A series of urea complexes with rare-earth nitrates: Synthesis, structure and thermal decomposition

Complexes of rare-earth nitrates with urea (Ur), [Nd(Ur)4(NO3)3], [Ln(H2O)(Ur)4(NO3)2]NO3 (Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Y), and [Lu(Ur)4(NO3)2]NO3, were synthesized and characterized by elemental analysis, IR spectroscopy, X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry. Molecular and crystal structures of [Sm(H2O)(Ur)4(NO3)2]NO3 and [Er(H2O)(Ur)4(NO3)2]NO3 were determined. All complexes were studied as precursors for preparing rare-earth oxides by solution combustion synthesis. Processes at 300-500 degrees C associated with conditions of combustion resulted in formation of rare-earth basic carbonates, which lost carbon dioxide at further heating. Powder X-ray diffraction showed formation of cubic rare-earth oxides at 900 degrees C.

Automated summary

Rare-earth nitrates complexes with urea were synthesized and characterized, with molecular and crystal structures determined for some of them. These complexes were studied as precursors for rare-earth oxides, with combustion processes forming rare-earth basic carbonates and eventually leading to the formation of cubic rare-earth oxides at 900 degrees C.