Thorium Dioxide Nanoscale Materials and Thin Films Prepared by Combustion Synthesis*

Thorium dioxide (ThO₂) is a highly considered nuclear fuel for generation IV breeder reactors and  ThO₂ thin film target materials are needed for basic nuclear science measurements. Here, we report on a novel solution combustion synthesis (SCS) method for ThO₂ nanoscale materials and thin films. An exothermic chemical reaction in thorium nitrate-2-methoxyethanol-acetylacetone solutions is investigated to prepare these materials. First, thermodynamic modeling of this system was completed to optimize conditions for SCS. Next, the effects of various process parameters, such as furnace temperatures and holding times, on the structure and morphology of ThO₂ nanopowders were investigated. The nanopowders are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), showing that the crystallinity and morphology of the products can be controlled by tuning processing conditions. Finally, SCS is combined with the spin coating method to create thin films of tunable thicknesses on different backings (e.g. carbon, aluminum). X-ray fluorescence analysis, electron microscopy, and alpha spectroscopy prove that films are highly uniform.

 

This method is a significant advance in targetry for nuclear science studies and has broad applications including stockpile stewardship.