Chen D, Bishop S R, Tuller H L. Nonstoichiometry in Oxide Thin Films Operating under Anodic Conditions: A Chemical Capacitance Study of the Praseodymium–Cerium Oxide System[J]. Chemistry of Materials, 2014, 26(22): 6622-6627.

ABSTRACT

While the properties of functional oxide thin fi lms often depend strongly on their oxygen stoichiometry, there have been few ways to extract this infor-mation reliably and in situ. In this work, the derivation of the oxygen non-stoichiometry of dense Pr 0.1 Ce 0.9 O 2 −  δ  thin fi lms from an analysis of chemical capacitance obtained by impedance spectroscopy is described. Measure-ments are performed on electrochemical cells of the form Pr 0.1 Ce 0.9 O 2 −  δ / Y 0.16 Zr 0.84 O 1.92 /Pr 0.1 Ce 0.9 O 2 −  δ  over the temperature range of 450 to 800  ° C and oxygen partial pressure range of 10 − 5  to 1 atm O 2 . With the aid of a defect equilibria model, approximations relate chemical capacitance directly to non-stoichiometry, without need for fi tting parameters. The calculated non-stoichiometry allows extraction of the thermodynamic constants defi ning defect generation. General agreement of these constants with bulk values derived by thermogravimetric analysis is found, thereby confi rming the suitability of this technique for measuring oxygen non-stoichiometry of thin oxide fi lms. Potential sources of error observed in earlier chemical capaci-tance studies on perovskite structured oxide fi lms are also discussed.  DOI:  10.1002/adfm.201202104   D. Chen, Prof. S. R. Bishop, Prof. H. L. TullerDepartment of Materials Science and EngineeringMassachusetts Institute of TechnologyCambridge, MA 02139, USA E-mail:   tuller@mit.edu    Prof. S. R. BishopInternational Institute for Carbon Neutral Energy Research (WPI-I2CNER)Kyushu UniversityNishi-ku Fukuoka 819-0395, Japan