Search

In this work, CDs@Eu-UiO-66(COOH)

A series of La-based metal−organic frameworks (La-MOFs) phosphors have been successfully synthesized by a facile solvothermal method without assistance of any surfactant or template. The results show that the ethanol volume ratio is important to obtain adjustable shape and size of La-MOFs in the synthesis process. The obtained samples possess flake-like architectures with about 3–5 μm in length. Under UV excitation, all the La-MOFs:Tb3+, Eu3+ phosphors exhibit the characteristic emissions of Tb3+ and Eu3+. Moreover, the emitting color of the as-obtained products can be acquired from green, green-yellow, yellow, yellow-orange, orange, to red owing to the efficient energy transfer (ET) between Tb3+ and Eu3+ions. The ET efficiency of the samples was calculated, and the maximum was found about 96.84%. Furthermore, the dipole–quadrupole interaction has been reasonable proved by the energy transfer between Tb3+ and Eu3+. These results indicated that La-MOFs:Tb3+, Eu3+ might be as a novel potential candidate as phosphors for displays and lightings.

In this work, BaYF5:20%Yb3+/2%Er3+/x%Bi3+ (abbreviated as BaYF5:Yb,Er,Bix, where x = 0-3.0) upconversion nanoparticles (UCNPs) with various doping concentrations of Bi3+ were synthesized through a simple hydrothermal method. The influence of the doping amount of Bi3+ on the microstructures and upconversion luminescence (UCL) properties of the BaYF5:Yb,Er,Bix UCNPs was studied in detail. The doping concentration of Bi3+ has little influence on the microstructures of the UCNPs but significantly impacts their UCL intensities. Under excitation of a 980 nm near-IR laser, the observed UCL intensities for the BaYF5:Yb,Er,Bix UCNPs display first an increasing trend and then a decreasing trend with an increase in the ratio x, giving a maximum at x = 2.5. A possible energy-transfer process and simplified energy levels of the BaYF5:Yb,Er,Bix UCNPs were proposed. The potential of the BaYF5:Yb,Er,Bix UCNPs as contrast agents for computerized tomography (CT) imaging was successfully demonstrated. An obvious accumulation of BaYF5:Yb,Er,Bix in tumor sites was achieved because of high passive targeting by the enhanced permeability and retention effect and relatively low uptake by a reticuloendothelial system such as liver and spleen. This work paves a new route for the design of luminescence-enhanced UNCPs as promising bioimaging agents for cancer theranostics.

A series of Tb-based metal–organic frameworks (Tb-MOFs) were successfully synthesized by a solvothermal method. The size and morphology of the as-obtained Tb-MOFs can be effectively controlled via regulating the experimental conditions such as the volume fraction of DMF and the molar ratio of Tb3+ to NaOH. It is found that all the samples exhibit strong green emissions under ultraviolet excitation, corresponding to 5D4 → 7FJ transitions of Tb3+. Interestingly, Tb-MOFs displayed an efficient and distinct luminescence quenching by Cu2+ in aqueous solutions. The competitive fluorescence detection experiments indicate that these Tb-MOFs sensors can be used as a high selective and sensitive sensor of Cu2+ detection with the detection limit of 10 µmol·L−1, which can be used as a promising fluorescence sensor for Cu2+ detection in daily life.

Hierarchically uniform three-dimensional europium-based metal–organic frameworks (Eu-MOFs) have been successfully fabricated via a facile and mild liquid precipitation method at room temperature. The morphology, structure, and composition of samples are well characterized by scanning electron microscopy, X-ray powder diffraction, fourier transform infrared spectroscopy, thermogravimetric analysis, and elemental analyses, respectively. These well-arranged Eu-MOFs architectures show red emission corresponding to the 5D0/7F2 transition of the Eu3+ ions under UV light excitation. Remarkably, these Eu-MOFs samples exhibit clear “turn-off” quenching response for styrene vapors with high selectivity and reusability. This Eu-MOFs fluorescent sensor realizes fast recognition for styrene with a response time of less than 1 min at room temperature. Moreover, good detection reproductivity could also be achieved in this sensor. Considering the easy preparation, high selectivity and excellent repeatability, the sensor system provides a convenient and reliable detection of volatile organic compound in everyday applications.

A series of novel Li1/3Sr1/3Eu1/3MoO4 phosphors have been fabricated via the conventional ceramic processing route at different sintering temperatures. The crystal structure, morphology and luminescent properties of the as-synthesized phosphors were characterized through X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) and photoluminescence (PL), respectively. It is found that the sintering temperature has significant influences on the crystallinity, morphology and luminescent properties of the obtained Li1/3Sr1/3Eu1/3MoO4 phosphors. In the selected sintering temperature range (600–1000 °C), all the obtained Li1/3Sr1/3Eu1/3MoO4 phosphors possess tetragonal scheelite structure, the synthesized phosphors changed gradually from quasi-spherical to polyhedral particles with a size of 1.0–5.0 μm. All the as-synthesized Li1/3Sr1/3Eu1/3MoO4 samples are typical red-emission phosphors, which can emit 591 nm and 615 nm red light under the excitation of 393 nm ultraviolet and 464 nm blue light, respectively. Moreover, the emission intensities of the phosphors firstly increase and then decrease with increasing sintering temperature, reaching the maximum at 800 °C. All the obtained Li1/3Sr1/3Eu1/3MoO4 phosphors displayed a pure red emission, which are promising red phosphors.

In this work, BaYF

A series of Eu2(MoO4)3 crystals with different crystal structures have been successfully fabricated via a conventional ceramics process under different sintering temperatures. Using X-ray diffraction (XRD), Rietveld refinement, Fourier transform infrared (FT-IR) spectra, scanning electron microscope (SEM), differential thermal analysis (DTA), photoluminescence (PL) and vibrating sample magnetometer (VSM), the microstructures, luminescent and magnetic properties of the as-fabricated Eu2(MoO4)3 crystals have been investigated in detail. XRD, FT-IR and Rietveld refinement results show that the crystal structure of the final Eu2(MoO4)3 crystals can be remarkably influenced by the sintering temperature, exhibiting the phase transformation from tetragonal to monoclinic and then orthorhombic in the region of 600–1000 °C. SEM images manifest the sintering temperature has significantly influence on grain size and dispersity of the samples, although it has negligible effect on their morphology. DTA results confirm that the phase transition temperature for tetragonal to monoclinic and monoclinic to orthorhombic is 624 and 887 °C, respectively. PL results reveal that the excitation and emission intensities of the Eu2(MoO4)3 crystals initially increase and then decrease with increasing sintering temperature, given the maximum at 900 °C. VSM results indicate that all the as-fabricated Eu2(MoO4)3 crystals exhibit paramagnetic property. Our work can offer a simple and effective strategy to adjust the crystal structure of Eu2(MoO4)3 crystals.

A series of BaGe(1−x)TixF6:Mn4+ solid solution phosphor crystals have been successfully synthesized by a facile hydrothermal method. The crystal structure, morphology and size of the obtained samples were characterized via X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The influences of Ti4+ doping concentration on the microstructures and photoluminescent (PL) properties of the as-synthesized crystals were also investigated comprehensively. The XRD results indicate that all the as-synthesized BaGe(1−x)TixF6:Mn4+ samples are single phase solid solution crystals, although the doping concentration of Ti4+ has a remarkable influence on the lattice parameters. The SEM results reveal that all the as-synthesized BaGe(1−x)TixF6:Mn4+ phosphor samples are microcrystals with a predominant rod-like morphology and lengths ranging from 1 to 8 μm and widths ranging from 0.2 to 2.5 μm. The PL spectra reveal that all the obtained crystals exhibit characteristic emission peaks of Mn4+ ion, and the intensity of the strongest red emission peak located at 636 nm distinctly fluctuated with x, showing the highest at x = 0.6. Under excitation of 467 nm blue light, all the obtained BaGe(1−x)TixF6:Mn4+ samples can emit a warm red color, with a correlated color temperature (CCT) of less than 4500 K. The temperature-dependent PL emission spectra show that the BaGe0.4Ti0.6F6:Mn4+ sample possesses outstanding thermal stability, which can retain 62.27% of its initial emission intensity (323 K) even at 423 K. Employing the synthesized BaGe0.4Ti0.6F6:Mn4+ sample as a red component, a high-performance WLED with a correlated color temperature (CCT) of 4343 K, a color rendering index (CRI) of 93.2 and a luminous efficiency of 100.2 lm W−1 was obtained. Our findings suggest that BaGe(1−x)TixF6:Mn4+ can be a promising candidate as the red phosphor used in warm WLEDs.

Na(1-x)Lix(Gd0.39Y0.39Yb0.2Er0.02)F4 (0 ≤ x ≤ 1) (denoted as Na(1-x)LixReF4) solid solution microcrystals with different microstructures have been synthesized by a facile hydrothermal method. The influences of Li+ ion concentration on the morphology, crystal structure, grain size, and upconversion emission of the microcrystals are deeply investigated. It is found that the substitution concentration of Li+ not only causes the phase transition but also induces variation in morphology and size. When the substitution concentration of Li+ ions is lower (x ≤ 0.3), the obtained Na(1-x)LixReF4 microcrystals possess hexagonal structure and exhibit hexagonal prism in morphology. Whereas at the higher substitution concentration of Li+ ions (x ≥ 0.6), the crystalline phase of the final Na(1-x)LixReF4 microcrystals transformed into tetragonal structure and their morphology changed into octahedron except for the sample Na(1-x)LixReF4 with x = 0.9. Predictably, the obtained Na(1-x)LixReF4 microcrystals at the moderate s...

A series of double tungstate solid-solution red phosphors LixNa1-xEu(WO4)2 (0 ≤x ≤ 1) have been successfully fabricated via the traditional solid-state reaction method, and the influences of Li/Na ratio on the microstructures and luminescence properties of the as-fabricated LixNa1-xEu(WO4)2 crystals were investigated in detail. The XRD and FT-IR results show that all the as-fabricated microcrystals are tetragonal symmetry with scheelite structure, and the doping concentration of Li+ has great influence on the lattice parameters of the finally obtained LixNa1-xEu(WO4)2 crystals. The SEM results indicate that all samples are well crystallized, exhibited irregular spherical particles with various mean grain size. Moreover, the mean grain size of the final LixNa1-xEu(WO4)2 solid solution crystals increases with increasing concentration of Li+ ions besides LiEu(WO4)2 and NaEu(WO4)2. The luminescence spectra reveal that all the LixNa1-xEu(WO4)2 phosphors can exhibit the two characteristic emissions located at 615 nm and 592 nm under 393 nm UV excitation. Moreover, the observed emission intensities of the emission peak at 615 nm are obviously fluctuant with x, whereas the intensities of the emission peak located at 592 nm have no obvious variation. All the obtained LixNa1-xEu(WO4)2 phosphors can emit warm pure red emissions with the correlated color temperature (CCT) from 2100 to 2300 K. Especially, for the as-fabricated Li.1Na.9Eu(WO4)2 phosphor, the coordinate (x = 0.6508, y = 0.3474) are much closer to the International Association of Lighting NTSC trichromatic coordinates specified red coordinate (x = 0.67, y = 0.33) than that of Y2O2S: Eu3+ (x = 0.63, y = 0.35), showing that is a promising warm red phosphor with excellent luminescence properties.

Molybdate based phosphors have efficient absorption in the ultraviolet (UV) region and can be used for UV-pumped light emitting. A series of NaGd0.5Tb0.5−xEux(MoO4)2 (0 ≤ x ≤ 0.5) multicolor tunable phosphors were prepared via a conventional solid-state reaction method. The as-prepared samples were well characterized by x-ray diffraction patterns, Fourier transform infrared spectroscopy, scanning electronic microscope, electron energy-dispersive spectroscopy, UV–vis diffused reflectance, photoluminescent spectra, decay curve and temperature-dependent photoluminescence spectra. The results indicate that the NaGd0.5Tb0.5−xEux(MoO4)2 (0 ≤ x ≤ 0.5) phosphors exhibit a good crystallinity and form a continuous solid solution with scheelite structure. Under UV excitation, NaGd0.5Tb0.5−xEux(MoO4)2 (0 ≤ x ≤ 0.5) phosphors exhibit characteristic emissions of Tb3+ (5D4 → 7FJ, J = 6, 5, 4, 3) and Eu3+ (5D0 → 7FJ, J = 0, 1, 2, 3, 4). The host NaGd(MoO4)2 has excellent energy transfer efficiency for rare earth ions, and the energy transfer from Tb3+ ions to Eu3+ ions is efficient, which can be confirmed by the decay curve. The energy transfer (ET) process between Tb3+ and Eu3+ was demonstrated to a reasonable type via a dipole–dipole interaction with ET efficiency of about nearly 95%. Moreover, the temperature-dependent luminescence properties indicated that the phosphors possessed good thermal stability. Interestingly, the luminescence color of NaGd0.5Tb0.5−xEux(MoO4)2 phosphors can be easily tuned from green to green-yellow, yellow, orange-yellow and ultimately to red by simply adjusting the related concentrations of Tb3+ and Eu3+ under a single wavelength excitation, which might have potential applications in the fields of as multi-color display and illumination.

La2−xEuxMo2O9 (0 ≤ x ≤ 0.6) solid solution microcrystals have been successfully fabricated by a facile hydrothermal derived synthesis process (i.e. the precursors were obtained via hydrothermal treat at 180 °C for 24 h and then calcined at 600 °C for 5 h). X-ray diffraction (XRD), scanning electron microscope (SEM), photoluminescence excitation and emission spectra (PL) and photoluminescence decay curves were used to characterize La2−xEuxMo2O9 samples. The effects of the Eu3+ ions concentration on the luminescence of the La2−xEuxMo2O9 microcrystals were also investigated in detail. The results show that the obtained La2−xEuxMo2O9 microcrystals are cubic phase continuous solid solution, and all can be efficiently excited by 335 nm ultraviolet and 464 nm blue light, exhibiting the strong red emission at 615 nm of Eu3+ ion. The obtained La2−xEuxMo2O9 microcrystals are promising red-emitting phosphors pumped by near-UV or blue light for the white light emitting diodes (WLEDs).

Ba(Gd1-xYx)0.78F5: 20 mol% Yb3+, 2 mol% Tm3+ (0 ≤ x ≤ 1.0) solid solution nanocrystals were successfully synthesized via a facile hydrothermal method, the obtained crystals were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), the transmission electron microcopy (TEM), energy dispersion spectrometry (EDS), photoluminescence (PL) as well as vibrating sample magnetometer (VSM), respectively. The influences of the concentration of yttrium ion (Y3+) on the microstructures, upconversion (UC) luminescent and magnetic properties of the Ba(Gd1-xYx)0.78F5: 20 mol% Yb3+, 2 mol% Tm3+ samples have been deeply investigated. XRD results showed that all the Ba(Gd1-xYx)0.78F5: 20 mol% Yb3+, 2 mol% Tm3+ crystals are continuous solid solution possess a pure cubic phase structure. SEM and TEM results revealed that all the obtained crystals are quasi-spherical nanocrystals with a diameter ranging from ∼55 nm to ∼240 nm, and the doping of Y3+ ion can inhibit the grain growth. PL spectra indicated that all the samples exhibit main blue emission centered at 478 nm ascribed to 1G4→3H6 transition of Tm3+ ions, and its UC emission intensity initially increases and then notably decreases with increasing content of Y3+ ion, giving the maximum at x = 0.8. VSM results showed that all the samples present benign paramagnetism in the magnetic range of −30 to 30 kOe at 300 K due to no coercivity or no remanence. Our results confirm that the UC luminescence properties of the Ba(Gd1-xYx)0.78F5: 20 mol% Yb3+, 2 mol% Tm3+ nanocrystals can be effectively modulated through the replacement of Gd3+ ions by Y3+ ions, which also can provide a relatively clear understanding of the formation process and the enhancement mechanism of UC emission for other rare earth polyfluoride solid solution nanocrystals.

Ln3+-doped fluoride is a far efficient material for realizing multicolor emission, which plays an important part in full-color displays, biolabeling, and MRI. However, studies on the multicolor tuning properties of Ln3+-doped fluoride are mainly concentrated on a complicated process using three or more dopants, and the principle of energy transfer mechanism is still unclear. Herein, multicolor tunable emission is successfully obtained only by codoping with Tb3+ and Eu3+ ions in β-NaGdF4 submicrocrystals via a facile hydrothermal route. Our work reveals that various emission colors can be obtained and tuned from red, orange-red, pink, and blue-green to green under single excitation energy via codoping Tb3+ and Eu3+ with rationally changed Eu3+/Tb3+ molar ratio due to the energy transfer between Tb3+ and Eu3+ ions in the β-NaGdF4 host matrix. Meanwhile, the energy transfer mechanism in β-NaGdF4: x Eu3+/y Tb3+ (x + y = 5 mol %) submicrocrystals is investigated. Our results evidence the potential of the dopan...

Three dimensional (3D) flower-like cerium pyrazine-2,3,5,6-tetracarboxylate metal–organic framework has been successfully prepared on a large scale through a simple and facile hydrothermal method without the assistance of any surfactant or template. The composition and structure of the samples were well characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction, elemental analysis, thermogravimetric analysis, scanning electron microscopy, and energy dispersive X-ray, respectively. The experimental results indicate that these 3D flower-like architectures with diameter of about 4 μm are composed of a large number of nanosheets. The presumed molecular formula of the cerium-based metal–organic framework is Ce2(pztc)(H2O)6. In addition, a possible mechanism for the formation of cerium pyrazine-2,3,5,6-tetracarboxylate architectures was proposed based on time-dependent experiments. Furthermore, the as-obtained flower-like cerium-based metal–organic framework architectures could be easily transformed into CeO2 microstructures with flower-like outlines through simply heat-treating in air.

Monoclinic LiFe(WO4)2 microcrystals have been fabricated by solid-state ceramic method. Microstructures, luminescent and magnetic properties of the as- fabricated microcrystals were characterized by X-ray diffraction, scanning electron microscopy, photoluminescence spectroscopy and Vibrating Sample Magnetometer. Influence of sintering temperature and sintering time on the microstructures, luminescent and magnetic properties of LiFe(WO4)2 microcrystals were studied. Below the sintering temperature 800 °C, the prepared samples exhibited spherical-like morphology. The crystallinity and purity of the microcrystals increased with increasing the sintering temperature. At higher 800 °C, the observed morphology of the obtained microcrystalline turned to be rods-like. All the LiFe(WO4)2 microcrystals exhibit the alike broad emission peak centered at 390 nm under excitation of 242 nm ultraviolet light except for difference in emission intensity. Due to the good crystallinity and microstructures, LiFe(WO4)2 microcrystals fabricated at 800 °C possess the maximum emission intensity. On the premise of the optimal sintering temperature (800 °C) and the predetermined range of sintering time (1–9 h), the sintering time has little influence on the microstructures and luminescent properties of the LiFe(WO4)2 microcrystals. In addition, all the well crystallized LiFe(WO4)2 microcrystals exhibit paramagnetism at room temperature.

Partially inverse spinel zinc ferrite has been synthesized by a molten salt route. It exhibits different cation occupancy and band gap from normal spinel zinc ferrite. Regarding that band structure plays an essential role in the gas sensing property of semiconducting material, the gas sensing properties of normal spinel and partially inverse spinel are measured and compared. With the favorable adsorption and moderate conductance, the partially inverse spinel zinc ferrite exhibits superior performance both in gas response and selectivity towards H 2 S. The optimum operating temperature is found to be 260 °C and the response time and recovery time are short. The excellent gas sensing properties is attributed to the favorable adsorption and change of it band structure due to special partially inverse spinel structure.

A series of NaGd(0.99-x%)F4: 1% Bi3+, x% Eu3+ (x = 0–50) and NaGd(1-x%)F4: x% Eu3+ (x = 0–50) nanocrystals (denoted as NGBF-x% Eu3+ and NGF-x% Eu3+, respectively) have been synthesized by hydrothermal method. The influence of Bi3+ and Eu3+ on microstructures and luminescence properties of the products are deeply investigated. The TEM results display that all the obtained products are irregular polyhedrons with a diameter in a range from 30 to 80 nm with the increasing substitution concentration of Eu3+. It was found that the introduction of Bi3+ hardly affects the morphology and size of the obtained products. Under the excitation of 393 nm NUV, all samples exhibit the typical emission of Eu3+ ions with main red and yellow emissions centered at 616 and 591 nm, respectively. After doping a small amount of Bi3+ ions, the largest emission intensity of the characteristic emissions of Eu3+ for the gained NGBF-x% Eu3+ nanocrystals appeared at x = 0.2, whereas it observed at x = 0.3 for the obtained NGF-x% Eu3+ nanocrystals. It is obviously that the introduction of 1% Bi3+ ions not only increases the emission intensity of Eu3+ ions significantly, but also reduces the doping concentration of Eu3+. Especially, studied NGBF-20% Eu3+ phosphor exhibits excellent stand up to thermal impact during thermal cycling between 298 and 473 K. A WLED device by merging a NUV chip, NGBF-20% Eu3+ phosphor and commercial (Sr,Ba)2SiO4: Eu2+ green phosphor/BaMgAl10O17: Eu2+ blue phosphor possesses suitable correlated color temperature (CCT, 7395 K) and high color rendering index (CRI, 90.8%). These results unambiguously show that the NGBF-x%Eu3+ nanocrystals are promising candidate for applications in WLEDs.

A series of Li0.1Na0.9Gd0.5Tb0.5-xEux(MoO4)2 phosphors were successfully prepared via a conventional solid-state reaction method. The influences of the doping concentration of Eu3+ on the microstructures and luminescence properties for the as-prepared Li0.1Na0.9Gd0.5Tb0.5-xEux(MoO4)2 phosphors were investigated systematically. Our results indicate that the doping of Eu3+ hardly affect the microstructures while markedly impact luminescence properties for the Li0.1Na0.9Gd0.5Tb0.5-xEux(MoO4)2 phosphors. Due to an effective energy transfer from Tb3+ to Eu3+ in the Li0.1Na0.9Gd0.5Tb0.5-xEux(MoO4)2 phosphors, the multicolor emissions have been realized via varying the doping concentration of Eu3+ from 0 to 0.5, which can be adjusted from green→yellow-green→yellow→orange→red and yellow-green→ yellow→orange→red upon excitation of two visible light wavelengths (486 and 464 nm), respectively. Moreover, the doping of Eu3+ also can significantly boost the thermal stability of Li0.1Na0.9Gd0.5Tb0.5(MoO4)2 phosphor, and the obtained Li0.1Na0.9Gd0.5Tb0.42Eu0.08(MoO4)2 phosphor possesses superior thermal stability, can be expected as a candidate phosphor for white light diodes.

Volatile organic compounds (VOCs) are extremely harmful to the human body and environment, thus it is greatly meaningful and urgent to detect VOCs. In this work, terbium-based metal-organic frameworks (Tb-MOFs) have been prepared successfully via a facile and efficient route. These well-constructed Tb-MOFs architectures exhibit characteristic green emission of Tb3+ ion upon excitation of UV light. It is noteworthy that the Tb-MOFs can act as a convenient and efficient luminescent sensor for VOCs. Especially, the Tb-MOFs displayed high selectivity and superior sensitivity towards the sensing of styrene solution and vapor through fluorescence quenching mechanism. The Tb-MOFs can realize fast detection for styrene vapor with a response time of 30 s. The mechanism of fluorescence quenching of Tb-MOFs induced by styrene was also discussed. More importantly, we have designed a logic gate operation with the combination of the sensor for the intelligent detection of styrene. This developed type of lanthanide luminescent metal-organic frameworks (Ln-MOFs) based on the combination of fluorescence sensor and logic gate has a great application prospect in the detection of VOCs in daily life.

A simple and facile hydrothermal method has been developed to enhance the fluorescence performance of YF3:xEu3+,y%Bi3+ (x = 0–0.2, y = 0–1.5) by optimizing the concentration of Eu3+ and Bi3+ and regulating the morphology/phase structure by controlling the amount of HNO3. The evolutionary mechanisms of the micro-topography and microstructure of the samples have been proposed, and the fluorescence and decay properties of the samples have been investigated. It was found that the fluorescence intensity of the sample has been greatly enhanced after addition of an opportune amount of Bi3+. The optimum concentrations of Eu3+ and Bi3+ for fluorescence are x = 0.125 and y = 0.5%, respectively. The significant enhancement in fluorescence performance could be obtained in the sample with the desired morphology at the optimum volume of HNO3 (VHNO3 = 11 mL).

Ln

Hierarchically uniform three-dimensional allium giganteum-like yttrium-based metal-organic framework architectures (Y-MOFs) have been successfully synthesized with use of polyvinylpyrrolidone (PVP) by a modified hydrothermal method. The allium giganteum-like architectures are made up of a large amount of nano-sheets. The morphology and grain size of the samples can be easily adjusted through the elaborate choice of reaction time and the content of PVP additives. A possible growth mechanism is proposed in detail. Under the UV light excitation, the Y-MOFs: xEu (x = 1, 2, 5, 10, 20, 50%) samples exhibit a strong red luminescence. The luminescence intensity increases first and then decreases with x value increasing, showing a maximum at x = 10%. Furthermore, the shape-preserved Y2O3:Eu3+ phosphors can be easily obtained via a heat-treating in the air using the corresponding MOFs as a precursor, which exhibit characteristic red emission and excellent thermal stability.

A novel lanthanide pyrazine-2,3,5,6-tetracarboxylate coordination polymer with a uniform three-dimensional (3D) flower-like architecture has been successfully synthesized via an efficient direct pr...