TY - JOUR
T1 - Electromechanically active pairs dynamics in Gd-doped ceria single crystal
AU - Santucci, Simone
AU - Zhang, Haiwu
AU - Kabir, Ahsanul
AU - Marini, Carlo
AU - Sanna, Simone
AU - Han, Jyn Kyu
AU - Ulbrich, Gregor
AU - Heppke, Eva Maria
AU - Castelli, Ivano Eligio
AU - Esposito, Vincenzo
PY - 2021
Y1 - 2021
N2 - Oxygen defective ceria, e.g. Gd-doped ceria, shows giant electromechanical properties related to a complex local rearrangement of its lattice. Although they are not entirely identified, the electroactive mechanisms arise from cations and oxygen vacancies (VO) pairs (Ce-VO), and the local structural elastic distortion in their surroundings. Here, we study the geometry and behaviour of Ce-Vo pairs in a grain boundaries-free bulk Ce0.9Gd0.1O1.95 single crystal under an AC electric field of ca. 11 kV/cm. The analysis was carried out through X-ray absorption spectroscopy (XAS) techniques at Ce L-III edge. Using Density Functional Theory (DFT) calculations, we investigated the effects of the strain on states' density and orbitals at the valence band edge. Our research indicates that the electrostriction increases at low temperatures. The electromechanical strain has a structural nature and can rise of one order of magnitude, i.e., from 5·10-4 at room temperature to 5·10-3 at -193 °C, due to an increase in the population of the electrically active pairs. At a constant VO concentration, the material can thus configure heterogeneous pairs and elastic nanodomains that are either mechanically responsive or not.
AB - Oxygen defective ceria, e.g. Gd-doped ceria, shows giant electromechanical properties related to a complex local rearrangement of its lattice. Although they are not entirely identified, the electroactive mechanisms arise from cations and oxygen vacancies (VO) pairs (Ce-VO), and the local structural elastic distortion in their surroundings. Here, we study the geometry and behaviour of Ce-Vo pairs in a grain boundaries-free bulk Ce0.9Gd0.1O1.95 single crystal under an AC electric field of ca. 11 kV/cm. The analysis was carried out through X-ray absorption spectroscopy (XAS) techniques at Ce L-III edge. Using Density Functional Theory (DFT) calculations, we investigated the effects of the strain on states' density and orbitals at the valence band edge. Our research indicates that the electrostriction increases at low temperatures. The electromechanical strain has a structural nature and can rise of one order of magnitude, i.e., from 5·10-4 at room temperature to 5·10-3 at -193 °C, due to an increase in the population of the electrically active pairs. At a constant VO concentration, the material can thus configure heterogeneous pairs and elastic nanodomains that are either mechanically responsive or not.
U2 - 10.1039/D1CP00748C
DO - 10.1039/D1CP00748C
M3 - Journal article
SN - 1463-9076
VL - 23
SP - 11233
EP - 11239
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
IS - 19
ER -