Electromechanical coupling in polaronic ceria
(2025) In JPhys Energy 7(3).- Abstract
Oxygen-defective metal oxides like cerium oxides exhibit giant electrostriction and field-induced piezoelectricity due to a dynamic electrosteric interplay between oxygen defects, V O ⋅ ⋅ , and the fluorite lattice. While such mechanisms are generally attributed to oxygen vacancies, recent results also highlight that trapped cationic defects, Ce Ce ′ , i.e. small polarons, can contribute to the electromechanical properties of ceria. Here, we study nanocrystalline 5% Ca- and 10% Gd-doped ceria thin films with a high density of point defects and a constant oxygen vacancy concentration at 5% molar. We deposit thin films at low temperatures to promote microstructure disorder, i.e. nano-crystallinity, where the oxygen vacancies have low... (More)
Oxygen-defective metal oxides like cerium oxides exhibit giant electrostriction and field-induced piezoelectricity due to a dynamic electrosteric interplay between oxygen defects, V O ⋅ ⋅ , and the fluorite lattice. While such mechanisms are generally attributed to oxygen vacancies, recent results also highlight that trapped cationic defects, Ce Ce ′ , i.e. small polarons, can contribute to the electromechanical properties of ceria. Here, we study nanocrystalline 5% Ca- and 10% Gd-doped ceria thin films with a high density of point defects and a constant oxygen vacancy concentration at 5% molar. We deposit thin films at low temperatures to promote microstructure disorder, i.e. nano-crystallinity, where the oxygen vacancies have low mobility due to high grain boundary interface densities. Still, the Ca2+ and Gd3+ dopants’ sizes and valence differences modulate trapping effects toward the defects in the lattice, giving an insight into the electromechanical nature of the defects in the material dominating the electrostriction. We find that electrosteric dopant-oxygen vacancy interactions only slightly affect the electromechanical properties, which mainly depend on the frequency and intensity of the applied electric field. On the other hand, n-type polaron, Ce Ce ′ , transport can emerge below the breakdown limit. These effects lead to an electromechanical coupling with a longitudinal electrostriction coefficient, M 33 , above 10−16 V2 m−2. Our results suggest that polaronic mechanisms substantially contribute to the electromechanical coupling in ceria. Also, the large ionic radius difference between Ce3+ and Ce4+ induces a large electro-strain upon polaron hopping, coupling electric stimuli to the observed electrostriction. This analysis provides new insights into the electromechanical effect of small polaronic semiconductive materials, opening new designing criteria for efficient electromechanical energy conversion.
(Less)
- author
- Tinti, Victor Buratto ; Vasiljevic, Milica ; Grønborg, Mathias ; Chen, Huaiyu LU ; Frederiksen, Valdemar ; Kantor, Innokenty LU ; Wallentin, Jesper LU ; Bruus, Henrik and Esposito, Vincenzo
- organization
- publishing date
- 2025-07-31
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- ceria, defect chemistry, electrostriction, impedance, nanostructure, polaron, thin film
- in
- JPhys Energy
- volume
- 7
- issue
- 3
- article number
- 035002
- publisher
- IOP Publishing
- external identifiers
-
- scopus:105002411753
- ISSN
- 2515-7655
- DOI
- 10.1088/2515-7655/adc628
- language
- English
- LU publication?
- yes
- additional info
- Publisher Copyright: © 2025 The Author(s). Published by IOP Publishing Ltd.
- id
- cd5b15e5-3e7f-400a-a926-529c6fb8f755
- date added to LUP
- 2025-04-21 16:57:40
- date last changed
- 2025-04-23 08:39:40
@article{cd5b15e5-3e7f-400a-a926-529c6fb8f755,
abstract = {{<p>Oxygen-defective metal oxides like cerium oxides exhibit giant electrostriction and field-induced piezoelectricity due to a dynamic electrosteric interplay between oxygen defects, V O ⋅ ⋅ , and the fluorite lattice. While such mechanisms are generally attributed to oxygen vacancies, recent results also highlight that trapped cationic defects, Ce Ce ′ , i.e. small polarons, can contribute to the electromechanical properties of ceria. Here, we study nanocrystalline 5% Ca- and 10% Gd-doped ceria thin films with a high density of point defects and a constant oxygen vacancy concentration at 5% molar. We deposit thin films at low temperatures to promote microstructure disorder, i.e. nano-crystallinity, where the oxygen vacancies have low mobility due to high grain boundary interface densities. Still, the Ca<sup>2+</sup> and Gd<sup>3+</sup> dopants’ sizes and valence differences modulate trapping effects toward the defects in the lattice, giving an insight into the electromechanical nature of the defects in the material dominating the electrostriction. We find that electrosteric dopant-oxygen vacancy interactions only slightly affect the electromechanical properties, which mainly depend on the frequency and intensity of the applied electric field. On the other hand, n-type polaron, Ce Ce ′ , transport can emerge below the breakdown limit. These effects lead to an electromechanical coupling with a longitudinal electrostriction coefficient, M 33 , above 10<sup>−16</sup> V<sup>2</sup> m<sup>−2</sup>. Our results suggest that polaronic mechanisms substantially contribute to the electromechanical coupling in ceria. Also, the large ionic radius difference between Ce<sup>3+</sup> and Ce<sup>4+</sup> induces a large electro-strain upon polaron hopping, coupling electric stimuli to the observed electrostriction. This analysis provides new insights into the electromechanical effect of small polaronic semiconductive materials, opening new designing criteria for efficient electromechanical energy conversion.</p>}},
author = {{Tinti, Victor Buratto and Vasiljevic, Milica and Grønborg, Mathias and Chen, Huaiyu and Frederiksen, Valdemar and Kantor, Innokenty and Wallentin, Jesper and Bruus, Henrik and Esposito, Vincenzo}},
issn = {{2515-7655}},
keywords = {{ceria; defect chemistry; electrostriction; impedance; nanostructure; polaron; thin film}},
language = {{eng}},
month = {{07}},
number = {{3}},
publisher = {{IOP Publishing}},
series = {{JPhys Energy}},
title = {{Electromechanical coupling in polaronic ceria}},
url = {{http://dx.doi.org/10.1088/2515-7655/adc628}},
doi = {{10.1088/2515-7655/adc628}},
volume = {{7}},
year = {{2025}},
}