Oxygen nonstoichiornetry and mixed conductivity of SrFe(1-x)M(x)O(3-delta) (M=A1, Ga): Effects of B-site doping
authors Patrakee, MV; Kharton, VV; Bakhteeva, YA; Shaula, AL; Leonidov, IA; Kozhevnikov, VL; Naumovich, EN; Yaremchenko, AA; Marques, FMB
nationality International
journal SOLID STATE SCIENCES
author keywords strontium ferrite; mixed conductor; oxygen nonstoichiometry; perovskite; brownmillerite; hole mobility; ionic conductivity
keywords BROWNMILLERITE CAAL0.5FE0.5O2.5+DELTA; HIGH-TEMPERATURE; IONIC TRANSPORT; PERMEABILITY; PEROVSKITES; STABILITY; MOSSBAUER; MEMBRANES; CERAMICS; SR2FE2O5
abstract The oxygen nonstoichiometry, electrical conductivity and Seebeck coefficient of perovskite-related SrFe(1-x)Ga(x)O(3-delta) (x = 0-0.2) and SrFe(1-x)Al(x)O(3-delta) (x = 0.1-0.3) were studied in the temperature range 923-1223 K at oxygen partial pressures varying from 10(-20) to 0.3 atm. The substitution of iron with gallium was found to promote long-range ordering of oxygen vacancies, resulting in the perovskite -> brownmillerite transition at moderate oxygen pressures, and to decrease the mobility of the p-type electronic charge carriers. Opposite tendencies are observed for aluminum doping, which causes a higher oxygen nonstoichiometry in oxidizing atmospheres. As suggested by atomistic simulations of highly oxygen-deficient ferrite lattices, this behavior is associated with oxygen-vacancy trapping near Al(3+) having energetically favorable tetrahedral coordination, whereas Ga(3+) cations with preferential octahedral coordination in the perovskite lattice tend to repulse vacancies towards oxygen sites surrounded by iron and thus destabilize the structure. The relatively low hole mobility, with activation energies of 0.18-0.33 eV, indicates a small-polaron conduction mechanism. Under reducing conditions the oxygen content and ionic transport in brownmillerite-type polymorphs of SrFe(1-x)Ga(x)O(3-delta), exhibiting a relatively wide range of oxygen stoichiometry variation, are both lower compared to the Al-containing materials characterized by the co-existence of perovskite- and brownmillerite-like domains. (C) 2006 Elsevier SAS. All fights reserved.
publisher ELSEVIER SCIENCE BV
issn 1293-2558
year published 2006
volume 8
issue 5
beginning page 476
ending page 487
digital object identifier (doi) 10.1016/j.solidstatesciences.2006.01.006
web of science category Chemistry, Inorganic & Nuclear; Chemistry, Physical; Physics, Condensed Matter
subject category Chemistry; Physics
unique article identifier WOS:000237156600009
  ciceco authors
  impact metrics
journal analysis (jcr 2017):
journal impact factor 1.861
5 year journal impact factor 1.892
category normalized journal impact factor percentile 43.674
dimensions (citation analysis):
altmetrics (social interaction):



 


Sponsors

1suponsers_list_ciceco.jpg