe, which resulted in high thermoelectric performance in Ge 1– x Pb x Te, , pseudobinary solid solutions of GeTe-AgSbTe 2 (TAGS-x) − and GeTe-AgSbSe 2 (TAGSSe-x), a series of Sb 2 T 3 (GeTe) n (GST)-based layered compounds, and Sb/Bi-doped GeTe , and GeTe 1– x Se x …”

General strategies to improve thermoelectric performance with an emphasis on tin and germanium chalcogenides as thermoelectric materials

“…On the other hand, Bi 2 Te 3 works as a good TE material near room temperature. Properties of (GeTe) 1− x (Bi 2 Te 3 ) solid solutions with 0 ≤ x ≤ 0.05 were studied by Christakudi et al 376 in a temperature range of 80 K to 350 K. Bi 2 Te 3 based alloys are suitable TE materials in the near room temperature region. Bi 2 Te 3 -GeTe pseudo-binary compounds effectively shift the operating temperature range to a higher temperature region.…”