Hydrothermal Synthesis of Novel K2YbF5:Er3+/Y3+ Microcrystals with Tunable Red–Green Upconversion Luminescence

Abstract

Well-formed and high-quality K 2 YbF 5 microrods have been successfully synthesized by a simple and mild hydrothermal route for the first time. X-ray diffraction, scanning electron microscopy, energy dispersive spectrometer, and photoluminescence spectra were adopted to characterize the as-prepared samples. It is found that the as-obtained samples belong to orthorhombic system and exhibit spindle-like microrods morphology with length of about 7-10 lm and diameter of about 3-6 lm. The upconversion (UC) luminescence properties of K 2 YbF 5 :x %Y 3? , 2 %Er 3? (x = 10, 30, 50, 70, 90) were systematically investigated. Under 980 nm laser excitation, the emission intensities and the corresponding output colors of K 2 YbF 5 :Y 3? /Er 3? could be precisely manipulated by adjusting the Y 3? doping concentration. This study provides a great opportunity for exploring other complex fluorides with improved UC luminescence properties.

Near-IR Emission Enhancement of K2LuF5: Yb3+/Er3+via the Cross-Relaxation Processes with the Assistance of Ce3+Ions

“…12 Er 3+ ions doped potassium lutetium fluorides not only exhibit high UC luminescence efficiency in the visible region, but also emit additional lights in the ultraviolet and NIR region. 13,14 From 1980s, Er 3+ ions doped UC nanoparticles were widely used in optical fiber amplification. 15 It drives from the 4 I 13/2 → 4 I 15/2 transition (∼1.54 μm) of Er 3+ ions which matches one of the low loss windows of optical fibers in optical communication networks.…”

KYb2F7:Er3+ based nanothermometers: controlled synthesis, enhanced red emission, and improved sensitivities via crystal-site engineering

“…78,79 Secondly, the Yb 3+ to Er 3+ energy transfer saturates the 4 I 13/2 level followed by the energy transfer upconversion (ETU) process ( 2 F 5/2 (Yb 3+ ) + 4 I 13/2 (Er 3+ ) → 2 F 7/2 (Yb 3+ ) + 4 F 9/2 (Er 3+ )) that directly populates the 4 F 9/2 level of Er 3+ ions. 80…”

“…78,79 Secondly, the Yb 3+ to Er 3+ energy transfer saturates the 4 I 13/2 level followed by the energy transfer upconversion (ETU) process ( 2 F 5/2 (Yb 3+ ) + 4 I 13/2 (Er 3+ ) -2 F 7/2 (Yb 3+ ) + 4 F 9/2 (Er 3+ )) that directly populates the 4 F 9/2 level of Er 3+ ions. 80 To further understand the influence of the substituting cations on the morphology, the TEM images of the KYb 1.8 M x-F 7 :Er 3+ (2 mol%) (M = Ca 2+ , Ti 4+ , Si 4+ , and Ge 4+ ) nanocrystals were presented in Fig. 5(c).…”

Compositional and Structural Versatility in an Unusual Family of anti-Perovskite Fluorides: [Cu(H2O)4]3[(MF6)(M′F6)]

“…Synthetic techniques such as these tend to result in compounds with less highly oxidized, and even reduced elements. In particular, many research groups have discovered that the simultaneous use of a mild hydrothermal method utilizing hydrofluoric acid as a fluorinating and complexing agent, together with an aqueous reducing agent, is highly successful for the synthesis of extended inorganic fluorides. − …”