Scanning Electron Microscopy

SEM is also a very powerful tool for characterizing microstructures. Secondary electron detectors allow us to see the shape of the sample, and the backscatter detector emphasizes differences in density. By imaging etched polished samples we can take advantage of both signals.

Here are some examples of partially transformed Mg₂GeO₄.

Mg₂GeO₄ olivine partially transformed to spinel (white) under hydrostatic conditions. Notice the lens shape morphology and the buds growing on the sides.

This sample of Mg₂GeO₄ olivine was partially transformed to the spinel phase by the martensitic-like mechanism at 10GPa and 800°C. In this case a mixture of backscatter and secondary signal allows the spinel lamellae to be visualized.

Pamela uses Electron Backscatter Diffraction (EBSD) in her studies. The EBSD is currently installed on the Scanning Electron Microscope (SEM) at the Electron Microanalysis and Imaging Laboratory (EMiL) at UNLV. EBSD allows the orientation of grains to be measured by the SEM. The software produces orientation maps, pole figures, and grain shape measurements.

EBSD map of deformed Mg₂GeO₄ specimen.