Abstract
AbstractLanthanide‐doped NaYF4 upconversion nano‐ and microcrystals were synthesized via a facile solvothermal approach. Thereby, the influence of volume ratios of ethylene glycol (EG)/H2O, molar ratios of NH4F/RE3+ (RE3+ represents the total amount of Y3+ and rare‐earth dopant ions), Gd3+ ion contents, types of activator dopant ions, and different organic co‐solvents on the crystal phase, size, and morphology of the resulting particles were studied systematically. A possible formation mechanism for the growth of crystals of different morphology is discussed. Our results show that the transition from the α‐ to the β‐phase mainly depends on the volume ratio of EG/H2O and the molar ratio of NH4F/RE3+, while the morphology and size could be controlled by the type of organic co‐solvent and Gd3+ dopant ions. Furthermore, the reaction time has to be long enough to convert α‐NaYF4 into β‐NaYF4 during the growth process to optimize the upconversion luminescence. The formation of larger β‐NaYF4 crystals, which possess a higher upconversion luminescence than smaller particles, proceeds via intermediates of smaller crystals of cubic structure. In summary, our synthetic approach presents a facile route to tailor the size, crystal phase, morphology, and luminescence features of upconversion materials.
Highlights
Lanthanide-doped upconversion (UC) materials constructing UC materials, a proper host material is carefully have attracted ample interest because of their multitude of chosen to have low lattice phonon energies, high transparency sharp emission bands originating from their ladder-like energy at the excitation and emission wavelength, and excellent levels, long luminescence lifetimes in the microsecond region, chemical stability
Lin’s group[21] used trisodium citrate (TSC) as the chelating crystals synthesized by a solvothermal method using hydroagent, studied several factors, like the amount of ligand, philic DSNTA as coordinating ligand and to relate these features reaction temperature, pH value, and fluoride source, for to their UCL
The strongest emission is observed for an cated in the green region, while the Yb/Tm system has a very enough to convert αglycol (EG)/H2O volume ratio of 2/1, which is tentatively attributed to different color output with β-NaYF4:Yb/Tm (x = 0.1651, y = the well-defined crystallographic facets (Figure 2e)
Summary
Effect of volume ratio of EG/H2O the crystals, which reveals the presence of Na, Y, Yb, F and a For the hydro/solvothermal method, the selected solvent can small amount of Er element. It confirms the successful synthesis influence the solubility, diffusion, and reactivity of the reagents of NaYF4:Yb/Er crystals. As can be seen from SEM and TEM images of β-NaYF4:Yb/Er synthesized by adjusting the volume ratio of EG/ethanol to (Figure 1c and d), the as-prepared sample contains fairly change the diffusion rate of ions in the solution. If the volume ratio of EG/H2O is lower than 1/3, the diffraction patterns of the obtained crystals match 42 well with the corresponding standard data of cubic NaYF4. EDS elemental mapping for (h) Na, (i) Y, (j) F, (k) Yb, and (l) Er of a single NaYF4:Yb/Er microparticle
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
