Improvement of Yttrium Oxyfluoride Coating with Modified Precursor Solution for Laser-Induced Hydrothermal Synthesis

In the semiconductor manufacturing process, the inner walls of the equipment are coated with yttrium-based oxides for etch resistance against plasma exposure. Yttrium oxyfluoride (YOF) particle synthesis and coating methods have been actively studied owing to their high erosion resistance compared to Y2O3 and Al2O3. Owing to the formation of a rough and porous coating layer by thermal spray-coating, the coating layer disintegrates, as the etching process has been conducted for a long time. Laser-induced synthesis and coating technology offer several advantages, including simplified process steps, ease of handling, and formation of a dense coating layer on the target material. In this study, YOF was coated on an aluminum substrate using a modified precursor solution. The NaF and HMTA were added to the precursor solution, resulting in enhanced synthetic reactivity and stabilizing the oxides. The material coated on the surface was analyzed based on the characteristics of composition, chemical bonding, and phase identification. We found that the coating properties can be improved by using an appropriate combination of modified precursor solutions and laser parameters. Therefore, the findings in this study are expected to be utilized in the field of coating technology.

Understanding the remarkable luminescence enhancement via SiO2 coating on TiO2:Eu3+ nanofibers

Red luminescence is enhanced by coating an SiO₂ layer on TiO₂:Eu³⁺ nanofibers, and the luminescence enhancement mechanism is discussed.

Interacting layered hydroxide nanosheets with KF leading to Y/Eu hydroxyfluoride, oxyfluoride, and complex fluoride nanocrystals and investigation of photoluminescence

Reacting nanosheets (∼4 nm thick) of RE₂(OH)₅NO₃·nH₂O layered hydroxyl nitrate with KF has led to various types of fluorides for photoluminescence.

Fine-tuning of multiple upconversion emissions by controlling the crystal phase and morphology between GdF3:Yb3+,Tm3+ and GdOF:Yb3+,Tm3+ nanocrystals

Fine-tuning of multi-color emission characteristics of upconversion lanthanide-ion-doped nanocrystals is of high importance for 3-D color displays, multi-color bio-imaging, and multiplexed cellular labeling.

Controllable Phase Transformation and Mid-infrared Emission from Er(3+)-Doped Hexagonal-/Cubic-NaYF4 Nanocrystals

The morphology of hexagonal phase NaYF₄:Er³⁺ nanorods synthesized by hydrothermal method changed greatly after a continuing calcination, along with a phase transformation to cubic phase. Photoluminescence (PL) spectra indicated that mid-infrared (MIR) emission was obtained in both hexagonal and cubic phase NaYF₄:Er³⁺ nanocrystals for the first time. And the MIR emission of NaYF₄:Er³⁺ nanocrystals enhanced remarkably at higher calcination temperature. To prevent uncontrollable morphology from phase transformation, the cubic phase NaYF₄:Er³⁺ nanospheres with an average size of ~100 nm were prepared via a co-precipitation method directly. In contrast, the results showed better morphology and size of cubic phase NaYF₄:Er³⁺ nanocrystals have realized when calcined at different temperatures. And PL spectra demonstrated a more intense MIR emission in the cubic phase NaYF₄:Er³⁺ nanocrystals with an increasing temperature. Besides, the MIR emission peak of Er³⁺ ions had an obvious splitting in cubic phase NaYF₄. Therefore, cubic phase NaYF₄:Er³⁺ nanospheres with more excellent MIR luminescent properties seems to provide a new material for nanocrystal-glass composites, which is expected to open a broad new field for the realization of MIR lasers gain medium.

Bright YAG:Ce Nanorod Phosphors Prepared via a Partial Wet Chemical Route and Biolabeling Applications

Cerium-doped yttrium aluminum garnet (YAG:Ce) nanorods were prepared via a partial wet chemical route followed by a calcination process by using Al2O3 nanorods as both templates and the reactant. These novel well-crystallized YAG:Ce phosphors with a 200-300 nm diameter and a 2-3 μm length have a high specific surface area while being virtually devoid of surface defects. The YAG:Ce nanorod phosphors possess good luminescent properties compared with granular YAG:Ce phosphors. Photoluminescence quantum yields of YAG:Ce nanorod phosphors are higher than those of granular ones. The YAG:Ce nanorod phosphors exhibit two luminescent decay times due to their unique morphology. The YAG:Ce nanorods exhibited good cytocompatibility with bone marrow mesenchymal stem cells and can be used as biolabel nanoparticles in bioimaging.

Dendrimer-based preparation and luminescence studies of SiO2 fibers doping Eu3+ activator in interstitial sites

The formation mechanism of SiO₂:Eu³⁺ fibers.

Crystal-site engineering control for the reduction of Eu(3+) to Eu(2+) in CaYAlO4: structure refinement and tunable emission properties

In this article, Eu-activated CaYAlO4 aluminate phosphors were synthesized by a solid-state reaction. Under UV light excitation, characteristic red line emission of Eu(3+) was detected in the range of 570-650 nm. In addition, we introduced crystal-site engineering approach into the CaYAlO4 host through incorporation of Si(4+)-Ca(2+) to replace Al(3+)-Y(3+), which would shrink the AlO6 octahedrons, accompanied by the expansion of CaO9 polyhedron, and then enable the partial reduction of Eu(3+) to Eu(2+). The crystal structure and underlying mechanism have been clarified on the basis of the Rietveld refinement analysis. The PL spectra of Ca0.99+xY1-xAl1-xSixO4:Eu0.01 (x = 0-0.30) exhibit both green emission of Eu(2+) (4f(6)5d(1)-4f(7), broadband around 503 nm) and red-orange emission of Eu(3+) ((5)D0-(7)F1,2, 593 and 624 nm) under UV light excitation with a quantum yield of 38.5%. The CIE coordinates of Ca0.99+xY1-xAl1-xSixO4:Eu0.01 (x = 0-0.30) phosphors are regularly shifted from (0.482, 0.341) to (0.223, 0.457) with increasing x, which would expand the application of Eu. Furthermore, this investigation reveals the correlations of structure and property of luminescent materials, which would shed light on the development of novel phosphors suitable for lighting and display applications.

Morphology control and multicolor-tunable luminescence of YOF:Ln3+ (Ln = Eu, Tb, Dy, Tm) nano-/microcrystals

Multiform YOF nano-/microcrystals have been synthesized and multicolor-tunable luminescence of YOF:Ln³⁺ (Ln = Eu, Tb, Dy, Tm, Tm/Dy) has been investigated.

Phase transition, morphology transformation and highly enhanced luminescence properties of YOF:Eu3+ crystals by Gd3+ doping

We report the crystal phase transition, morphology transformation, and greatly enhanced luminescence properties of YOF crystals by Gd³⁺ doping.

Highly thermostable lanthanide metal–organic frameworks exhibiting unique selectivity for nitro explosives

The solvent-free Eu-MOF with high red emission intensity and the microporous instinct exhibits high sensitivity for 2,4,6-trinitrophenol with K_sv constant 6.24 × 10⁴ M⁻¹.

Synthesis, morphology and spectroscopic properties of red-luminescent rhombohedral YOF: Yb3+, Er3+ powders

Rhombohedral YOF: Yb³⁺, Er³⁺ prepared by calcinating exhibit duality of morphology; efficient red light emission could be obtained when the powders are excited by 980 nm laser beam.

Monodisperse lanthanide oxyfluorides LnOF (Ln = Y, La, Pr-Tm): morphology controlled synthesis, up-conversion luminescence and in vitro cell imaging

Lanthanide oxyfluorides LnOF (Ln = Y, La, Pr-Tm) nano/micro-materials with a variety of well-defined morphologies including nanorods, nanospindles, nanorod-bundles and nanospheres, have been successfully synthesized via a facile precipitation technique followed by a heating treatment. It is found that the pH values, fluoride sources and dosage of urea in the initial reaction systems play critical roles in the morphology determination of the LnOF products and the possible formation mechanism for these diverse architectures has been presented. XRD, FT-IR, TG-DTA, SEM, TEM, as well as up-conversion (UC) luminescence spectra are used to characterize the synthesized samples. Under 980 nm NIR laser excitation, red, green and blue UC luminescence are observed from Yb(3+)/Er(3+), Yb(3+)/Ho(3+) and Yb(3+)/Tm(3+) co-doped YOF nanospheres. The MTT assay indicates that YOF nanospheres exhibit good biocompatibility. Especially, the emission spectrum of YOF: 0.20Yb(3+), 0.04Er(3+) nanospheres is dominated by a single red emission at 660 nm, which falls into the "optical window" of biological tissues. The application of YOF: 0.20Yb(3+), 0.04Er(3+) nanospheres in the cell imaging is also investigated, which shows a bright-red emission without background noise.