Morphological characterization of jarosite groups formed from Fe(III) biologically oxidized with different numbers of Acidithiobacillus ferrooxidans was conducted using FE-SEM. The higher population of A. ferrooxidans resulted in more distinct jarosite mineral shape, and stronger Raman intensities for potassium jarosite, ammoniojarosite and argentojarosite. The morphology of the jarosites might be dependent on iron-oxidizing activity of A. ferrooxidans.The technique was applied to identify jarosite compounds formed during microbially mediated dissolution of arsenopyrite by A. ferrooxidans. It is difficult to identify this jarosite compound by X-ray diffraction and Raman spectroscopy because amounts are typically low and the crystallization is poor in minerals formed by microbially mediated oxidation. However, FE-SEM image provided helpful information for identification of jarosite compounds.The results suggest that morphology would provide useful information for identification and history of jarosite minerals as geochemical samples.

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Austenitic stainless steel PNC316 was subjected to grain boundary engineering (GBE). It was found that the grain boundary engineered PNC316 (PNC316-GBEM) had a coincidence site lattice (CSL) fraction of 86% and that the network of random grain boundaries was perfectly divided by the CSL boundaries. The thermal stability and the void swelling behavior of PNC316-GBEM were investigated by means of SEM and TEM analyses. After thermal aging at 973 K for 100 h, structural changes were observed neither in the grain boundary networks of PNC316-GBEM nor in another sample of PNC316-GBEM subjected to 20% additional cold rolling, PNC316-GBEM20%CW. PNC316-GBEM showed a higher void swelling rate than as-received PNC316 (PNC316-AS). However, with additional 20% cold rolling after GBE, the void swelling rate decreased to as low as that of PNC316-AS