MCF Summer Seminar

July 19, 2024

2:00 p.m. ET

124 Roberts Hall

Scanning Transmission Electron Microscopy Studies of Highly-Alloyed Electroceramics, presented by Charles Evans

Ceramics are an extremely versatile class of materials which can have many useful electrical properties, such as piezoelectricity and ferroelectricity. By alloying a ceramic with a high percentage (tens of mole percent) of a substituent element, it is possible for them to exhibit new properties which are not present in the base materials. For example, barium titanate (a ferroelectric) alloyed with a high percentage of zirconium exhibits relaxor properties. Characterization of these materials can be challenging, however: relaxors in particular were famously described as a "hopeless mess" for characterization. In this talk we'll explore several scanning transmission electron microscopy techniques – HAADF, PACBED, and DPC – and their uses and drawbacks for characterizing these kinds of highly-alloyed ceramics. We'll also look at several image simulation and analysis techniques which can be very useful in understanding the STEM image contrast observed for these materials.

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