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Miami University
Dr. John Rakovan

Associate Professor
Department of Geology
Phone: 513-529-3245
Fax: 513-529-1542
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Dr. John Rakovan
Dr. John Rakovan "My research involves the integration of low temperature geochemistry and mineralogy in the study of crystal surfaces and water-rock interactions found in natural systems. In particular, I am interested in environmentally significant processes such as crystal growth, metal sorption, trace element partitioning and other surface mediated reactions."


Description of Research
One of the major goals of my research program is to examine the structure and behavior of mineral surfaces in order to understand the mechanisms that control the fate of metals in the environment, including toxic species and radionuclides. The behavior of mineral surfaces in reactions with the environment is dictated by properties that differ from the bulk properties of the mineral. This is a consequence of incomplete coordination and bonding of atoms at surfaces; the same principle behind the unique properties of nanoparticles. This work has significantly increased our understanding of atomic scale mechanisms of crystal growth and heterogeneous reactivity at the mineral-water interface; key processes in the fate and transport of elements (such as heavy metals) in natural aqueous systems. Ultimately, incorporation of a contaminant into a mineral structure is the most stable configuration in terms of bioavailability and dispersal potential. A related research focus of mine is investigation of the structural response of apatite to the incorporation of U, Th and other radionuclides. The ultimate goals of this work are the assessment of this mineral as a potential solid nuclear-waste form and development of synthesis methods for this application. Much of this work utilizes surface sensitive analytical techniques such as AFM, STM and XPS. Bulk structural studies rely upon powder and single crystal X-ray diffraction as well as synchrotron based diffraction and spectroscopy including EXAFS, XANES and SXRFMA. My research group makes extensive use of the unique synchrotron facilities at the National Synchrotron Light Source (NSLS), Brookhaven National Laboratory, and the Advanced Photon Source (APS), Argonne National Laboratory.

Undergraduate researcher's roles in your lab
I have a strong commitment to undergraduate and graduate experience based education through directed research. Undergraduates are also involved in many of these aspects of research and work closely with my entire group. The research activities of almost all of these students have lead to publications, presentations, field experiences, and in some cases awards and grants.

Graduate student's role in your lab
Graduate students at both the MS and PHD levels work in my group in all stages of the research endeavor from development of hypotheses to experimental design and execution to data analysis and presentation. The research leads to publications, presentations, field experiences, and in some cases awards and grants.

Presentations

Funding
$100.000 Grant from the State of Ohio
Nanomaterials in our Environment

$100.000 Grant from the State of Ohio
Nanomaterials in our Environment
Publications

Lupulescu, M.V., Rakovan, J., Robinson, and Hughes, J. (2005) Fluoropargasite, a new member of the group 2, calcic amphiboles, from Edenville, Orange County, New York. Canadian Mineralogist. 43, 1439-1444.

Krekeler, K., Hammerly, E., Rakovan, J. and Guggenheim, S. (2005) Microscopy Studies of the Palygorskite to Smectite Transformation. Clay and Clay Minerals, 53, 92-99.

Losey*, A., Rakovan, J., Hughes, J.M., Francis, C.A. and Dyar, M.D. (2004) Structural Variation in the lithiophilite-triphylite series and other olivine-group structures. Canadian Mineralogist, 42, 1105-1115.

Meng, Y., Newville, M., Sutton, S., Rakovan, J., and Mao, H.K. (2003) Fe and Ni impurities in synthetic diamond. American Mineralogist. 88, 1555-1559.

Rakovan, J., Reeder, R.J., Elzinga, E.J., Cherniak, D. Tait, C.D. and Morris, D.E. (2002) Characterization of U(VI) in the apatite structure by X-ray absorption spectroscopy. Environmental Science and Technology. 36, 3114-3117.

Bosze*, S. and Rakovan, J. (2002) Surface structure controlled sectoral zoning of the Rare Earth Elements in fluorite from Long Lake, N.Y. and Bingham, N.M. Geochim. Cosmochim. Acta. 66, 997-1009.

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