LiNbO3 Particles Research Articles

Lithium niobate particles with a tunable diameter and porosity for optical second harmonic generation.

Uniform, porous particles of lithium niobate (LiNbO3) can be used as contrast agents in bioimaging, drug delivery carriers, nonlinear optical emitters, biosensors, photocatalysts and electrode materials in lithium-ion batteries. In this article, we introduce a hydrothermal method to prepare uniform, mesoporous LiNbO3 particles with a tunable diameter and porosity. These properties are each tuned by adjusting the reaction times of the hydrothermal process. This approach forms mesoporous LiNbO3 particles without the addition of organic additives (e.g., surfactants) or hard templates (e.g., silica). Formation of these LiNbO3 particles proceeds through an aqueous sol–gel reaction in which niobium hydroxide species are generated in situ and undergo a condensation reaction in the presence of lithium hydroxide to form a colloidal solution. A hydrothermal reaction using this solution resulted in the formation of uniform, solid, and semi-crystalline particles. A post-calcination step induces crystallinity in the product and transforms the particles into mesoporous materials composed of a rhombohedral LiNbO3 phase. An increase in reaction time results in an increase in the diameter of these particles from 580 to 1850 nm, but also decreases their porosity. These LiNbO3 particles were active towards second harmonic generation (SHG), and their SHG response resembled that of larger crystals of rhombohedral LiNbO3. This work also offers a viable strategy for manufacturing other materials (e.g., tantalates, titanates, niobates) with tunable dimensions and porosity that enable a broad range of applications in photonics, energy, and catalysis.

Surface plasmon resonance triggered promising visible light photocatalysis of LiNbO3 ceramic supported Ag nanoparticles

AbstractLiNbO3 ceramic was fabricated using solid‐state reaction route. Silver nanoparticles (NPs) were loaded on LiNbO3 at room temperature using silver nitrate and polyethylene glycol reagents, without the use of external heat and light energy. The X‐ray diffraction showed only LiNbO3 phase in Ag‐loaded LiNbO3 sample with no peak related to Ag metal due to small fraction of Ag loading. X‐ray energy diffraction spectroscopy elemental color mapping confirmed the uniform loading of Ag metal on LiNbO3 particles. Ag metal was loaded in the form of NPs as visualized under transmission electron microscope. Ag NPs‐loaded LiNbO3 showed enhanced absorption of visible light owing to the phenomenon of surface plasmon resonance (SPR). The loading of Ag NPs had no effect on the band gap energy of LiNbO3 ceramic. X‐ray photoelectron spectroscopy technique confirmed the metallic chemical state of Ag in Ag NPs‐loaded LiNbO3. Ag NPs‐loaded LiNbO3 degraded 97% rhodamine‐B model dye from the solution when irradiated for 240 minutes under visible light. The dye degradation follows pseudo‐first‐order kinetic having k‐value (kinetic rate constant) of as 0.013 min−1. The •OH (hydroxyl) and (superoxide) radicals were the main active species behind the photocatalytic activity of Ag NPs‐loaded LiNbO3. Thus, Ag NPs‐loaded LiNbO3 could be a potential material for degrading organic dyes from water.

Kinetic theory simulation of LiNbO3 thin films deposition distribution by pulsed laser deposition

ABSTRACTIn this paper, the progress of LiNbO3 thin films formation was simulated by kinetic theory method. The whole Plused Laser Deposition (PLD for short) process was considered: LiNbO3 particles were sublimated to high density plasma after laser erosion and propagated into space and then deposited into thin films. And the thickness of LiNbO3 thin films was discussed, which reflected the surface roughness and crystal type.The particles speed and distribution in the plasma were considered and discussed, and the roughness distribution of the films along the radius has been discussed. The thickness change could indicate the growth mode of the films along the radius. The detailed explanation of the PLD experiment was established.

Analysis of the oxidized surface of 90Nb-10Zr alloy after exposure to lithiated water with 0.01 M LiOH at 360 °C/18.6 MPa

The microstructural characteristics of oxide films on 90Nb–10Zr (wt%) alloy in lithiated water were investigated to understand the oxidation process of β-Nb precipitates in Zr–1Nb (wt%) alloy. The outer layer of the alloy is faceted, and has loosely packed LiNbO3 particles. Pores and nano-sized LiNbO3 are present between the outer and the compact Nb2O5 inner layer. Nb2O5 reacted with LiOH to form LiNbO3 and it dissolved into the corrosive environment to leave pores in the oxide films. The Zr oxidised and dissolved in Nb2O5. A degradation mechanism is proposed on the corrosion resistance of the Zr–1Nb alloy in lithiated water.

Effects of Nb2O5 as seeds and trisodium citrate as suppressing agent on LiNbO3 formation

This study is to understand the effect of Nb2O5 on the formation and morphology of LiNbO3 particles during hydrothermal synthesis. Trisodium citrate (Na3C6H5O7) is for the first time used as a selective crystallographic growth suppressing agent. The morphology of LiNbO3 is examined using scanning electron microscopy and the crystal structure of the material is characterized using X-ray diffraction. The morphology of LiNbO3 evolves into novel flower structures as the synthesis time increases to 5 days. The crystal structures of the synthesized materials are consistent with the morphology evolution.

Bottom-up synthesis of up-converting submicron-sized Er3+-doped LiNbO3 particles

A new and simple wet chemical synthesis method is proposed to prepare submicron-sized Erbium-doped LiNbO3 powders. The synthesis procedure comprises the co-precipitation of lithium and erbium ions from common precursors and their subsequent reaction with niobium ethoxide. A systematic characterization by means of X-Ray Diffraction (XRD), X-ray Fluorescence (XRF), Inductively Coupled Plasma (ICP-OES), Atomic Absorption (AAS), Field Emission Scanning Electron Microscopy (FE-SEM), as well as by the examination of the luminescence properties, evidence that with this method a congruent Er3+-doped LiNbO3 single phase material can be obtained without using complex and time-consuming processing steps. The synthesized powders exhibit efficient IR to VIS up-conversion emissions under 974 nm pumping.

Lithium niobate bulk crystallization promoted by CO2 laser radiation

The crystallization induced by laser radiation is a very promising technique to promote glass/ceramic transformation, being already used to produce crystalline patterns on glass surfaces. In this work, a SiO2–Li2O–Nb2O5 glass, prepared by the sol–gel route, was submitted to CO2 laser radiation and conventional heat-treatments in order to induce the LiNbO3 crystallization. The structure and morphology of the samples prepared by both routes was analyzed as a function of exposure time, radiation power and heat-treatment temperatures by XRD, Raman spectroscopy and SEM. The results reveal a correlation between the crystallization degree of LiNbO3 particles and glass matrix with the heat treatment type and experimental parameters. An heat-treatment at 650°C/4h was necessary to induce crystallization in heat treatments samples while 4W/500s was enough for laser radiation ones, corresponding a reduction time processing of ∼14000s.

Mild, Quasireverse Emulsion Route to Submicrometer Lithium Niobate Hollow Spheres

A water/ethylene glycol (H2O/EG) system has been designed to synthesize lithium niobate (LiNbO3) powders by a mild, one-step quasireverse emulsion method. A morphology transformation from initial nuclei to flowerlike structures and then to hollow spheres is confirmed by the time-dependent experiment. The as-obtained LiNbO3 hollow spheres are formed via Ostwald ripening under solvothermal conditions, and their absorption edge in UV/vis diffuse reflectance spectra can be effectively tuned by the current morphology control strategies. This facile, efficient, and economic work provides a new route to simply and mildly synthesize hollow LiNbO3 particles and is a good initiation in the morphology control study of LiNbO3 powders.

Fiber Drawing of LiNbO<sub>3</sub>-Doped Mixed Alkali Tellurite Glasses

A transparent mixed alkali tellurite glass of 10Li2O-10Na2O-80TeO2 containing LiNbO3 crystals with a diameter of about 4μm and with the amount of about 6 mass% is prepared using an incorporation method, and LiNbO3-doped tellurite glass fibers are drawn. LiNbO3 particles in the fiber and bulk samples are well dispersed. The samples also have a good transparency. The mixed alkali tellurite glass with a high thermal stability against crystallization and with a high refractive index of n=1.98 is very suitable for incorporation of LiNbO3 crystals and for LiNbO3-doped fiber drawing. This technique will be applicable for fabrications of nonlinear optical glass fibers containing various nonlinear optical crystals.