Solid state reactions of CeO2, ThO2 and PuO2 with ammonium sulphate

Solid state reactions of CeO2, ThO2 and PuO2 with (NH4)2SO4 were investigated by chemical, IR, thermal and X-ray diffraction methods. At 250 C, CeO2, ThO2 and PuO2 formed tetrasulphate compounds i.e., (NH4)4Ce(SO4)4, (NH4)4Th(SO4)4 and (NH4)4Pu(SO4)4, respectively. On further heating (NH4)4Ce(SO4)4 decomposed to give (NH4)2Ce(SO4)3, (NH4)Ce(SO4)2 and Ce2(SO4)3; where, cerium undergoes change in oxidation state from +4 to +3. The decomposition of (NH4)4M(SO4)4 (M = Th or Pu) led to the formation of (NH4)2M(SO4)3 and M(SO4)2. Crystal data for solid reaction products were determined from their X-ray powder diffraction data. Dissolution of the products formed at 350-360 C during the reactions of CeO2, ThO2 and PuO2 with (NH4)2SO4 was also investigated. (orig.)