Synthesis of Thorium Dioxide Nanocrystals via Molten Salt Thermal Decomposition for Nuclear Energy-Related Applications

In addition to uranium, thorium is a vital nuclear element that has broad potential for future nuclear energy applications. Herein, we report the synthesis of cubic structured ThO2 nanocrystals (NCs) based on the decomposition of their nitrate salt in air and in a molten salt medium. Both the processes yield pure ThO2 NCs with average sizes of <100 nm. The ThO2 NCs synthesized in the molten salt medium exhibit better crystallinity and a larger average size of ∼75.1 nm with a narrow size distribution owing to the high-temperature liquid growth environment. The ceramic sintered from the salt-derived ThO2 NCs exhibits a considerably higher relative density of 94.6% and similar thermal properties compared with the ceramic fabricated from fine nanopowders (<10 nm) obtained from direct thermolysis of metal nitrate. This study shows that thermal decomposition in a molten salt medium could be an efficient method for producing highly crystalline metal-oxide NCs of thorium-based fuels used in nuclear energy applications.