Th diffusion in monazite

Diffusion of Th has been characterized in synthetic monazite under dry conditions. The synthetic monazites (either pure CePO4, NdPO4, or a mixed LREE phosphate containing Ce, Nd, and Sm) were grown via a Na2CO3–MoO3 flux method. The sources of diffusant for the experiments were either synthesized ThSiO4 or CaTh(PO4)2 powders mixed with CePO4. Experiments were performed by placing source and monazite in Pt capsules and annealing capsules in 1-atm furnaces for times ranging from 3 weeks to a few hours, at temperatures from 1350 to 1550 °C. The Th distributions in the monazite were profiled by Rutherford Backscattering Spectrometry (RBS).