title: Phase transition of a cobalt-free perovskite as a high-performance cathode for intermediate-temperature solid oxide fuel cells.
abstract: It is generally recognized that the phase transition of a perovskite may be detrimental to the connection between cathode and electrolyte. Moreover, certain phase transitions may induce the formation of poor electronic and ionic conducting phase(s), thereby lowering the electrochemical performance of the cathode. Here, we present a study on the phase transition of a cobalt-free perovskite (SrNb(0.1)Fe(0.9)O(3-δ), SNF) and evaluate its effect on the electrochemical performance of the fuel cell. SNF exists as a primitive perovskite structure with space group P4mm (99) at room temperature. As evidenced by in situ high-temperature X-ray diffraction measurements over the temperature range of 600 to 1000 °C, SNF undergoes a transformation to a tetragonal structure with a space group I4/m (87). This phase transition is accompanied by a moderate change in the volume, allowing a good cathode/electrolyte interface on thermal cycling. According to the electrochemical impedance spectroscopy evaluation, the I4/m phase exhibits positive effects on the cathode's performance, showing the highest oxygen reduction reaction activity of cobalt-free cathodes reported so far. This activity improvement is attributed to enhanced oxygen surface processes.
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry & Chemical Engineering, Nanjing University of Technology, No. 5 Xin Mofan Road, Nanjing 210009, PR China.
authors.forename: Shanshan
authors.initials: S
authors.lastname: Jiang
authors.forename: Wei
authors.initials: W
authors.lastname: Zhou
authors.forename: Yingjie
authors.initials: Y
authors.lastname: Niu
authors.forename: Zhonghua
authors.initials: Z
authors.lastname: Zhu
authors.forename: Zongping
authors.initials: Z
authors.lastname: Shao
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry*; D011211:Electric Power Supplies; D004563:Electrochemistry; D004566:Electrodes; D008958:Models, Molecular; D008968:Molecular Conformation; D010087:Oxides / Q000737:chemistry*; D044367:Phase Transition; D013696:Temperature; D014025:Titanium / Q000737:chemistry*; D015019:Yttrium / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry
chemical_list: D017610:Calcium Compounds; D010087:Oxides; C059910:perovskite; D015019:Yttrium; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide; C091417:yttria