Precise Tuning of the Nanostructured Surface leading to the Luminescence Enhancement in SrAl2O4 Based Core/Shell Structure

Abstract

Intensive research has been focused on the synthesis of long-lasting SrAl2O4:EuDy in luminescent materials field. Traditionally, SrAl2O4:EuDy is synthesized in bulk form by solid state. However, their development remains restrained due to this technique is not compatible with large-scale production, sustainability and nanometer-scale requirements. Despite nano-range particles have been obtained by chemical routes, photoluminescence response decreases and application became unpractical. It remains a challenge to synthesize nonrare-earth (RE) phosphors with high photoluminescence. One major challenge for the luminescent materials community is to devise methods to deliver innovative, sustainable and cost effective solutions for the reduction of RE because of the lack of RE availability. Here, we suggest a solution based on molten salts, obtaining nanosheets or micro/nanostructured SrAl2O4:Eu, Dy particles with core-shell structure, employing only 50% of standard amounts of RE. Core-size and shell thickness and crystallinity can be tuned by post-thermal treatment, through which can be modulated the Eu+2 fraction. We find that our methodology leads the functional features of the analogous micron counterpart. These results can be considered a great achievement to scale-up the process. Besides, the harmful collateral effect of nanotechnology must be addressed by using new safe by design core-shell nanostructures.

Unveiling the role of the hexagonal polymorph on SrAl2O4-based phosphors

“…†). The particles with type I and II morphology could be formed by shell-like SrAl 2 O 4 formation and a core of Al 2 O 3 , as has been observed previously, 27 when the dissolution-diffusion transport mechanism ("template mechanism") is the dominant mechanism in molten salt route.…”

“…Al MAS NMR and 2D MQ-MAS 27 Al NMR study: one more step to reveal the origin of the macroscopic photoluminescence response of the hexagonal polymorph Solid-state NMR has specic and important advantages compare to XRD by studying the local structure around a selected nucleus, with no limitations due to disorder in the sample. NMR is a local probe that detects all the structures regardless of whether they are related to crystalline phase, amorphous phase.…”

“…The 27 Al quantitative one pulse MAS NMR spectra at 20 T of the powders synthesized with different ZnO content at 1000 C are shown in Fig. 7.…”

“…8(a) illustrates the 27 Al MAS (experimental (blue) and simulated (red)) and MQ-MAS spectra and with its simulation of the alumina precursor (g-Al 2 O 3 phase). The observed 27 Al line shapes are characteristic of a distribution of 27 Al chemical shi and quadrupolar coupling constant. 1D and 2D spectra are very satisfactorily simulated using a fully random distribution of quadrupolar and isotropic chemical shi interactions as expressed within the GIM model.…”

The trap bag concept of afterglow luminescence

“…Strontium aluminate phosphors (SrAl 2 O 4 : Eu 2+ , Dy 3+ ) demonstrate excellent afterglow luminescence properties 1 . These include an increased luminescence duration, high light intensity, non-toxicity, and good chemical resistance.…”