[Preparation and luminescence properties of nanocrystals Gd2O3: Eu3+]

Nanocrystalline Gd2O3 doped with europium was synthesized by the low-temperature combustion method. By using the X-ray diffraction (XRD), high resolution transmission electron microscopy( HRTEM), and fluorescence spectrophotometer, the structural, morphological and luminescence properties of the nanocrystal were investigated. The results show that by varying the glycine-to-metal nitrate (G/M) molar ratio and the annealing temperature, nanocrystalline Gd2O3: Eu3+ with different structure and grain size could be achieved. The structure changed from cubic to monoclinic with the increment of G/M ratio after the samples had been calcined at 800 degrees C for 0.5 hour. When the G/M ratio was 0.83 and 1.0, the nanosized and pure cubic phase Gd2O3: Eu3+ was produced. The crystalline size became bigger with increasing the annealing temperature. The grain size was about 10-30 nm. The main emission peak in cubic Gd2O3: Eu3+ nanocrystal was at 612 nm(the (5)D0-->F2 transition). In addition, a red shift for charge transfer state occurred in the excitation spectrum.