Search

Two antimony nitrates were synthesized by the low temperature molten salt method. Both of them reveal large birefringence; especially, noncentrosymmetric (NH4)3SbF3(NO3)3 exhibits a strong SHG coefficient of about 3.3 × KDP.

Birefringent materials with large birefringence play an important role in in laser science and technology owing to their ability to modulate polarized light. However, the lack of systematic and effective synthesis strategies severely hinders the development of novel superior birefringent materials. Herein, the cation-anion synergetic interaction strategy was proposed to successfully synthesize two excellent UV birefringent materials, RbSb(C

The modulation of optical anisotropy for two novel UV birefringent materials [C(NH2)3]2Sb3F3(HPO3)4 and [C(NH2)3]SbFPO4·H2O has been successfully achieved via anion-directing regulation structures.

A tin phosphate halide, centrosymmetric Sn2PO4F, was successfully transformed into noncentrosymmetric Sn2PO4Cl with excellent comprehensive performance by the substitution of F− with Cl−.

Two molybdenyl carbonates with different dimensional structures exhibit huge differences in band gaps, 0D Cs3MoO4(HCO3) exhibiting a much larger band gap than 1D Cs2MoO3(CO3).

A novel fluoroberyllate KSb(BeF3)F3 featuring unique [BeF3]∞− polyanion chains was successfully developed via a totally fluorine strategy, which endows it with a wide bandgap (5.3 eV) and large birefringence (0.11@546 nm).

A beryllium-free deep-UV carbonate, KLi2CO3F, has been successfully designed through chemical co-substitution with KBBF as the prototype, which exhibits an enhanced interlayer interaction and enlarged birefringence.

As a typical transition metal oxide anode material, ZnMoO4 can deliver a higher theoretical capacity of 951.6 mAh g−1 due to its variable oxidation state and alloying reaction. However, lower conductivity and huge volumetric expansion restrict its further development. Herein, the modified sol–gel method is applied to synthesize a series of (1-x)ZnMoO4-xZnFe2O4 (x = 0.1, 0.2, 0.3, 0.4, and 0.5) composites. The effects of compound proportion of ZnFe2O4 on the crystal phase structure and morphology for ZnMoO4 have been investigated in detail. All the composites have been conducted on electrochemical measurements, and the results illustrate that the composites display better electrochemical performance than that of ZnMoO4. Especially for 0.6ZnMoO4-0.4ZnFe2O4, it can deliver a capacity of 550.7 mAh g−1 after 500 cycles at a current density of 200 mA g−1. Moreover, it also presents the higher capacity at higher current density. The improvement of electrochemical performance should be attributed to the synergistic effect of ZnFe2O4 and ZnMoO4.

Transition metal oxides (TMOs) based compounds are recognized as high-energy anodes in next-generation lithium-ion batteries (LIBs) due to their extremely high theoretical capacity. However, the lower intrinsic conductivity, fast fading cyclic stability and dramatic volume expansion during discharge/charge processes greatly hinder the practical application of TMOs as anodes in LIBs. In this study, we have designed and constructed MoO3/ZnCo2O4 QDs@C@rGO/MoO3 (denoted as GMZCO) sandwich-structured hybrid nanocomposites via an effective route, and have proposed the formation mechanism of this unique nanostructured composite on the basis of the systematic results of the microstructures. Due to the unique sandwich structure and the synergistic enhancement effect of the ZnCo2O4 QDs, α-MoO3 and rGO, the as-constructed GMZCO exhibits the superior electrochemical performances when used as anode for LIBs. The obtained GMZCO can maintain high capacity of 1281 mAh g−1 at 0.2 A g−1 after 300 cycles, and can deliver as high as specific capacity of 913 mAh g−1 at 1 A g−1 after 500 cycles, revealing the higher capacity and excellent cyclic stability. What deserves to be mentioned most is that GMZCO can keep a capacity of 541 mAh g−1 after 1400 cycles even at higher current density of 3 A g−1, having outstanding rate capability. This work paves a novel approach for design TMOs with unique microstructures as a promising anode for the high-performances LIBs.

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

Despite being difficult to identify, extremely dilute oxygen vacancies have been widely reported to play an important role in enhancing magnetism in ZnFe2O4. The mechanisms underlying this enhanced magnetism have not been well understood for a long time and remain controversial because the formation of oxygen vacancy-rich ZnFe2O4 can be accompanied by changes in the chemical/physical characteristics, especially the composition, particle size, surface morphology and cation distribution, which can significantly affect the magnetization. An open and important question is whether and to what extent the enhanced magnetization can be attributed only to oxygen vacancies. In this study, the relationship between the magnetization and oxygen vacancies in ZnFe2O4 was definitively determined by using a carefully designed “shake-and-heat” treatment to prepare vacancy-rich samples while keeping the other crystal/surface parameters constant. Compared to the nearly vacancy-free paramagnetism samples, the vacancy-rich samples exhibited a higher magnetization of approximately 5 emu/g at both 300 K and 2 K. The Fe3+-O2--Fe3+ superexchange paths broken by oxygen vacancies then resulting in the Fe3+-Fe3+ ferromagnetism configuration. Meanwhile, the oxygen vacancy is highly diluted then the ferromagnetism configuration is confined in a single super-cell, favoring a short-range magnetic ordering at room temperature. The concentration of oxygen vacancies was calculated to be 0.68% by magnetization measurement. Our results may shed a light on how oxygen vacancies affect magnetism.

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.

Two fluoride nitrates named RbSnF2NO3 and Rb2SbF3(NO3)2 have been successfully synthesized using a rapid evaporation concentration method by introducing Sn2+/Sb3+ cations with stereochemically active lone pairs into the nitrate system. The discrepancy in the cation sizes and coordination modes induces the different symmetries of these two title compounds, RbSnF2NO3 crystallizing in a centrosymmetric (CS) space group of C2/m, while Rb2SbF3(NO3)2 in a noncentrosymmetric (NCS) space group of P21. In particular, NCS Rb2SbF3(NO3)2 exhibits a strong second harmonic generation (SHG) response of approximately 2.7 times that of benchmark KH2PO4 (KDP) and an appropriate birefringence (0.06@1064 nm) for phase matching, indicating that Rb2SbF3(NO3)2 is a promising UV nonlinear optical material. Detailed structural and theoretical analysis confirmed that the large nonlinear optical coefficient was derived from the synergistic effect of the π-conjugated planar triangular NO3 groups and the Sb3+ cations with stereochemically active lone pairs.

Two new metal phosphate–oxalates (denoted SCU-26 and SCU-27) were prepared under solvent-free conditions using isonicotinic acid as a structure-directing agent. SCU-26 has a neutral layered structure showing intense blue-green luminescence with a high quantum yield of 28.35%. SCU-27 has an anionic layered structure with a high proton conductivity of 9.0 × 10−4 S cm−1 at 85 °C under 95% relative humidity.

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.

The design of an unique micro/nanoscale structure and the composite construction with conductive materials are the two effective means to improve the electrochemical energy storage for transition metal oxides anode. However, the rational design and controllable synthesis of complex ternary transition metal oxide (such as CoMoO4) composite with polyhedron morphology is still a challenge. Herein, we report a facile and effective strategy to synthesize rhombic dodecahedron-like (denoted as RD-like) CoMoO4/C composite, which involves the initial pre-reaction between the newly made ZIF-67 with H2MoO4 in ethanol and the subsequent calcination for the resultant precursor powders in air. It is found that the calcination temperature plays a key role in determining the microstructures and the content of the generated activated carbon. Below 400 °C, the CoMoO4/C composite cannot be derived, whereas the perfect and regular RD morphology for CoMoO4/C composite also cannot be acquired over 500 °C. Moreover, a plausible mechanism for the construction of RD-like CoMoO4/C composite has also been proposed and explained. Benefiting from its unique structural merits and the significant synergistic effect of the in-situ composite activated carbon, the obtained RD-like CoMoO4/C composite at 500 °C displays outstanding electrochemical performances with high reversible capacity (532.5 mAh g−1/500th cycle at 1C), excellent cycling stability and better rate capability when it tested as anode materials for lithium-ion batteries. It is conceivable that this three-in-one strategy can be extended to design and construct other cobalt-based oxyacid/C composites with unique polyhedron morphology, and markedly boost their electrocehmical performaces.

A novel noncentrosymmetric (NCS) metal-free formic-borate, (NH4)3[B(OH)3]2(COOH)3, has been discovered, which exhibits an infrequent graphite-like structure. The alliance of two types of π-conjugated planar anions BO33- and COOH- produced an optimized layered structure to maximize the anisotropic polarizability, resulting in an extremely large birefringence (0.156@546 nm), larger than that of the classical commercial UV birefringent material α-BBO (0.122@546 nm). This strategy that structural optimization could enhance birefringence will guide the discovery of large birefringence materials, especially in the UV region.

Two new metal phosphates, namely, Zn(HPO4)(C6H11NO2) (1) and (C5H10NO2)Ga4(PO4)4F·3H2O (2), were prepared under surfactant-thermal conditions. Single-crystal X-ray diffraction analyses reveal that compound 1 has a zigzag-chain structure decorated with homoproline and compound 2 has a three-dimensional zeolite-like structure templated by proline. Notably, compound 2 remains stable in both boiling water and aqueous solutions with a pH range of 2-12. It shows a proton conductivity of 8.89 × 10-4 S cm-1 at 85 °C and 95% relative humidity.

CoMoO4 has gained great attention as an anode material for lithium-ion batteries owing to its high theoretical capacity of 980 mAh g-1 and relatively high electrochemical activity. Unfortunately, CoMoO4 anode also has some drawbacks such as low electronic/ionic conductivity, inferior cyclic stability, and relative severe volumetric expansion during the lithiation/delithiation process, greatly inhibiting its further development and application. Herein, we report Co0.8Zn0.2MoO4/C nanosheet composite constructed via a novel and facile one-stone-three-birds strategy. The preparation of the Co0.8Zn0.2MoO4/C nanosheet is based on the following two-step process: the formation of Co/Zn nanosheet precursors derived from Co/Zn-ZIF rhombic dodecahedra via solvothermal pretreatment, followed by a calcination treatment with molybdic acid (H2MoO4) in air. The as-prepared Co0.8Zn0.2MoO4/C is monoclinic crystal structured composite with the in situ formed active carbon, which is well-defined nanosheet with a rough surface and mean thickness of 60-70 nm for a single sheet. This Co0.8Zn0.2MoO4/C nanosheet composite possesses a larger surface area of 37.60 m2 g-1, showing a mesoporous structure. When used as anode materials, the as-obtained Co0.8Zn0.2MoO4/C composite can deliver as high as a discharge capacity of 1337 mAh g-1 after 300 cycles at 0.2C and still retain the capacity of 827 mAh g-1 even after 600 cycles at 1C, exhibiting outstanding lithium storage performances. The higher capacity and superior cyclic stability of the Co0.8Zn0.2MoO4/C composite should be ascribed to the synergistic effect of the substitution of Zn2+, in situ composited active carbon and the as-constructed unique microstructure for the Co0.8Zn0.2MoO4/C composite. Our present work provides a facile one-stone-three-birds strategy to effectively construct the architectures and significantly enhance electrochemical performances for other transition metal electrode materials.

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.

Yb3+, Tm3+ co-doped β-NaY1-xGdxF4 (0 ≤ x ≤ 1.00) microcrystals have been synthesized via a facile hydrothermal method. The influences of the concentration of Gd3+ on the morphology, grain size and upconversion luminescence of the as-synthesized co-doped β-NaY1-xGdxF4 crystals have been investigated in detail. Powder X-ray diffraction results confirm that the obtained β-NaY1-xGdxF4 crystals are pure hexagonal solid solution. Scanning electron microscope results indicate that the morphology of the final obtained β-NaY1-xGdxF4 crystals gradually changes from hexagonal prism to sphericity with increasing x, and the grain size monotonically decreases accordingly. The upconversion emission intensity of Tm3+ in the β-NaY1-xGdxF4 microcrystals increases initially and then decreases sharply with increasing x, giving the maximum at x = 0.04. The observed upconversion emission intensity located at 475 nm in co-doped β-NaY0.74Gd0.04F4 microcrystal is 1.5 times greater than that of the co-doped β-NaYF4 microcrystal. A superior upconversion host matrix of β-NaY1-xGdxF4 solid solution can be obtained at the feasible concentration of Gd3+ (0

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.

The series of alkali-metal tin chloride sulfates A

The fermentation of biomass allows for the generation of major renewable ethanol biofuel that has high energy density favorable for direct alcohol fuel cells in alkaline media. However, selective conversion of ethanol to either CO