Electronic and physical characterization of hydrothermally grown single crystal ThO2.

摘要

This dissertation focused on extracting the geometric and electronic structure of hydrothermally synthesized ThO2 single crystals. Not only do these results allow for future crystal growth to be pursued in an informed and purposeful direction, but they provide insight into the nature of ThO2 in single crystal form and the manner in which the properties differ when compared to the other forms found in literature (powders, colloids, etc).;The valence and conduction bands were studied with ultraviolet photoemission, inverse photoemission, and x-ray absorption near edge structure in order to ascertain the band gap and investigate the 5f band behavior. The experimental techniques were compared to the results of real space Green's function calculations.;Long range order was measured with x-ray diffraction and compared to the local order structure from extended x-ray absorption near structure. The average fluorite structure was confirmed and an O-shell splitting was analyzed. In order to remove experimenter bias from the extended x-ray absorptionnear structure analysis, a Latin hypercube sampling code was written. This software increased both speed and efficiency in searching for local minima in the parameters' space as well as selecting out the true minimum.;A depth resolved x-ray photoemission experiment extracted shake-up satellites representative of additional final states. The results provided information concerning the valence and conduction bands. A surface to core-level shift was observed. Two new satellites were discovered and their results interpreted. Finally, a Debye temperature was extracted for the crystals using the Th 4f core levels.