Nanocrystalline lanthanide-doped Lu3Ga5O12 garnets: interesting materials for light-emitting devices

Nanocrystalline Lu3Ga5O 12, with average particle sizes of 40 nm, doped with a wide variety of luminescent trivalent lanthanide ions have been prepared using a sol-gel technique. The structural and morphological properties of the powders have been investigated by x-ray powder diffraction, high resolution transmission electron microscopy and Raman spectroscopy. Structural data have been refined and are presented for Pr3 +, Eu3 +, Gd3 +, Ho3 +, Er3 + and Tm3 + dopants, while room temperature excited luminescence spectra and emission decay curves of Eu3 +-, Tm3 +- and Ho3 +-doped Lu3Ga5O 12 nanocrystals have been measured and are discussed. The Eu3 + emission spectrum shows typical bands due to (J = 0, 1, 2, 3, 4) transitions and the broadening of these emission bands with the non-exponential behaviour of the decay curves indicates the presence of structural disorder around the lanthanide ions. Lanthanide-doped nanocrystalline Lu3Ga5O 12 materials show better luminescence intensities compared to Y2O3, Gd3Ga5O 12 and Y3Al5O 12 nanocrystalline hosts. Moreover, the upconversion emission intensity in the blue-green region for the Tm3 +- and Ho3 +-doped samples shows a significant increase upon 647.5 nm excitation with respect to other common oxide hosts doped with the same lanthanide ions. © 2010 IOP Publishing Ltd.