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Barium Non‐Stoichiometry Role on the Properties of Ba 1+ x Ce 0.65 Zr 0.20 Y 0.15 O 3–δ Proton Conductors for IT‐SOFCs
Author(s) -
Barison S.,
Battagliarin M.,
Cavallin T.,
Daolio S.,
Doubova L.,
Fabrizio M.,
Mortalò C.,
Boldrini S.,
Gerbasi R.
Publication year - 2008
Publication title -
fuel cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.485
H-Index - 69
eISSN - 1615-6854
pISSN - 1615-6846
DOI - 10.1002/fuce.200800021
Subject(s) - barium , materials science , stoichiometry , sintering , barium oxide , perovskite (structure) , conductivity , chemical stability , analytical chemistry (journal) , inorganic chemistry , electrical resistivity and conductivity , hydrogen , oxide , mineralogy , chemistry , crystallography , metallurgy , organic chemistry , electrical engineering , engineering
Proton conducting perovskite oxides have been widely investigated because of their potential as electrolytes for intermediate temperature solid oxide fuel cells. Among them, BaCeO 3 ‐ based materials exhibit good proton conductivity under a humidified hydrogen‐containing atmosphere, but rather poor chemical stability in CO 2 atmosphere. The substitution with Zr for Ce improves the chemical stability but reduces proton conductivity due to difficulties in fabricating dense materials. In the present work, single phase nanostructured powders of Ba 1+ x Ce 0.65 Zr 0.20 Y 0.15 O 3–δ ( x = 0, 0.05, 0.10) solid solutions have been prepared by a modified sol–gel Pechini method with the final aim of evaluating the role of barium on their chemical and electrical properties. A significant influence of barium excess on the preparation and on properties of these materials has been demonstrated. In fact, density measurements evidenced that a 5 or 10 mol% nominal barium excess sensibly favoured the sintering process. Impedance analyses of sintered pellets confirmed the necessity of barium excess in order to avoid the lowering of proton conductivity, which has been evidenced for samples having stoichiometric barium content. Moreover, an unforeseen increase in chemical stability in CO 2 ‐containing atmosphere with the growth of the barium excess was detected by thermogravimetric analyses.