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@ARTICLE{Song:904008,
author = {Song, Jia and Zhu, Shaochen and Ning, De and Bouwmeester,
Henny},
title = {{D}efect chemistry and transport properties of
perovskite-type oxides {L}a 1−x {C}a x {F}e{O} 3−δ},
journal = {Journal of materials chemistry / A},
volume = {9},
number = {2},
issn = {2050-7488},
address = {London [u.a.]},
publisher = {RSC},
reportid = {FZJ-2021-05578},
pages = {974 - 989},
year = {2021},
abstract = {Structural evolution, electrical conductivity, oxygen
nonstoichiometry and oxygen transport properties of
perovskite-type oxides La1−xCaxFeO3−δ (x = 0.05, 0.10,
0.15, 0.20, 0.30 and 0.40) are investigated. All
investigated compositions exhibit, under ambient air, a
phase transition from room-temperature orthorhombic (space
group Pbnm) to rhombohedral (space group R[3 with combining
macron]c) at elevated temperature. The transition
temperature is found to decrease gradually from 900 °C for
x = 0.05 to 625 °C for x = 0.40. Analysis of the data of
oxygen nonstoichiometry obtained by thermogravimetry shows
that under the given experimental conditions the Ca dopant
is predominantly compensated by formation of electron holes
rather than by oxygen vacancies. Maximum electrical
conductivity under air is found for the composition with x =
0.30 (123 S cm−1 at 650 °C). Analysis of the temperature
dependence of the mobility of the electron holes in terms of
Emin–Holstein's theory indicates that small polaron theory
fails for the compositions with high Ca contents x = 0.30
and x = 0.40. This is tentatively explained by the increased
delocalization of charge carriers with increasing Ca dopant
concentration. The oxygen transport properties of
La1−xCaxFeO3−δ in the range 650–900 °C are evaluated
using the electrical conductivity relaxation (ECR)
technique. Combined with data of oxygen non-stoichiometry,
the obtained results enable calculation of the oxygen
vacancy diffusion coefficient and associated ionic
conductivity. Both parameters increase with increasing Ca
content in La1−xCaxFeO3−δ, while it is found that the
effective migration barrier for oxygen diffusion decreases
with decreasing oxygen vacancy formation enthalpy.},
cin = {IEK-1},
ddc = {530},
cid = {I:(DE-Juel1)IEK-1-20101013},
pnm = {1232 - Power-based Fuels and Chemicals (POF4-123)},
pid = {G:(DE-HGF)POF4-1232},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000609149500021},
doi = {10.1039/D0TA07508F},
url = {https://juser.fz-juelich.de/record/904008},
}