Insights into the europium-doped yttrium oxalate thermal decomposition mechanism

• The thermal decomposition mechanism of Y/Eu oxalate precursor has been proposed.
• The formation of the (Y,Eu)2O2CO3 intermediary phase during the decomposition.
• The structural, morphological and luminescence characterizations have been achieved.

We report on the synthesis and characterization of Eu3+-doped Y2O3 nanocrystalline particles prepared by the oxalate (co)-precipitation method. Based on thermogravimetric analyses coupled with mass spectrometry, and correlated with FT-IR analyses and X-ray diffraction (XRD) measurements performed on the Eu3+-doped Y2O3 oxalate-type precursor, a thermal decomposition mechanism has been proposed. The yttrium oxy-carbonate formation, as an intermediate product during the decomposition process, was evidenced. The XRD analysis has indicated the formation of crystalline cubic Y2O3 structure at a temperature above 900 K after the complete decomposition of the yttrium oxy-carbonate intermediate. Transmission electron microscopy (TEM) investigations sustain the nanocrystalline nature of the Y2O3:Eu particles, with spherical and polyhedral shapes, and with an average size in the range of 5–10 nm. The photoluminescence (PL) measurements have revealed a strong red emission peak at 613 nm corresponding to the 5D0 → 7F2 forced electric dipole transition of the Eu3+ ions under an excitation wavelength of 254 nm. The emission strongly increased with the increase of the calcination temperature from 773 K, when the yttrium oxy-carbonate decomposition process has been started.