A study was made Pb diffusion in synthetic (CePO4) and natural monazites under dry 1atm conditions. Powdered mixtures of pre-reacted CePO4 and PbZrO3 were used as the Pb source for in-diffusion experiments conducted within sealed Pt capsules for durations of a few hours to several weeks. Following diffusion annealing, the Pb concentration profiles were measured using Rutherford back-scattering spectroscopy and secondary ion mass spectrometry. At 1100 to 1350C, the Arrhenius relationship for in-diffusion in synthetic monazite was:

D (m2/s) = 9.4 x 10-1 exp[-592(kJ/mol)/RT]

D.J.Cherniak, E.B.Watson, M.Grove, T.M.Harrison: Geochimica et Cosmochimica Acta, 2004, 68[4], 829-40