TY - JOUR
T1 - Oxygen storage capability in Co- and Fe-containing perovskite-type oxides
AU - Klimkowicz, Alicja
AU - Świerczek, Konrad
AU - Takasaki, Akito
AU - Dabrowski, Bogdan
N1 - Funding Information:
The project was funded by the National Science Centre Poland (NCN) on the basis of the decision number DEC-2011/01/B/ST8/04046 .
PY - 2014/4/1
Y1 - 2014/4/1
N2 - In this paper we report on oxygen storage-related properties of selected Co- and Fe-containing perovskite-type oxides, and analyze their advantages and disadvantages in relation to the Mn-based, A-site ordered BaYMn2O5 + δ system. In particular, the crystal structure of reduced and oxidized Ln0.5A′0.5Co0.5Fe0.5O3 - δ (Ln: La, Sm; A′: Sr, Ba) and La0.6Sr0.4Co0.8Fe0.2O3 - δ is given, results of in situ XRD observation of the oxidation process of the reduced materials is presented, as well as oxygen storage capacity and kinetics measured on oxidation/reduction cycles in isothermal and non-isothermal conditions are reported. Rietveld refinement of the crystal structure carried out for reduced compounds revealed the presence of brownmillerite-type phase for La0.6Sr0.4Co0.2Fe0.8O2.42, La0.5Sr0.5Co0.5Fe0.5O2.53 and Sm0.5Sr0.5Co0.5Fe0.5O2.53. Upon oxidation these materials transform to perovskite-type phase. On the contrary, La0.5Ba0.5Co0.5Fe0.5O3 - δ and A-site cation ordered Sm0.5Ba0.5Co0.5Fe0.5O3 - δ possess the same crystal structure in the reduced and oxidized forms. What's more is that the oxidation process causes a significant decrease of the unit cell volume for each studied compound. Rapid in situ XRD studies (1 min scans), performed every 5 C during oxidation of the materials, allowed to observe ongoing structural changes. TG measurements revealed unusually low onset temperatures of oxidation, with reduced La0.5Sr0.5Co0.5Fe0.5O3 - δ oxidizing at about 40 C. Isothermal oxidation/reduction cycles measured with changing of the atmosphere between air and 5 vol.% H2 in Ar, performed in 400-600 C allowed to establish oxygen storage-related properties of the studied materials, and it was found that La0.5Sr0.5Co0.5Fe0.5O3 - δ shows enhanced kinetics of the reduction process, while for La0.6Sr0.4Co0.8Fe0.2O3 - δ the measured reversible oxygen storage capacity can exceed 4.2 wt.%, well above that of the BaYMn2O5 + δ system. While these results are very promising, the main drawback arises from a low stability of the considered Co- and Fe-containing oxides, especially in terms of their long-time performance.
AB - In this paper we report on oxygen storage-related properties of selected Co- and Fe-containing perovskite-type oxides, and analyze their advantages and disadvantages in relation to the Mn-based, A-site ordered BaYMn2O5 + δ system. In particular, the crystal structure of reduced and oxidized Ln0.5A′0.5Co0.5Fe0.5O3 - δ (Ln: La, Sm; A′: Sr, Ba) and La0.6Sr0.4Co0.8Fe0.2O3 - δ is given, results of in situ XRD observation of the oxidation process of the reduced materials is presented, as well as oxygen storage capacity and kinetics measured on oxidation/reduction cycles in isothermal and non-isothermal conditions are reported. Rietveld refinement of the crystal structure carried out for reduced compounds revealed the presence of brownmillerite-type phase for La0.6Sr0.4Co0.2Fe0.8O2.42, La0.5Sr0.5Co0.5Fe0.5O2.53 and Sm0.5Sr0.5Co0.5Fe0.5O2.53. Upon oxidation these materials transform to perovskite-type phase. On the contrary, La0.5Ba0.5Co0.5Fe0.5O3 - δ and A-site cation ordered Sm0.5Ba0.5Co0.5Fe0.5O3 - δ possess the same crystal structure in the reduced and oxidized forms. What's more is that the oxidation process causes a significant decrease of the unit cell volume for each studied compound. Rapid in situ XRD studies (1 min scans), performed every 5 C during oxidation of the materials, allowed to observe ongoing structural changes. TG measurements revealed unusually low onset temperatures of oxidation, with reduced La0.5Sr0.5Co0.5Fe0.5O3 - δ oxidizing at about 40 C. Isothermal oxidation/reduction cycles measured with changing of the atmosphere between air and 5 vol.% H2 in Ar, performed in 400-600 C allowed to establish oxygen storage-related properties of the studied materials, and it was found that La0.5Sr0.5Co0.5Fe0.5O3 - δ shows enhanced kinetics of the reduction process, while for La0.6Sr0.4Co0.8Fe0.2O3 - δ the measured reversible oxygen storage capacity can exceed 4.2 wt.%, well above that of the BaYMn2O5 + δ system. While these results are very promising, the main drawback arises from a low stability of the considered Co- and Fe-containing oxides, especially in terms of their long-time performance.
KW - Chemical stability
KW - Crystal structure
KW - Oxygen storage materials (OSMs)
KW - Perovskite oxides
UR - http://www.scopus.com/inward/record.url?scp=84893266406&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84893266406&partnerID=8YFLogxK
U2 - 10.1016/j.ssi.2014.01.018
DO - 10.1016/j.ssi.2014.01.018
M3 - Article
AN - SCOPUS:84893266406
SN - 0167-2738
VL - 257
SP - 23
EP - 28
JO - Solid State Ionics
JF - Solid State Ionics
ER -