Modulating electric fields at oxide heterointerfaces via radiation damage
ORAL · Invited
Abstract
Next generation nuclear reactor components built from metal alloys are subject to highly irradiating environments; under these extreme conditions irradiation and corrosion may couple in unique ways resulting in outcomes distinct from corrosion under ambient conditions. Understanding this coupling is critical to identify potential mechanisms for corrosion mitigation to extend material lifetimes.
Under oxidizing environments, oxide layers may form above metal underlayers and act as protective coatings. Subsequent radiation damage produces defects, like oxygen vacancies, which are expected to alter transport mechanisms that impact corrosion. In prior work, superlattice films of Fe2O3 / Cr2O3 grown epitaxially along the (0001) axis exhibited interfacial electronic band offsets that were highly dependent on the details of the atomic-scale structure of each interface [1]. This suggests that migration of charged point defects, a proxy for corrosion, could be controlled by built-in electric fields at oxide interfaces.
Here we perform a detailed study of irradiated Fe2O3 / Cr2O3 heterostructures to probe the coupling of irradiation-induced point defects with interfacial crystal structure via their built-in electric fields. We perform density functional theory modeling to compute the effect of oxygen vacancies on electronic band offset. These calculations are paired with 4D-STEM differential phase contrast and electron energy loss spectroscopy techniques to measure nanoscale changes in electric field on Fe2O3 / Cr2O3 heterostructures before and after Fe+ ion irradiation. Our results show clear evidence that irradiation drives substantial modulation of interfacial electric fields dependent on atomistic structure of the interface. We show that irradiation can selectively induce built-in electric fields, altering their direction; this suggests a pathway to engineering oxide interfaces that can electrically control the spatial distribution of defects, with implications for the design of corrosion-resistant materials for extreme environments.
[1] Kaspar, et al, Adv Mater, 28, 1616 (2016)
Under oxidizing environments, oxide layers may form above metal underlayers and act as protective coatings. Subsequent radiation damage produces defects, like oxygen vacancies, which are expected to alter transport mechanisms that impact corrosion. In prior work, superlattice films of Fe2O3 / Cr2O3 grown epitaxially along the (0001) axis exhibited interfacial electronic band offsets that were highly dependent on the details of the atomic-scale structure of each interface [1]. This suggests that migration of charged point defects, a proxy for corrosion, could be controlled by built-in electric fields at oxide interfaces.
Here we perform a detailed study of irradiated Fe2O3 / Cr2O3 heterostructures to probe the coupling of irradiation-induced point defects with interfacial crystal structure via their built-in electric fields. We perform density functional theory modeling to compute the effect of oxygen vacancies on electronic band offset. These calculations are paired with 4D-STEM differential phase contrast and electron energy loss spectroscopy techniques to measure nanoscale changes in electric field on Fe2O3 / Cr2O3 heterostructures before and after Fe+ ion irradiation. Our results show clear evidence that irradiation drives substantial modulation of interfacial electric fields dependent on atomistic structure of the interface. We show that irradiation can selectively induce built-in electric fields, altering their direction; this suggests a pathway to engineering oxide interfaces that can electrically control the spatial distribution of defects, with implications for the design of corrosion-resistant materials for extreme environments.
[1] Kaspar, et al, Adv Mater, 28, 1616 (2016)
*This work was supported by FUTURE (Fundamental Understanding of Transport Under Reactor Extremes), an EFRC funded by the US DOE, Office of Science, Basic Energy Sciences (BES).
–
Publication: E.A. Peterson, D. Liu, S. Mills, T. Kaspar, A. Minor, B. Uberuaga, et al., "Atomistic and electronic structure of irradiated oxide interfaces: A correlative DPC-STEM and DFT study" to be submitted
Presenters
-
Elizabeth Peterson
- Los Alamos National Laboratory (LANL)