ABSTRACT
Solid solutions based on bismuth and antimony chalcogenides with atomic substitutions in Bi and Te sublattices are known to be high-performance thermoelectrics for use in thermoelectric modules for operation above room temperature at optimal compositions and charge carrier concentrations. še bulk Bi2Te3-based thermoelectric materials remain essential for industrial application1−4 in spite of signi›- cant achievements over the last few years in the development of new nanobulk materials.5−8 In Chapter 7, thermoelectric properties of n-and p-type Bi2Te3-based solid solutions with substitutions Bi → Sb and Te → Se, S are considered through the temperature interval 300-550 K. An increase in the ›gure-ofmerit Z is shown to be observed for the compositions with optimum relations between the e¤ective density-of-states mass (m/m0), the carrier mobility with account of degeneracy (μ0), and the lattice
7.1 Introduction .......................................................................................7-1 7.2 Review of the Figure-of-Merit Features of šermoelectrics
Based on Bismuth and Antimony Chalcogenides ....................... 7-2 7.3 šermoelectric Properties ............................................................... 7-3
7.4 E¤ective Mass, Charge Carrier Mobility, and Lattice šermal Conductivity ...................................................................... 7-6 E¤ective Mass • Charge Carrier Mobility • Lattice šermal Conductivity
7.5 Figure-of-Merit Optimization .......................................................7-10 7.6 Review of Galvanomagnetic Properties of šermoelectrics
Based on Bismuth and Antimony Chalcogenides ......................7-11 7.7 Many-Valley Model of Energy Spectrum .................................... 7-12 7.8 Galvanomagnetic Properties ........................................................ 7-13 7.9 Conclusions...................................................................................... 7-15 References .................................................................................................... 7-15
thermal conductivity (κL) as a function of temperature, composition, and carrier concentration.9−14 Changes of scattering mechanism of charge carriers due to substitutions of atoms in the Bi and Te sublattices are taken into account for calculations of the m/m0, μ0 and κL values15−17 in terms of the parabolic model of the energy spectrum for isotropic scattering mechanism. še materials under consideration have a complex band structure described by a many-valley model of energy spectrum.18−25 Changes of the parameters of ellipsoidal constant-energy surface and scattering of charge carriers a¤ect the thermoelectric and galvanomagnetic properties of the solid solutions. šerefore, the features of the ›gure of merit for solid solutions were analyzed and optimized simultaneously using thermoelectric and galvanomagnetic properties.
