Single and multicomponent garnets nanoparticles – Synthesis and luminescence

YAG:Ce3+ Phosphor: From Micron-Sized Workhorse for General Lighting to a Bright Future on the Nanoscale

“…The matrix approach made use of an oven, without separate combustion step . The resulting particles are either large crystals ,,, or sintered materials. − ,, The solvothermal procedure is a one-step synthesis to yield either agglomerated − or individual nanocrystals. ,− One paper reports subsequent calcining in a matrix, yielding large crystals …”

“…Most glycothermal syntheses of nano YAG are performed using aluminum isopropoxide and hydrated acetate precursors. ,,− ,, This type of precursors yields phase pure YAG particles after reaction at temperatures as low as 225–300 °C for 2 h to several days. ,,− ,, Other precursor materials like carbonates are reported as well, as they are suspected to result in higher pressures and thus possibly allow for crystallization at lower reaction temperatures or shorter reaction times. , However, in a synthesis using carbonates, the resulting pressures during the reaction at 300 °C reported by Li et al and Aboulaich et al (10 and 3.2 MPa) are in the same range as pressures reported for systems based on acetates and aluminum isopropoxide. , Li and co-workers use a mixture of water and ethanol as solvent and report intermediate phases of Y 2 O 3 +YAM (after 2 h heating at 260 °C), and YAP+YAM+YAG (after 2 h heating at 280 °C) before phase pure YAG is formed after 2 h at 290 °C (50 nm particles, Figure A) . In contrast, only 5 min reaction at 300 °C is enough to form 30 nm sized phase pure YAG particles when using 1,4 butylene glycol and water as solvents (Figure B) as reported by Aboulaich et al The effect of pressure on the more commonly used set of chemicals aluminum isopropoxide and acetates in 1,4 butanediol was studied by Dantelle et al They observe crystallization at lower reaction temperatures when higher pressures are used (externally controlled by pumping H 2 ), but high pressures also induce aggregation of the YAG nanoparticles.…”

“…When dried precursors are used, the water formed during the 1,4 butanediol cyclization reaction is just enough to keep the reaction going while the nanoparticles stay small and individual. Similar deaggregation effects of diethylene glycol addition were reported by Wiatrowska et al, who obtained 30 nm sized nonaggregated YAG particles after a synthesis at 225 °C for 24–84 h in Ar atmosphere . In addition, they report a small fraction of Y 2 O 3 phase, which can be prevented by using excess Al isopropoxide which has no effect on the final particle size.…”

The effect of BaF2 concentration and particle size distribution on the luminescence efficiency of YAG:Ce3+ phosphors

“…The most intense emission corresponds to the transition from the 5d lowest sublevel to the two levels of the 4f-shell. The splitting of the 4f level into the 2 F 5/2 and 2 F 7/2 states leads to the doublet character of the Ce 3+ emission ions [24]. The luminescence decay kinetics for all investigated powders excited by LED chip working in pulsed mode was studied.…”

Deep submicrometer YAG:Ce phosphor particles with high photoluminescent quantum yield prepared by flame spray synthesis

“…Yttrium aluminum garnet (Y 3 Al 5 O 12 , YAG) is a ceramic material of high importance as a host of rare earth ions for optical applications . Among the lanthanide ions, cerium (Ce 3+ ) is one of the most interesting for doping YAG producing YAG:Ce phosphors extensively studied for blue to white light conversion . However, obtaining the desired cubic YAG phase is not straightforward and requires high calcination temperatures and long dwell times for many synthesis methods.…”