Probing the electrical properties and defect chemistry in oxide ion conductors and mixed ionic-electronic conductors

Oxide ion conductors and mixed ionic-electronic conductors (MIECs) find important technical applications in a variety of electrochemical devices. For example, pure oxide ion conductors with high oxide ion conductivity (σo) and negligible electronic conductivity (σe) can be used as electrolyte in solid oxide fuel cells (SOFCs). MIECs that simultaneously display both high σo and σe can be used as electrode materials in SOFCs and can be made into catalytic membranes for oxygen/hydrogen separation.
Deep understanding of the defect chemistry is essential to tune/improve the σo and σe and therefore the electrochemical performance of the oxide ion conductors and MIECs. This requires characterisation of electrical properties using impedance spectroscopy and dc methods with systematic measurements as a function of frequency, temperature and oxygen partial pressure. This will allow separation of grain and grain boundary conductivities, identifying the nature of charge carriers (electrons, holes, and ions), separation σi from σe.
The electrical properties of new oxide ion conductors and MIECs will be characterised using an impedance analyser and a dc conductivity/Seebeck coefficient test system. Both systems are coupled with high temperature furnaces, mass flow controller, and oxygen sensors to enable measurements at a wide range of frequency (dc, or 1mHz - 1MHz), temperature (20-1000 °C) and oxygen partial pressure (10-30 – 1 bar).

This position is collaborative between University of Birmingham and University of Nottingham. The student will primarily be based at Nottingham.