Analysing the effect of the crystal structure on upconversion luminescence in Yb³⁺,Er³⁺-co-doped NaYF₄ nanomaterials

Abstract

NaYF4:Yb:Er nanoparticles (UCNP) were synthesized under mild experimental conditions to obtain a pure cubic lattice. Upon annealing at different temperatures up to Tan = 700 °C phase transitions between hexagonal phase and the cubic phase were induced. Based on the TRANES analysis it was possible to resolve the lattice phase transition in more detail, which was not possible with the standard techniques.

Rapid Synthesis of Sub‐10 nm Hexagonal NaYF4‐Based Upconverting Nanoparticles using Therminol® 66

“…T66 is ac ommercially available, high-boiling organic fluid that consists of am ixture of terphenyls, hydrogenated terphenyls, and hydrogenated polyphenyls ( Figure S1 in the Supporting Information), and it is frequentlye mployed as a heat-transfer liquid. [35][36][37] Importantly,i ti sc ommonly used in industrial processes and has been previously used to prepare quantum dots of various sizes with high reproducibility. [38][39][40] Yb 3 + -sensitized UCNPsa re limited in deep-tissue imaging applications, as the absorption peak of Yb 3 + ions is centered at l = 980 nm, which overlaps with the absorption band of water molecules.…”

Self-assembled pearl-necklace patterned upconverting nanocrystals with highly efficient blue and ultraviolet emission: femtosecond laser based upconversion properties

“…5 shows the Raman spectrum for UCN-PNs, where the bands appeared at 260 cm À1 , 303 cm À1 , 364 cm À1 and 395 cm À1 (below 700 cm À1 ) conrm the formation of hexagonal-phases. 35,36 Beyond 700 cm À1 , the appearance of strong bands at 725 cm À1 , 2887 cm À1 and 3512 cm À1 are evidences for the presence of cubic-phases conjugated with oleic acid (capping agent). Thus both the results obtained from XRD and Raman conrmed the formation of UCN-PNs with major b-phase along with a less extent of a-phase.…”

Constructing a “Native” Oxyfluoride Layer on Fluoride Particles for Enhanced Upconversion Luminescence

“…This is consistent with the previous findings in refs. and . 3) The coupling between low‐energy phonons of NaYF 4 and high‐energy phonons of YOF facilitates energy transfer UC between mismatched energy levels.…”