Band Gap Transition Studies of U:ThO2 Using Cathodoluminescence

ORAL

Abstract

The Department of Defense has an interest in thorium dioxide (ThO$_2$) and uranium dioxide (UO$_2$) as possible candidates for use in designing neutron detectors. Three U$_x$:Th$_{1-x}$O$_2$ (x= 0.00, 0.01, 0.22) hydrothermally grown single crystals were examined using cathodoluminescence to interrogate the changing electronic properties of ThO$_2$ as it became an alloy. Both depth-resolved and temperature-dependent cathodoluminescence studies were performed to examine the crystal structure and the defects present. An ultra-high vacuum system operating at 10$^{-8}$ Torr was used with electron beam energies ranging from 2 to 14 keV. Spectra were taken on all three samples before and after a proprietary chemical cleaning process involving a crown ether/picric acid solution was applied to the crystals to remove surface contaminants. Spectral deconvolution of the spectra showed evidence of both direct and indirect gap photon transitions from the O~2p to Th~6d at 4.2 eV and 4.8 eV respectively. Uranium-doped spectra showed evidence of the midgap O 2p to U 5f quadrupole transition and O~2p to U~6d transition at 5 eV.

–

Authors

  • Joshua Reding

    Air Force Institute of Technology

  • Zachary Richards

    Washington State University, Department of Physics, Bowling Green State University, 104 Overman Hall, OH 43403, USA, Nuclear Radiation Center, PO Box 641300, Washington State University, Pullman, WA 99164-1300, USA, Institute of Nuclear and Physical Engineering, Slovak University of Technology in Bratislava, Ilkovi\v{c}ova 3, 812 19 Bratislava, Slovak Republic, Air Force Institute of Technology, Oak Ridge Institute of Science and Education, Bowling Green State University, Department of Chemistry and Biochemistry, Southern Illinois University, Purdue University, University of Toledo

  • Zachary Richards

    Washington State University, Department of Physics, Bowling Green State University, 104 Overman Hall, OH 43403, USA, Nuclear Radiation Center, PO Box 641300, Washington State University, Pullman, WA 99164-1300, USA, Institute of Nuclear and Physical Engineering, Slovak University of Technology in Bratislava, Ilkovi\v{c}ova 3, 812 19 Bratislava, Slovak Republic, Air Force Institute of Technology, Oak Ridge Institute of Science and Education, Bowling Green State University, Department of Chemistry and Biochemistry, Southern Illinois University, Purdue University, University of Toledo