Flame-made Y2O3:Yb3+/Er3+ upconversion nanoparticles: Mass production synthesis, multicolor tuning and thermal sensing studies

Aerosol Flame Synthesis and Manipulating Upconversion Luminescence of Ultrasmall Y2O3:Yb3+/Ho3+ Nanoparticles

“…From the XRD results, the diffraction peak positions and relative intensities of Y2O3:Yb 3+ /Ho 3+ UCNPs are consistent with the pure cubic phase Y2O3 typical PDF card (JCPDS file No. 86-1107) [28]. With the change of doping concentration, there is no obvious diffraction peak drift or impurity peaks in the XRD spectrum of Y2O3:Yb 3+ /Ho 3+ UCNPs, indicating that the UCNPs with different doping ratios are highly crystallized and are all pure Y2O3 cubic phases.…”

“…The required chemicals were weighed according to the precalculated stoichiometric ratio, then mixed and dissolved in n-butanol. 2-EHA were added into the mixed n-butanol solution next for replacing nitrate ions, so that the precursor can volatilize better in the reaction process, and promote the formation of uniform ultrasmall nanoparticles according to the gas-to-particles reaction route [28], [38]. Otherwise, there would be a considerable part of large-size hollow particles in the synthesized nanoparticles that were generated according to the droplets-to-particles reaction route, which would have an unexpected impact on the UCL properties of nanoparticles [28], [38], [39].…”

“…2-EHA were added into the mixed n-butanol solution next for replacing nitrate ions, so that the precursor can volatilize better in the reaction process, and promote the formation of uniform ultrasmall nanoparticles according to the gas-to-particles reaction route [28], [38]. Otherwise, there would be a considerable part of large-size hollow particles in the synthesized nanoparticles that were generated according to the droplets-to-particles reaction route, which would have an unexpected impact on the UCL properties of nanoparticles [28], [38], [39]. To avoid this trouble, the molar ratio of rare-earth-ion cations to 2-EHA is set to 1:3 to ensure that 2-EHA can completely replace nitrate ions.…”

“…In the swirl flame environment, the fuel and oxidant are injected into the burner respectively, which can greatly eliminate the risk of flashback. The flames generated by adjacent slits can ignite each other to develop a tubular swirl flame, which greatly improves the stability of flame and creates a stable high-temperature environment for the continuous synthesis of large-scale production of UCNPs [28], [40], [41].…”

“…Generally, the UCNPs are composed of inorganic matrix and doping with appropriate rare-earth-ions [1], which has been successfully demonstrated in Y2O3 [10], [28]- [31], NaYF4 [32], LiYF4 [33], YVO4 [34], CaF2 [4] hosts. In these compounds, Y2O3 is a typical UC matrix due to its outstanding characters such as large bandgap (~5.8 eV), wide spectral range in optical transparency (0.2~8 μm), high refractive index (~2), low phonon energy (~600 cm -1 ), high breakdown strength, excellent thermal stability and electronic properties [10], [35], [36].…”