Hydrothermal Alteration of BaxMIVxCe2-2x(PO4)2 (MIV= Zr, Hf) Monazites as Hosts for Minor Actinides

Abstract BaxMIV xCe2-2x (PO4)2 [MIV=Zr, Hf] monazite-like compounds were succesfully synthesized by solid state reaction for x=0.2 (MIV=Zr) and x=0.1 (MIV=Hf). The low miscibility of BaMIV(PO4)2 (MIV=Zr, Hf) compounds in CePO4 was explained on the basis of the monoclinic-to-trigonal phase transition that occurs at 733 K in BaZr(PO4)2 and at 798 K in BaHf(PO4)2. The hydrothermal alteration of these compounds was tested using a modified MCC-1 static leaching test in acid (1 mol·dm-3 HCl) and basic (1 mol dm-3 KOH) solutions at 373 K, 473 K and 573 K; both the experimental fluids and the reacted solid specimens were analyzed by different analytical techniques and the reaction mechanisms were elucidated. All the tested compounds are stable in 1 mol·dm-3 HCl until 573 K. The stability of the monazites in 1 mol·dm-3 KOH is a function of the temperature.

POPA Karin;  KONINGS Rudy;  WISS Thierry;  LEISTE H.; 

2008-01-18

SPRINGER

JRC42859

0236-5731,   

http://www.springerlink.com/content/b01272x3g1822280/?p=b096dcd826114e7fb4294c721a2e4398&pi=9,    https://publications.jrc.ec.europa.eu/repository/handle/JRC42859,   

10.1007/s10967-007-0910-x,