LiCa3MgV3O12:Sm3+: A new high-efficiency white-emitting phosphor

A novel single-phased white-light-emitting phosphor Sm³⁺ doped LiCa₃MgV₃O₁₂ (LCMV) was developed. The LCMV host was one self-activated bluish-green emitting phosphor, which possessed an efficient excitation band in the 250–400?nm wavelength range and showed an intense broadband bluish-green emission with internal quantum efficiency (IQE) of 39%. Doping Sm³⁺ ions in to LCMV host induced tunable-color emissions, due to the energy transfer from [VO₄]^3? to Sm³⁺ ions. Importantly, under 340?nm excitation, the LCMV:Sm³⁺ can emitted bright white light by combining the self-activated luminescence of LCMV host and the red emissions of Sm³⁺ ions, and the IQE of the white-emitting composition-optimized LCMV:0.01Sm³⁺ phosphors reached up to 45%. These white-emitting LCMV:Sm³⁺ phosphors have potential applications in white light-emitting diodes and optical display devices.     

Structural and luminescent properties of Eu3+-doped double perovskite BaLaMgNbO6 phosphor

Eu³⁺-activated BaLaMgNbO₆ red-emitting phosphors were synthesized by a high-temperature solid-state reaction method. Phase analysis and luminescence were characterized by X-ray diffraction (XRD) and photoluminescence excitation and emission spectra. The XRD patterns showed that BaLaMgNbO₆ had a monoclinic structure with space group P21/n. The excitation spectra consisted of a broad charge-transfer band and some sharp f-f absorption peaks characteristic of Eu³⁺. The intensity ratio of I₆₁₅/I₅₉₀ was used to detect the chemical environment of Eu³⁺. The chromaticity coordinates of BaLa_0.7Eu_0.3MgNbO₆ were (0.67, 0.33), indicating that the BaLaMgNbO₆:Eu³⁺ phosphors were excellent red-emitting phosphors. Under excitation by near-ultraviolet (UV) and blue light, the phosphor not only exhibited intense red emission but also showed high color quality. The Ozawa and Dexter energy-transfer theories were employed to calculate the theoretical quenching concentration and determine the concentration quenching mechanism. In addition, the activation energy of BaLa_0.7Eu_0.3MgNbO₆ was calculated through the Arrhenius equation. A configurational coordinate diagram was used to explain the thermal quenching mechanism.     

Synthesis,structure and luminescent properties of Eu3+ doped Ca3LiMgV3O12 color-tunable phosphor

A new vanadate Ca₃LiMgV₃O₁₂ and its Eu³⁺-doped counterparts were synthesized. Rietveld confinement result of Ca₃LiMgV₃O₁₂ host indicates that it belongs to cubic space group Ia-3d with parameters of a =?12.4300?Å, V =?1920.49?ų, Z?=?8. Under UV excitation, pure Ca₃LiMgV₃O₁₂ exhibits a bluish-green broadband emission at 490?nm, while Eu³⁺ doped Ca₃LiMgV₃O₁₂ shows one bluish-green broad band with a series of red sharp peaks, which originate from the V⁵⁺-O^2- charge transfer and the Eu³⁺ intra-4f transitions, respectively. The occurrence of VO₄→Eu³⁺ energy transfer is confirmed by decay lifetime analysis and time-resolved emission spectra. It is found that emitting color varies from bluish-green to orange-red with increasing Eu³⁺ concentration. VO₄ bluish-green and Eu³⁺ red emission shows different thermal quenching response with increasing temperature, due to their different activation energy.     

pH dependent hydrothermal synthesis of Ca14Al10Zn6O35:0.15Mn4+ phosphor with enhanced photoluminescence performance and high thermal resistance for indoor plant growth lighting

Artificial light source for indoor cultivation has been vastly impeded by the lack of high far red emitting phosphors. Recently, Mn⁴⁺ activated phosphors were reported to be promising luminescent materials to solve above matter. In this study, controllable design of Ca₁₄Al₁₀Zn₆O₃₅:0.15Mn⁴⁺ (CAZO:0.15Mn⁴⁺) far red emitting phosphors was realized via pH assisted hydrothermal approach. The pure CAZO:0.15Mn⁴⁺ phosphors were obtained merely when the reaction pH was 1 or 2. Meanwhile, by adjusting the pH value of the reaction solution, far red emission CAZO:0.15Mn⁴⁺ phosphors with grains, sphere-like as well as aggregated bulk particles can be achieved at pH =?4, pH =?6 and pH =?10, respectively. Furthermore, the structures and morphologies depended photoluminescence (PL) performances of CAZO:0.15Mn⁴⁺ were checked. The best PL performance was found for the phosphor produced at pH =?6, while over acidic or alkaline conditions would lower the emission intensity. In addition, this phosphor also exhibit good thermal resistance which can maintain 78% initial intensity at 150?°C. The practical indoor tobacco cultivation demonstrated that CAZO:0.15Mn⁴⁺ obtained through this pH adjusted hydrothermal route is a promising phosphor for indoor plant growth lighting.     

Organic template-directed indium phosphite-oxalate hybrid material: Synthesis and characterization of a novel 3D |C6H14N2|[In2(HPO3)3(C2O4)] compound with intersecting channels

A novel anionic three-dimensional indium phosphite-oxalate hybrid material, formulated as |C₆H₁₄N₂|[In₂(HPO₃)₃(C₂O₄)] (1) was prepared under hydrothermal conditions by using 1,4-diazabicyclo[2.2.2]octane (dabco) as a structure directing agent (SDA). Single-crystal X-ray diffraction analysis reveals that compound 1 crystallizes in the orthorhombic system space group Pna2₁ (No. 33) having unit cell parameters a = 12.4143(13) Å, b = 7.7166(8) Å, c = 18.327(2) Å, V = 1755.6(3) Å³, and Z = 4 with R₁ = 0.0282, wR₂ = 0.0632. The novel 3D open framework is constructed from InO₆ octahedra, HPO₃ pseudo-tetrahedra and C₂O₄ units. The assembly of these building units generates intersecting 8- and 12-membered ring (MR) channels along two different directions. To the best of our knowledge, it is the first reported indium phosphite-oxalate hybrid material. Further characterization of compound 1 was performed using X-ray powder diffraction (XRD), infrared (IR) spectra, thermal gravimetric analyses (TGA), inductively coupled plasma (ICP) and elemental analyses.     

Single-phased emission-tunable Ca3Si2O7:Ce,Eu phosphors for white light-emitting diodes

A series of single-phased emission-tunable Ca₃Si₂O₇:Ce³⁺, Eu²⁺ phosphors has been prepared by the solid-state reaction method. The phosphors show two intense emission bands at about 450 nm and 610 nm, which are attributed to the 5d→4f transitions of Ce³⁺ and Eu²⁺ ions, respectively. The emission colors of Ca₃Si₂O₇:Ce³⁺, Eu²⁺ phosphors vary from blue (0.148, 0.147) to white (0.309, 0.260), and eventually to orange (0.407, 0.319) by tuning the Eu²⁺/Ce³⁺ ratio. Energy transfer from Ce³⁺ to Eu²⁺ is studied by luminescence spectra and energy transfer efficiency. The results show an electric quadrupole–quadrupole interaction plays an important role in the process of energy transfer. The phosphors with tunable emission are suitable for application in white light-emitting diodes.     

The luminescence and structural characteristics of Eu-doped NaBaPO4 phosphor

Eu³⁺-doped NaBaPO₄ was prepared by a high-temperature solid-state reaction. The phase formation was confirmed by X-ray powder diffraction measurements. The laser site-selective excitation and emission spectra have been investigated in the ⁵D₀ → ⁷F₀ region by using a pulsed, tunable and narrowband dye laser. The excitation spectra corresponding to the ⁷F₀ → ⁵D₀ transition consist of two transitions at 579.6 nm Eu(I) and 578.9 nm Eu(II), indicating the Eu³⁺ ions occupy two crystallographic sites of Ba²⁺ ions. The decay lifetimes of the two Eu³⁺ sites were measured. Two crystallographic sites for Eu³⁺ ions doped in NaBaPO₄ lattice were assigned from the luminescence characteristic and structure features. Meanwhile, the charge compensation mechanism of Eu³⁺ doping in NaBaPO₄ was discussed.     

Synthesis and Luminescence Properties of Y3Al5O（12）：Eu^（3＋） Phosphors under Vacuum Ultraviolet Excitation

采用凝胶–燃烧法合成了掺Eu3＋的Y3Al5O12（YAG：Eu3＋）荧光粉。分别采用X射线衍射（XRD）、扫描电子显微镜（SEM）、发光光谱等测试手段分析了不同温度下煅烧所得粉体的物相、形貌与发光性质。XRD和SEM结果表明：YAG：Eu3＋的最低合成温度为900℃,并且在该反应过程中没有中间相YAP（YAlO3）和YAM（YAl）的产生。1 100℃合成的晶粒尺寸比较均匀,平均粒径在90 nm左右。发光光谱的测试表明：在592 nm监控下的真空紫外激发光谱由峰值位于147、156、169nm和214nm的系列激发带组成,其分别归属于铝酸根的基质吸收以及Y3＋和Eu3＋的电荷迁移带吸收。在147nm激发下YAG：Eu3＋荧光粉最强发射峰位于592nm处,属于Eu3＋的5D0→7F1跃迁。Eu3＋在基质中的最佳掺杂摩尔分数为4%。     

The role of Eu2O3 and CeO2 on the phase formation,infrared emission and magnetic properties of Co0.6Zn0.4Fe2O4 ceramics by a solvothermal method

Nanosized Eu₂O₃ and CeO₂ co-addition CoZn ceramics have been achieved via a hydrothermal method by adjusting the mol ratios of Eu and Ce. The as-prepared samples were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), Fourier transform infrared (FTIR), Vibrating sample magnetometer (VSM) and Infrared emission measurement (IRE-2). The particle morphologies of the as-prepared samples evolve from spherical, to self-assembled nanoparticles, and irregular nanoparticles when the mol ratios (x) of Eu and Ce was changed from 0:10 to 10:0. Correspondingly, the main phases of the as-prepared samples change from both cubic spinel CoFe₂O₄ and CeO₂, pure cubic cerianite CeO₂, to amorphous. Meanwhile, the as-prepared samples appear transformed from a ferromagnetic behavior with a saturation magnetization 66.4 emu/g to a paramagnetic behavior with a saturation magnetization of 0.55 emu/g at turning point x=3.5:6.5. While the infrared emissivity is increasing as the x from 0:10 to 3.5:6.5, reach the maximum at 3.6:6.4, and then remain stable when further increasing x till 10:0. Those may be due to the amorphous tendency rising and the particle sizes gradual decreasing with x increasing from 0:10 to 10:0. What is more important is that the solvothermal method is proved to be an efficient way to prepare CoZn nano-ceramics in this study which may open new pathways to magnetic and far infrared therapy.     

Photoluminescence enhancement of novel K(Y,Lu)CaWO6: Eu3+ red phosphor prepared by controllable citrate-EDTA complexing method

Novel double-perovskite K(Y_0.95-xLu_xEu_0.05)CaWO₆ red phosphors were successfully prepared by the controllable citrate-EDTA complexing method. XRD with structure refinement, FTIR, Raman and photoluminescence spectra were combined to systematically investigate the structure parameters and luminescence properties of prepared phosphors. The substitution of Lu³⁺ with smaller ionic radius resulted in the lower symmetry even with the same space group of C2/m, which was also directly observed from the red shift and splitting of Raman T_2?g(1) mode. The concentration higher than x?=?0.6 made the intensity alteration in the excitation spectra from charge transfer band to 4f?4f of Eu³⁺. The obvious enhancements of red emission at 615?nm were obtained under both blue and ultraviolet lights, respectively, and reached almost the same intensity at x?=?0.6. Meanwhile, the more standard red light could be found by the gradual shifts of CIE chromaticity coordinates and bigger ratio of red/orange emission. The substitution of Lu³⁺ improved the quality and emission intensity of red light of this double perovskite system and the composition optimized phosphor of K(Y_0.35Lu_0.6Eu_0.05)CaWO₆ exhibited great potential in the application of white LEDs.     

新型Sr2V2O7:Eu3+荧光材料的制备及表征

以高纯度的SrCO3、NH4VO3、Eu2O3和Yb2O3等为主要原料,采用高温固相法合成荧光粉。X-粉末衍射及荧光光谱证实合成了一种在可见光范围内有广泛吸收的发黄光的钒酸盐体系荧光粉。其中Eu3+的最佳掺杂摩尔浓度比为0.09,最佳煅烧温度为1223K。     

Facile Synthesis of Amine-Functionalized Eu3+-Doped La(OH)3 Nanophosphors for Bioimaging

Here, we report a straightforward synthesis process to produce colloidal Eu³⁺-activated nanophosphors (NPs) for use as bioimaging probes. In this procedure, poly(ethylene glycol) serves as a high-boiling point solvent allowing for nanoscale particle formation as well as a convenient medium for solvent exchange and subsequent surface modification. The La(OH)₃:Eu³⁺ NPs produced by this process were ~3.5 nm in diameter as determined by transmission electron microscopy. The NP surface was coated with aminopropyltriethoxysilane to provide chemical functionality for attachment of biological ligands, improve chemical stability and prevent surface quenching of luminescent centers. Photoluminescence spectroscopy of the NPs displayed emission peaks at 597 and 615 nm (λ_ex = 280 nm). The red emission, due to ⁵D₀ → ⁷F₁ and ⁵D₀ → ⁷F₂ transitions, was linear with concentration as observed by imaging with a conventional bioimaging system. To demonstrate the feasibility of these NPs to serve as optical probes in biological applications, an in vitro experiment was performed with HeLa cells. NP emission was observed in the cells by fluorescence microscopy. In addition, the NPs displayed no cytotoxicity over the course of a 48-h MTT cell viability assay. These results suggest that La(OH)₃:Eu³⁺ NPs possess the potential to serve as a luminescent bioimaging probe.     

Synthesis,structural characterization and luminescent properties of Tb3+-doped AgLaP2O7 phosphors

Silver lanthanum diphosphates doped with terbium, AgLa_1-xTb_xP₂O₇ (x=0%, 1%, 5%, 10%, 15% and 20%), were prepared by solid state reaction at T=500°. The obtained compounds were investigated by means of a multi-methodological approach, involving the Scanning Electron Microscopy (SEM) equipped with energy dispersive X-Ray spectroscopy (EDS) for morphological investigation and semi-quantitative chemical analysis, respectively; powder X-ray diffraction (PXRD) for structural characterization and Rietveld refinement; Fourier Transform InfraRed (FTIR) and Raman spectroscopies for qualitative study. Finally, emission spectra were collected in order to detect the fluorescence properties of the compounds.The unit cell parameters and the space group of all the family members were determined by PXRD data. The compounds crystallize in the orthorhombic Pnma space group, with the AgLaP₂O₇ cell constants equal to: a?=?8.6706(1) Å, b?=?5.3218(1) Å, c?=?12.8839(1) Å and cell volume V?=?594.51(1) ų. A decreasing trend for unit cell parameters was observed at increase of dopant concentration. For the pure phase, the investigation was completed with the structure solution via Direct Methods and Rietveld refinement. The crystal structure consists of compact layers of LaO₉ polyhedra, down the c axis, bridged by P₂O₇ diphosphate groups and by zig-zag chains of AgO₉ polyhedra down b.The FTIR and Raman analysis supports the chemical structure, highlighting the deformation (δPO₃) and stretching (νPO₃) vibration of PO₃ groups, and the characteristic bands of P₂O₇^4- groups attributed to the symmetric and asymmetric stretching (ν_s and ν_as) of P-O-P bridge, respectively.The luminescence properties of Tb³⁺ activating ion in AgLa_1-xTb_xP₂O₇ (x=1%, 5%, 10%, 15% and 20%) were also examined. No concentration quenching of the main ⁵D₄-→⁷F₅ emission, responsible for the well known green emission of Tb³⁺ ion, was observed in the studied concentration range, whereas a concentration quenching of the emission from ⁵D₃ level, due to ⁵D₃^-→⁵D₄ cross relaxation process, was revealed.     

Eu3+ doped monetite and its use as fluorescent agent for dental restorations

It is essential but challenging to distinguish the dental restorations from the surrounding teeth when removing filling materials from cavity. In this study, Eu³⁺ doped monetite was proposed as a fluorescent agent for dental restorations to meet this challenge. Eu³⁺ doped monetite with enhanced fluorescent property was obtained via a precipitation method. The presence of Eu³⁺ could prevent the phase transformation of brushite to monetite. However, all the brushite particles transformed to monetite at 300?°C and to tricalcium phosphate at 800?°C. The emission intensity increased with the addition of Eu³⁺ and reached the maximum when 12?mol% Eu³⁺ was added into the aqueous solution. With either 254?nm or 393?nm excitation, Eu³⁺ doped monetite showed the strongest fluorescence emission peaking at 616?nm and other two moderate bands peaking at 699?nm and 593?nm. The excitation spectra at the emission wavelength of 616?nm showed strong absorption peaks at 254?nm and 393?nm. We further investigate the fluorescence properties of Eu³⁺ doped monetite in one type of dental restorations. Glass ionomer cement with Eu³⁺ doped monetite exhibited clear fluoresce with origin color under UV irradiation at 254?nm, showing that Eu³⁺ doped monetite is a promising fluorescent agent for dental restorations.     

Red-emitting enhancement of Bi4Si3O12:Sm3+ phosphor by Pr3+ co-doping for White LEDs application

In this account, Bi₄Si₃O₁₂:Sm³⁺ and (Bi₄Si₃O₁₂:Sm³⁺, Pr³⁺) red phosphors were prepared by solution combustion method fueled by citric acid at 900 °C for 1 h. The effects of co-doping Pr³⁺ ions on red emission properties of Bi₄Si₃O₁₂:Sm³⁺ phosphors, as well as the mechanism of interaction between Sm³⁺ and Pr³⁺ ions were investigated by various methods. X-ray diffraction (XRD) and Scanning electron microscopy (SEM) revealed that smaller amounts of doped rare earth ions did not change the crystal structure and particle morphology of the phosphors. The photoluminescence spectroscopy (PL) indicated that shape and position of the emission peaks of (Bi₄Si₃O₁₂:Sm³⁺, Pr³⁺) phosphors excited at λ_ex=403 nm were similar to those of Bi₄Si₃O₁₂:Sm³⁺ phosphors. The strongest emission peak was recorded at 607 nm, which was attributed to the ⁴G_5/2→⁶H_7/2 transition of the Sm³⁺ ion. The photoluminescence intensities of Bi₄Si₃O₁₂:Sm³⁺ phosphors were significantly improved by co-doping with Pr³⁺ ions and were maximized at Sm³⁺ and Pr³⁺ ions doping concentrations of 4 mol% and 0.1 mol%, respectively. The characteristic peaks of Sm³⁺ ions were displayed in the emission spectra of (Bi₄Si₃O₁₂:Sm³⁺, Pr³⁺) phosphors excited at respectively λ_ex=443 nm and λ_ex=481 nm (Pr:³H₄→³P₂, ³H₄→³P₀). This indicated the existence of Pr³⁺→Sm³⁺ energy transfer in (Bi₄Si₃O₁₂:Sm³⁺, Pr³⁺) phosphors.     

Effect of europium concentration on the photoluminescent and thermoluminescent properties of HfO2:Eu3+ nanocrystals

This work is aimed to determine the influence of the europium concentration on the photoluminescent and thermoluminescent properties of the HfO₂:Eu³⁺ synthesized by hydrothermal method. Samples were prepared at Eu³⁺ contents of 0, 1, 3, 5 and 7?at%. The structural, morphological, photoluminescent and thermoluminescent characteristics of the material, as well as the kinetic parameters of the glow curve when it was exposed to UV radiation at 254?nm are presented. The maximum response for the photoluminescence and thermoluminescence properties, with an integrated signal more than six times greater than the signal obtained for the intrinsic sample, was found for the sample with 5?at% Eu³⁺. Nanocrystal sizes of 28?nm were obtained for the pure sample and 46?nm for the sample doped with the highest concentration of Eu³⁺.The microcrystals showed a preferential growth in the (022) direction.     

单分散Gd2O3:Eu3+@SiO2的合成及性能

采用溶胶-凝胶法合成SiO₂包覆Gd₂O₃:Eu³⁺球型核壳粒子,并对所得产物进行XRD,FT-IR,SEM,TEM,XDS,PL等测试。XRD结果显示:壳层Gd₂O₃:Eu³⁺在600℃开始结晶,随着煅烧温度的升高结晶性提高。SEM,TEM测试结果显示所得核壳粒子具有高分散、均匀球型形貌、粒径大小300nm左右。在255nm的紫外光激发下,合成的荧光粉具有很强的610nm的特征红光。     

Insight into the evolution mechanism of carbon film and Eu valence in carbon coated BaMgAl10O17: Eu2+ phosphor annealed in air

Performing carbon coating on the surface of phosphors has been proven to be an effective strategy to enhance the oxidation resistance, which is an important factor to achieve stable luminescent devices. Therefore, a good understanding of the protection mechanism favors a continuous improvement of oxidation resistance of phosphors. In present paper, the evolution of the carbon layer, Eu valence (Eu²⁺/Eu³⁺), and luminescent properties for the C coated BaMgAl₁₀O₁₇: Eu²⁺ phosphor when annealed at high temperature is investigated carefully. Decrease of carbon layer promotes the appearance color transition from black to white as the annealing temperature rises to 1000?°C in air. As expected, the decrease of carbon layer will enhance the luminescence intensity, but risk the possible oxidation of Eu²⁺ to Eu³⁺, which inhibits the blue emission ascribed to Eu²⁺. The results indicate that luminescence intensity of phosphor is dependent on the synergistic effect of carbon thickness and Eu²⁺/Eu³⁺ ratio. Additionally, a reduction reaction of Eu³⁺ to Eu²⁺ is observed in C coated BaMgAl₁₀O₁₇: Eu²⁺ phosphor when annealed at high temperature, which also contributes to the higher luminescence intensity.     

The synthesis and photophysical property of [HNEt3][Cuq2IEu(hfac)3] complex

A new bimetallic complex [HNEt₃][Cuq₂IEu(hfac)₃] (q⁻ = 8-hydroxyquinolinato, hfac⁻ = hexafluoroacetylacetonate) was prepared simply with only one step and characterized. Upon excitation of the organic ligand q⁻, the sensitized europium luminescence was achieved.     

Promoting effect of calcium on reduction of NO by C3H6 over V2O5/ZrO2 catalysts

The reduction of nitrogen monoxide by propene on V₂O₅/ZrO₂ doped with or without calcium has been studied by FTIR spectroscopy as well as by analysis of the reaction products. Considerable promoting effect of calcium doping on the reduction of nitrogen monoxide by propene was observed on the V₂O₅/ZrO₂ catalysts. For the reaction of a mixture of NO+C₃H₆, carbonyl and carboxylate species were observed above 373 K, although nitrate species formed at room temperature on V₂O₅/ZrO₂ doped with calcium. No bands due to a compound including both carbon and nitrogen atoms were observed. Thus, the redox mechanism, i.e. propene reduces the catalyst and nitrogen monoxide oxidizes the catalyst, is confirmed on V₂O₅/ZrO₂ catalysts doped with or without calcium. The analysis of the V=O band in the region of 1100–900 cm⁻¹ indicates that this promotion is mainly due to new V=O species formed by the addition of calcium onto the catalyst. This species is easily reproduced in comparison with the other V=O species on the surface in the reoxidation process of the catalyst.