Basic thermoelectric p‐type materials for the medium temperature range (600 to 900 K) are GeTe‐based materials. Hot‐pressed samples of (GeTe)1−x[(Ag2Te)1‐y(Sb2Te3)y]x solid solutions with y = 0.6, y = 0.75 are prepared. Their thermoelectric properties (thermoelectric power S, electric conductivity σ and thermal conductivity K) in the temperature range 300 to 750 K are measured. The thermoelectric figure of merit Z = S2σ/K for some compositions in calculated. The best p‐type new material is the composition (GeTe)0.8[(Ag2Te)0.4(Sb2Te3)0.6]0.2 with Zmax = 2.4 × 10−3 K−1 at about 700 K.

Subject classification: 72.20.Pa; S8.13; S8.15The thermoelectric parameters (thermoelectric power S, electrical conductivity s and thermal conductivity j) from the system (GeTe) 1--x (AgBiTe 2 ) x are measured in the temperature range from 300 to 800 K on hot-pressed samples with x ¼ 0.03, 0.10, 0.15, 0.20. The thermoelectric figure of merit Z and the Ioffe criterion ZT average are calculated. The maximum value ZT ¼ 1.32 at T ¼ 700 K is found for the composition containing 3 mol% AgBiTe 2 . This value is practically the same as for TAGS 85, a material widely applied in USA space devices, and determines the utility of the new thermoelectric material.

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.

The rhombohedral–cubic phase transition in the system Ge1–xAgx/2BIx/2 Te is studied by means of high temperature X‐ray analysis. The temperature and composition changes of the rhombohedral lattice parameters are found. Conclusions are made about the chemical bonds in the case of GeTe‐based solid solution with heterovalent [Ag and Sb(Bi)] and isovalent [Pb(Sn)] replacing the Ge cations.

No abstract