Structural Studies and Thermal Analysis in the Cs₂MoO₄–PbMoO₄ System with Elucidation of β-Cs₂Pb(MoO₄)₂

Abstract

The quaternary compound Cs 2 Pb(MoO 4 ) 2 was synthesized and its structure was characterized using X-ray and neutron diffraction from 298 to 773 K, while thermal expansion was studied from 298 to 723 K. The crystal structure of the high-temperature phase β-Cs 2 Pb(MoO 4 ) 2 was elucidated, and it was found to crystallize in the space group R 3̅ m (No. 166), i.e., with a palmierite structure. In addition, the oxidation state of Mo in the low-temperature phase α-Cs 2 Pb(MoO 4 ) 2 was studied using X-ray absorption near-edge structure spectroscopy. Phase diagram equilibrium measurements in the Cs 2 MoO 4 –PbMoO 4 system were performed, revisiting a previously reported phase diagram. The equilibrium phase diagram proposed here includes a different composition of the intermediate compound in this system. The obtained data can serve as relevant information for thermodynamic modeling in view of the safety assessment of next-generation lead-cooled fast reactors.

Reaction Capsule Design for Interaction of Heavy Liquid Metal Coolant, Fuel Cladding, and Simulated JOG Phase at Accident Conditions

“…MOX phases are not considered as major corrosive chemicals. However, JOG phases comprise oxidizing substances such as cesium molybdate, but also iodides and tellurides as found experimentally [36][37][38][39], and have been validated by thermodynamic calculations [40][41][42][43].…”