Tailoring the structure and thermoelectric properties of BaTiO3 via Eu2+ substitution
Xiao X, Widenmeyer M, Xie W, Zou T, Yoon S, Scavini M, Checchia S, Zhong Z, Hansmann P, Kilper S, Kovalevsky A, Weidenkaff A (2017)
Publication Type: Journal article
Publication year: 2017
Journal
Book Volume: 19
Pages Range: 13469-13480
Journal Issue: 21
DOI: 10.1039/c7cp00020k
Abstract
A series of Ba1-xEuxTiO3-delta (0.1 <= x <= 0.9) phases with similar to 40 nm particle size were synthesized via a Pechini method followed by annealing and sintering under a reducing atmosphere. The effects of Eu2+ substitution on the BaTiO3 crystal structure and the thermoelectric transport properties were systematically investigated. According to synchrotron X-ray diffraction data only cubic perovskite structures were observed. On the local scale below about 20 angstrom (equal to similar to 5 unit cells) deviations from the cubic structure model (Pm% (3) over barm) were detected by evaluation of the pair distribution function (PDF). These deviations cannot be explained by a simple symmetry breaking model like in EuTiO3-delta. The best fit was achieved in the space group Amm2 allowing for a movement of Ti and Ba/Eu along < 110 > of the parent unit cell as observed for BaTiO3. Density functional calculations delivered an insight into the electronic structure of Ba1-xEuxTiO3-delta. From the obtained density of states a significant reduction of the band gap by the presence of filled Eu2+ 4f states at the top of the valence band was observed. The physical property measurements revealed that barium-europium titanates exhibit n-type semiconducting behavior and at high temperature the electrical conductivity strongly depended on the Eu2+ content. Activation energies calculated from the electrical conductivity and Seebeck coefficient data indicate that at high temperatures (800 K < T < 1123 K) the conduction mechanism of Ba1-xEuxTiO3-delta (0.1 <= x <= 0.9) is a polaron hopping when 0 <= x <= 0.6 and is a thermally activated process when 0.6 < x < 1. Besides, the thermal conductivity increases with increasing Eu2+ concentration. Due to a remarkable improvement of the power factor, Ba0.1Eu0.9TiO3-delta showed a ZT value of 0.24 at 1123 K.
Authors with CRIS profile
Involved external institutions
Università degli studi di Milano
Italy (IT)
Max-Planck-Institut für Festkörperforschung
Germany (DE)
Universität Stuttgart
Germany (DE)
University of Aveiro / Universidade de Aveiro
Portugal (PT)
Italy (IT)
Max-Planck-Institut für Festkörperforschung
Germany (DE)
Universität Stuttgart
Germany (DE)
University of Aveiro / Universidade de Aveiro
Portugal (PT)
How to cite
APA:
Xiao, X., Widenmeyer, M., Xie, W., Zou, T., Yoon, S., Scavini, M.,... Weidenkaff, A. (2017). Tailoring the structure and thermoelectric properties of BaTiO3 via Eu2+ substitution. Physical Chemistry Chemical Physics, 19(21), 13469-13480. https://doi.org/10.1039/c7cp00020k
MLA:
Xiao, Xingxing, et al. "Tailoring the structure and thermoelectric properties of BaTiO3 via Eu2+ substitution." Physical Chemistry Chemical Physics 19.21 (2017): 13469-13480.
BibTeX: Download