Polycrystalline Eu 1–x Ca x TiO 3–δ (0 ≤ x ≤ 1) samples were synthesised to investigate the interrelations among the crystal structure, local structural disorder, and thermoelectric properties. The Ca 2+ substitution is locally modifying (squeezing) the crystal structure, resulting in distinct differences between the long-range and local scales, e.g., the sample with x = 0.2 shows a cubic structure in long-range scale, while tetragonal distortions are observed locally. Additionally, the contraction of the unit cell volume with an accompanying reduction of the overall symmetry facilitates the accommodation of smaller Eu 3+ (instead of Eu 2+ ). The lattice imperfections induced by Ca 2+ substitution significantly improve electron concentration and simultaneously dramatically reduce thermal conductivity (i.e., as large as 50% compared with pristine sample) at room temperature. The average thermoelectric figure of merit of Eu 0.2 Ca 0.8 TiO 3–δ is enhanced by almost 100% compared with that of the pristine EuTiO 3 . This work demonstrates that controlling lattice deformation offers new ways to enhance the thermoelectric performance of titanates.

A squeeze on the perovskite structure improves the thermoelectric performance of Europium Calcium Titanates / X. Xiao, M. Widenmeyer, K. Mueller, M. Scavini, S. Checchia, C. Castellano, D. Ma, S. Yoon, W. Xie, U. Starke, K. Zakharchuk, A. Kovalevsky, A. Weidenkaff. - In: MATERIALS TODAY PHYSICS. - ISSN 2542-5293. - 7(2018), pp. 96-105.

A squeeze on the perovskite structure improves the thermoelectric performance of Europium Calcium Titanates

M. Scavini;S. Checchia;C. Castellano;
2018

Abstract

Polycrystalline Eu 1–x Ca x TiO 3–δ (0 ≤ x ≤ 1) samples were synthesised to investigate the interrelations among the crystal structure, local structural disorder, and thermoelectric properties. The Ca 2+ substitution is locally modifying (squeezing) the crystal structure, resulting in distinct differences between the long-range and local scales, e.g., the sample with x = 0.2 shows a cubic structure in long-range scale, while tetragonal distortions are observed locally. Additionally, the contraction of the unit cell volume with an accompanying reduction of the overall symmetry facilitates the accommodation of smaller Eu 3+ (instead of Eu 2+ ). The lattice imperfections induced by Ca 2+ substitution significantly improve electron concentration and simultaneously dramatically reduce thermal conductivity (i.e., as large as 50% compared with pristine sample) at room temperature. The average thermoelectric figure of merit of Eu 0.2 Ca 0.8 TiO 3–δ is enhanced by almost 100% compared with that of the pristine EuTiO 3 . This work demonstrates that controlling lattice deformation offers new ways to enhance the thermoelectric performance of titanates.
EuTiO3; Lattice deformation; Thermoelectric transport properties
Settore CHIM/03 - Chimica Generale e Inorganica
Settore FIS/03 - Fisica della Materia
2018
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/635416
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