title: Improved conductivity of NdFeO₃ through partial substitution of Nd by Ca: a theoretical study.
abstract: NdFeO3 is an important candidate material for gas sensors and intermediate-temperature solid oxide fuel cells (IT-SOFC). However, its low conductivity prohibits its applications. In this study, we report that the doping of Ca by partially replacing Nd can effectively increase its conductivity. Through the electronic structure analysis of Nd(1-x)Ca(x)FeO3 (x = 0.00, 0.25, 0.50, 0.75 or 1.00) based on the first-principles density functional theory calculations, it is found that the hole states introduced by Ca substitution appear just above the Fermi level, which implies a high mobility of electrons/holes along the Fe-O-Fe bonding network. Specifically, it becomes easier to form O vacancies after Ca doping. Since the diffusion of O anions occurs through a vacancy hopping mechanism, the ion conductivity is also improved. These findings help us to gain an in-depth understanding of the colossally increased conductivity of Ca doped NdFeO3 and turn the electronic conduction for its practical application in gas sensors and IT-SOFC.
authors.affiliation: Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China. xing@ustb.edu.cn.
authors.forename: You
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Centre for Clean Environment and Energy and Griffith School of Environment, Griffith University, Gold Coast Campus, QLD 4222, Australia. h.zhao@griffith.edu.au.
authors.forename: Yun
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Physics, International Center of Quantum and Molecular Structures, and Materials Genome Institute, Shanghai University, Shanghai 200444, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Ren
authors.affiliation: Centre for Clean Environment and Energy and Griffith School of Environment, Griffith University, Gold Coast Campus, QLD 4222, Australia. h.zhao@griffith.edu.au.
authors.forename: Porun
authors.initials: P
authors.lastname: Liu
authors.affiliation: Centre for Clean Environment and Energy and Griffith School of Environment, Griffith University, Gold Coast Campus, QLD 4222, Australia. h.zhao@griffith.edu.au.
authors.forename: Huijun
authors.initials: H
authors.lastname: Zhao
authors.affiliation: Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China. xing@ustb.edu.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Chemistry, University of Science and Technology Beijing, Beijing 100083, China.
authors.forename: Jinxia
authors.initials: J
authors.lastname: Deng
authors.affiliation: Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China. xing@ustb.edu.cn.
authors.forename: Xianran
authors.initials: X
authors.lastname: Xing