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Abstract: Au–Cu bimetallic catalysts with Au/Cu ratios ranging from 3/1 to 20/1 were prepared on silica gel support by a two-step method. The catalysts were characterized by ICP, XRD and TEM. The results showed that, irrespective of Au/Cu ratios, all the bimetallic nanoparticles had significantly reduced particle sizes (3.0–3.6nm) in comparison with monometallic gold catalysts (5.7nm). Both CO oxidation and PROX reactions were employed to evaluate the catalytic activities of Au–Cu bimetallic catalysts. For CO oxidation, the alloy catalysts show non-monotonic temperature dependence showing a valley in the intermediate temperature range. The catalyst with Au/Cu ratio of 20/1 gave the highest activity at room temperature, but its activity showed the deepest valley with increasing the reaction temperature. On the other hand, the catalyst with Au/Cu ratio of 3/1 exhibited the best performance for PROX reaction. For the Au/Cu ratios investigated, the bimetallic catalysts showed superior performance to monometallic gold catalysts, demonstrating the synergy between gold and copper. [ABSTRACT FROM AUTHOR]

Abstract: ZnO nanoparticles (NPs) have been successfully synthesized by the chemical precipitation method in different atmospheres at 500°C. The annealing atmospheres were argon, forming gas (50% Ar/50% O2) and air, respectively. The effects of annealing atmosphere on the structure and optical properties of ZnO NPs were investigated in detail by X-ray diffraction, transmission electron microscope, photoluminescence and Raman scattering measurements. The results showed that the as-prepared ZnO NPs had a hexagonal wurtzite structure, and all the samples kept the overall crystal structure of bulk ZnO. From the Raman and photoluminescence spectra, it can be seen that the content of oxygen in different annealing atmospheres strongly influenced the crystallization and light emission of the ZnO NPs. The results revealed that the content of oxygen in air was the optimal condition for growing the ZnO NPs with the best crystalline quality and optical properties. Defect emission was significantly enhanced by annealing in Ar atmosphere, which indicated that the green defect emission was most likely due to oxygen vacancy. Moreover, the effect mechanism of annealing atmospheres on the structure and optical properties of ZnO NPs were also investigated. [Copyright &y& Elsevier]

Abstract: ZnO nanoparticles (NPs) have been successfully prepared by the chemical precipitation method at a low temperature of 200°C. X-ray diffraction (XRD), transmission electron microscope (TEM), photoluminescence (PL) and Raman were used to investigate the effect of annealing temperature on the structure and optical properties of ZnO NPs. The XRD analyses revealed that the average size of the as-prepared samples was about 8nm under 200°C, which had a good agreement with TEM images. Raman spectra showed that the E2 (high) mode became stronger and sharper with the increase of annealing temperature, but the intensity of phonon peak located at 580cm−1 was relatively suppressed. The position of ultraviolet (UV) emission peak in the room-temperature PL spectra showed a red-shift when the annealing temperature was increased. In addition, after annealing under 500°C, the intensity of the UV peak became strongest and the intensity of the green emission almost disappeared, which indicated that ZnO NPs have much better crystallization after annealing. [Copyright &y& Elsevier]

K 2 O–Na 2 O–Nb 2 O 5 –SiO 2 –B 2 O 3 glass-ceramics was prepared via melt-quenching and controlled crystallization route. To investigate the effect of crystallization treatment schedule on the dielectric properties of potassium sodium niobate (KNN) glass-ceramics, this report measured six glass samples with different crystallization treatment by XRD, SEM and LCR measurements. By means of changing heat-treatment schedule, it could be inferred that crystallization process and optimal treatment condition for KNN glass-ceramic with pore-free and high energy density. When the original glass samples crystallized at 707 °C for 2 h and 900 °C for 3 h, this crystallization treatment was beneficial to obtaining the glass-ceramic samples with purer perovskite structure K 0.1 Na 0.9 NbO 3 crystal phase and finer grains which possessed relative higher energy storage density (1.899 J/cm 3 ). The crystallization behavior and dielectric properties have exhibited a regular change at different crystallization temperature. Comprehensive results and analysis demonstrated that crystallization treatment played a role in dielectric properties of KNN glass-ceramics. In order to optimize energy storage, this experiment controlled transition from matrix glass phase of high breakdown strength (BDS) to ferroelectric crystal phase of high dielectric constant. [ABSTRACT FROM AUTHOR]

Bandgap engineering of Cu 2 In x Zn 1−x Sn(S,Se) 4 alloy films for photovoltaic application has been investigated. Cu 2 In x Zn 1−x Sn(S,Se) 4 (0 ≤ x ≤ 0.6) alloy films with different In contents and a single kieserite phase were fabricated by using a simple low-cost sol-gel method. The influence of In content on the structure, morphology, and optical and electrical properties of Cu 2 In x Zn 1−x Sn(S,Se) 4 films was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscope (TEM), X-Ray photoelectron spectroscopy (XPS), optical absorbance, and room-temperature Hall measurements. The results of XRD, TEM, and XPS demonstrated the substitution of some Zn atoms by In in Cu 2 In x Zn 1−x Sn(S,Se) 4 films. The Hall measurements show that the carrier concentration of the Cu 2 In x Zn 1−x Sn(S,Se) 4 (0 ≤ x ≤ 0.6) decreases with increasing In content and that the p-type Cu 2 In x Zn 1−x Sn(S,Se) 4 films with preferable electrical properties can be obtained by adjusting the In content during film deposition. The optical measurements indicate that the bandgap of Cu 2 In x Zn 1−x Sn(S,Se) 4 films with kesterite structure can be continuously tuned in the range of 1.13–1.01 eV as x is increased from 0 to 0.6. Our results show that the Cu 2 In x Zn 1−x Sn(S,Se) 4 alloy is a potentially applicable material for bandgap grading absorption layers in high-power-conversion-efficiency solar cells. [ABSTRACT FROM AUTHOR]

• WMP can be used alone as a precursor to produce alkali-activated binder. • Na 2 O greatly impact on strength, and modulus on setting time of WMP-based binder. • Higher pre-curing temp & high-temp curing time boost early strength, not late. • Sealed curing method promotes steady strength growth in WMP-based binder. Marble, as a widely used building decoration material, produces a significant amount of waste marble powder (WMP) during processing. To investigate the potential of WMP as a precursor in the preparation of alkali-activated binders, this paper uses WMP as the only precursor and conducts a series of macroscopic mechanical and microscopic characterization tests. The variables included the alkali activator modulus (Ms), Na 2 O dosage, and curing conditions. The results showed that increasing the Na 2 O dosage shortened the setting time of the binders, reduced the fluidity, and improved the strength. With the increase in the modulus of the alkali activator, the binder setting time was prolonged, the fluidity first increased and then decreased, and the strength decreased. Increasing the precuring temperature and prolonging the high-temperature curing time was beneficial to developing early strength. Sealed curing was more favorable for stable strength development than standard curing. Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR) characterization tests revealed that the dissolution of WMP occurred in the alkali activator, and the hydration products contained carbonate, C-S-H, N-C-S-H, and other substances. The results of the gray correlation analysis showed that the Na 2 O dosage had a greater influence on the binder fluidity than the alkali activator modulus, while the setting time was the opposite. The effects of the four studied factors on the long-term flexural and compressive strengths of the specimens were in the consistent order of Na 2 O dosage > alkali activator modulus > precuring temperature > high-temperature curing time. [ABSTRACT FROM AUTHOR]

(1 − x )BaTiO 3 – x BaFe 12 O 19 ( x = 0.02, 0.04, 0.06, 0.08, 0.10 and 0.12) composites with core–shell heterostructure could be facilely synthesized via combined microwave hydrothermal and sonochemical method in an optimized condition. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that the core–shell heterostructure with a BaTiO 3 core and BaFe 12 O 19 shell were successfully prepared. The saturation magnetization of samples increased from 0.51 to 28.61 emμ/g during BaFe 12 O 19 content increases from 0.02 to 0.12, which is higher than the calculated expected values for all samples. A broad dielectric peak appeared in the range of 200 ∼ 300 °C, which shifted toward high temperatures with increasing frequency. [ABSTRACT FROM AUTHOR]

LiMnPO 4 nanoplates with a thickness of ca. 13 nm have been synthesised by a facile solvothermal approach in mixed water-DEG (diethylene glycol) solvents with the mediation of CTAB (cetyltrimethyl ammonium bromide). The coordinative effect of CTAB and DEG promotes the crystal orientation growth of LiMnPO 4 along ac plane. The structure and morphology of the product were characterized by XRD, SEM, TEM, BET, FT-IR and Raman spectra. A possible formation mechanism of LiMnPO 4 nanoplates assembled in layer-by-layer style is put forward on the basis of the above characterization results. A continuous and uniform carbon layer is coated on the surface of the LiMnPO 4 nanoplates after heat treatment with sucrose. The obtained LiMnPO 4 /C composite exhibits high discharge capacities of 148.6 mA h g −1 at 0.1 C, 127.6 mA h g −1 at 1 C and 93.8 mA h g −1 at 5 C and it possesses excellent cycling performance with capacity retention ratios of 96.9% and 92.7% after 100 cycles and 500 cycles at 0.1 C and 1 C, respectively. [ABSTRACT FROM AUTHOR]

Abstract: The face-centered tetragonal (FCT) ordered L10 CoPt nanoparticles (NPs) are prepared by the sol–gel method. Their structure and magnetic properties are characterized by the X-ray diffraction (XRD), the transmission electron microscope (TEM) and the vibrating sample magnetometer (VSM). The results indicate that the CoPt NPs heated at 400°C are the disordered face-centered cubic (FCC) structure, whereas the samples annealed at the temperature above 600°C exhibit an ordered FCT structure. TEM images show the increase of the particle size as the annealing temperature increases. SAED images show the appearance of the L10 phase at 800°C, and the maximum coercivity is 254,720.3A/m. [Copyright &y& Elsevier]

Abstract: Zn0.98−x Cu x V0.02O (x=0, 0.01, 0.02 and 0.03) samples were synthesized by the sol–gel technology to dope up to 3% Cu in ZnO. Investigations of structural, optical and magnetic properties of the samples have been done. The results of X-ray diffraction (XRD), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) indicated that the V and Cu ions were incorporated into the crystal lattices of ZnO. With Cu doping concentration increasing up to 2at%, the XRD results showed that all diffraction peaks corresponded to the wurtzite structure of ZnO. Photoluminescence (PL) measurements showed that Zn0.98−x Cu x V0.02O powders exhibited that the position of the ultraviolet (UV) emission peak of the samples showed an obvious red-shift and the green emission peak enhanced significantly with Cu doping in ZnVO nanoparticle. Magnetic measurements indicated that room temperature ferromagnetism (RTFM) of Zn0.98−x Cu x V0.02O was an intrinsic property when Cu concentration was less than 3at%. The saturation magnetization (M s) of Zn0.98−x Cu x V0.02O (x=0, 0.01 and 0.02) increased with the increase of the Cu concentration. [Copyright &y& Elsevier]

Abstract: Eu-doped ZnO nanosheets with irregular porous microstructure were successfully prepared by a simple hydrothermal method. The microstructures, morphologies and optical properties of the as-prepared nanosheets were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopy (PL) and Raman spectroscopy. XRD and XPS results indicated that trivalent europium ions were successfully doped into the crystal lattice of ZnO matrix. Nanosheets with irregular porous can be seen from the TEM images. PL spectroscopy indicated that the peaks located at 580, 587 and 614nm were attributed to the 4f–4f intrashell transitions of 5D0→7F0, 5D0→7F1 and 5D0→7F2 of Eu3+ ions,respectively, and the intensity ratio of 5D0→7F2 to 5D0→7F1 indicated that Eu3+ ions were incorporated into wurtzite ZnO host by substitution on the Zn sublattice and located at a low-symmetry site (C3v) without inversion center. [Copyright &y& Elsevier]

Abstract: The wurtzite-type Zn0.99−x Mn0.01Cu x S (x =0, 0.003, 0.01) nanowires were prepared by a simple hydrothermal method at 180°C. The structure and morphology of the samples were characterized by X-ray diffraction (XRD), X-ray absorption fine structure (XAFS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron micrograph (FESEM) and X-ray photoelectron spectrum (XPS). The results showed that both the Mn2+ and Cu2+ ions substituted for the Zn2+ sites in the host ZnS. The ethylenediamine-mediated template was observed, which was used to explain the growth mechanism of the nanowires. The color-tunable emission can be obtained by adjusting the concentrations of Mn2+ and Cu2+ ions. The ferromagnetism was observed around room temperature. [Copyright &y& Elsevier]

Abstract: Nanocrystalline samples of ZnS and Zn1−x Mn x S were synthesized by the solvothermal method without any surface-active agents and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), near-edge X-ray-absorption fine structure technique (XANES), photoluminescence (PL) and UV–vis. The results showed that the Mn2+ ions were substitutionally incorporated into the ZnS host and the size of the particles was decreased as the Mn doped-ratio increased. The yellow-orange emission from the Mn2+ 4T1–6A1 transition was observed in the PL spectra, the peak intensity ratio of which to that of sulfur vacancies increased with the increase of the Mn2+ concentration, and showed a maximum when the concentration of Mn2+ was kept at 3%. [Copyright &y& Elsevier]