Thorium and Rare Earth Monoxides and Related Phases

Area of Science:

• Solid-state chemistry
• Materials science
• Nuclear energy

Background:

• Thorium dioxide was historically significant for its refractory and electronic properties.
• Thorium represents an abundant nuclear fission energy reserve for future infrastructure.
• Thorium monoxide (ThO) has been theoretically studied but not synthesized in bulk.

Purpose of the Study:

• To investigate the solid-state chemistry of thorium monoxide (ThO) and related rare earth monoxides.
• To determine the stability of ThO under high-pressure and high-temperature conditions.
• To explore the potential for synthesizing ThO and mixed Th-Nd oxides.

Main Methods:

• First-principles computations were employed to predict material properties.
• Ab initio calculations incorporated temperature effects up to 1000 K using lattice dynamics.
• The quasi-harmonic approximation was used to model high-pressure and high-temperature behavior.

Main Results:

• Computational results confirm the stabilization of pure ThO at pressures above 30 GPa.
• The study suggests the possibility of synthesizing (Th,Nd)O at 1000 K and 5 GPa.
• Lanthanide monoxides exhibit diverse properties, including ferromagnetic semiconducting behavior and metallic characteristics.

Conclusions:

• High-pressure and high-temperature conditions are crucial for stabilizing thorium monoxide.
• Computational methods provide valuable insights into the synthesis of novel materials.
• Thorium-based materials hold promise for future energy applications and advanced electronics.