Nanocrystalline lanthanide-doped Lu3Ga5O12garnets: interesting materials for light-emitting devices

Nanocrystalline Lu 3 Ga 5 O 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 Pr 3+ , Eu 3+ , Gd 3+ , Ho 3+ , Er 3+ and Tm 3+ dopants, while room temperature excited luminescence spectra and emission decay curves of Eu 3+ -, Tm 3+ -and Ho 3+ -doped Lu 3 Ga 5 O 12 nanocrystals have been measured and are discussed.The Eu 3+ emission spectrum shows typical bands due to 5 D 0 → 7 F J (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 Lu 3 Ga 5 O 12 materials show better luminescence intensities compared to Y 2 O 3 , Gd 3 Ga 5 O 12 and Y 3 Al 5 O 12 nanocrystalline hosts.Moreover, the upconversion emission intensity in the blue-green region for the Tm 3+ -and Ho 3+ -doped samples shows a significant increase upon 647.5 nm excitation with respect to other common oxide hosts doped with the same lanthanide ions.