Yttria-stabilised zirconia (YSZ), is a widely known oxygen ion conductor. A common application for this ceramic is as an electrolyte in solid oxide fuel cells (SOFC’s). Nevertheless, recently it has been demonstrated that electronic conduction can be introduced to this electrolyte, under the application of a small dc bias or in the increment of oxygen partial pressure (pO2), at high temperatures [1].
Similar behaviour has been observed during flash sintering (FS). This technique applies an electrical potential difference across the sample at high temperatures; and joule heating has been identified as one of its sintering mechanisms. Also, during FS an increment in conductivity has been observed, although, it has been discussed that in the case of YSZ dc ionic current is not enough to provoke joule heating during FS [2]. Therefore, there is the question if there is also an electronic contribution.
For these reasons, the electrical properties of cubic calcia-stabilised zirconia (CSZ) were studied under the application of a dc bias and different pO2. Samples were prepared by solid state reaction and impedance spectroscopy was used for the analysis of the electrical properties. Three electrical components were identified: bulk, grain boundary and, sample-electrode interphase. It was noticed that the resistance of the sample-electrode response was highly dependent on the presence of the potential difference, and the change in pO2. A discussion on this behaviour will be given in the following poster.
References
[1] M. Jovaní, H. Beltrán-Mir, E. Cordoncillo, and A. R. West, “Atmosphere- and Voltage-Dependent Electronic Conductivity of Oxide-Ion-Conducting Zr1-xYxO2-x/2 Ceramics,” Inorg. Chem., vol. 56, no. 12, pp. 7081–7088, 2017.
[2] M. Yu, S. Grasso, R. Mckinnon, T. Saunders, and M. J. Reece, “Review of flash sintering: materials, mechanisms and modelling,” Advances in Applied Ceramics, vol. 116, no. 1. pp. 24–60, 2017.
Advanced characterisation , Electrochemical behavior , Conduction of electrons and ions
