Preparation, Growth Mechanism, Upconversion, and Near-Infrared Photoluminescence Properties of Convex-Lens-like NaYF₄ Microcrystals Doped with Various Rare Earth Ions Excited at 808 nm

Abstract

Preparation of rare earth ions doped photoluminescence materials with controlled morphology was desired to fulfill the requirement of different applications. In the work, convex-lens-like NaYF 4 microcrystals doped with various rare earth ions were prepared by adjusting preparation parameters including the reaction time, reaction temperature, NaOH concentration, ratio of oleic acid to 1-octadecene, and types of doping ions. A possible growth mechanism of convex-lenslike NaYF 4 microcrystals is proposed based on reaction time and temperature-dependent morphology evolution. The formation of microconvex-lens includes the three processes of NaYF 4 nanoparticles selfassemble, dissolution−nucleation, and regrowth. Doping ions dependent near-infrared and upconversion luminescence properties of convex-lenslike NaYF 4 microcrystals were investigated excited at 808 nm. The visible upconversion luminescence was observed in the

Dual-Wavelength Excited Intense Red Upconversion Luminescence from Er3+-Sensitized Y2O3 Nanocrystals Fabricated by Spray Flame Synthesis

“…For the fabrication of co-doped (e.g., Er 3+ /Tm 3+ ) UCNPs with high crystallinity and quantum efficiency, liquid-phase synthesis methods (solvothermal and hydrothermal) were demonstrated to be effective [ 7 , 25 ]. However, in liquid-phase synthesis strategies, the governing parameters including shielding gas, reaction time, temperature, pressure and concentration must be controlled strictly and the synthesis process always takes tens of hours with a low production rate [ 26 , 27 ]. It greatly restricts the practical applications of the high quality UCNPs.…”

Enhanced Red Emission in Er3+-Sensitized NaLuF4 Upconversion Crystals via Energy Trapping

“…Trivalent lanthanide (Ln)-doped upconversion (UC) nano-/microcrystals, which can convert two or more low-energy photons into a single high-energy photon through an anti-Stokes process, hold great promise in diverse fields such as biological imaging, − solar cells, , anticounterfeiting, , therapeutics, , and solid-state lasers. , Ln-doped UC materials show various advantages, including low toxicity, long luminescence lifetimes, and high photochemical stability. − However, one of the major drawbacks of UC nano-/micromaterials is their low luminescence efficiency. Relative to blue and green emissions, red emission (600–700 nm) can induce deep penetration and cut down tissue damage due to the lack of efficient endogenous absorbers. − Thus, an effective strategy to enhance the red UC emission is urgently needed, especially for their practical application in bioimaging.…”

“…Trivalent lanthanide (Ln)-doped upconversion (UC) nano-/ microcrystals, which can convert two or more low-energy photons into a single high-energy photon through an anti-Stokes process, 1 hold great promise in diverse fields such as biological imaging, 2−6 solar cells, 7,8 anticounterfeiting, 9,10 therapeutics, 11,12 and solid-state lasers. 13,14 Ln-doped UC materials show various advantages, including low toxicity, long luminescence lifetimes, and high photochemical stability. 15−19 However, one of the major drawbacks of UC nano-/ micromaterials is their low luminescence efficiency.…”

Revisiting the Enhanced Red Upconversion Emission from a Single β-NaYF4:Yb/Er Microcrystal By Doping with Mn2+ Ions

“…Photon UC in lanthanide-doped nanomaterials has drawn much attention recently due to their superior spectroscopic properties [ 1 , 2 ]. As the most significant near-infrared (NIR) to visible UC structures, the lanthanide-sensitized UC based on the ET from Yb 3+ to Er 3+ (Tm 3+ /Ho 3+ ) in β-NaYF 4 nanocrystals has been studied intensively owing to its promising applications in color display [ 3 , 4 ], super-resolution nanoscopy [ 5 , 6 ], security printing [ 7 , 8 ], laser materials [ 9 – 11 ], and biological luminescent labels [ 12 – 14 ].…”