Microwave-assisted synthesis and upconversion luminescence of NaYF4:Yb, Gd, Er and NaYF4:Yb, Gd, Tm nanorods

Abstract

Anisotropic rare-earth ion (RE3+) doped fluoride upconversion particles are emerging as a potential candidate in diverse areas, ranging from biomedical imaging to photonics. Here, we develop a facile strategy to synthesize NaYF4:Yb, Er, Gd and NaYF4:Yb, Tm, Gd upconversion nanorods via microwave synthesis route by controlling the synthesis time and compared the optical properties of similar nanorods prepared via solvothermal technique. With the increase in synthesis time, the phase of the particle was found to change from mixed-phase to purely hexagonal and the morphology of the particles change the mixed phase of spherical and rod-shaped particles to completely nanorods for a synthesis time of 60 minutes. Further, the intrinsically hydrophobic particles changed to hydrophilic by removal of oleic capping via acid treatment and the amine-functionalized silica coating. The upconversion luminescence, as well as laser power-dependent emission properties of the surface-modified particles, elucidate that the surface modification route influence the upconversion luminescence as well as solvent-dependent emission properties. Moreover, the laser power-dependent studies elucidate that the upconversion process in a multi-photon process.

Nanocrystals Incorporated with Mordenite Zeolite Composites with Enhanced Upconversion Emission for Cu2+ Detection

“…Under the excitation of a 980 nm laser, the upconversion luminescence spectrum of NaREF4:Yb/Er@DSi1.0MOR exhibits a characteristic emission of Er 3+ in the visible region, in which the emission peaks located at 521, 542, and 654 nm can be well attributed to the radiative transitions of Er 3+ : 2 H11/2→ 4 I15/2, 4 S3/2→ 4 I15/2, and 4 F9/2→ 4 I15/2, respectively, as shown in Figure 5 [42,43]. After heat treatment, the upconversion emission intensity of Er 3+ is drastically enhanced; even Er 3+ : 2 H9/2→ 4 I15/2 radiative transition at 409 nm can be clearly observed in NaREF4:Yb/Er@DSi1.0MOR-HT.…”

Energy transfer between optically trapped single ligand-free upconversion nanoparticle and dye

“…The advances in the synthesis of upconversion particles, particularly on the nanoscale, made them as an efficient optical probe for single-cell and single-particle studies [22]. Various approaches such as different synthesis routes, post-synthesis annealing, co-doping, etc, are applied to improve the inherent luminescence of the upconversion particles [23][24][25]. Among the various UCNPs studied so far, NaYF 4 :Yb,Er is still considered as the popular candidate due to its inherent advantages such as low phonon energy, high chemical stability, isomorphic capacitance, low lattice symmetry and local symmetry of the active centers, etc [26].…”

Multiple fluorescence-temperature feedback in Y7O6F9:Er/Yb crystal-embedded polyacrylonitrile fibers

“…Some works have been reported on the temperature-dependent up-conversion luminescence of rareearth ions. [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] Among various temperature-dependent fluorescence parameters, the temperature-based fluorescence intensity ratio (FIR) can circumvent the disturbances of the local environment and provide real-time feedback results. [41][42][43][44][45][46][47][48][49][50] In addition, Nd 3+ -based thermometers were proposed for bio-applications, and new multipurpose strategies, Cr 3+ -based Boltzmann thermometers, were demonstrated to be particularly promising.…”