Comparison of thermal and hydrothermal decomposition methods in the synthesis of thorium dioxide

The synthesis of thorium dioxide (ThO₂) with precise control over its microstructure and surface properties plays a critical role in nuclear technology. In this study, the conversion of thorium oxalate to ThO₂ was investigated using both thermal and hydrothermal decomposition methods, and the effects of key process parameters, including temperature and pH, on morphology, particle size, and surface characteristics were analyzed. The results showed that hydrothermal decomposition at moderate temperature (220 °C) and pH ≈ 1 produces spherical particles with a uniform size distribution, an average particle size of approximately 0.4 μm, and a high specific surface area of 18.3 m²/g, whereas thermal decomposition at 700 °C preserves the morphology of the precursor and yields larger particles (~ 2 μm). A comprehensive comparison of the two approaches provides guidance for selecting the most suitable method for different applications.