TY - JOUR
T1 - Mechanistic insights into proton diffusion in Σ3 BaZrO3 (210)[001] tilt grain boundary
AU - Yue, Shaofeng
AU - Jing, Yuhang
AU - Sun, Yi
AU - Zhao, Junqing
AU - Aluru, N. R.
N1 - This work is supported by the National Science Foundation under grant # 1545907 , the National Center for Supercomputing Applications (NCSA), the NSF of China under Grant No. 12172112 , 11932005 and 11432005 , and the International Postdoctoral Exchange Fellowship Program of China under Grants No. 20140016 .
PY - 2022/1/15
Y1 - 2022/1/15
N2 - The acceptor-doped BaZrO3 (BZY) shows considerable bulk proton conductivity. However, the higher grain boundary (GB) resistances significantly limit the overall transport of protons in polycrystalline samples. The fundamental questions about the proton diffusion mechanism at the defects are still unclear. By performing detailed density functional theory (DFT) calculations, we have studied the diffusion properties of protons in GB, where the presence of large free space and hydrogen bond leads to a significant proton trapping in GB structure. By comparing the characteristics of proton diffusion in BZY and BZY-GB, we found that in both structures, the local lattice deformation is important in both the proton rotation and transfer steps involved in proton diffusion. By calculating the change in bond strength, the decrease of A ions during the proton rotation process in GB leads to a significant change in the bond strength of the remaining O and A ions, and for the increase in the number of oxygen donor and B ion interaction bonds during the proton transfer process in GB, both of which increase the energy barrier for local lattice deformation such as O–B rotational motion, thus inhibiting the proton diffusion in GB. Our results give mechanical insights into the high resistance to proton diffusion in GB, clarifying the sources of energy barriers for proton diffusion in GB, and lay the foundation for industrial applications of proton conductors.
AB - The acceptor-doped BaZrO3 (BZY) shows considerable bulk proton conductivity. However, the higher grain boundary (GB) resistances significantly limit the overall transport of protons in polycrystalline samples. The fundamental questions about the proton diffusion mechanism at the defects are still unclear. By performing detailed density functional theory (DFT) calculations, we have studied the diffusion properties of protons in GB, where the presence of large free space and hydrogen bond leads to a significant proton trapping in GB structure. By comparing the characteristics of proton diffusion in BZY and BZY-GB, we found that in both structures, the local lattice deformation is important in both the proton rotation and transfer steps involved in proton diffusion. By calculating the change in bond strength, the decrease of A ions during the proton rotation process in GB leads to a significant change in the bond strength of the remaining O and A ions, and for the increase in the number of oxygen donor and B ion interaction bonds during the proton transfer process in GB, both of which increase the energy barrier for local lattice deformation such as O–B rotational motion, thus inhibiting the proton diffusion in GB. Our results give mechanical insights into the high resistance to proton diffusion in GB, clarifying the sources of energy barriers for proton diffusion in GB, and lay the foundation for industrial applications of proton conductors.
KW - Density functional theory
KW - Energy barrier
KW - Grain boundary
KW - Lattice deformation
KW - Proton diffusion
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U2 - 10.1016/j.ceramint.2021.09.297
DO - 10.1016/j.ceramint.2021.09.297
M3 - Article
AN - SCOPUS:85116466046
SN - 0272-8842
VL - 48
SP - 2097
EP - 2104
JO - Ceramics International
JF - Ceramics International
IS - 2
ER -