Abstract
By combining experimental data with density functional theory-based ab initio molecular dynamics modeling, this work provides evidence that nonclassical electrostriction in isovalent Zr-doped ceria is due to the correlated anharmonic motion of dynamic elastic dipoles associated with multiple [ZrO8]-local bonding units with a high Zr concentration (Zr0.1Ce0.9O2). Introduction of 0.5 mol % trivalent or divalent codopants (Sc, Yb, La, or Ca) reduces the longitudinal electrostriction strain coefficient by more than a factor of 10, produces a 3-fold decrease in the relative dielectric permittivity, and increases the elastic modulus. Since these changes depend neither on the radius nor on the valency of the codopant, we conclude that the responsible species are charge-compensating oxygen vacancies (VO). For trivalent dopants (Do0.005Zr0.1Ce0.895O1.9975), oxygen vacancies are present at a concentration ratio 1:40 with respect to Zr, giving, for random distribution, a characteristic interaction distance of ≤2.3 unit cells (1.2 nm). Oxygen vacancies participate in [ZrO7-VO] local bonding units, disrupting the correlated dynamic displacements of the connected [ZrO8]-local bonding units. Such correlated motion of dynamic elastic dipoles may also explain the exponential increase in the longitudinal electrostriction strain coefficient with an increase in Zr concentration to <0.2 mole fraction and must be taken into account for further development of nonclassical electrostrictors based on Zr-doped ceria.
| Original language | English |
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| Journal | Chemistry of Materials |
| DOIs | |
| Publication status | Published Online - 7 Aug 2024 |
Funding
X-ray absorption spectroscopy studies and data analysis by A.I.F. were supported by NSF Grant number DMR-2312690. I.L. acknowledges the BSF program grant 2022786 for his contribution to the XAS studies. These grants are the two parts of the NSF-BSF grant awarded to A.I.F. and I.L., respectively. The work on the development of the theoretical description and the properties of the elastic dipoles was supported by the Israel-US Binational Science Foundation regular program (Y.Q. and I.L. grant 2020108). The work on the development of novel electrostrictive materials was supported by the US Army Research Office (ARO grant #W911NF2110263, I.L.). This research used beamline 7-BM (QAS) of the National Synchrotron Light Source II (NSLS-II), a U.S. DOE Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under contract no. DE-SC0012704. The authors acknowledge support of the beamline experiments by the Synchrotron Catalysis Consortium funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Grant No. DE-SC0012335. This research used the Theory and Computation facility of the Center for Functional Nanomaterials (CFN), which is a U.S. Department of Energy Office of Science User Facility, at Brookhaven National Laboratory under Contract No. DE-SC0012704. The authors gratefully acknowledge Drs. Lu Ma and Steven Ehrlich for their support of the XAS measurements at the 7-BM beamline. Publisher Copyright: © 2024 American Chemical Society.
All Science Journal Classification (ASJC) codes
- General Chemistry
- General Chemical Engineering
- Materials Chemistry