Chemical Vapor Deposition of Phase‐Pure Uranium Dioxide Thin Films from Uranium(IV) Amidate Precursors

Abstract

Homoleptic uranium(IV) amidate complexes have been synthesized and applied as single-source molecular precursors for the chemical vapor deposition of UO 2 thin films.T hese precursors decompose by alkene elimination to give highly crystalline phase-pure UO 2 films with an unusual branched heterostructure.

Irradiation-Driven Restructuring of UO2 Thin Films: Amorphization and Crystallization

“…The lack of simple and efficient thin-film deposition methods for UO 2 impedes radiation damage investigation at the nanoscale level. Safety concerns for radioactive UO 2 limit the available deposition methods to magnetron sputtering (MS), − chemical vapor deposition (CVD), , and polymer-assisted deposition (PAD). , MS allows deposition of films with preferred crystallographic orientation on selected single-crystalline substrates ,− ,− and requires high-vacuum instrumentation and special handling conditions for pyrophoric metallic uranium as a source material. The CVD method uses toxic volatile organouranium precursors. ,, Films exhibit good adhesion to substrates, but they often contain other oxides of uranium.…”

“…Safety concerns for radioactive UO 2 limit the available deposition methods to magnetron sputtering (MS), − chemical vapor deposition (CVD), , and polymer-assisted deposition (PAD). , MS allows deposition of films with preferred crystallographic orientation on selected single-crystalline substrates ,− ,− and requires high-vacuum instrumentation and special handling conditions for pyrophoric metallic uranium as a source material. The CVD method uses toxic volatile organouranium precursors. ,, Films exhibit good adhesion to substrates, but they often contain other oxides of uranium. The PAD method uses a solution of uranyl nitrate and polyethylenimine to be deposited by spin coating. ,,, Further burning off the organic residues and obtaining crystalline UO 2 require a slow (1 °C/min) heating to high temperatures (1000 °C).…”

“…The CVD method uses toxic volatile organouranium precursors. 41,42,50 Films exhibit good adhesion to substrates, but they often contain other oxides of uranium. The PAD method uses a solution of uranyl nitrate and polyethylenimine to be deposited by spin coating.…”

Structural properties of ultra-small thorium and uranium dioxide nanoparticles embedded in a covalent organic framework

“…1,5,6 Actinide nanoparticles are also known to play a major role in the migration of radionuclides through environmental systems, [7][8][9][10][11] and have been proposed as agents for targeted alpha-therapy, [12][13][14][15][16][17] and for applications in thermopower 18 and heterogeneous catalysis. [19][20][21][22][23][24] Further innovation in these areas will require methods to synthesize and characterize actinides at the nanoscale, an area that is relatively unexplored and beyond current predictive capabilities. For stable d-block metals, it has been well-established that as grain size is reduced to the nanoscale in discrete particles certain electronic, magnetic, and chemical phenomena may emerge that do not occur in bulk solids or in molecular systems.…”

Recent Advances in Nuclear Forensic Chemistry

“…There is a growing need within the nuclear forensic community for particulate uranium- and plutonium-based CRMs with a known isotopic composition, as most current CRMs for nuclear forensic applications are only available as bulk materials. ,− Without microanalytical control measurements on independently verified and standardized particulate materials, forensic analysis of seized nuclear materials could potentially be deemed inadmissible in certain courts. , Production of these standard materials relies upon the development of controllable synthetic routes, which are in turn dependent upon a mechanistic understanding of the formation processes. Within the past few years, a relatively large amount of progress in this realm has led to the discovery of new or substantially improved processes to synthesize these nanomaterials − and has also resulted in significant improvements for their characterization. We predict that a firmer understanding of the chemistry involved in actinide nanomaterials synthesis will result in significant improvements to the quality of reference materials for nuclear forensic analysis and, furthermore, that this research will improve the capability of microanalysis as a tool for nuclear forensic fingerprinting.…”