Rare earth (Eu3+, Tb3+, Er3+)-doped gadolinium gallium garnet (Gd3Ga5O12, GGG) nanocrystalline powder and thin film phosphors were prepared by the Pechini sol-gel process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM) as well as photo luminescence (PL) spectra were used to characterize the resulting powder and film samples. Both the powders and the coatings crystallized completely at 800 degrees C. The dopant rare earth ions show their characteristic emissions in Gd3Ga5O12 phosphors, i.e., D-5(0)-F-7(J) (J = 1, 2, 3, 4) transitions for Eu3+, D-5(4)-F-7(J) (J = 3, 4, 5, 6) transitions for Tb3+ and (H-2(11/2)- I-4(15/2), S-4(3/2) - I-4(15/2)) transitions for Er, respectively. In addition, the near infrared emission spectra (NIR) and the near infrared to visible upconversion (anti-Stokes) luminescence of Er3+ were also observed in the Er3+-doped Gd3Ga5O12 samples. Possible mechanism responsible for the upconversion luminescence of Er3+ was proposed. (c) 2005 Elsevier B.V. All rights reserved.