Synthesis of β-Phase NaYF₄:Yb,Er Upconversion Nanocrystals and Nanorods by Hot-Injection of Small Particles of the α-Phase

Abstract

-NaYF 4 :Yb,Er upconversion nanocrystals are synthesized by a hotinjection method employing purified -NaYF 4 :Yb,Er particles with a size of approximately 2-3 nm as single-source precursor. The method allows to prepare either spherical nanoparticles with different sizes or nanorods by simply controlling the addition rate of the solution of -phase particles and performing the synthesis either in the absence or in the presence of seed particles. The luminescence properties of the different particles are compared also including core-shell particles.

Near-Infrared Light-Triggered Drug Release from Ultraviolet- and Redox-Responsive Polymersome Encapsulated with Core–Shell Upconversion Nanoparticles for Cancer Therapy

“…The major limiting reason was attributed to surface-associated quenching in part to poor integrity of the shell, or the inert shell was too thin. − In addition, small-sized UCNPs with β-phased NaYF 4 are proved for much higher upconversion efficiency than those with α phase. − There are several strategies for preparing high Yb 3+ -doped UCNPs to enhance upconversion efficiency. − In this study, an artificially constructed core–shell structure with a hybrid of α-phased NaYF 4 :Yb/Tm core and β-phased NaYF 4 shell was fabricated. As described in the previous reports, , with the mixture of α and β-phased nanocrystals, hybrid UCNPs showed well-controlled size and high upconversion efficiency. The NaYF 4 :Yb/Tm core particles were utilized as a host template to regulate the shell growth of the NaYF 4 lattice.…”

“…27−29 In this study, an artificially constructed core− shell structure with a hybrid of α-phased NaYF 4 :Yb/Tm core and β-phased NaYF 4 shell was fabricated. As described in the previous reports, 30,31 with the mixture of α and β-phased nanocrystals, hybrid UCNPs showed well-controlled size and high upconversion efficiency. The NaYF 4 :Yb/Tm core particles were utilized as a host template to regulate the shell growth of the NaYF 4 lattice.…”

Current Advances in Lanthanide‐Doped Upconversion Nanostructures for Detection and Bioapplication

“…In a whole, high‐temperature coprecipitation is the most widely used method and lots of high quality UCNPs with varying composition, size and shape have been prepared . Especially, sub‐10 nm UCNPs can also be obtained by this method (Figure g–i) …”

Synthesis of NaYF4:Yb, Er up-conversion luminophore from nitrate flux

“…It should be noted that the cubic α-phase is a high-temperature phase in NaF-RF 3 systems, and it is nonequilibrium one under our synthesis conditions. Cubic-hexagonal transitions (α → β transitions) in NaRF 4 phases have been reported in the numerous publications describing NaRF 4 phase syntheses by a variety of techniques [4][5][6][7][8][9][10][11]. Temperature increase and/or extension of the synthesis duration promote the aforementioned α → β phase transition.…”

“…β-NaRF 4 phases, when codoped with Yb-Er, Yb-Tm, or Yb-Ho ions, are well known as effective up-conversion phosphors that convert IR radiation to the visible spectral range [1,2]. The number of publications devoted to these materials is huge, see for example [3][4][5][6][7][8][9][10][11][12][13]. The main areas of their potential application are biomedical applications and lighting sources [11][12][13].…”