KF-mediated controlled-synthesis of potassium ytterbium fluorides (doped with Er³⁺) with phase-dependent upconversion luminescence

Abstract

Potassium ytterbium fluorides with predictable crystal phases and architectures, such as KYb 3 F 10 nanoparticles, KYb 2 F 7 sub-microplates, microrods, KYbF 4 microplates, micro-bipyramids, K 2 YbF 5 microprims and microrods have been successfully synthesized by simply 10 tuning the molar ratio of KF to Yb 3+ via a facile and general solution-based route. The influence of the KF dosage on phase and morphology evolution of potassium ytterbium fluorides has been systematically investigated and discussed. And the mechanism about how KF/Yb 3+ molar ratio influences the anisotropic growth and phase, morphology evolution was proposed. Taking K 2 YbF 5 mcirorods as an example, the possible formation mechanism was presented on the basis of XRD patterns and the corresponding SEM images of the intermediate products obtained at different reaction time intervals. Additionally, the upconversion luminescence properties of Er 3+ ions (2 15 mol%) doped potassium ytterbium fluorides with different crystalline phases and architectures were studied in detail. Importantly, this study may provide a great opportunity for systematical study of the general synthesis and luminescence properties of potassium ytterbium fluorides with predictable crystal phases and well-defined morphologies, which can offer a reference for the precisely controlled synthesis of other rare earth fluoride compounds.

Hydrothermal Synthesis and Solid-State Laser Refrigeration of Ytterbium-Doped Potassium-Lutetium-Fluoride (KLF) Microcrystals

“…The K 3 LuF 6 phase was not observed using hydrothermal synthesis, even with a KF/RE 3+ ratio as high as 60. This observation is consistent with previous experiments that show only four phases of (KF) x ·(YbF 3 ) y crystals in hydrothermal synthesis . In contrast with the nonstoichiometric sodium-RE-fluoride system, to the best of our knowledge, the potassium-RE-fluoride phases we report are stoichiometric.…”

“…This observation is consistent with previous experiments that show only four phases of (KF) x •(YbF 3 ) y crystals in hydrothermal synthesis. 36 In contrast with the nonstoichiometric sodium-REfluoride system, 28 to the best of our knowledge, the potassium-RE-fluoride phases we report are stoichiometric. The diffraction patterns of these products prepared with different for all syntheses.…”

“…This observation is consistent with previous experiments that show only four phases of (KF) x •(YbF 3 ) y crystals in hydrothermal synthesis. 34 The diffraction patterns of these products prepared with different KF/RE ratios can be indexed to orthorhombic K 2 LuF 5 , trigonal KLuF 4 , orthorhombic KLu 2 F 7 , and cubic KLu 3 F 10 . More details of these four crystallographic phases are listed in Table 1.…”

Controllable Synthesis of Monodisperse Er3+-Doped Lanthanide Oxyfluorides Nanocrystals with Intense Mid-Infrared Emission

“…1(d) also displays some sub-micron oblate spheroids. It should be noted from the above results that both the state and dosage of KF play an important role in the morphology and size distribution of the GdOF:0.05Er precursors23. Since the urea is more easily hydrolyzed in the heavily acidic conditions (pH = 2), and the solid KF may hinder the nucleation process and decrease the nucleation rate, resulting in an isotropic growth and larger size in products.…”

Color-tunable luminescence, energy transfer and temperature sensing behavior of hexagonal NaYF4:Ce3+/Tb3+/Eu3+ microcrystals

“…In order to realize favorable optical performance, the host materials, where Ln 3+ ions reside, should be appropriately selected, because the radiative and nonradiative transitions as well as energy transfer of Ln 3+ ions are highly dependent on the crystalline field surrounding them. Till now, large number of rare earth inorganic compounds, including oxides [10,11], oxysulfides [12,13], oxyfluorides [14,15], sulfides [16], fluorides [17][18][19], chlorides [20,21], phosphates [22] and vanadates [23], have been selected as host materials for the doping of rare earth ions. Among the as-reported host materials, Ln 3+ -doped fluorides with general formula NaLnF 4 , possessing low phonon energy, good optical transparency and adequate thermal and environmental stability, have been regarded as excellent host lattices for achieving desirable optical performance.…”