TY - JOUR
T1 - Impact of Aliovalent Alkaline-Earth metal solutes on Ceria Grain Boundaries
T2 - A density functional theory study
AU - Boland, Tara M.
AU - Rez, Peter
AU - Crozier, Peter A.
AU - Singh, Arunima K.
N1 - Funding Information:
The authors thank start-up funds from Arizona State University and the National Science Foundation grant number DMR-1308085 , DMR-1840841 , and DMR-1906030 . This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which was supported by National Science Foundation grant number TG-DMR150006 . The authors acknowledge Research Computing at Arizona State University for providing HPC resources that have contributed to the research results reported within this paper.
Publisher Copyright:
© 2020
PY - 2021/2/15
Y1 - 2021/2/15
N2 - Ceria has proven to be an excellent ion-transport and ion-exchange material when used in polycrystalline form and with a high-concentration of aliovalent doped cations. Despite its widespread application, the impact of atomic-scale defects in this material are scarcely studied and poorly understood. In this article, using first-principles simulations, we provide a fundamental understanding of the atomic-structure, thermodynamic and electronic properties of undoped grain-boundaries (GBs) and alkaline-earth metal (AEM) doped GBs in ceria. Using density-functional theory simulations, with a GGA+U functional, we find the Σ3 (111)/[1¯01] GB is energetically more stable than the Σ3 (121)/[1¯01] GB due to the larger atomic coherency in the Σ3 (111)/[1¯01] GB plane. We dope the GBs with ∼20% [M]GB (M=Be, Mg, Ca, Sr, and Ba) and find that the GB energies have a parabolic dependence on the size of solutes, the interfacial strain and the packing density of the GB. We see a stabilization of the GBs upon Ca, Sr and Ba doping whereas Be and Mg render them energetically unstable. The electronic density of states reveal that no defect states are present in or above the band gap of the AEM doped ceria, which is highly conducive to maintain low electronic mobility in this ionic conductor. The electronic properties, unlike the energetic properties, exhibit complex inter-dependence on the structure and chemistry of the host and the solutes. This work makes advances in the atomic-scale understanding of aliovalent cation doped ceria GBs serving as an anchor to future studies that can focus on understanding and improving ionic-transport.
AB - Ceria has proven to be an excellent ion-transport and ion-exchange material when used in polycrystalline form and with a high-concentration of aliovalent doped cations. Despite its widespread application, the impact of atomic-scale defects in this material are scarcely studied and poorly understood. In this article, using first-principles simulations, we provide a fundamental understanding of the atomic-structure, thermodynamic and electronic properties of undoped grain-boundaries (GBs) and alkaline-earth metal (AEM) doped GBs in ceria. Using density-functional theory simulations, with a GGA+U functional, we find the Σ3 (111)/[1¯01] GB is energetically more stable than the Σ3 (121)/[1¯01] GB due to the larger atomic coherency in the Σ3 (111)/[1¯01] GB plane. We dope the GBs with ∼20% [M]GB (M=Be, Mg, Ca, Sr, and Ba) and find that the GB energies have a parabolic dependence on the size of solutes, the interfacial strain and the packing density of the GB. We see a stabilization of the GBs upon Ca, Sr and Ba doping whereas Be and Mg render them energetically unstable. The electronic density of states reveal that no defect states are present in or above the band gap of the AEM doped ceria, which is highly conducive to maintain low electronic mobility in this ionic conductor. The electronic properties, unlike the energetic properties, exhibit complex inter-dependence on the structure and chemistry of the host and the solutes. This work makes advances in the atomic-scale understanding of aliovalent cation doped ceria GBs serving as an anchor to future studies that can focus on understanding and improving ionic-transport.
KW - Aliovalent Dopants
KW - Ceria
KW - Grain-Boundaries
UR - http://www.scopus.com/inward/record.url?scp=85097574963&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85097574963&partnerID=8YFLogxK
U2 - 10.1016/j.actamat.2020.11.023
DO - 10.1016/j.actamat.2020.11.023
M3 - Article
AN - SCOPUS:85097574963
SN - 1359-6454
VL - 205
JO - Acta Materialia
JF - Acta Materialia
M1 - 116481
ER -