Throughout her time as a PhD candidate in Case Western Reserve University’s Department of Earth, Environmental and Planetary Sciences, Jemila Edmond has been a frequent user of the ThermoFisher Apreo scanning electron microscope (SEM) in the Swagelok Center for Surface Analysis of Materials. Now, as a SCSAM fellow, she hopes to use the Apreo to measure the concentration of iron and sulfur across layers of FeS that have formed from the reaction of  Fe metal and the mineral pyrite (FeS2). This type of analysis allows her to calculate the diffusion coefficients of these materials at deep Earth and planetary pressures.

Though Edmond has conducted other analyses using the Apreo, this is her first project with a goal of getting quantitative energy-dispersive spectroscopy (EDS) results rather than qualitative, specifically, “accurate and precise elemental atomic percentages” In the past, she has done scanning electron microscopy on other high pressure-high temperature multi anvil and piston-cylinder apparatus experiments, primarily using iron oxide, aluminum, titanium and chromium samples.

Focusing on understanding how pressure affects diffusion in iron compounds, specifically across the pressure-induced electronic spin transition in Fe, Edmond has been surprised by how much time it takes to gather high-quality, standards-based, quantitative EDS data,. “To get good data on just one sample, it can take over two hours,” she said.

"SEM/EDS is the best resource we can utilize in order to quantify the f chemical reactions produced in these small scale experiments with high precision,” Edmond added. “It is quick, efficient and readily available here at CWRU.”

During her fellowship, Edmond has appreciated learning about the variance of FeS compounds at high pressures, as well as analytical standards to compare her samples with. She usually works with “different” but “very similar” banded iron formations when studying diffusion at high pressure.

"Working with Jemila has been so much fun,” said Jeffrey Pigott, SCSAM executive director. “Jemila has really picked up using the Apreo for SEM/EDS and has learned a lot about all of the care that goes into and challenges involved with doing quantitative EDS correctly. I am really happy that I can help her to understand her high-pressure, high-temperature experiments better."

Edmond hopes to produce a paper with the data from her SCSAM fellowship.