Prospects for Engineering Thermoelectric Properties in La 1/3 NbO 3 Ceramics Revealed via Atomic-Level Characterization and Modeling.

Autor:	Kepaptsoglou D; SuperSTEM Laboratory, SciTech Daresbury Campus , Daresbury WA4 4AD, U.K., Baran JD; Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, U.K., Azough F; School of Materials, University of Manchester , Manchester M13 9PL, U.K., Ekren D; School of Materials, University of Manchester , Manchester M13 9PL, U.K., Srivastava D; School of Materials, University of Manchester , Manchester M13 9PL, U.K., Molinari M; Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, U.K.; Department of Chemistry, University of Huddersfield , Huddersfield HD1 3DH, U.K., Parker SC; Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, U.K., Ramasse QM; SuperSTEM Laboratory, SciTech Daresbury Campus , Daresbury WA4 4AD, U.K., Freer R; School of Materials, University of Manchester , Manchester M13 9PL, U.K.
Jazyk:	angličtina
Zdroj:	Inorganic chemistry [Inorg Chem] 2018 Jan 02; Vol. 57 (1), pp. 45-55. Date of Electronic Publication: 2017 Dec 19.
DOI:	10.1021/acs.inorgchem.7b01584
Abstrakt:	A combination of experimental and computational techniques has been employed to explore the crystal structure and thermoelectric properties of A-site-deficient perovskite La 1/3 NbO 3 ceramics. Crystallographic data from X-ray and electron diffraction confirmed that the room temperature structure is orthorhombic with Cmmm as a space group. Atomically resolved imaging and analysis showed that there are two distinct A sites: one is occupied with La and vacancies, and the second site is fully unoccupied. The diffuse superstructure reflections observed through diffraction techniques are shown to originate from La vacancy ordering. La 1/3 NbO 3 ceramics sintered in air showed promising high-temperature thermoelectric properties with a high Seebeck coefficient of S 1 = -650 to -700 μV/K and a low and temperature-stable thermal conductivity of k = 2-2.2 W/m·K in the temperature range of 300-1000 K. First-principles electronic structure calculations are used to link the temperature dependence of the Seebeck coefficient measured experimentally to the evolution of the density of states with temperature and indicate possible avenues for further optimization through electron doping and control of the A-site occupancies. Moreover, lattice thermal conductivity calculations give insights into the dependence of the thermal conductivity on specific crystallographic directions of the material, which could be exploited via nanostructuring to create high-efficiency compound thermoelectrics.
Databáze:	MEDLINE
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