Article Dans Une Revue Journal of Solid State Chemistry Année : 2005

Synthesis and characterization of uranium (IV) phosphate-hydrogenphosphate hydrate and cerium (IV) phosphate-hydrogenphosphate hydrate

Résumé

A new uranium (IV) phosphate of proposed formula $U_2(PO_4)_2HPO_4·H_2O$, i.e. uranium phosphate-hydrogenphosphate hydrate (UPHPH), was synthesized in autoclave and/or in polytetrafluoroethylene closed containers at $150\~C$ by three ways: from uranium (IV) hydrochloric solution and phosphoric acid, from uranium dioxide and phosphoric acid and by transformation of the uranium hydrogenphosphate hydrate $U(HPO_4)_2·nH_2O. The new product appears similar to the previously published thorium phosphate-hydrogenphosphate hydrate $Th_2(PO_4)_2HPO_4·H_2O$ (TPHPH). From preliminary studies, it was found that UPHPH crystallizes in monoclinic system (a= 2.1045(5)nm, b=0.6561(2)nm, c=0.6949(2)nm, $\Beta=91.67(3)~ and V=0.9768(10)nm$^3$). Heated under inert atmosphere, this compound is decomposed above 400~C into uranium phosphate-triphosphate $U_2(PO_4)P_3O_{10}, uranium diphosphate $\alpha-UP_2O_7$ and diuranium oxide phosphate $U_2O(PO_4)_2$. Crystallized cerium (IV) phosphate-hydrogenphosphate hydrate $Ce_2(PO_4)_2HPO_4·H_2O$ (CePHPH) was also synthesized from ($NH_4)_2Ce(NO_3)_6$ and phosphoric acid solutions by the same method (monoclinic system: a=2.1045(5)nm, b=0.6561(2)nm, c=0.6949(2)nm, $\Beta=91.98(1)~ and V=0.9588(9)nm$^3$). When heating above 600~C, cerium (IV) is reduced into Ce (III) and forms a mixture of CePO$_4$ (monazite structure) and CeP$_3$O$_9$.

Dates et versions

in2p3-00024192 , version 1 (31-05-2005)

Identifiants

Citer

V. Brandel, Nicolas Clavier, N. Dacheux. Synthesis and characterization of uranium (IV) phosphate-hydrogenphosphate hydrate and cerium (IV) phosphate-hydrogenphosphate hydrate. Journal of Solid State Chemistry, 2005, 178, pp.1054-1063. ⟨10.1016/j.jssc.2005.01.005⟩. ⟨in2p3-00024192⟩
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