Synthesis and luminescence properties of nanocrystalline Gd3Ga5O12:Eu3+ by a homogeneous precipitation method

Nanocrystalline Gd3Ga5O12:Eu3+ with cubic phase was prepared by a urea homogeneous precipitation method. X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric and differential thermal analysis (TG-DTA) and photoluminescence spectra were used to characterize the samples. The effects of the initial solution pH value and urea content on the structure of the sample were studied. The XRD results show that pure phase Gd3Ga5O12 can be obtained at pH =6 and pH =8 of the initial solution. The average crystallite size can be calculated as in the range of 24-33 nm. The average crystallite size decreases with increasing molar ratio of urea to metal ion. The results of excitation spectra and emission spectra show that the emission peaks are ascribed to D-5(0)-> F-7(J) transitions of Eu3+, and the magnetic dipole transition originated from D-0 -> F-7(1) of Eu3+ is the strongest; the broad excitation bands belong to change transfer band of Eu-O and the host absorption of Gd3Ga5O12. An efficient energy transfer occurs from Gd3+ to Eu3+.