TY - JOUR
T1 - Oxygen nonstoichiometry and defect structure analysis of B-site mixed perovskite-type oxide (La, Sr)(Cr, M)O3-δ (M=Ti, Mn and Fe)
AU - Oishi, Masatsugu
AU - Yashiro, Keiji
AU - Sato, Kazuhisa
AU - Mizusaki, Junichiro
AU - Kawada, Tatsuya
PY - 2008/11
Y1 - 2008/11
N2 - The defect chemical relationships in various B-site mixed LaCrO3-based ceramics were investigated by means of high-temperature gravimetry. The nonstoichiometric deviation, δ, in (La0.7Sr0.3)(Cr1-yTiy)O3-δ (y=0.1, 0.2 and 0.3) (LSCT), (La0.75Sr0.25)(Cr0.5Mn0.5)O3-δ (LSCM) and (La0.75Sr0.25)(Cr0.5Fe0.5)O3-δ (LSCF) were measured as a function of oxygen partial pressure, PO2, at temperatures between 973 and 1373 K. The effects of partial replacement of the donor on Cr-sites were examined in LSCT. In LSCM and LSCF, effects of the partial substitution of isovalent transition metals on Cr-sites are discussed. Oxygen nonstoichiometries of various B-site mixed LaCrO3-based ceramics were compared with those of A-site substituted perovskite-type oxides, (La1-xSrx)MO3-δ (where x=0-0.3, M=Cr, Mn and Fe). The partial substitution of the different elements on Cr-sites drastically changed the PO2 and temperature dependence of oxygen vacancy formation in LaCrO3-based ceramics. The defect equilibrium relationships of the localized electron well explained the oxygen vacancy formation in B-site mixed LaCrO3-based ceramics. Oxygen vacancy formation in (La0.7Sr0.3)(Cr1-yTiy)O3-δ (y=0.1 and 0.2) and (La0.7Sr0.3)(Cr0.7Ti0.3)O3-δ was explained by redox reaction of Cr and Ti ions, respectively. The defect equilibrium relationships of LSCM and LSCF were interpreted by redox reaction of Mn ions and Fe ions, respectively. No significant change in valence state of Cr3+ ions in LSCM and LSCF was confirmed under the experimental conditions.
AB - The defect chemical relationships in various B-site mixed LaCrO3-based ceramics were investigated by means of high-temperature gravimetry. The nonstoichiometric deviation, δ, in (La0.7Sr0.3)(Cr1-yTiy)O3-δ (y=0.1, 0.2 and 0.3) (LSCT), (La0.75Sr0.25)(Cr0.5Mn0.5)O3-δ (LSCM) and (La0.75Sr0.25)(Cr0.5Fe0.5)O3-δ (LSCF) were measured as a function of oxygen partial pressure, PO2, at temperatures between 973 and 1373 K. The effects of partial replacement of the donor on Cr-sites were examined in LSCT. In LSCM and LSCF, effects of the partial substitution of isovalent transition metals on Cr-sites are discussed. Oxygen nonstoichiometries of various B-site mixed LaCrO3-based ceramics were compared with those of A-site substituted perovskite-type oxides, (La1-xSrx)MO3-δ (where x=0-0.3, M=Cr, Mn and Fe). The partial substitution of the different elements on Cr-sites drastically changed the PO2 and temperature dependence of oxygen vacancy formation in LaCrO3-based ceramics. The defect equilibrium relationships of the localized electron well explained the oxygen vacancy formation in B-site mixed LaCrO3-based ceramics. Oxygen vacancy formation in (La0.7Sr0.3)(Cr1-yTiy)O3-δ (y=0.1 and 0.2) and (La0.7Sr0.3)(Cr0.7Ti0.3)O3-δ was explained by redox reaction of Cr and Ti ions, respectively. The defect equilibrium relationships of LSCM and LSCF were interpreted by redox reaction of Mn ions and Fe ions, respectively. No significant change in valence state of Cr3+ ions in LSCM and LSCF was confirmed under the experimental conditions.
KW - B-site mixing
KW - Defect structure
KW - LaCrO
KW - Oxygen nonstoichiometry
KW - Perovskite-type oxides
KW - SOFC
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U2 - 10.1016/j.jssc.2008.08.015
DO - 10.1016/j.jssc.2008.08.015
M3 - Article
AN - SCOPUS:55549103683
SN - 0022-4596
VL - 181
SP - 3177
EP - 3184
JO - Journal of Solid State Chemistry
JF - Journal of Solid State Chemistry
IS - 11
ER -