Supporting dataset for the publication "Electromechanical coupling in polaronic ceria"

In this dataset, you can find the raw and processed data related to the publication: Electromechanical coupling in polaronic ceria

Abstract: Oxygen-defective metal oxides like cerium oxides exhibit giant electrostriction and field-induced piezoelectricity due to a dynamic electrosteric interplay between oxygen defects,, and the fluorite lattice. While such mechanisms are generally attributed to oxygen vacancies, recent results also highlight that trapped cationic defects, Ce^4+/3+, i.e. small polarons, can contribute to the electromechanical properties of ceria thin films. However, electromechanical polaron mechanisms have not been investigated yet. Here, we study nanocrystalline 5% Ca- and 10% Gd-doped ceria thin films with a high density of point defects. Keeping the oxygen vacancy concentration constant at 5 % molar, we deposit thin films at low temperatures to promote disorder, where the oxygen vacancies have low mobility due to high grain boundary interface densities. Still, the Ca²⁺ and Gd³⁺ dopants' sizes and valence differences are expected to modulate trapping effects toward the oxygen defects in the lattice. 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, polaron transport can emerge below the breakdown limit. These effects lead to step-wise electromechanical coupling with an electrostriction coefficient, M, above 10^-16 V²m^-2. Our results suggest that polaronic mechanisms substantially contribute to the electromechanical coupling in ceria, especially where electrochemical reduction occurs at the electrode interface. This analysis provides new insights into the electromechanical effect of small polaronic semiconductive materials, opening new designing criteria for electromechanical energy conversion.