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Open AccessArticle

Correlation between Crystal Structure and Thermoelectric Properties of Sr1−xTi0.9Nb0.1O3−δ Ceramics

1
Instituto de Ciencia de Materiales de Madrid (ICMM). Consejo Superior de Investigaciones Científicas (CSIC). Sor Juana Inés de la Cruz 3, E-28049 Madrid, Spain
2
Departamento de Química Inorgánica, Universidad Complutense de Madrid, E-28040 Madrid, Spain
3
INTEQUI, Universidad Nacional de San Luis, CONICET, Fac. Qca., Bqca. y Far. (Chacabuco y Pedernera, 5700), San Luis, Argentine
4
Departamento de Física de Materiales, Universidad Complutense de Madrid, E-28040 Madrid, Spain
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Departamento de Física Aplicada, Universidad de Castilla-La Mancha, E-13071 Ciudad Real, Spain
6
Institut Laue Langevin, BP 156X, F-38042 Grenoble, France
*
Author to whom correspondence should be addressed.
Crystals 2020, 10(2), 100; https://doi.org/10.3390/cryst10020100
Received: 14 January 2020 / Revised: 6 February 2020 / Accepted: 7 February 2020 / Published: 9 February 2020
(This article belongs to the Special Issue Conducting Ceramics)
Polycrystalline Sr1−xTi0.9Nb0.1O3−δ (x = 0, 0.1, 0.2) ceramics have been prepared by the solid state method and their structural and thermoelectric properties have been studied by neutron powder diffraction (NPD), thermal, and transport measurements. The structural analysis of Sr1-xTi0.9Nb0.1O3−δ (x = 0.1, 0.2) confirms the presence of a significant amount of oxygen vacancies, associated with the Sr-deficiency of the materials. The analysis of the anisotropic displacement parameters (ADPs) indicates a strong softening of the overall phonon modes for these samples, which is confirmed by the extremely low thermal conductivity value (κ ≈ 1.6 W m-1 K−1 at 823 K) found for Sr1−xTi0.9Nb0.1O3−δ (x = 0.1, 0.2). This approach of introducing A-site cation vacancies for decreasing the thermal conductivity seems more effective than the classical substitution of strontium by rare-earth elements in SrTiO3 and opens a new optimization scheme for the thermoelectric properties of oxides.
Keywords: ceramics; strontium titanate; perovskite; thermoelectric materials; neutron diffraction; oxygen vacancies; anisotropic displacement parameters ceramics; strontium titanate; perovskite; thermoelectric materials; neutron diffraction; oxygen vacancies; anisotropic displacement parameters
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MDPI and ACS Style

Prado-Gonjal, J.; López, C.A.; Pinacca, R.M.; Serrano-Sánchez, F.; Nemes, N.M.; Dura, O.J.; Martínez, J.; Fernández-Díaz, M.; Alonso, J. Correlation between Crystal Structure and Thermoelectric Properties of Sr1−xTi0.9Nb0.1O3−δ Ceramics. Crystals 2020, 10, 100.

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