title: Nanocrystalline lanthanide-doped Lu3Ga5O12 garnets: interesting materials for light-emitting devices.
abstract: 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 5D(0)-->7F(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.
authors.affiliation: Department of Physics, Yogi Vemana University, Kadapa, India.
authors.forename: V
authors.initials: V
authors.lastname: Venkatramu
authors.forename: M
authors.initials: M
authors.lastname: Giarola
authors.forename: G
authors.initials: G
authors.lastname: Mariotto
authors.forename: S
authors.initials: S
authors.lastname: Enzo
authors.forename: S
authors.initials: S
authors.lastname: Polizzi
authors.forename: C K
authors.initials: CK
authors.lastname: Jayasankar
authors.forename: F
authors.initials: F
authors.lastname: Piccinelli
authors.forename: M
authors.initials: M
authors.lastname: Bettinelli
authors.forename: A
authors.initials: A
authors.lastname: Speghini