Synthesis and electrochemical assessment of Ce0.5Yb0.5O1.75 ceramics and derived composite electrolytes

• Published in: Materials research bulletin 2015-10, Vol.70, p.449-455
• Main Authors: Martins, Natércia C.T., Rajesh, Surendran, Marques, Fernando M.B.
• Format: Article
• Language: English
• Subjects: Composites; Electrochemical properties; Electronic conductivity; Ionic conductivity; Oxides
• ISSN: 0025-5408; 1873-4227
• DOI: 10.1016/j.materresbull.2015.05.008

[Display omitted] •Ce0.5Yb0.5O1.75 prepared for the first time through solid state reaction.•High energy milling needed to assist the ceramic route.•Ce0.5Yb0.5O1.75 is oxide-ion conductor in air and n-type conductor at low pO2.•Ce0.5Yb0.5O1.75 decomposes slightly when exposed to alkaline carbonates.•Composites based on Ce0.5Yb0.5O1.75 show standard electrical performance. Ce0.5Yb0.5O1.75 was prepared for the first time through high temperature (1600°C for 5h) solid state reaction, after high energy milling to enhance the mechano-chemical interaction of precursor oxides (CeO2 and Yb2O3). Single phase formation was confirmed by powder X-ray diffraction. Impedance spectroscopy data obtained under wide temperature (300–800°C) and oxygen partial pressure (0.21 to about 10−25atm) ranges indicates that this material exhibits predominant oxide-ion conductivity under oxidizing conditions while n-type electronic conductivity prevails at low oxygen partial pressure. The mixed oxide shows modest ionic conductivity (1.1×10−3Scm−1 at 800°C) with activation energy of 1.3eV in the 600–800°C temperature range. When combined with molten carbonates (Li2CO3+Na2CO3, 1:1 molar ratio) to produce composite electrolytes, Ce0.5Yb0.5O1.75 slightly decomposed. However, the composite electrical performance is still acceptable and closely matches the conductivity of similar materials (>0.1Scm−1 immediately above 500°C).