Linking the Electrical Conductivity and Non-Stoichiometry of Thin Film Ce 1-x Zr x O 2-δ by a Resonant Nanobalance Approach

• Published in: Materials 2021-02, Vol.14 (4)
• Main Authors: Kogut, Iurii, Wollbrink, Alexander, Steiner, Carsten, Wulfmeier, Hendrik, El Azzouzi, Fatima-Ezzahrae, Moos, Ralf, Fritze, Holger
• Format: Article
• Language: English
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma14040748

Bulk ceria-zirconia solid solutions (Ce Zr O , CZO) are highly suited for application as oxygen storage materials in automotive three-way catalytic converters (TWC) due to the high levels of achievable oxygen non-stoichiometry δ. In thin film CZO, the oxygen storage properties are expected to be further enhanced. The present study addresses this aspect. CZO thin films with 0 ≤ x ≤ 1 were investigated. A unique nano-thermogravimetric method for thin films that is based on the resonant nanobalance approach for high-temperature characterization of oxygen non-stoichiometry in CZO was implemented. The high-temperature electrical conductivity and the non-stoichiometry δ of CZO were measured under oxygen partial pressures O in the range of 10 -0.2 bar. Markedly enhanced reducibility and electronic conductivity of CeO -ZrO as compared to CeO and ZrO were observed. A comparison of temperature- and O -dependences of the non-stoichiometry of thin films with literature data for bulk Ce Zr O shows enhanced reducibility in the former. The maximum conductivity was found for Ce Zr O , whereas Ce Zr O showed the highest non-stoichiometry, yielding δ = 0.16 at 900 °C and O of 10 bar. The defect interactions in Ce Zr O are analyzed in the framework of defect models for ceria and zirconia.