Composites of Bi{sub 2-x}Sb{sub x}Te{sub 3} nanocrystals and fullerene molecules for thermoelectricity

Journal Article · Sat Sep 15 00:00:00 EDT 2012 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/J.JSSC.2012.03.065· OSTI ID:22149802

Kytin, V. G. ^[1]; Popov, M. Yu.; Buga, S. G.; Stepanov, P. B.; Blank, V. D. ^[2]

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1. M.V. Lomonosov Moscow State University, Faculty of Physics, Leninskie Gory 1-3, Moscow 119991 GSP-1 (Russian Federation)
2. Technological Institute for Superhard and Novel Carbon Materials, Troitsk, Moscow Region 142190 (Russian Federation)

New nanocomposite thermoelectric material composed from nanocrystallites of Bi-Sb-Te alloys covered by C{sub 60} molecules has been synthesized and studied. An increase of fullerene content leads to the growth of hole concentration in p-type materials and reduction of electron concentration in n-type materials. The fullerene molecules provide additional scattering of phonons reducing lattice heat conductivity. Reduction of heat conductivity exceeds the reduction of electrical conductivity for fullerene content less than 0.5 volume % and essential enhances the thermoelectric figure of merit. The maximum value of thermoelectric figure of merit equals to 1.17 at 450 K was observed in Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} composite containing 0.5 volume % C{sub 60} molecules. The experimental results were analyzed in a frame of the model based on the Boltzmann equation. The analysis considers light and heavy electrons and holes and accounts the intervalley scattering of charge carriers. The calculations of the kinetic coefficients shows that the improvement of the thermoelectric figure of merit originates from the reduction of the lattice heat conductivity caused by fullerene molecules. The dependencies of the thermoelectric figure of merit on the acceptor concentration were calculated. - Graphical abstract: New nanocomposite thermoelectric material composed from nanocrystallites of Bi-Sb-Te alloys covered by C{sub 60} molecules has been synthesized and studied. An increase of fullerene content leads to the growth of hole concentration in p-type materials and reduction of electron concentration in n-type materials. The fullerene molecules provide additional scattering of phonons reducing lattice heat conductivity and enhances the thermoelectric figure of merit. The maximum value of thermoelectric figure of merit equal to 1.17 at 450 K was observed in Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} composite containing 0.5 volume % fullerene molecules. Simulations of thermoelectric properties were made in frame of four bands, 12 valleys Boltzmann equation approach. Simulated and measured temperature dependencies of thermoelectric properties were compared to get unknown model parameters. These parameters were used to calculate dependencies of thermoelectric properties on acceptor concentration. Calculated dependencies of thermoelectric figure of merit on acceptor concentration are presented in the figure for p-type composites with 0 vol.% C{sub 60} (solid lines) and 0.5 vol.% C{sub 60} (dashed lines). Highlights: Black-Right-Pointing-Pointer C{sub 60} doping of Bi-Sb-Te has acceptor effect. Black-Right-Pointing-Pointer Fullerene molecules prevent recrystallization in Bi-Sb-Te nanocomposites. Black-Right-Pointing-Pointer C{sub 60} in Bi-Sb-Te nanocomposites essentially reduces lattice thermal conductivity. Black-Right-Pointing-Pointer Thermoelectric figure of merit in nanocomposite C{sub 60}-Bi-Sb-Te enhanced.

• OSTI ID: 22149802
• Journal Information: Journal of Solid State Chemistry, Vol. 193; Other Information: Copyright (c) 2012 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
77 NANOSCIENCE AND NANOTECHNOLOGY
ALLOYS
BOLTZMANN EQUATION
CHARGE CARRIERS
COMPOSITE MATERIALS
ELECTRIC CONDUCTIVITY
FULLERENES
NANOSTRUCTURES
RECRYSTALLIZATION
SIMULATION
SOLIDS
THERMAL CONDUCTIVITY
THERMOELECTRIC MATERIALS
THERMOELECTRIC PROPERTIES
THERMOELECTRICITY