Photoluminescence properties of YVO4:Eu3+,Ba2+ nanoparticles prepared by an ion exchange method

YVO₄:Ba²⁺ nanoparticles with a Ba²⁺ doping concentration x=0%, 1%, 3%, 5%, 7% and 9% were synthesized by a solvothermal method and then they were codoped with Eu³⁺ ions by an ion exchange method to form the YVO₄:Eu³⁺,Ba²⁺ nanoparticles. It was found that the photoluminescence intensity of the as-prepared YVO₄:Eu³⁺,Ba²⁺ nanoparticles steadily increased with x until x=7%, and then decreased for higher x. Thermal annealing resulted in considerable enhancement in their photoluminescence, and higher annealing temperature led to stronger photoluminescence enhancement. The emission intensity of the YVO₄:Eu³⁺,Ba²⁺ (x=7%) nanoparticles annealed at 500 °C was about 205% stronger than the sample without Ba²⁺ doping. Thermal annealing of the ion-exchanged YVO₄:Eu³⁺,Ba²⁺ nanoparticles at 500 °C and 700 °C resulted in photoluminescence enhancement of about 14 times and 27 times, respectively. The asymmetric ratio of Eu³⁺ in the ion-exchanged YVO₄:Eu³⁺,Ba²⁺ nanoparticles was found to increase after annealing.     

Fabrication of 2D photonic crystal assisted Y2O3:Eu thin-film phosphors by direct nano-imprinting

The effect of a two-dimensional Y₂O₃:Eu³⁺ photonic crystal (PC) pattern on the extraction efficiency of photoluminescence from the underlying Y₂O₃:Eu³⁺ thin-film phosphor was investigated. The photonic crystal structure was fabricated using a direct nano-imprint process with a Pechini-type Y₂O₃:Eu³⁺ sol as the nano-imprint resin and a patterned polydimethylsiloxane (PDMS) stamp as the mold. The elevated pressure and temperature of the nano-imprinting process converts the Y₂O₃:Eu³⁺ sol into a Y₂O₃:Eu³⁺ gel resulting in high definition transfer of the 2D patterns of the master template into the gel on top of the Y₂O₃:Eu³⁺ thin-film phosphor layer. The extraction efficiency of the 2D Y₂O₃:Eu³⁺ gel PC-assisted Y₂O₃:Eu³⁺ thin-film phosphor was approximately 3.7 times higher than a non-PC Y₂O₃:Eu³⁺ gel coated Y₂O₃:Eu³⁺ thin-film phosphor.     

A New Sol–Gel Material Doped with an Erbium Complex and Its Potential Optical‐Amplification Application

The crystal structure of a ternary Er(DBM)₃phen complex (DBM = dibenzoylmethane; phen = 1,10‐phenanthroline) and its in‐situ synthesis via a sol–gel process are reported. The infrared (IR), diffuse reflectance (DR), and fluorescence spectra of the pure complex and the Er³⁺/DBM/phen co‐doped luminescent hybrid gel, formed via an in‐situ method (ErDP gel), have been investigated. The results reveal that the erbium complex is successfully synthesized in situ in the ErDP gel. Excitation at the maximum absorption wavelength of the ligands resulted in the typical near‐IR luminescence (centered at around 1.54 μm) resulting from the ⁴I_13/2 → ⁴I_15/2 transition of the Er³⁺ ion, which contributes to the efficient energy transfer from the ligands to the Er³⁺ ion in both the Er(DBM)₃phen complex and the ErDP gel (an antenna effect). The full width at half maximum (FWHM) centered at 1541 nm in the emission spectrum of the ErDP gel is 72 nm, which has potential for optical‐amplification applications. Further theoretical analysis on the Er³⁺ ion in the ErDP gel shows that it appears to be a promising candidate for tunable lasers and planar optical amplifiers.     

Electrospinning Derived One‐Dimensional LaOCl: Ln3+ (Ln = Eu/Sm,Tb, Tm) Nanofibers,Nanotubes and Microbelts with Multicolor‐Tunable Emission Properties

One‐dimensional LaOCl: Ln³⁺ (Ln³⁺ = Eu³⁺/Sm³⁺, Tb³⁺, Tm³⁺) nanofibers, nanotubes, and quasi‐1D microbelts are successfully prepared by a sol–gel/electrospinning process. XRD, FT‐IR, SEM, TEM, as well as photoluminescence (PL) and cathodoluminescecne (CL) spectra are used to characterize the resulting samples. Through a heat treatment process at high temperature, the as‐prepared samples are well‐crystallized with the tetragonal structure of LaOCl. Under ultraviolet radiation and low‐voltage electron beam excitation, the LaOCl: Eu³⁺, LaOCl:Sm³⁺, LaOCl: Tb³⁺, and LaOCl: Tm³⁺ samples give the characteristic transitions of Eu³⁺ (⁵D_{0, 1, 2} → ⁷F_{0, 1, 2, 3, 4}), Sm³⁺ (⁴G_5/2 → ⁶H_{5/2, 7/2, 9/2}), Tb³⁺ (⁵D_{3, 4} → ⁷F_{2, 3, 4, 5, 6}), and Tm³⁺ (¹D₂, ¹G₄ → ³F₄, ³H₆), respectively. Moreover, there exists simultaneous luminescence of Tb³⁺, Tm³⁺, Eu³⁺, or Sm³⁺ individually when codoping them in the single‐phase LaOCl host (for example, LaOCl: Tb³⁺, Eu³⁺/Sm³⁺; LaOCl: Tm³⁺, Eu³⁺/Sm³⁺; LaOCl: Tb³⁺, Tm³⁺, Eu³⁺/Sm³⁺ systems), which is beneficial to tune the emission colors. Under low‐voltage electron beam excitation (1–5 kV), a variety of colors can be efficiently adjusted in a wide triangle region enveloped by three CIE chromaticity coordinate points [LaOCl:Eu³⁺, (x = 0.6039, y = 0.3796); LaOCl: Tb³⁺, (x = 0.2452, y = 0.5236); LaOCl: Tm³⁺, (x = 0.1456, y = 0.0702)] for mono‐ and co‐doped LaOCl: Ln³⁺ (Eu³⁺, Sm³⁺, Tb³⁺, Tm³⁺) samples, making these materials have potential applications in field‐emission display devices.     

Hydrothermal Synthesis and Luminescent Properties of BiPO4:Eu3+ Phosphors

In this study, BiPO₄:Eu³⁺ phosphors were synthesized by a facile hydrothermal route at different temperatures. The BiPO₄:Eu³⁺ particles were characterized by x-ray powder diffraction (XRD), infrared spectra, and luminescence spectroscopy. The XRD results reveal that the BiPO₄:Eu³⁺ particles present different phases for different hydrothermal temperatures. It is found that a hexagonal phase is formed at 100°C, which transforms to a low-temperature monoclinic phase (MP) when the hydrothermal temperature is increased to 150°C. This low-temperature MP transforms to high-temperature MP when the temperature is increased beyond 200°C. The luminescent properties of the BiPO₄:Eu³⁺ particles were studied using an excitation wavelength of 270 nm. The emission spectra display the bands associated with the ⁵D₀ → ⁷F _J (J = 1, 2, 3, and 4) electronic transitions of the Eu³⁺ cations. The intensity of the emission spectra increases with increasing hydrothermal temperature. These results demonstrate that BiPO₄:Eu³⁺ with different phases can be obtained through the hydrothermal method, which may enrich the solution chemistry for preparation of advanced materials with tailored functionality.     

Synthesis of Magnetic,Up‐Conversion Luminescent,and Mesoporous Core–Shell‐Structured Nanocomposites as Drug Carriers

The synthesis (by a facile two‐step sol–gel process), characterization, and application in controlled drug release is reported for monodisperse core–shell‐structured Fe₃O₄@nSiO₂@mSiO₂@NaYF₄: Yb³⁺, Er³⁺/Tm³⁺ nanocomposites with mesoporous, up‐conversion luminescent, and magnetic properties. The nanocomposites show typical ordered mesoporous characteristics and a monodisperse spherical morphology with narrow size distribution (around 80 nm). In addition, they exhibit high magnetization (38.0 emu g^?1, thus it is possible for drug targeting under a foreign magnetic field) and unique up‐conversion emission (green for Yb³⁺/Er³⁺ and blue for Yb³⁺/Tm³⁺) under 980 nm laser excitation even after loading with drug molecules. Drug release tests suggest that the multifunctional nanocomposites have a controlled drug release property. Interestingly, the up‐conversion emission intensity of the multifunctional carrier increases with the released amount of model drug, thus allowing the release process to be monitored and tracked by the change of photoluminescence intensity. This composite can act as a multifunctional drug carrier system, which can realize the targeting and monitoring of drugs simultaneously.     

The effect of different lattice sites substitution on photoluminescence characteristics of Eu2+/Ce3+ doped M5(ZO4)3X

The empirical formula of Van Uitert is applied to calculating the emission wavelengths of haloapatite and silicon apatite phosphors doped with Eu²⁺/Ce³⁺. The relationship between emission wavelengths and occupied lattice sites of Eu²⁺/Ce³⁺ is discussed in haloapatite crystal. For phosphors of haloapatite and silicon apatite doped with Eu²⁺, the emission bands of the long-wave region are interpreted reasonably. Phosphors Sr₅(PO₄)₂SiO₄ doped with Eu²⁺/Ce³⁺ are synthesized by high temperature solid state reaction under two different atmospheres, the spectral characteristics of Eu²⁺/Ce³⁺ occupying different lattice sites are studied. The luminescent materials Sr₅(PO₄)₂SiO₄ doped with Eu²⁺/Ce³⁺ are promising blue-green phosphors for application in white-LEDs.     

Polyhedron Transformation toward Stable Narrow‐Band Green Phosphors for Wide‐Color‐Gamut Liquid Crystal Display

A robust and stable narrow‐band green emitter is recognized as a key enabler for wide‐color‐gamut liquid crystal display (LCD) backlights. Herein, an emerging rare earth silicate phosphor, RbNa(Li₃SiO₄)₂:Eu²⁺ (RN:Eu²⁺) with exceptional optical properties and excellent thermal stability, is reported. The resulting RN:Eu²⁺ phosphor presents a narrow green emission band centered at 523 nm with a full width at half maximum of 41 nm and excellent thermal stability (102%@425 K of the integrated emission intensity at 300 K). RN:Eu²⁺ also shows a high quantum efficiency, an improved chemical stability, and a reduced Stokes shift owing to the modified local environment, in which [NaO₈] cubes replace [LiO₄] squares in RbLi(Li₃SiO₄)₂:Eu²⁺ via polyhedron transformation. White light‐emitting diode (wLED) devices with a wide color gamut (113% National Television System Committee (NTSC)) and high luminous efficacy (111.08 lm W^?1) are obtained by combining RN:Eu²⁺ as the green emitter, K₂SiF₆:Mn⁴⁺ as the red emitter, and blue‐emitting InGaN chips. Using these wLEDs as backlights, a prototype 20.5 in. LCD screen is fabricated, demonstrating the bright future of stable RN:Eu²⁺ for wide‐color‐gamut LCD backlight application.     

ZnO基荧光粉的制备及荧光光谱分析

采用高温固相合成法制备了ZnO基荧光粉,并利用XRD、SEM等方法分析表征样品。实验结果表明,以氯化铵为助剂,在900℃煅烧2h制得了晶粒较小晶形完整分散性较好的ZnO：Zn荧光粉,用387nm的紫外光激发,获得了较宽的绿光发射;掺入Eu离子,在800℃煅烧合成了ZnO：Eu荧光粉,说明Eu离子掺杂有降低烧结温度的作用,另外用465nm光激发ZnO：Eu荧光粉获得了700nm的红光发射。     

Design and Synthesis of Multifunctional Drug Carriers Based on Luminescent Rattle‐Type Mesoporous Silica Microspheres with a Thermosensitive Hydrogel as a Controlled Switch

A novel approach for the fabrication of multifunctional microspheres integrating several advantages of mesoporous, luminescence, and temperature responses into one single entity is reported. First, the hollow mesoporous silica capsules are fabricated via a sacrificial template route. Then, Gd₂O₃:Eu³⁺ luminescent nanoparticles are incorporated into the internal cavities to form rattle‐type mesoporous silica nanocapsules by an incipient‐wetness impregnation method. Finally, the rattle‐type capsules serve as a nanoreactor for successfully filling temperature‐responsive hydrogel via photoinduced polymerization to form the multifunctional composite microspheres. The organic–inorganic hybrid microspheres show a red emission under UV irradiation due to the luminescent Gd₂O₃:Eu³⁺ core. The in vitro cytotoxicity tests show that the samples have good biocompatibility, which indicates that the nanocomposite could be a promising candidate for drug delivery. In addition, flow cytometry and confocal laser scanning microscopy (CLSM) confirm that the sample can be effectively taken up by SKOV3 cells. For in vitro magnetic resonance imaging (MRI), the sample shows the promising spin‐lattice relaxation time (T₁) weighted effect and could potentially apply as a T₁‐positive contrast agent. This composite drug delivery system (DDS) provides a positive temperature controlled “on‐off”drug release pattern and the drug, indomethacin (IMC), is released fast at 45 °C (on phase) and completely shut off at 20 °C (off phase). Meanwhile Gd₂O₃:Eu³⁺ plays an important role as the luminescent tag for tracking the drug loading and release process by the reversible luminescence quenching and recovery phenomenon. These results indicate that the obtained multifunctional composite has the potential to be used as a smart DDS for biomedical applications.     

New Ternary Europium Aluminate Luminescent Nanoribbons for Advanced Photonics

Developing novel one‐dimensional (1D) luminescent nanostructures (e.g., nanowires and nanoribbons) is highly desired for enabling progress in nanophotonics and other emerging optical technologies. Previous studies on 1D luminescent nanostructures were mostly focused on elemental and binary semiconductor materials, the light emission of which originates from the radiative recombination of electrons and holes via either intrinsic states or extrinsic defect states. Herein, three kinds of ternary europium aluminate nanoribbons are reported that have localized Eu²⁺ luminescent centers and exhibit new compositions, new crystal lattice structures, and new luminescence properties and mechanisms. These three europium aluminate nanoribbons are: blue luminescent EuAl₆O₁₀ with a new composition and a new tetragonal lattice structure, green luminescent EuAl₂O₄ with a monoclinic lattice structure, and orange luminescent EuAl₂O₄ with a new hexagonal lattice structure and extremely large band width and Stokes shift of emission. These materials have promising applications as nanometer‐scale light generators and waveguides in nanophotonics and as light converting phosphors in warm white light‐emitting diodes.     

Organic–Inorganic Hierarchical Self‐Assembly into Robust Luminescent Supramolecular Hydrogel

Luminescent hydrogels are of great potential for many fields, particularly serving as biomaterials ranging from fluorescent sensors to bioimaging agents. Here, robust luminescent hydrogels are reported using lanthanide complexes as emitting sources via a hierarchical organic–inorganic self‐assembling strategy. A new organic ligand is synthesized, consisting of a terpyridine unit and two flexibly linked methylimidazole moieties to coordinate with europium(III) (Eu³⁺) tri‐thenoyltrifluoroacetone (Eu(TTA)₃), leading to a stable amphiphilic Eu³⁺‐containing monomer. Synergistic coordination of TTA and terpyridine units allows the monomer to self‐assemble into spherical micelles in water, thus maintaining the luminescence of Ln complexes in water. The micelles further coassemble with exfoliated Laponite nanosheets coated with sodium polyacrylate into networks based on the electrostatic interactions, resulting in the supramolecular hydrogel possessing strong luminescence, extraordinary mechanical property, as well as self‐healing ability. The results demonstrate that hierarchical organic–inorganic self‐assembly is a versatile and effective strategy to create luminescent hydrogels containing lanthanide complexes, giving rise to great potential applications as a soft material.     

Novel Red-Emitting Microwave-Assisted-Sintered LiSrPO4: Eu3+ Phosphors for Application in Near-UV White Light-Emitting Diodes

Novel red-emitting LiSr_1?x PO₄:xEu³⁺ phosphors with various concentrations (x = 0.03, 0.05, 0.07, 0.1) of Eu³⁺ ions were synthesized by microwave-assisted sintering at 1200°C for 3 h in air. The microstructural and luminescent characteristics of the LiSrPO₄:Eu³⁺ phosphors were investigated and are discussed here. x-Ray diffraction (XRD) results showed that the prepared LiSr_1?x PO₄:xEu³⁺ phosphors presented an impurity phase of Eu₂O₃ when the Eu³⁺ ions exceeded x = 0.05. Photoluminescence (PL) results showed a series of emission states ⁵D₀ → ⁷F₀, ⁵D₀ → ⁷F₁, ⁵D₀ → ⁷F₂, ⁵D₀ → ⁷F₃, and ⁵D₀ → ⁷F₄ (corresponding to the typical 4f → 4f intraconfiguration forbidden transitions of Eu³⁺) with a major emission peak at around 617 nm. The optimum concentration of Eu³⁺ for LiSr_1?x PO₄:xEu³⁺ prepared by microwave-assisted sintering was found to be 0.05. The lifetime values of LiSr_1?x PO₄:xEu³⁺ phosphors with doping concentrations of Eu³⁺ ions of 0.03, 0.05, 0.07, and 0.1 were found to be 3.32 ms, 3.30 ms, 2.84 ms, and 2.60 ms, respectively. Moreover, the chromaticity values (x, y) of all of the LiSr_1?x PO₄:xEu³⁺ phosphors were located in the red region (0.65, 0.34).     

Luminescence properties of Ca4GdO(BO3)3:Eu in ultraviolet and vacuum ultraviolet regions

The luminescent properties of Ca₄GdO(BO₃)₃:Eu³⁺ were investigated under excitation of UV and VUV light. Separate two broad bands at around 259 and 184 nm were observed in the excitation spectrum of Ca₄GdO(BO₃)₃:Eu³⁺. These peaks were assigned to the charge transfer transition of Eu³⁺-O²⁻ and Gd³⁺-O²⁻, respectively. Owing to the favorable spectral position in their broad intense excitation band, Eu³⁺ ions show a intense emission under 258 nm excitation in Ca₄GdO(BO₃)₃:Eu³⁺. This spectral position was determined by the free oxygen ions O (1). Ca₄GdO(BO₃)₃ doped with Eu³⁺ ion seems to be a preferable candidate as red lamp phosphor. On the other hand, a weak band with a maximum at about 184 nm was observed below 200 nm in the excitation spectrum of Ca₄GdO(BO₃)₃:Eu³⁺. This phosphor do not emit effectively under the 147 nm excitation. This unfavorable profile was also due to the O (1) ions, which played a role to the shifting towards the lower energy sides. The luminescence of Eu³⁺ ions in Ca₄GdO(BO₃)₃ was somewhat different from that observed in the other borates phosphors, but resembled to those observed in the oxide phosphors (e.g. Gd₂O₃, Y₂O₃ and Gd₂SiO₅). Such behavior was recognized by the detailed analysis of crystallographical surroundings around activator.     

Synthesis of Luminescent ZrO2:Eu3+ Nanoparticles and Their Holographic Sub‐Micrometer Patterning in Polymer Composites

Here, the facile synthesis of fluorescent ZrO₂:Eu³⁺ nanoparticles with luminescence quantum yield of up to 8.7% that can be easily dispersed in organic solvents and utilized for the preparation of organic/inorganic volume holographic gratings is presented. The nanoparticles are prepared through a one‐step solvothermal process resulting in spherical particles with a mean size of 4 nm that were highly crystalline directly after the synthesis, without any need for calcination treatment. Detailed luminescence studies of the nanoparticles as a function of Eu³⁺ content demonstrate that the dopant concentration and its site symmetry play an important role in the emissive properties and lifetime of the luminescent centers. It is shown that the luminescence quantum yield of the colloidal ZrO₂:Eu³⁺ nanoparticles increases with dopant concentration up to a critical concentration of 11 mol% while the luminescence lifetime is shortened from 1.8 to 1.4 ms. Holographic photopolymerization of suitable monomer mixtures containing the luminescent nanoparticles demonstrated the ability to inscribe volume Bragg gratings (refractive index contrast n₁ up to 0.011) with light‐emissive properties, evidencing the high suitability of this approach for the fabrication of tailored nanomaterials for elaborate and demanding applications.     

Improving spectral response of monocrystalline silicon photovoltaic modules using high efficient luminescent down‐shifting Eu3+ complexes

One way to improve the spectral response of solar cells in the ultraviolet (UV) region is to convert high energy photons into lower energy ones via luminescent down‐shifting (LDS) technique. Eu³⁺ complexes are excellent LDS species because of their high luminescence quantum efficiency and large Stokes‐shift. In this paper, we aim to optimize the LDS property of Eu³⁺ complexes for monocrystalline silicon (c‐Si) photovoltaic (PV) modules by chemical modification of the UV absorbing antenna ligands. Our results show that the LDS performances of Eu³⁺ complexes are strongly dependent on their absorption and emission properties. By carefully modifying the absorption and emission features, the LDS performances of Eu³⁺ complexes can be significantly improved. The spectroscopic features of the Eu³⁺ complex with a bispinene‐containing bipyridyl ligand match well with the requirement of ideal LDS species for the c‐Si PV module. Simple coating of polyvinyl acetate film doped with this complex onto the surface of c‐Si PV module leads to increase of the external quantum efficiency in the UV region and enhancement of the PV module efficiency η (from 16.05% to 16.37%). Copyright © 2012 John Wiley & Sons, Ltd.     

Pressure‐Driven Eu2+‐Doped BaLi2Al2Si2N6: A New Color Tunable Narrow‐Band Emission Phosphor for Spectroscopy and Pressure Sensor Applications

A series of BaLi₂Al₂Si₂N₆ (BLASN): xEu²⁺ phosphors are successfully synthesized and their crystal structure and luminescence properties under varying hydrostatic pressures are reported herein. Structure variation is analyzed using in situ high‐pressure X‐ray diffraction and Rietveld refinements. Based on decay curves and Gaussian fitting of emission spectra, the presence of two photoluminescence centers is demonstrated. BaLi₂Al₂Si₂N₆: 0.01Eu²⁺ exhibits an evident peak position shift from 532 to 567 nm with an increase in pressure to ≈20 GPa. The possible factors and mechanisms for the variations are studied in detail. At a pressure of 16 GPa, BLASN: Eu²⁺ realizes a narrow yellow emission with a full width at half maximum of ≈70 nm. The addition of BLASN: Eu²⁺ (16 GPa) to the commercial white light‐emitting diodes combination consisting of an InGaN chip, β‐SiAlON: Eu²⁺, and red K₂SiF₆:Mn⁴⁺, can increase the color gamut by ≈15%, demonstrating the promising potential of pressure‐driven BLASN: Eu²⁺ for wide‐color gamut spectroscopy applications. Moreover, the emission shifts arising from pressure variation and the distinct color changes enable its potential utility as an optical pressure sensor; the material exhibits high pressure sensitivity (dλ/dP ≈ 1.58 nm GPa^?1) with the advantage of visualization.     

Efficient Mechanoluminescent Elastomers for Dual‐Responsive Anticounterfeiting Device and Stretching/Strain Sensor with Multimode Sensibility

In this work, an environmentally friendly and novel oxide‐based mechanoluminescent material, Sr₃Al₂O₆: Eu³⁺, which can serve as the alternative for the widely used but environmentally hazardous transition metal–doped sulfides is reported. This oxide could exhibit highly efficient photoluminescence, but even more efficient mechanoluminescence as embedded into polydimethylsiloxane matrix under mechanical stimulation. The emitting color of the resultant Sr₃Al₂O₆: Eu³⁺/polydimethylsiloxane elastomer composites could be further manipulated by adjusting the synthesis atmosphere of the Sr₃Al₂O₆: Eu³⁺ based on its unique self‐reduction characteristic. Moreover, by combining the wavelength selectivity of photoluminescence and dynamic stress response of mechanoluminescence, Sr₃Al₂O₆: Eu³⁺ enables the design of two types of intriguing devices. They are a dual‐responsive anticounterfeiting flexible device activated by either photons or mechanics, and a comprehensive stretching/strain sensor capable of sensing both strain level and stretching states. In comparison to the conventional luminescent materials, with a rare combination of efficient photoluminescence, highly sensitive mechanoluminescence, and facile color tunability, Sr₃Al₂O₆: Eu³⁺ is much more versatile and ideal for various advanced applications.     

Nd3+ doped fluorochlorozirconate glass:3.9 μm MIR emission properties and energy transfer

The Nd3+ doped fluorochlorozirconate (FCZ) glass was prepared by melt-quenching method. The 3.9 μm emission from Nd3+ ions is attributed to the two-photon absorption process. The strong emission transition at 3.9 μm fluorescence peak intensity, corresponding to the 4G11/2→2K13/2 transition, is directly proportional to the NaCl concentration. With the increase of the Cl- ions amount, the mid-infrared (MIR) luminescent intensity is significantly enhanced. Additionally, the Judd-Ofelt (J-O) parameter Ω2 is larger than that of the fluorozirconate (FZ) glass, which indicates the covalency of the bond between RE ions and ligand is stronger as Cl- ions substitution of F- ions in chloride FZ glass. The X-ray diffraction (XRD) patterns show that the amorphous glassy state keeps the FZ glass network structure. In brief, the advantageous spectroscopic characteristics make the Nd3+-doped FCZ glass be a promising candidate for application of 3.9 μm emission.     

Luminescence properties of tunable red-green emitting phosphor Ba2Ca(BO3)2:Eu3+, Tb3+

A series of Eu3+ or Tb3+ doped Ba2Ca(BO3)2 phosphors were synthesized by a high temperature solid state method, and the luminescence properties are investigated. Ba2Ca(BO3)2:Tb3+ can show an obvious green emission, and the peak locates at 551 nm, which corresponds to the 5D4→7F5 transition of Tb3+. Ba2Ca(BO3)2:Eu3+ can present the characteristic emission of Eu3+, and the peak locates at 600 nm, which is ascribed to the 5D0→7F2 transition of Eu3+. In order to achieve the emission-tunable phosphors, the Eu3+/Tb3+ co-doped Ba2Ca(BO3)2 are synthesized. When tuning the Eu3+ or Tb3+ concentration, Ba2Ca(BO3)2:Eu3+, Tb3+ can both show the tunable emission, which may be induced by the energy transfer from Tb3+ to Eu3+.