Synthesis of apatite phosphates containing Cs+, Sr2+ and RE3+ ions and chemical durability studies

Crystallization of Cs, Sr and selected rare earth ions in apatite phosphate structure was investigated. Compounds of the formula CsLaSr3(PO4)3OH (CSOH), CsLaSr3(PO4)3F (CSF) and the simulated waste forms of the compositions CsLa0.8Nd0.1Sm0.1Sr3(PO4)3OH (CNSOH) and CsLa0.7Nd0.1Sm0.1Eu0.1Sr3(PO4)3F (CNSEF) were synthesized and characterized by powder XRD, TGA and SEM techniques. The leachability behaviour of the single phases was studied for a period of one month by MCC-5 test using powder specimen. The leachability of Cs and other rare earth ions was found to be negligible. The leach rates (LRi) of Sr and P were observed as follows: CSOH – LRSr = 10−3–10−4 g/m2/d, LRP = 10−4 g/m2/d; CSF – LRSr = 10−3–10−5 g/m2/d, LRP = 10−4–10−5 g/m2/d; CNSOH and CNSEF – LRSr = 10−3–10−4 g/m2/d, LRP = 10−4–10−5 g/m2/d.

New chemically durable hydroxy and fluoro apatite phosphate wasteforms CsLa0.8Nd0.1Sm0.1Sr3(PO4)3OH and CsLa0.7Nd0.1Sm0.1Eu0.1Sr3(PO4)3F are fabricated.Figure optionsDownload as PowerPoint slideHighlights
► Novel apatite phosphates CsLaSr3P3(PO4)3OH and CsLaSr3(PO4)3F are reported.
► New hydroxyapatite wasteform CsLa0.8Nd0.1Sm0.1Sr3P3O12OH is fabricated.
► Fluoro analogue CsLa0.7Nd0.1Sm0.1Eu0.1Sr3P3O12F incorporates ‘Eu3+’.
► Negligible leachability of Cs and rare earth ions demonstrated.