Sur les phases de structure scheelite dans les systems molyboate de plutonium — Molybdate de lithium ou sodium

Structural and thermal studies on Na2Th(MoO4)3, Na2Pu(MoO4)3, Na4Th(MoO4)4 and Na4Pu(MoO4)4

“…3 During heating, TG curve did not show any weight change up to 1000 • C, whereas DTA curve showed an endothermic peak at 740 • C due to the melting of the compound. Two peritectic changes at 706 and 714 • C corresponding to Na 4 Pu(MoO 4 ) 4 and Na 2 Pu(MoO 4 ) 3 are reported by Tabuteau et al [1] in the liquid-solid phase diagram of Na 2 MoO 4 -Pu(MoO 4 ) 2 . The cooling DTA curve of Na 2 Pu(MoO 4 ) 3 gave an exothermic peak at 570 • C due to crystallisation of the compound.…”

“…The XRD data of Na 2 Th(MoO 4 ) 3 and Na 2 Pu(MoO 4 ) 3 were indexed on tetragonal cell with the cell parameters a = 0.52884 (4) nm and c = 1.15659 (14) nm and a = 0.52277 (8) nm and c = 1.13810 (15) nm, respectively, which were comparable with the reported data in the literature [1]. The similarities in the cell parameters of Na 2 Th(MoO 4 ) 3 and Na 2 Pu(MoO 4 ) 3 suggest that the compounds are isostructural.…”

“…6) showed two endothermic peaks at 590 and 705 • C, due to phase change and melting of the compound, respectively. Tabuteau et al [1] have reported peritectic change of Na 4 Pu(MoO 4 ) 4 at 706 • C. During cooling DTA curve showed a single exothermic peak at 520 • C due to the solidification of the compound. When Na 4 Pu(MoO 4 ) 4 was heated in a thermoanalyzer up to 1400 • C, TG curve showed only one step weight loss between 1000 and 1400 • C. By weight loss calculation and from XRD patterns, the end products at 1400 • C were identified as a mixture of Na 4 PuO 5 and PuO 2 .…”

“…Tabuteau et al [1,2] have studied alkali metal-plutoniummolybdenum-oxygen quaternary system by means of liquid- * Corresponding author. Fax: +91 22 25505151.…”

Tungstate Based Ceramics Obtained By Spark Plasma Sintering Method – Possible Material for Consolidation of Radioactive Wastes’ Components

“…Among them, solid solutions of tungstates and molybdates of cerium [17], thorium, uranium, plutonium [18][19][20]. Moreover, tungstates and isostructural molybdates with scheelite structure can be formed in precipitation processes in alkali chloride melts and possess high chemical stability in relation to them [21][22][23].…”