Luminescence Spectroscopy and Near-Infrared to Visible Upconversion of Nanocrystalline Gd₃Ga₅O₁₂:Er³⁺

Abstract

The near-infrared to visible upconversion properties of nanocrystalline Gd3Ga5O12:Er3+ (1 and 5%) were studied following excitation of the 4I9/2 exited state with 800 nm radiation. Intense green and red emissions were observed from the (2H11/2, 4S3/2) → 4I15/2 and 4F9/2 → 4I15/2 transitions, respectively. The upconverted decay times in the 1% sample were identical compared to those obtained with 488 nm excitation, indicating that ESA was responsible for populating the upper emitting states. However, as the Er3+ concentration was increased to 5%, the upconverted decay times were lengthened and deviated from exponentiality, indicating the presence of energy transfer upconversion. In addition, an enhancement of the red (4F9/2 → 4I15/2) upconversion emission was observed in the 5% sample and occurred via an energy transfer process of the type (4I9/2, 4I11/2) → (4I13/2, 4F9/2).

Synthesis, structural investigation and luminescence spectroscopy of nanocrystalline Gd3Ga5O12 doped with lanthanide ions

“…and it results to be 100 s, similar to that found for a GGG:Er 3+ nanocrystalline sample of the same composition prepared by a combustion synthesis (122 s) [6]. The radiative lifetime of the emitting states, estimated from a Judd-Ofelt analysis for a Er 3+ -doped GGG single crystal, is 200-220 s [19].…”

“…3, inset). The upconversion process can be tentatively assigned to the usual mechanism commonly reported in the literature for Er 3+ -doped materials [6]. It is worth to remark that the upconversion emission for the Er 3+ CP sample in the red region (around 650 nm, not shown) was very weak.…”

“…On the other hand, lanthanide-doped nanostructured materials have gained importance for possible applications as imaging or display devices in which the resolution is inversely related to the particle size [4,5]. The luminescence properties have been investigated for Pr 3+ -, Ho 3+ -and Er 3+ -doped GGG nanocrystalline powders prepared by a combustion synthesis [6,7]; these materials appear to show efficient visible upconversion emission after excitation with IR radiation. To the best of our knowledge, only a few papers have been published on the preparation and optical properties of lanthanide-doped nanocrystalline GGG * Corresponding author.…”

Structural and luminescence investigation on gadolinium gallium garnet nanocrystalline powders prepared by solution combustion synthesis

“…Moreover, the up-conversion processes are more efficient in lanthanide-doped GGG than in Y 2 O 3 or Lu 2 O 3 prepared with the same synthesis technique. This was explained by a much lower concentration of adsorbed contaminants (carbonate and hydroxide ions) on the surface of the GGG nanocrystals [26,27] with respect to Y 2 O 3 or Lu 2 O 3 nanocrystalline materials.…”

A General Strategy to Enhance Upconversion luminescence in Rare-Earth-Ion-Doped Oxide Nanocrystals

“…Such endeavors gain a lot from UC nanocrystals' unique capability that they can upconvert the absorbed, usually infrared and Near Infrared (NIR) light, into visible and ultraviolet radiations via the embedded rare-earth ions (Auzel, 2004;Vetrone et al, 2003). Unfortunately, these nanocrystals display a serious shortcoming, since their luminescent efficiency is inadequate to meet the requirements of many practical applications (Suyver et al, 2005;Sivakumar et al, 2007).…”