The Application of Impedance Spectroscopy to Characterise Electro-materials and Devices

D. C. Sinclair
1Department of Materials Science & Engineering, Mappin Street, University of Sheffield, UK
Corresponding Author: [email protected]

Impedance Spectroscopy (IS) is a readily available and versatile technique (typically scanning from mHz to MHz) to characterise the electrical properties of a wide variety materials including polar dielectrics, semi-conductors, composites, mixed ionic-electronic conductors and solid electrolytes [1-6]. In addition, its sensitivity to thin layer effects makes it an excellent tool to probe interfacial phenomena such as grain boundaries, surface layers and core-shell effects in ceramics and electrode/electrolyte phenomena in solid-state electrochemical devices such as batteries and fuel cells. 

In this tutorial we will review the fundamental concepts behind this technique and then use specific examples (based on ferroelectrics, oxide-ion conductors, barrier-layer capacitors) to illustrate how to establish the electrical microstructures of electrically homogeneous and heterogeneous ceramics and how to discriminate between ionic, electronic and mixed ionic-electronic conduction. Emphasis will be given towards; (i) how to apply multi-immitance fitting of experimental data when undertaking equivalent circuit analysis; (ii) selection of appropriate electrode materials; (iii) the use of dc bias measurements to probe non-ohmic contacts and Schottky barriers; (iv) the use of variable oxygen partial pressure (pO2) measurements to establish the type(s) of conduction carrier (i.e.  n, p or ions (eg O2-). Selected examples (time permitting) of using IS to characterise devices such as multi-layer ceramic capacitors, Li-batteries and solid oxide fuel cells will also be discussed.

In the final section, we will highlight the application (and limitations) of micro-contact impedance spectroscopy as a local-probe technique to interrogate thin films and inter- and intra-granular regions in electroceramics [7]. 


References
[1] A.K. Jonscher, Dielectric Relaxation in Solids, Chelsea Dielectrics Press, London (1983)
[2] J.R. MacDonald, Impedance Spectroscopy Theory, Experiment, and Applications, John Wiley and Sons, New Jersey (2005)
[3] D.C Sinclair and A.R. West, J Appl. Phys., 66, 3850-3856 (1989)
[4] E.J. Abram, D.C. Sinclair and A.R. West, J. Electroceram., 10, 165-177 (2003)
[5] D.P. Almond and C.R. Bowen, Phys. Rev. Lett., 92, 157601 (2004).
[6] J.P. Heath, J.S. Dean, J.H. Harding, D.C. Sinclair, J. Am. Ceram. Soc., 98, 1925-1931 (2015)
[7] R.A. Veazey, A.S. Gandy, D.C. Sinclair and J.S. Dean, J. Am. Ceram. Soc., https://doi.org/10.1111/jace.16236 (2018)