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Factors Influencing Ferrihydrite Crystallinity In Natural And Synthetic Systems
Citation:
FORD, R. G., F. M. Michel, AND J. Thompson. Factors Influencing Ferrihydrite Crystallinity In Natural And Synthetic Systems. Presented at American Chemical Society, 235th National Meeting, New Orleans, LA, April 06 - 10, 2008.
Impact/Purpose:
To explore the factors that influence ferrihydrite crystallinity during its formation.
Description:
Recent investigations of the structure of the mineral ferrihydrite indicate that disparities in the number of peaks observed in powder x-ray diffraction patterns can be attributed to differences in crystallite size. This has lead to the conclusion that specimens previously referred to as distinct mineral structures, i.e., the purported "2-line" and "6-line" forms of ferrihydrite, can be attibuted to a single mineral phase. A method of synthesis employing the slow aerial oxidation of solutions of ferrous salts has been employed to explore the factors that influence ferrihydrite crystallinity during its formation. Observations from these syntheses have been used as a point of reference for characterizing a range of natural ferrihydrite specimens formed in varying environments. These results point to the importance of precipitation temperature and the presence of solution impurities on the crystallinity of ferrihydrite.