Title  Impact of the Synthesis Process on Structure Properties for AFCI Fuel Candidates	Researchers K. Czerwinski Collaborators Al Sattelberger, Argonne National Laboratory
Background  Synthesis of actinium mononitrides using carbothermic reduction of the corresponding oxides has a few outstanding issues, including the formation of secondary phases such as oxides and carbides and low densities of the final product. Furthermore the requirement of a high process temperature at 1700°C, for more than 12 hours is also a drawback particularly for Americium-bearing samples. Therefore, it is important to explore the use of other possible routes to synthesize actinide mononitrides.   A low temperature process is used in this research to produce actinide mononitrides using a fluoride route in which the first step is to mix the actinide oxide with NH4HF2. The second step involves the heat-treatment of the resulting ammonium actinide fluoride salts in ammonia atmosphere. Using different analytical techniques available, the experimental conditions can be studied and optimized to synthesize the required materials with high phase purity.  Such available techniques are X-ray Powder Diffraction (XRD), Thermogravimetry and Differential Scanning Calorimetry (TG/DSC), and microscopic techniques such as Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM).  Once the experimental conditions are studied and optimized, a number of actinide nitride systems (uranium, thorium, and neptunium) will be synthesized and characterized to provide knowledge on the chemistry of the systems. Characterization of these nitride systems will include chemical phase identification, lattice parameter refinements, morphological studies, microstructural verifications, thermal behavior, reaction mechanism, and reaction kinetics.	Research Objectives and Methods The research objectives are: To explore a low-temperature fluoride route to synthesize · actinide nitrides. · To characterize actinide nitrides structurally and thermally. · To use high resolution TEM techniques to explore the microstructure of the radioactive samples. Scanning Electron Microscopic images of the (a)7NH4F.6UF4 and (b) (NH4)4ThF8 samples. (a) 7NH4F.6UF4 particles are well-crystallized (hexagonal unit cell with a rhomb-centered, a (b) = 15.40 Å and c = 10.49 Å and UN2 is cubic (fcc) with a = 5.310 Å) (b) Well-crystallized (NH4)4ThF8 acicular-shaped particles (triclinic unit cell with lattice parameters a = 8.477, b = 8.364, and c = 7.308 Å).
Students  Chinthaka Silva G   Charles Yeamans G	Department Chemistry
Final Report	Annual Report
Proposal 02/04/05	Quarterly Reports  01/01/06-03/31/06