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Heusler Ni–Mn–(Ga, In, Sn, Sb) materials can provide large magnetic-field-induced strain, giant magnetocaloric and magnetoresistance effects based on their first-order solid-state martensitic transformation. In the present work, effects of Co doping on martensitic transformation behavior in melt-spun Ni–Mn–Sn ribbons were studied by x-ray diffraction, scanning/transmission electron microscopy, and thermal analysis. Experimental results showed that both martensitic transition and austenite Curie temperatures increased linearly with Co addition to Ni49Mn39Sn12; and meanwhile, crystal structures of the martensite evolved from four-layered orthorhombic (4O) to five-layered orthorhombic (10M), and then seven-layered monoclinic (14M). The compositional dependence of the martensitic transition temperatures was well correlated with changes of valence electron concentration (e/a) and unit-cell volume of high-temperature austenite. It was proposed that both increase of valence electron concentration and shrinkage of austenite unit-cell volume with Co addition are favorable to the occurrence of martensitic transformation. In addition, the Curie temperature of austenite increases with Co addition, which was ascribed to the enhancement of ferromagnetic exchange interaction. [ABSTRACT FROM PUBLISHER]

Abstract: Shape memory alloy In–21at.% Tl nanowires were prepared by a mechanical injection method. Transmission electron microscopy observations revealed that the nanowires are composed of polycrystals. At room temperature, the nanowires were characterized as martensite with dense twins, and the twining plane was identified as {101} of the face-centered tetragonal structure. The nanowire growth direction was found to be primarily along <110>. By in situ heating, reversible phase transformations between the martensite and the parent phase were observed. [Copyright &y& Elsevier]

Abstract: The thermal stability of functionalized carbon nanotubes (CNTs) has been studied experimentally by direct in situ observations using a heating stage in a transmission electron microscope, from room temperature (RT) to about 1000°C. It was found that the thermal stability of the functionalized CNTs was significantly reduced during the in situ heating process. Their average diameter dramatically expanded from RT to about 500°C, and then tended to be stable until about 1000°C. The X-ray energy dispersive spectroscopy analysis suggested that the diameter expansion was associated with coalescence of the carbon structure instead of deposition with additional foreign elements during the heating process. [Copyright &y& Elsevier]

Abstract: We have studied the radiation effects in Fe–Zr diffusion couples, formed by thermal annealing of a mechanically bonded binary system at 850°C for 15days. After irradiation with 3.5MeV Fe ions at 600°C, a cross sectional specimen was prepared by using a focused-ion-beam-based lift out technique and was characterized using scanning/transmission electron microscopy, selected-area diffraction and X-ray energy dispersive spectroscopy analyses. Comparison studies were performed in localized regions within and beyond the ion projected range and the following observations were obtained: (1) the interaction layer consists of FeZr3, FeZr2, Fe2Zr, and Fe23Zr6; (2) large Fe23Zr6 particles with smaller core particles of Zr-rich Fe2Zr are found within the α-Fe matrix; (3) Zr diffusion is significantly enhanced in the ion bombarded region, leading to the formation of an Fe–Zr compound; (4) grains located within the interaction layer are much smaller in the ion bombarded region and are associated with new crystal growth and nanocrystal formation; and (5) large α-Fe particles form on the surface of the Fe side, but the particles are limited to the region close to the interaction layer. These studies reveal the complexity of the interaction phase formation in an Fe–Zr binary system and the accelerated microstructural changes under irradiation. [Copyright &y& Elsevier]

Abstract: Herein a simple and effective approach is introduced to functionalize single walled carbon nanotubes (SWCNTs) by in-situ grafting of hydroxyapatite (HA). The pristine SWCNTs were chemically activated through introduction of carboxylic groups on their surfaces by refluxing in the mixture of H2SO4 and HNO3. The resulting carboxylated SWCNTs were further utilized for grafting of HA. The Fourier transform infrared and Raman spectroscopic studies demonstrated the formation of HA and its grafting over SWCNTs. The phase composition of HA and existence Ca2+ and PO4 3− ions were studied using X-ray diffraction and energy dispersive X-ray analyses, respectively. The surface morphology of functionalized SWCNTs was analyzed using scanning electron microscopy and transmission electron microscopy. Thermogravimetric analysis confirmed the existence of HA on SWCNTs by exhibiting different thermogram for pure HA and functionalized SWCNTs. Overall, this method produced uniform grafting of low crystalline HA on carboxylated SWCNTs with strong interfacial bonding. [Copyright &y& Elsevier]

Abstract: Silver nanoparticles (Ag-NPs) were synthesized using a facile green chemistry synthetic route. The reaction occurred at ambient temperature with four reducing agents introduced to obtain nanoscale Ag-NPs. The variables of the green synthetic route, such as acidity, concentration of starting materials, and molar ratio of reactants were optimized. Dispersing agents were employed to prevent Ag-NPs from aggregating. Advanced instrumentation techniques, such as X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible spectroscopy (UV–vis), and phase analysis light scattering technique (ZetaPALS) were applied to characterize the morphology, particle size distribution, elemental composition, and electrokinetic behavior of the Ag-NPs. UV–vis spectra detected the characteristic plasmon at approximately 395–410nm; and XRD results were indicative of face-centered cubic phase structure of Ag. These particles were found to be monodispersed and highly crystalline, displaying near-spherical appearance, with average particle size of 10.2nm using citrate or 13.7nm using ascorbic acid as reductants from particle size analysis by ZetaPALS, respectively. The rapid electrokinetic behavior of the Ag was evaluated using zetapotential (from −40 to −42mV), which was highly dependant on nanoparticle acidity and particle size. The current research opens a new avenue for the green fabrication of nanomaterials (including variables optimization and aggregation prevention), and functionalization in the field of nanocatalysis, disinfection, and electronics. [Copyright &y& Elsevier]

Abstract: In the present work, modulated four- and five-layered orthorhombic, seven-layered monoclinic (4O, 10M and 14M) and unmodulated double tetragonal (L10) martensites are characterized in Heusler Ni–Mn–Sn alloys using X-ray diffraction, high-resolution transmission electron microscopy, electron diffraction techniques and thermal analysis. All modulated layered martensites exhibit twins and stacking faults, while the L10 martensite shows fewer structural defects. The substitution of Sn with Mn in Ni50Mn37+ x Sn13− x (x =0, 2, 4) enhances the martensitic transition temperatures, while the transition temperatures decrease with increasing Mn content for constant Sn levels in Ni50− y Mn37+ y Sn13 (y =0, 2, 4). The compositional dependence of the martensitic transition temperatures is mainly attributed to the valence electron concentration (e/a) and the unit-cell volume of the high-temperature phase. With increasing transition temperatures (or e/a), the resultant martensitic crystal structure evolves in a sequence of 4O →10M →14M → L10 in bulk Ni–Mn–Sn alloys. [Copyright &y& Elsevier]

Abstract: Magnetic high density polyethylene (HDPE) polymer nanocomposites (PNCs) with different loadings of iron@iron oxide core-shell nanoparticles (NPs) were fabricated by in-situ thermal decomposition of organometallic iron precursors in the HDPE-xylene solution. Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) measurement indicated that the HDPE chains were physically adsorbed onto the surface of NPs instead of forming chemical bonding during the formation of these PNCs. Transmission electron microscopy (TEM) micrographs revealed that the iron core NPs surrounded with iron oxide shell were formed in the HDPE hosting matrix with good dispersion, an inter-network structure was formed when the particle loading reached 10.0 wt%. Mössbauer spectrum analysis showed that the oxidization content of the iron NPs decreased with increasing the particle loading. The X-ray diffraction (XRD) analysis and differential scanning calorimetry (DSC) characterization demonstrated that the crystalline structure of HDPE matrix was not influenced by the incorporation of the NPs; however, fusion heat and crystalline fraction of the HDPE matrix decreased with the introduction of these NPs. The melt rheological behaviors were significantly changed as indicated by different complex viscosities, storage moduli and loss moduli between pristine HDPE and its PNCs. Magnetic property investigation revealed a soft ferromagnetic behavior for these HDPE PNCs at room temperature and the coercivity was decreased with increasing the particle loading. Thermal gravimetric analysis (TGA) demonstrated that the thermal stability of these HDPE PNCs was enhanced in the presence of the NPs. Dielectric properties of the HDPE PNCs were also investigated and discussed in detail. [Copyright &y& Elsevier]

Abstract: Acid functionalized single walled carbon nanotubes were covalently grafted to chitosan by first reacting the oxidized carbon nanotubes with thionyl chloride to form acyl-chlorinated carbon nanotubes which are subsequently dispersed in chitosan and covalently grated to form composite material, CNT–chitosan, 1, which was washed several times to remove un-reacted materials. This composite has been characterized by FTIR, 13C NMR, TGA, SEM and TEM and has been shown to exhibit enhanced thermal stability. The reaction of 1, with poly lactic acid has also been accomplished to yield CNTchitosan–g-poly(LA), 2 and fully characterized by the above techniques. Results showed covalent attachment of chitosan and chitosan–poly lactic acid to the carbon nanotubes. [Copyright &y& Elsevier]