engleski

Synthesis, identification and thermal decomposition of double sulfates of La, Ce, Pr or Nd with ethanolammonium

On evaporation at room temperature of an aqueous reaction mixture of Ln(III) sulphate and ethanolammonium sulphate in molar ratio higher than 1:16 crystal products with a waxy feel were obtained. They were identified by means of the x-ray powder diffraction and it was concluded that they are isostructural. The results of elemental analysis and the mass losses by TGA indicated the formation of double sulphates with the general formula: (HOCH2CH2NH3)4Ln2(SO4)5 ; (Ln=La, Ce, Pr or Nd). Their thermal decomposition in the temperature range from ambient up to 1173 K took place in a similar way, and mainly Ln2O2SO4 was obtained as final product. The exception was the Ce compound, which decomposed to CeO2. The double sulphates decomposed in many not well-defined steps. From the mass losses occuring during thermal decomposition, the mode of thermal decomposition was presumed. The x-ray powder diffraction patterns of Ln2O2SO4 (Ln=La, Pr and Nd) show that they are isostructural.

double sulphates; lanthanides; synthesis; thermal studies

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