Simultaneous electrical impedance and optical absorption spectroscopy for rapid characterization of oxygen vacancies and small polarons in doped ceria

1Citations
Citations of this article
10Readers
Mendeley users who have this article in their library.

Abstract

Mixed ionic-electronic conductors (MIECs) play a central role in emerging energy conversion and energy efficient computational technologies. However, it is both challenging and resource demanding to characterize MIECs over the broad range of experimental conditions of interest, thereby significantly limiting their study and applications. Here, a novel method of a simultaneous measurement of electrical conductivity and optical absorption of thin films in out-of-equilibrium state, i.e. during a reduction process, is employed for a comprehensive study of a MIEC oxide, PrxCe1−xO2−δ (PCO). It enables, orders of magnitude faster than by established techniques, characterization of the oxygen vacancy and small polaron formation and transport as a function of temperature (demonstrated here down to 200 °C), in a wide range of deviation from stoichiometry, δ. For instance, at 600 °C the PCO properties were obtained during a ten minute reduction process, in the pO2 range from 1 to 10−13 bar. The experimental results show that the oxygen vacancy mobility is constant while the small polaron mobility is linear in δ, in the whole pO2 range, which yields the total conductivity quadratic in δ. Furthermore, the method was applied to study the modification of PCO's transport properties with composition change. It was shown that increasing x from 0.1 to 0.2 suppresses the ionic mobility and, at the same time, enhances the small polaron mobility. Finally, the optically determined δ was used to define an instantaneous oxygen activity in PCO that can be accessed in the out-of-equilibrium experiments. This work opens up new possibilities to study the effects of microstructure, strain and other applied external stimuli on the transport and thermodynamic properties of PCO and similar types of MIEC materials.

Cite

CITATION STYLE

APA

Kalaev, D., & Tuller, H. L. (2023). Simultaneous electrical impedance and optical absorption spectroscopy for rapid characterization of oxygen vacancies and small polarons in doped ceria. Physical Chemistry Chemical Physics, 25(7), 5731–5742. https://doi.org/10.1039/d2cp04901e

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free