A series of Pb-doped Bi-based alloys, alpha-Bi1-xPbxPd (0 <= x <= 0.5) and beta-Bi2-xPbxPd (0 <= x <= 0.6), were synthesized by facile solid-state reaction method. The powder X-ray diffraction confirmed that the crystal structure of samples remained the same after Pb-doping and the cell volume decreased with increasing Pb content. The influence of Pb-doping effect on superconductivity of BiPd and Bi2Pd alloys has been systematically examined by the magnetic susceptibility and resistivity measurements. Both alloy systems have shown bulk superconductivity and metallic conductivity in normal state. Furthermore, the superconducting onset temperature (T-c) gradually decreased with higher Pb content for both systems. The T-c dropped from 3.7 K for BiPd to 2.7 K for Bi0.8Pb0.2Pd, whereas the T-c dropped from 5.3 K for Bi2Pd to 2.4 K for Bi1.5Pb0.5Pd.

A new FeSe-based superconductor (C2H8N2) x FeSe with ethylenediamine intercalated into FeSe was successfully synthesized by the solvothermal method, which is the first superconducting instance by metal-free organic molecule intercalation. Elemental analysis and TG-IR-GC/MS data reveal that the ethylenediamine molecules in the interlayer space are separate and intact. The X-ray diffraction (XRD) pattern indicates that the intercalation compound is an orthorhombic lattice rather than a tetragonal lattice applying to almost all the previous FeSe-based superconductors at room temperature. The magnetism measurements display a sharp superconducting transition at ∼10 K which is assigned to (C2H8N2) x FeSe, and a tiny drop in susceptibility at ∼30 K.

Here we report the facile synthesis of alkali metal intercalation compounds A(x)NbS(2) (A = Li, Na) through the reaction of bulk 3R phase of NbS2 with organometallic compounds in solution. Especially, the Na insertion compound of various compositions was obtained as a new polytype of A(x)NbS(2) compared with the 2H phase reported previously. Upon intercalation the structure of the host was preserved, which was confirmed by XRD and HRTEM analysis. The interlayer distances for Li0.44NbS2 and Na0.82NbS2 were expanded by 0.187 angstrom and 0.938 angstrom as a result of Li and Na intercalation, respectively. The electrical transport properties were studied in the temperature range 4-298 K, exhibiting metallic conductivity and slight variation in the resistivity value in general. Interestingly, a minimum resistivity which was ascribed to the localized electrons in the crystal lattice emerged for all the investigated samples. (C) 2015 Elsevier B.V. All rights reserved.

A new polymorph of potassium intercalation compound of 3RNb(1.1)S(2) with chemical composition K0.77Nb1.1S2 was synthesized for the first time by a facile solution-phase method. Its structure was comprehensively characterized by powder XRD and high-resolution TEM. Furthermore, its hydrated derivatives K-x Nb1.1S2 center dot yH(2)O were synthesized via soft chemistry strategy using etching agents of ethanol, water and an I-2/CH3CN solution, respectively. Superconducting transition at 4.0 K was observed for the product with the doping content x = 0.12. While superconductivity disappeared in products KxNb1.1S2 center dot yH(2)O (x = 0.48 and 0.35) which displayed a metal-to-semiconductor transition at low temperature. In addition, the XPS analysis revealed an upward shift in the Fermi level in K0.12Nb1.1S2 center dot yH(2)O compared with the host or K0.77Nb1.1S2.

A new Ruddlesden-Popper type scandium oxyfluoride, Sr2ScO3F, was synthesized by a conventional solid state reaction route. The detailed structure of Sr2ScO3F was investigated using X-ray diffraction (XRD) and selected area electron diffraction (SAED). The disorder distribution pattern of fluorine anions was determined by the F-19 nuclear magnetic resonance (NMR) spectrum. The compound crystallizes in a K2NiF4-type tetragonal structure (space group I4/mmm) with O/F anions disordered over the apical sites of the perovskite-type Sc(O,F)(6) octahedron layers interleaved with strontium cations. Ultraviolet-visible (UV-vis) diffuse reflection spectrum of the prepared Sr2ScO3F indicates that it has an absorption in the UV-vis region. The photocatalytic activity of Sr2ScO3F was further investigated, showing an effective photodegradation of Rhodamine-B (RB) within 2 h under UV light irradiation. (C) 2015 Elsevier Ltd. All rights reserved.

Titanium oxyhydroxy-fluoride, TiO0.9(OH)0.9F1.2 · 0.59H2O rods with a hexagonal tungsten bronze (HTB) structure, was synthesized via a facile one-step solvothermal method. The structure, morphology, and component of the products were characterized by X-ray powder diffraction (XRD), thermogravimetry (TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), inductively coupled plasma optical emission spectroscopy (ICP-OES), ion chromatograph, energy-dispersive X-ray (EDX) analyses, and so on. Different rod morphologies which ranged from nanoscale to submicron scale were simply obtained by adjusting reaction conditions. With one-dimension channels for Li/Na intercalation/de-intercalation, the electrochemical performance of titanium oxyhydroxy-fluoride for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) was also studied. Electrochemical tests revealed that, for LIBs, titanium oxyhydroxy-fluoride exhibited a stabilized reversible capacity of 200 mAh g−1 at 25 mA g−1 up to 120 cycles in the electrode potential range of 3.0–1.2 V and 140 mAh g−1 at 250 mA g−1 up to 500 cycles, especially; for SIBs, a high capacity of 100 mAh g−1 was maintained at 25 mA g−1 after 115 cycles in the potential range of 2.9–0.5 V.

Two novel nanocrystalline materials, hexagonal TiOF2 (hTiOF(2), space group R (3) over barc hexagonal) nanocubes and LiTiOF2 (space group R3c hexagonal), were prepared by a one-step solvothermal method and the lithiation of hTiOF(2) precursor, respectively. All the products have been characterized by means of X-ray diffraction, thermogravimetry, scanning electron microscopy, transmission electron microscope and high resolution transmission electron microscope. Furthermore, Rietveld analysis has been used to evaluate the structure of LiTiOF2. The electrochemical properties were evaluated using the products as cathode for half-cells in lithium-ion batteries (LIBs). It is confirmed that hTiOF(2) and LiTiOF2 have the same frame and the Li intercalation/de-intercalation mechanism of hTiOF(2) is discussed. An electrochemical activation process is confirmed in the charge-discharge cycles of hTiOF(2) half-cells. The hTiOF(2) half-cell after activation delivered a high specific capacity of 200 mAh g(-1) at 1C in the range of 3.0-0.8 V and maintained a specific capacity of 120 mAh g(-1) at 20C over 1000 cycles, which is a very satisfying performance. (C) 2015 Elsevier Ltd. All rights reserved.

CdSnO3 materials have been extensively studied as gas-sensing materials. However, there are few reports on the synthesis and use of porous CdSnO3 nanostructures for energy storage. Herein, we report highly porous CdSnO3 nanoparticles prepared using citric acid with sizes in the range of similar to 7.8 nm to 28.7 nm and the application of these nanoparticles as an anode material for rechargeable Li-ion batteries ( LIBs). Electrochemical measurements showed that the highly porous CdSnO3 nanoparticles delivered a high reversible capacity of similar to 515 mA h g(-1) for up to 40 cycles at a current rate of 70 mA g(-1). Even at a high rate of 150 mA g(-1), the porous CdSnO3 could still deliver a capacity of 506 mA h g(-1). It is observed that the electrochemical performance of the highly porous CdSnO3 nanoparticles is much better than that (similar to 370 mA h g(-1) for up to 40 cycles) of a counterpart obtained without citric acid, which also demonstrates the capacity enhancement and high rate capacity.

We derive a priori interior Hessian estimates for special Lagrangian equation with critical and supercritical phases in general higher dimensions. Our unified approach leads to sharper estimates even for the previously known three dimensional and convex solution cases.

A variety of microbially mediated metabolic pathways impact biogeochemical cycling in terrestrial subsurface environments. However, the role that viruses have in influencing microbial mortality and microbial community structure is poorly understood. Here we investigated the production of viruses and change in microbial community structure within shallow alluvial aquifer sediment slurries amended with (13)C-labeled acetate and nitrate. Biostimulation resulted in production of viruses concurrent with acetate oxidation, (13)CO2 production and nitrate reduction. Interestingly, change in viral abundance was positively correlated to acetate consumption (r(2)=0.6252, P<0.05) and (13)CO2 production (r(2)=0.6572, P<0.05); whereas change in cell abundance was not correlated to acetate consumption or (13)CO2 production. Viral-mediated cell lysis has implications for microbial community structure. Betaproteobacteria predominated microbial community composition (62% of paired-end reads) upon inoculation but decreased in relative abundance and was negatively correlated to changes in viral abundance (r(2)=0.5036, P<0.05). As members of the Betaproteobacteria decreased, Gammaproteobacteria, specifically Pseudomonas spp., increased in relative abundance (82% of paired-end reads) and was positively correlated with the change in viral abundance (r(2)=0.5368, P<0.05). A nitrate-reducing bacterium, Pseudomonas sp. strain Alda10, was isolated from these sediments and produced viral-like particles with a filamentous morphology that did not result in cell lysis. Together, these results indicate that viruses are linked to carbon biogeochemistry and community structure in terrestrial subsurface sediments. The subsequent cell lysis has the potential to alter available carbon pools in subsurface environments, additionally controlling microbial community structure from the bottom-up.

Here we report using the transition metal difluoride ZnF2 to fluorinate K2NiF4-type cuprates La2-xSrxCuO4 (x = 0, 1.5, 0.3). Unlike other fluorinating agents, the technique is nontoxic, easy to handle and the byproduct ZnO can be removed. After fluorination, the fluorinated product of La2CuO4 suffers a phase transformation and unit cell expansion. While La1.85Sr0.15CuO4 and La1.7Sr0.3CuO4 indicate no change in structure after fluorination, their space groups still are I/4mmm, however, their lattices become larger, too. We emphasis the structural characterizations for fluorinated product of La1.7Sr0.3CuO4 by high-resolution transmission electron microscopy (HRTEM) images and electron diffraction (ED) patterns. Moreover, we determine the chemical formula to be La1.54Sr0.46CuO3.1F0.9 and the fluorine ions are prone to be located in the apical sites of the Cu(O, F)(6) octahedron in the structure of post-treated fluorinated product of La1.7Sr0.3CuO4. Magnetization investigations demonstrate that partial replacement of the lanthanum by strontium changes the magnetism of post-treated fluorinated products of La2-xSrxCuO4 (x = 0, 0.15, 0.3) and they exhibit a paramagnetic behavior. (C) 2014 Elsevier B.V. All rights reserved.

We construct singular solutions to special Lagrangian equations with subcritical phases and minimal surface systems. A priori estimate breaking families of smooth solutions are also produced correspondingly. A priori estimates for special Lagrangian equations with certain convexity are largely known by now.

In this work, AgInS(2) hierarchical flowerlike nanoarchitectures, which are composed of ultrathin nanowires, were synthesized by thermolysis of a mixed solution of AgNO(3), InCl(3)·4H(2)O and n-dodecanethiol at elevated temperature. The average diameter and length of the nanowires composing the nanoarchitectures can reach 5 nm and ∼300 nm, respectively. We investigated the growth process of the nanoarchitectures and the effects of reaction parameters by XRD, SEM and TEM. In particular, the use of InCl(3)·4H(2)O played a decisive role in the synthesis of the nanoarchitectures. Moreover, it was found that polyhedra formed in the initial reaction time, and then the nanowires grew on the facets of these polyhedra, which resulted in the nanoarchitectures. The reaction temperature and the concentration of metal salts could influence the size of the nanowires.

CuInS2 nanocrystals were synthesized by one-pot thermolysis of a mixture solution of metal chlorides, 1-dodecanethiol (DT) and oleic acid in noncoordinating solvent 1-octadecene. Interestingly, in this synthesis, different structures and shapes were obtained by simply varying the dosage of DT. At a low dosage of DT, wurtzite nanoplates formed in the initial reaction stage and then they further grew to nanoplates with wurtzite-zincblende polytypism as the reaction proceeded. On the contrary, a high dosage of DT produced zincblende nanoparticles. The formation processes of nanoplates and nanoparticles were studied and a growth mechanism was proposed. Our research will aid in solution-synthesis of ternary chalcogenide nanocrystals and the development of their optoelectronic devices.

HLaNb2O7 nanosheets and Ag nanoparticles/clusters were assembled to produce a novel 3D metal/semiconductor hybrid material (Ag/HLaNb2O7) by direct reaction of the undried D-glucopyranose derivative of HLaNb2O7 with [Ag(NH3)2]+ ion aqueous solution. The as-prepared samples were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-visible diffusive reflectance spectroscopy and nitrogen adsorption–desorption isotherms. The results showed that the simple self-assembly of HLaNb2O7 nanosheets and Ag nanoparticles/clusters formed a mesoporous material with a broad pore size distribution in the range of about 10–35 nm. The mesopores derived from the interspaces between HLaNb2O7 nanosheets and were attributed to Ag nanoparticles, rather than Ag clusters in the interlayer space of HLaNb2O7. The catalytic activity experiments revealed that the product (Ag/HLaNb2O7) was an excellent catalyst for the catalytic reduction of 4-nitrophenol (4-NP) and rhodamine B (RhB) by NaBH4 aqueous solution.

In this work, nanocrystalline-assembled bundle-like CuO structures were successfully synthesized in large-quantity by a friendly, facile two-step process. The bundle-like CuO particles are produced by thermolysis of bundle-like Cu(OH)2 precursors, which exhibit excellent high specific capacity, high stability, and especially high rate performance for anode materials in lithium-ion batteries, superior to that of most reported CuO-based anodes. The assembled structure of CuO endows it with high rate capacities of 666 mAh g−1, 609 mAh g−1, and 499 mAh g−1 at a current rate of 0.3 C, 1 C and 2 C after 50 cycles, respectively. Even at a high rate of 6 C, the bundle-like CuO can still deliver a capacity of 361 mAh g−1. It is observed that the electrochemical performance of the nanocrystalline-assembled bundle-like CuO is much better than that of CuO nanoparticles obtained by destroying the assembled bundle-like CuO through grinding. XRD analysis of both the electrodes after ending the discharge/charge proved that during the discharge/charge process, the conversion reactions occurring in the assembled structures have better reversibility, leading to the high rate capacity and cycling performances. The better reversibility originates from the better contact area for CuO/electrolyte, enhancing many sites to the access of Li+ in the electrolyte Li+. In addition, the assembled bundle-like CuO architectures can also relieve the volume variations during the Li+ uptake–release process, which also contributes to the excellent electrochemical performance. The high rate capacity and enhanced cycling stability of the bundle-like CuO structure make it a promising candidate as an anode material for high-performance Li-ion batteries.

Carbon was successfully intercalated into the interlayer space of the Dion-Jacobson type layered perovskite HLaNb2O7 by pyrolysis of the precursor of a D-glucopyranose derivative of HLaNb2O7. Firstly, the D-glucopyranose derivative of HLaNb2O7 (D-glucopyranose-HLaNb2O7) was prepared by the grafting reaction between the n-decoxyl derivative of HLaNb2O7 and D-glucopyranose. The interlayer distance of D-glucopyranose-HLaNb2O7 was decreased to 15.4 angstrom, compared to that of 27.6 angstrom for n-decoxyl-HLaNb2O7. IR and solid-state C-13 CP/MASNMRspectra indicated that oxyalkyl chains were removed and glucopyranose rings were introduced. After pyrolysis of the D-glucopyranose derivative at 300 degrees C under flowing Ar, a novel intercalation compound of HLaNb2O7 with carbon (carbon-HLaNb2O7) was obtained. XRD pattern and HRTEM image both displayed the interlayer distance of about 12 angstrom. Raman and solid-state C-13 CP/MAS NMR spectra revealed that the intercalated carbon was mainly polycyclic aromatic carbon. The UV-VIS-near-IR spectrum showed that the carbon-HLaNb2O7 appreciably absorbed light at wavelengths below 855 nm and the band gap energy was only about 0.65 eV, which was much smaller than those of HLaNb2O7 and its derivatives, indicating that the intercalation with carbon can effectively modify the band gaps of Dion-Jacobson type layered perovskites.

Various CuO nanostructures have been well studied as anode materials for lithium ion batteries (LIBs); however, there are few reports on the synthesis of porous CuO nanostructures used for anode materials, especially one-dimensional (1D) porous CuO. In this work, novel 1D highly porous CuO nanorods with tunable porous size were synthesized in large-quantities by a new, friendly, but very simple approach. We found that the pore size could be controlled by adjusting the sintering temperature in the calcination process. With the rising of calcination temperature, the pore size of CuO has been tuned in the range of ∼0.4 nm to 22 nm. The porous CuO materials have been applied as anode materials in LIBs and the effects of porous size on the electrochemical properties were observed. The highly porous CuO nanorods with porous size in the range of ∼6 nm to 22 nm yielded excellent high specific capacity, good cycling stability, and high rate performance, superior to that of most reported CuO nanocomposites. The CuO material delivers a high reversible capacity of 654 mA h g(-1) and 93% capacity retention over 200 cycles at a rate of 0.5 C. It also exhibits excellent high rate capacity of 410 mA h g(-1) even at 6 C. These results suggest that the facile synthetic method of producing a tunable highly porous CuO nanostructure can realize a long cycle life with high reversible capacity, which is suitable for next-generation high-performance LIBs.

It was shown that aluminum metal matrix nanocomposites (MMNCs) can be simply recast and maintain good nanoparticle dispersion and property enhancement. Pure aluminum nanocomposites with 1.5 volume % TiC0.7N0.3 nanoparticle addition were produced by ultrasonic dispersion and cast in a permanent mold. The initial castings showed a significantly refined grain structure as well as 20% enhancement in yield strength, 24% enhancement in tensile strength and 7% enhancement in elongation. The materials were then remelted and cast four additional times. Scanning electron microscopy (SEM) analysis showed the nanoparticles remained well dispersed, and tensile testing showed maintained mechanical property enhancement.