Iron Oxide-Induced Thermal Effects on Solid-State Upconversion Emissions in NaYF₄:Yb,Er Nanocrystals

Abstract

Multifunctional materials exhibiting photon upconversion show promising applications for biological imaging and sensing. In this study, we examine the solid-state upconversion emission of NaYF4:Yb,Er nanoparticles in the presence of iron oxide nanoparticles. Fe3O4 nanoparticles (6 nm) were mixed with NaYF4:Yb,Er nanoparticles (either 10 or 50 nm) in varying proportions by drying chloroform solutions of nanoparticles onto glass slides. Upconversion spectra were acquired, and a laser power-dependent emission was observed and correlated with the iron oxide content in the mixture. Changes in the lattice temperature of the upconverting particles were monitored by careful observation of the relative intensities of the (2)H11/2 and (4)S3/2 →( 4)I15/2 transitions. The emission characteristics observed are consistent with an iron oxide-induced thermal effect that is dependent on both the laser power and the proportion of iron oxide. The results highlight that the thermal effects of mixed nanoparticle systems should be considered in the design of luminescent upconverting hybrid materials.

Enhanced anti-stocks luminescence in LaNbO4:Ln3+ (Ln3+ = Yb3+, Er3+/Ho3+/Tm3+) with abundant color

“…As shown in Fig. 3, the crystallization belongs to monoclinic system, and space group is I112/b (15), and cell parameters are 3 , and Z ¼ 4. Signicantly, as the annealing temperature increases from 500 C to 1000 C and reaction time grows from 0.5 h to 3 h, the diffraction peaks become obviously stronger and sharper, implying that the high annealing temperature and longer reaction time contribute to the high crystallinity of the samples.…”

“…38 For LNO:Yb 3+ /Tm 3+ , Tm 3+ ions are excited from ground state 3 H 6 level to 1 G 4 level by three energy transfer processes and the mechanism is expressed as follows: rstly, 3 H 6 (Tm) + 2 F 5/2 (Yb) / 3 H 5 (Tm) + 2 F 7/2 (Yb), and then the energy level 3 H 5 relaxes to 3 F 4 . Secondly, 3 [39][40][41] The concentration of sensitizer and activator is a signicant factor of the UCL properties. The concentration affects the relative amount of Ln 3+ in the samples and the average distance between adjacent dopant ions, leading to a signicant impact on the optical properties of the samples.…”

“…Up-conversion luminescence (UCL), a process that can convert near-infrared excitation into visible emission, also known as anti-Stokes shi, has recently gained more and more attention. [1][2][3][4][5][6][7][8] The energy transfer process, in which two or more low-energy photons are converted into one high-energy photon, has great potential applications in laser materials, data storage, near-infrared quantum counters, solar energy, traditional light, display technologies, biological imaging and so on. [9][10][11][12][13][14][15][16][17][18][19][20] Multiple metastable levels of the lanthanides just perfectly meet the requirement of these applications.…”

Calcination-free micromolding in capillaries for nanopatterning of inorganic upconversion luminescent layers on flexible plastic sheets

“…Fig. 3c shows an energy band diagram of Er 3+ and Yb 3+ and the emission mechanism [34][35][36][37][38]. These results demonstrate that the PEI-modified NaYF 4 nanoparticles serve as visible upconversion luminescent and near-IR fluorescent nanoparticles excited with near-IR light.…”

Optical temperature sensing by upconversion luminescence of Er doped Bi5TiNbWO15ferroelectric materials

“…13 Some successful applications on the FIR technique by Er 3+ doped materials have been investigated. 4,[14][15][16][17] Most of the recent study interest relevant to the host materials was focused on the fluoride glasses due to the low phonon energy of the crystal lattice. 18,19 Nevertheless, less attention has paid to the host of Aurivillius bismuth layered-structure ferroelectrics (BLSFs).…”