Tailoring Nonstoichiometry and Mixed Ionic Electronic Conductivity in Pr0.1Ce0.9O2-δ/SrTiO3 Heterostructures

George F. Harrington; Dmitri Kalaev; Bilge Yildiz; Kazunari Sasaki; Nicola H. Perry; Harry L. Tuller

doi:10.1021/acsami.9b08864

Tailoring Nonstoichiometry and Mixed Ionic Electronic Conductivity in Pr_0.1Ce_0.9O_2-δ/SrTiO₃ Heterostructures

George F. Harrington, Dmitri Kalaev, Bilge Yildiz, Kazunari Sasaki, Nicola H. Perry, Harry L. Tuller

Department of Chemistry

Research output: Contribution to journal › Article › peer-review

9 Citations (SciVal)

Abstract

The oxygen deficiency or excess, as reflected in the nonstoichiometry of oxide films, plays a crucial role in their functional properties for applications such as micro solid oxide fuel cells, catalysis, sensors, ferroelectrics, and memristors. High concentrations of oxygen vacancies may be beneficial or detrimental according to the application, and hence there is interest in controlling the oxygen content of films without resorting to compositional changes. Here, we demonstrate that substantial changes in the nonstoichiometry of Pr_0.1Ce_0.9O_2-δ (PCO), a model mixed ionic electronic conductor, can be achieved by fabricating multilayers with an inert material, SrTiO₃ (STO). We fabricated heterostructures using pulsed laser deposition, keeping the total thickness of PCO and STO constant while varying the number of layers and thickness of each individual layer, to probe the effects of the PCO/STO interfaces. Conductivity measurements as a function of oxygen partial pressure (P_O₂) and temperature showed a significant weakening of the P_O₂ dependence compared to bulk PCO, which scaled with the density of interfaces. We confirmed that this change was due to variations in nonstoichiometry, by optical transmission measurements, and show that the lower oxygen content is consistent with a decrease in the effective oxygen reduction enthalpy of PCO. These results exemplify the dramatic differences in properties between films and their bulk counterparts, achievable by interface engineering, and provide generalized insight into tailoring the properties of mixed ionic electronic conductors at the nanoscale.

Original language	English
Pages (from-to)	34841-34853
Number of pages	13
Journal	ACS Applied Materials and Interfaces
Volume	11
Issue number	38
DOIs	https://doi.org/10.1021/acsami.9b08864
Publication status	Published - 25 Sept 2019

Bibliographical note

Funding Information:
G.F.H. gratefully acknowledges financial support from a Kakenhi Grant-in-Aid for Encouragement of Young Scientists (B) Award (no. JP18K13992) and the Platform of Inter/Transdisciplinary Energy Research Support Program (Q-pit) at Kyushu University. The authors are also grateful for support from the Progress 100 program of Kyushu University and the International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), both supported by MEXT, Japan, and the Center of Innovation Science and Technology based Radical Innovation and Entrepreneurship Program (COI Program) and by the Japan Science and Technology Agency (JST) (grant no. JPMJCE1318). D.K., H.L.T, and B.Y. acknowledge support for their research from the Department of Energy, Basic Energy Sciences under award no. DE-SC0002633 (Chemomechanics of Far-From-Equilibrium Interfaces).

Funding

G.F.H. gratefully acknowledges financial support from a Kakenhi Grant-in-Aid for Encouragement of Young Scientists (B) Award (no. JP18K13992) and the Platform of Inter/Transdisciplinary Energy Research Support Program (Q-pit) at Kyushu University. The authors are also grateful for support from the Progress 100 program of Kyushu University and the International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), both supported by MEXT, Japan, and the Center of Innovation Science and Technology based Radical Innovation and Entrepreneurship Program (COI Program) and by the Japan Science and Technology Agency (JST) (grant no. JPMJCE1318). D.K., H.L.T, and B.Y. acknowledge support for their research from the Department of Energy, Basic Energy Sciences under award no. DE-SC0002633 (Chemomechanics of Far-From-Equilibrium Interfaces).

Keywords

ceria
electro-chemo-mechanics
mixed ionic electronic conductors
multilayer heterostructures
oxide heterointerfaces

ASJC Scopus subject areas

General Materials Science

Access to Document

10.1021/acsami.9b08864

Cite this

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title = "Tailoring Nonstoichiometry and Mixed Ionic Electronic Conductivity in Pr0.1Ce0.9O2-δ/SrTiO3 Heterostructures",

abstract = "The oxygen deficiency or excess, as reflected in the nonstoichiometry of oxide films, plays a crucial role in their functional properties for applications such as micro solid oxide fuel cells, catalysis, sensors, ferroelectrics, and memristors. High concentrations of oxygen vacancies may be beneficial or detrimental according to the application, and hence there is interest in controlling the oxygen content of films without resorting to compositional changes. Here, we demonstrate that substantial changes in the nonstoichiometry of Pr0.1Ce0.9O2-δ (PCO), a model mixed ionic electronic conductor, can be achieved by fabricating multilayers with an inert material, SrTiO3 (STO). We fabricated heterostructures using pulsed laser deposition, keeping the total thickness of PCO and STO constant while varying the number of layers and thickness of each individual layer, to probe the effects of the PCO/STO interfaces. Conductivity measurements as a function of oxygen partial pressure (PO2 ) and temperature showed a significant weakening of the PO2 dependence compared to bulk PCO, which scaled with the density of interfaces. We confirmed that this change was due to variations in nonstoichiometry, by optical transmission measurements, and show that the lower oxygen content is consistent with a decrease in the effective oxygen reduction enthalpy of PCO. These results exemplify the dramatic differences in properties between films and their bulk counterparts, achievable by interface engineering, and provide generalized insight into tailoring the properties of mixed ionic electronic conductors at the nanoscale.",

keywords = "ceria, electro-chemo-mechanics, mixed ionic electronic conductors, multilayer heterostructures, oxide heterointerfaces",

author = "Harrington, {George F.} and Dmitri Kalaev and Bilge Yildiz and Kazunari Sasaki and Perry, {Nicola H.} and Tuller, {Harry L.}",

note = "Funding Information: G.F.H. gratefully acknowledges financial support from a Kakenhi Grant-in-Aid for Encouragement of Young Scientists (B) Award (no. JP18K13992) and the Platform of Inter/Transdisciplinary Energy Research Support Program (Q-pit) at Kyushu University. The authors are also grateful for support from the Progress 100 program of Kyushu University and the International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), both supported by MEXT, Japan, and the Center of Innovation Science and Technology based Radical Innovation and Entrepreneurship Program (COI Program) and by the Japan Science and Technology Agency (JST) (grant no. JPMJCE1318). D.K., H.L.T, and B.Y. acknowledge support for their research from the Department of Energy, Basic Energy Sciences under award no. DE-SC0002633 (Chemomechanics of Far-From-Equilibrium Interfaces).",

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T1 - Tailoring Nonstoichiometry and Mixed Ionic Electronic Conductivity in Pr0.1Ce0.9O2-δ/SrTiO3 Heterostructures

AU - Harrington, George F.

AU - Kalaev, Dmitri

AU - Yildiz, Bilge

AU - Sasaki, Kazunari

AU - Perry, Nicola H.

AU - Tuller, Harry L.

N1 - Funding Information: G.F.H. gratefully acknowledges financial support from a Kakenhi Grant-in-Aid for Encouragement of Young Scientists (B) Award (no. JP18K13992) and the Platform of Inter/Transdisciplinary Energy Research Support Program (Q-pit) at Kyushu University. The authors are also grateful for support from the Progress 100 program of Kyushu University and the International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), both supported by MEXT, Japan, and the Center of Innovation Science and Technology based Radical Innovation and Entrepreneurship Program (COI Program) and by the Japan Science and Technology Agency (JST) (grant no. JPMJCE1318). D.K., H.L.T, and B.Y. acknowledge support for their research from the Department of Energy, Basic Energy Sciences under award no. DE-SC0002633 (Chemomechanics of Far-From-Equilibrium Interfaces).

PY - 2019/9/25

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N2 - The oxygen deficiency or excess, as reflected in the nonstoichiometry of oxide films, plays a crucial role in their functional properties for applications such as micro solid oxide fuel cells, catalysis, sensors, ferroelectrics, and memristors. High concentrations of oxygen vacancies may be beneficial or detrimental according to the application, and hence there is interest in controlling the oxygen content of films without resorting to compositional changes. Here, we demonstrate that substantial changes in the nonstoichiometry of Pr0.1Ce0.9O2-δ (PCO), a model mixed ionic electronic conductor, can be achieved by fabricating multilayers with an inert material, SrTiO3 (STO). We fabricated heterostructures using pulsed laser deposition, keeping the total thickness of PCO and STO constant while varying the number of layers and thickness of each individual layer, to probe the effects of the PCO/STO interfaces. Conductivity measurements as a function of oxygen partial pressure (PO2 ) and temperature showed a significant weakening of the PO2 dependence compared to bulk PCO, which scaled with the density of interfaces. We confirmed that this change was due to variations in nonstoichiometry, by optical transmission measurements, and show that the lower oxygen content is consistent with a decrease in the effective oxygen reduction enthalpy of PCO. These results exemplify the dramatic differences in properties between films and their bulk counterparts, achievable by interface engineering, and provide generalized insight into tailoring the properties of mixed ionic electronic conductors at the nanoscale.

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