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Kemp D, De Souza RA. One Stone, Two Birds: Using High Electric Fields to Enhance the Mobility and the Concentration of Point Defects in Ion-Conducting Solids. J Am Chem Soc 2024; 146:4783-4794. [PMID: 38344804 PMCID: PMC10885144 DOI: 10.1021/jacs.3c12843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
Improving the ionic conductivity of outstanding, composition-optimized crystalline electrolytes is a major challenge. Achieving increases of orders of magnitude requires, conceivably, highly nonlinear effects. One known possibility is the use of high electric fields to increase point-defect mobility. In this study, we investigate quantitatively a second possibility that high electric fields can increase substantially point-defect concentrations. As a model system, we take a pyrochlore oxide (La2Zr2O7) for its combination of structural vacancies and dominant anti-Frenkel disorder; we perform molecular-dynamics simulations with many-body potentials as a function of temperature and applied electric field. Results within the linear regime yield the activation enthalpies and entropies of oxygen-vacancy and oxygen-interstitial migration, and from three independent methods, the enthalpy and entropy of anti-Frenkel disorder. Transport data for the nonlinear regime are consistent with field-enhanced defect concentrations and defect mobilities. A route for separating the two effects is shown, and an analytical expression for the quantitative prediction of the field-dependent anti-Frenkel equilibrium constant is derived. In summary, we demonstrate that the one stone of a nonlinear driving force can be used to hit two birds of defect behavior.
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Affiliation(s)
- Dennis Kemp
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
| | - Roger A De Souza
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
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Ding H, Hadaeghi N, Zhang MH, Jiang TS, Zintler A, Carstensen L, Zhang YX, Kleebe HJ, Zhang HB, Molina-Luna L. Translational Antiphase Boundaries in NaNbO 3 Antiferroelectrics. ACS APPLIED MATERIALS & INTERFACES 2023; 15:59964-59972. [PMID: 38085261 DOI: 10.1021/acsami.3c15141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2023]
Abstract
Planar defects are known to be of importance in affecting the functional properties of materials. Translational antiphase boundaries (APBs) in particular have attracted considerable attention in perovskite oxides, but little is known in lead-free antiferroelectric oxides that are promising candidates for energy storage applications. Here, we present a study of translational APBs in prototypical antiferroelectric NaNbO3 using aberration-corrected (scanning) transmission electron microscopy (TEM) techniques at different length scales. The translational APBs in NaNbO3 are characterized by a 2-fold-modulated structure, which is antipolar in nature and exhibits a high density, different from the polar nature and lower density in PbZrO3. The high stability of translational APBs against external electric fields and elevated temperatures was revealed using ex situ and in situ TEM experiments and is expected to be associated with their antipolar nature. Density functional theory calculations demonstrate that translational APBs possess only slightly higher free energy than the antiferroelectric and ferroelectric phase energies with differences of 29 and 33 meV/f.u., respectively, justifying their coexistence down to the nanoscale at room temperature. These results provide a detailed atomistic elucidation of translational APBs in NaNbO3 with antipolar character and stability against external stimuli, establishing the basis of defect engineering of antiferroelectrics for energy storage devices.
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Affiliation(s)
- Hui Ding
- Department of Materials and Earth Sciences, Technical University of Darmstadt, Darmstadt 64289, Germany
| | - Niloofar Hadaeghi
- Department of Materials and Earth Sciences, Technical University of Darmstadt, Darmstadt 64289, Germany
| | - Mao-Hua Zhang
- Department of Materials and Earth Sciences, Technical University of Darmstadt, Darmstadt 64289, Germany
| | - Tian-Shu Jiang
- Department of Materials and Earth Sciences, Technical University of Darmstadt, Darmstadt 64289, Germany
| | - Alexander Zintler
- Department of Materials and Earth Sciences, Technical University of Darmstadt, Darmstadt 64289, Germany
| | - Leif Carstensen
- Department of Materials and Earth Sciences, Technical University of Darmstadt, Darmstadt 64289, Germany
| | - Yi-Xuan Zhang
- Department of Materials and Earth Sciences, Technical University of Darmstadt, Darmstadt 64289, Germany
| | - Hans-Joachim Kleebe
- Department of Materials and Earth Sciences, Technical University of Darmstadt, Darmstadt 64289, Germany
| | - Hong-Bin Zhang
- Department of Materials and Earth Sciences, Technical University of Darmstadt, Darmstadt 64289, Germany
| | - Leopoldo Molina-Luna
- Department of Materials and Earth Sciences, Technical University of Darmstadt, Darmstadt 64289, Germany
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Elangovan H, Barzilay M, Huang J, Liu S, Cohen S, Ivry Y. Engineering Individual Oxygen Vacancies: Domain-Wall Conductivity and Controllable Topological Solitons. ACS NANO 2021; 15:13380-13388. [PMID: 34355902 PMCID: PMC8631733 DOI: 10.1021/acsnano.1c03623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 08/03/2021] [Indexed: 06/13/2023]
Abstract
Nanoscale devices that utilize oxygen vacancies in two-dimensional metal-oxide structures garner much attention due to conductive, magnetic, and even superconductive functionalities they exhibit. Ferroelectric domain walls have been a prominent recent example because they serve as a hub for topological defects and hence are attractive for next-generation data technologies. However, owing to the light weight of oxygen atoms and localized effects of their vacancies, the atomic-scale electrical and mechanical influence of individual oxygen vacancies has remained elusive. Here, stable individual oxygen vacancies were engineered in situ at domain walls of seminal titanate perovskite ferroics. The atomic-scale electric-field, charge, dipole-moment, and strain distribution around these vacancies were characterized by combining advanced transmission electron microscopy and first-principle methodologies. The engineered vacancies were used to form quasi-linear quadrupole topological defects. Significant intraband states were found in the unit cell of the engineered vacancies, proposing a meaningful domain-wall conductivity for miniaturized data-storage applications. Reduction of the Ti ion as well as enhanced charging and electric-field concentration were demonstrated near the vacancy. A 3-5% tensile strain was observed at the immediate surrounding unit cells of the vacancies. Engineering individual oxygen vacancies and topological solitons thus offers a platform for predetermining both atomic-scale and global functional properties of device miniaturization in metal oxides.
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Affiliation(s)
- Hemaprabha Elangovan
- Department
of Materials Science and Engineering, Technion−Israel
Institute of Technology, Haifa 3200003, Israel
- Solid
State Institute, Technion−Israel
Institute of Technology, Haifa 3200003, Israel
| | - Maya Barzilay
- Department
of Materials Science and Engineering, Technion−Israel
Institute of Technology, Haifa 3200003, Israel
- Solid
State Institute, Technion−Israel
Institute of Technology, Haifa 3200003, Israel
| | - Jiawei Huang
- School
of Science, Westlake University, Hangzhou, Zhejiang 310024, China
- Institute
of Natural Sciences, Westlake Institute
for Advanced Study, Hangzhou, Zhejiang 310024, China
- Key
Laboratory for Quantum Materials of Zhejiang Province, Hangzhou, Zhejiang 310024, China
| | - Shi Liu
- School
of Science, Westlake University, Hangzhou, Zhejiang 310024, China
- Institute
of Natural Sciences, Westlake Institute
for Advanced Study, Hangzhou, Zhejiang 310024, China
- Key
Laboratory for Quantum Materials of Zhejiang Province, Hangzhou, Zhejiang 310024, China
| | - Shai Cohen
- Nuclear
Research Centre-Negev, Beer-Sheva 84190, Israel
| | - Yachin Ivry
- Department
of Materials Science and Engineering, Technion−Israel
Institute of Technology, Haifa 3200003, Israel
- Solid
State Institute, Technion−Israel
Institute of Technology, Haifa 3200003, Israel
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