The unoccupied electronic structure characterization of hydrothermally grown ThO₂ single crystals

Authors

T D. Kelly, Air Force Institute of TechnologyFollow
J C. Petrosky, Air Force Institute of TechnologyFollow
D Turner, Oak Ridge Institute for Science and Education
J W. McClory, Air Force Institute of Technology
J M. Mann, Air Force Institute of Technology
J W. Kolis, Clemson University
Xin Zhang, University of Nebraska-LincolnFollow
Peter A. Dowben, University of Nebraska-LincolnFollow

Date of this Version

2014

Citation

P hys. Status Solidi RRL 8 (2014)

Comments

U.S. Government work

Abstract

Single crystals of thorium dioxide ThO₂, grown by the hydrothermal growth technique, have been investigated by ultraviolet photoemission spectroscopy (UPS), inverse photoemission spectroscopy (IPES), and L₃, M₃, M₄, and M₅ X-ray absorption near edge spectroscopy (XANES). The experimental band gap for large single crystals has been determined to be 6 eV to 7 eV, from UPS and IPES, in line with expectations. The combined UPS and IPES, place the Fermi level near the conduction band minimum, making these crystals n-type, with extensive band tailing, suggesting an optical gap in the region of 4.8 eV for excitations from occupied to unoccupied edge states. Hybridization between the Th 6d/5f bands with O 2p is strongly implicated.