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Abstract: Taking the use of Nb and Si elemental powders as raw materials, Nb/Nb5Si3 composites were successfully fabricated by a spark plasma sintering (SPS) technology. The influence of sintering temperatures on microstructures of the synthesized composites was mainly investigated. The results show that there exists a critical sintering temperature T c (1400°C) in the synthesis of Nb/Nb5Si3 composites by SPS technology. When sintering temperature is lower than T c, an intermediate Nb3Si phase is produced in the fabricated samples. Moreover, the relative density of the samples is lower. Only if the sintering temperature is higher than T c, the intermediate Nb3Si phase is thoroughly eliminated, Nb particles become a finer size and desirable Nb/Nb5Si3 composites up to 99.59% theoretic density are achieved. [Copyright &y& Elsevier]

Abstract: By adopting a feasible microwave-induced solution combustion synthesis (MISCS) method, pure and well-crystallized BaMgAl10O17:Eu2+ (BAM) nanoscale blue phosphors were successfully prepared. The crystallinity, particle size, morphology, chemical composition and luminescent properties were characterized by XRD, FE-SEM, EDS and spectrofluorometer, respectively. The results show that the obtained BAM phosphors have spherical morphology, good crystallinity, and strong blue emission under vacuum ultraviolet (VUV) light excitation compared to those prepared by conventional solution combustion method. [Copyright &y& Elsevier]

Abstract: Co/BaTiO3 nanofibers with diameter of 100nm have been successfully prepared using the novel electrospinning technique followed by subsequent reductive annealing treatment. The synthesized Co/BaTiO3 nanofibers were demonstrated to be polycrystalline with a double-phase heterostructure, containing both Co metal phase and BaTiO3 tetragonal phase by TEM, XPS and Raman spectroscopy analysis. Magnetization measurements revealed that the electrospun nanofibers had unique temperature-dependent magnetic properties. The simplicity and effectiveness of electrospinning make it a competitive approach to get one-dimensional heterogeneous nanostructure. The achievements shown here may also help to find new multiferroic materials. [Copyright &y& Elsevier]

Abstract: Using Mo, Si, and C element powders as starting materials, a field-activated and pressure-assisted combustion synthesis (FAPACS) was employed to synthesize high-density bulk MoSi2–SiC composite in one step. Effects of sintering temperatures (1100, 1200, 1400 and 1600°C) on microstructures and densification were investigated. With the exception of 1100°C, at which synthesis was incomplete, the FAPACS was characterized by the four stages, i.e. initial expansion, slight shrinkage, abrupt shrinkage and slight expansion. The study shows that the sintering ability at the higher temperature is better than that at the relatively lower temperature. When the sintering temperature reaches 1400 or 1600°C with holding time of 10min, the high-temperature transitional phases, i.e. Mo4.8Si3C0.6, were presented and the produced SiC particles are agglomerate. The relative density of the products (holding time: 10min) was improved tremendously from 59% to 96.0% over the range 1100–1400°C, and a smaller enhancement in densification up to 98.5% was achieved between 1400 and 1600°C. Moreover, an extended holding time (up to 20min) at 1600°C resulted in nearly Mo4.8Si3C0.6-free and dense MoSi2–SiC products with the relative density of 99.0%. Simultaneously, a locally uniform distribution of SiC in the synthesized MoSi2 matrix was achieved. And the interfaces between the synthesized phases are clean without impurities (e.g. SiO2) and porosities. Thereby, in order to pursue an equilibrium among densification, microstructural uniformity and formation of transitional phases, the most suitable sintering temperature and holding time for fabrication of MoSi2–SiC by FAPACS are recommended to be 1600°C and 20min in the present work. [Copyright &y& Elsevier]

Abstract: Spark plasma sintering was employed to synthesize high-density bulk MoSi2 in one step, using Mo and Si element powders as starting materials. Influence of sintering temperature on sintering behavior and microstructures of MoSi2 were investigated. The sintering behavior at whatever temperature (1473, 1673 and 1873K) is characterized by four stages, i.e., initial expansion, slight shrinkage, abrupt shrinkage and slight expansion. The maximum shrinkage displacement increased with increasing sintering temperature. When the sintering temperature reaches 1673K or 1873K, the second phases, i.e., SiO2 and Mo5Si3/Mo4.8Si3C0.6, were uniformly distributed in the synthesized MoSi2 matrix accompanied with a small amount of porosity. Most of SiO2 and Mo5Si3/Mo4.8Si3C0.6 particles were concentrated at grain boundaries. The relative density of the products (atomic ratio: Mo/2.00Si) was improved tremendously from 89% to 98.2% over the range 1473–1673K, and much smaller enhancement up to 99.0% was achieved from 1673 to 1873K. At the same time, the grain size and amount of second phase particles (mainly Mo5Si3/Mo4.8Si3C0.6) consistently increased with increasing temperature over 1473–1873K. However, the use of a slight excess of Si (e.g., atomic ratio: Mo/2.06Si) at 1673K resulted in dense products of MoSi2 nearly free of Mo5Si3/Mo4.8Si3C0.6, with the relative density of 99.2% and the average grain size of 5–10μm. Thereby, in order to pursue an equilibrium among densification, microstructural refinement and formation of second phases, the most suitable sintering temperature and stoichiometry for fabrication of MoSi2 by SPS are recommended to be 1673K and a hyperstoichiometry of Mo/2.06Si in the present work. [Copyright &y& Elsevier]

Abstract: In order to achieve combustion synthesis (CS) of high-density and fine-structured TiC–Al2O3–Al composites, the activation of combustion reactions of 3TiO2–3C–(4+ x) Al system with x ≥10mol was conducted by means of external electric field. During the field-activated combustion synthesis (FACS), liquid Al in excess stoichiometric amount was generated and it infiltrated into the synthesized TiC–Al2O3 ceramic matrix with porosities, which directly results in a dense TiC–Al2O3–Al composites. The influence of electric field on CS process of the reactive system and the resulting microstructures of TiC–Al2O3–Al composites was investigated. The results show that an external electric field can effectively improve the adiabatic combustion temperature of the reactive system. Therefore a self-sustaining combustion of the system can be induced thermodynamically. In the experiments, both practical combustion temperature and propagation velocity of combustion wave were obviously enhanced with increasing field strength, whereas sizes of the synthesized TiC and Al2O3 particles were significantly decreased at the same time. Under an electric field of 25Vcm−1, TiC–Al2O3–Al composites with a relative density of 92.5% was successfully fabricated through the combustion reaction in the system with x =14mol, in which TiC and Al2O3 particles possess fine-structured sizes of 0.2–1.0μm, with uniform distribution in metal Al. [Copyright &y& Elsevier]

Abstract To resolve the worldwide water scarcity crises, there is an urgent need to develop highly efficient adsorbent for water purification. For the first time, Copper Iodide (CuI), homogeneously coating on carbon cloth (CuI@CC), is fabricated and investigated as a highly efficient, self-cleaning and easy-recycling adsorbent toward cationic organic dyes with good repeatability. Using the carbon cloth as a substrate, CuI is fabricated successfully via electroplating deposition followed by iodination procedure at ambient temperature. By combining the flexibility from the carbon fiber with the splendid adsorptive ability of the CuI coating, the CuI@CC is not only free-standing and flexible but also a highly efficient adsorbent. Notably, the CuI coating is also self-cleaning to decompose adsorbed organics through photocatalysis, which guarantees its great repeatability to a great extent. By installing the CuI@CC on the designed filtration device, the procedure of recycling and application is convenient and can avoid secondary pollution of water as well. This newly developed CuI coating is expected to be a novel adsorbent as a promising solution to the water crisis. Graphical abstract Image 1 Highlights • Novel CuI coating on carbon fiber was designed and successfully fabricated for the first time. • It exhibited a highly absorptive efficiency toward cationic dyes. • It possesses a splendid self-cleaning characteristic under UV light. • CuI@CC is free-standing and flexible with excellent recyclability. [ABSTRACT FROM AUTHOR]

Abstract Due to the low neutron activation and favourable self-passivating properties, Si is introduced to tungsten matrix by spark plasma sintering (SPS) technique. The phase evolution progress and mechanical properties of the composites are investigated. The results show that Si prefers to react with residual oxygen in the powders to form SiO y (y = 1, 1.5, 2) at low Si addition (≤3 at%). In this case, the formation of W 5 Si 3 is suppressed. But when further increasing the Si content up to 32 at%, W 5 Si 3 phase starts to form and its content increases with the elevating ratio of silicon suboxide to SiO y. Combined the results of XPS and tensile testing, it is concluded that silicon oxide is beneficial to the strength of W but not beneficial to the elongation. However, W 5 Si 3 shows positive effects on both strength and elongation. W-32Si composite achieves the best properties with tensile strength 353 MPa and elongation 4.58%. Also, the thermal conductivities were measured, which reveal a growing trend with testing temperature in W-Si composites in contrast with pure W. Highlights • High densification W-Si composites were successfully fabricated by SPS. • The phase transition progress was clarified by XPS and thermodynamic analyses. • Schematic diagram of phase evolution progress in W-Si composites was illustrated. • The correlation of thermal-mechanical properties with microstructure was clarified. [ABSTRACT FROM AUTHOR]

Freestanding heterostructured Ag/C nanofiber network was synthesized by a facile electrospinning method. By integrating Ag into the carbon matrix, the Ag/C nanofiber reached a conductivity of 976 S/cm, among the highest values currently reported for one-dimensional conductive materials. Besides the achievable high conductivity, the assembled Ag/C nanofiber network exhibited excellent flexibility, which could remain intact and hold its original appearance even after bending at an 180° angle. Sheet resistance of the Ag/C nanofiber network was as low as 9.6 Ω/sq. Moreover, the sheet resistance increased only by 6% even after the network suffered 1000 bending cycles, indicating its good flexibility and durability. Additionally, the Ag/C nanofiber network was further assembled into a flexible transparent electrode. A low sheet resistance of 22.1 Ω/sq was achieved at 80% transparency, indicating its potential use in the booming flexible electronic devices. [ABSTRACT FROM AUTHOR]

Abstract: A photocatalyst LaNiO3 with perovskite structure was synthesized via a sol–gel combustion technique. The effect of calcination process on the crystallinity, structure and visible-light-driven photocatalytic property of LaNiO3 has been studied. The photocatalysts were characterized by XRD, SEM, BET and UV–vis diffuse reflectance spectrum. The results showed that a single perovskite phase of LaNiO3 was obtained by suitable calcination process. The powder had high surface area. The band-gap of LaNiO3 was 2.26eV, possessing potential visible-light-induced photocatalytic activity. The photocatalytic activity of the LaNiO3 powders was evaluated by degradation of methyl orange in water under visible light irradiation. The photo-degradation of MO over LaNiO3 was a zero-order reaction and the rate constant k of the best sample in our experiments is 0.1520 (10−2 gL−1 h−1). The degradation percentage after 5h on the sample was about 74.9%. [Copyright &y& Elsevier]

Abstract: (Ba2−x Eu x )ZnSi2O7 blue–green phosphors were prepared by a sol–gel (SG) process. The crystallization processes of the phosphor precursors were characterized by X-ray diffraction (XRD) and thermogravimetric analysis (TG). The properties of the resulting phosphors were characterized by photoluminescence (PL) spectroscopy. The shape and size of the sample were observed by transmission electron microscopy (TEM). The results of TG and XRD indicate that the (Ba2−x Eu x )ZnSi2O7 phosphors crystallize completely at 900°C. The emission spectrum shows a single band centered at 500nm, which corresponds to the 4f 65d 1 →4f 7 transition of Eu2+. The excitation spectrum is a broad band extending from 260 to 465nm, which matches the emission of ultraviolet light-emitting diodes (UV-LEDs). The critical quenching concentration of Eu2+ in Ba2ZnSi2O7:Eu2+ phosphor is about 0.10mol. The value of the critical transfer distance is calculated as 15.1Å. The corresponding concentration quenching mechanism is verified to be the electric multipole–multipole interaction. [Copyright &y& Elsevier]

Abstract: Long lasting alkaline earth silicates, Ba2ZnSi2O7:Eu, Dy, Ba2ZnSi2O7:Eu, Nd and Ba2ZnsSi2O7:Eu, Dy, Nd were prepared by the combustion-assisted synthesis (CAS) method. The obtained phosphors were characterized by means of X-ray diffraction (XRD) and their photoluminescence spectrum (PSL). The emission spectrum shows a single band centered at 503nm, which corresponds to the 4f65d1 →4f7 transition of Eu2+. The Ba2ZnSi2O7:Eu phosphors showed blue-green afterglow (λ em =503nm) when Dy3+ and Nd3+ ions were doped. The electron affinity (ea) value for Eu2+ in [EuO8] was calculated to be 1.63eV. When the concentration quenching of Dy3+ and Nd3+ was over 0.07, the afterglow of the phosphors is enhanced. [Copyright &y& Elsevier]

Abstract: Nanocrystalline LaMnO3 powders were synthesized by sol–gel combustion method. The effect of citric acid (CA) to metal nitrates (MN) molar ratio of the precursor solution on the structure of gels and as-synthesized powders, combustion behavior, and microstructure of as-synthesized powders was investigated with the help of thermal analysis, infrared spectra, X-ray diffraction technique and scanning electron microscopy. The results show that the structure of gels and as-synthesized powders is influenced significantly by the molar ratio of citric acid to metal nitrates. The combustion rate decreases with increasing the CA/MN molar ratio. The crystallite size of the as-formed LaMnO3 powders increases with increasing the CA/MN molar ratio. The crystalline phases transform from cubic phase to orthorhombic phase with increasing the CA/MN molar ratio from 0.5 to 1.5. [Copyright &y& Elsevier]

Abstract: Nb/Nb5Si3 composites were successfully fabricated by a spark plasma sintering (SPS) technology. The effects of element (Nb and Si) proportions on the microstructures of the synthesized composites were mainly investigated. The results show that element proportions strongly affect the microstructures of Nb/Nb5Si3 composites; Nb/Nb5Si3 in situ composites up to 99.59% of theoretical density were fabricated by SPS technology, and the microstructures of the fabricated composites comprise the synthesized Nb5Si3 and the uniformly distributed Nb particles. Moreover, with the increase in the Si content from 6% to 20% (atom fraction), the volume fraction of the synthesized Nb5Si3 in the composites increases, whereas the content and size of Nb particles decrease obviously. The higher shrinkage and densification for Si content (16at.% and 20at.%) close to the eutectic composition take place. When sintering temperature over 1400°C, the shrinkage obviously retards and finally stops. [Copyright &y& Elsevier]

Abstract: Starting from powder mixture of MoO3–CuO–Al–Si system, a process of self-propagation high-temperature synthesis and casting (SHS-casting) was employed to fabricate Cu–MoSi2 composite successfully with assistance of thermit reactions of Al–CuO and Al–MoO3. DTA measurements and Gibbs energies change calculations were made to determine sequence of reactions for in situ synthesis of the composite. First, the thermit reaction between Al and CuO took place. The next was the thermit reaction between Al and MoO3, followed by a series of reactions in Mo–Si system to form MoSi2 and Mo5Si3. Enrichment of Si may aid in depression of transitional phase Mo5Si3. With an environment of high adiabatic temperatures, silicon got molten. Thus, generation of MoSi2 may result from a coverage effect of continuous liquid Si to particles of Mo. Due to melting of copper, the Cu–MoSi2 solidified directionally with an aligned composite structure by means of a steep temperature gradient. [Copyright &y& Elsevier]

A porous B2-NiTi compound with fine pore size and homogeneous pore distribution has been successfully fabricated by a novel phase leaching top-down process. In this process, NiTi-NiGd duplex pre-alloys were firstly prepared. Then NiGd phase was etched out in nitric acid solution, leaving NiTi to form pore structures. The pore size could be refined by increasing the cooling rate of the pre-alloys. The porosity could be tailored by changing the volume fraction of NiGd, which was related to the compositions of pre-alloys. The pore size can be refined to ∼0.27 μm in the sample with a porosity of 29%. This sample shows the highest damping capacity (0.08 at ambient temperature) and Young's modulus (6.2 GPa). These excellent damping and mechanical properties should be attributed to the enlargement of stress-strain localization areas of the refined pore structure. However, increasing the porosity to a further extent results in a larger pore size and degrades the damping property. The present homogeneous and fine porous NiTi is considered to be good candidates as damping materials in engineering application. • Fine and homogeneous distributed pores are introduced by a phase leaching process. • Pore size can be refined by increasing the cooling rates of pre-alloys. • Porosity can be tailored by adjusting the pre-alloy composition. • Highest damping capacity is obtained from samples with the largest interface area. [ABSTRACT FROM AUTHOR]