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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Preparation and visible light photocatalytic activity of Bi{sub 2}O{sub 3}/Bi{sub 2}WO{sub 6} heterojunction photocatalysts

The Bi{sub 2}O{sub 3}/Bi{sub 2}WO{sub 6} heterojunction photocatalysts were prepared by a two-step solvothermal process using Bi(NO{sub 3}){sub 3}-ethylene glycol solution as Bi source. The catalysts were characterized by X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, and UV-vis diffuse reflection spectroscopy. The heterostructure catalysts are composed of Bi{sub 2}O{sub 3} nanoparticles as modifier and 3D Bi{sub 2}WO{sub 6} microspheres as substrate. Bi{sub 2}O{sub 3} nanoparticles with diameters of about 10-15 nm are tightly grown on the lateral surface of the Bi{sub 2}WO{sub 6} microspheres. The hierarchical Bi{sub 2}O{sub 3}/Bi{sub 2}WO{sub 6} microspheres exhibit higher photocatalytic activity than the single phase Bi{sub 2}WO{sub 6} or Bi{sub 2}O{sub 3} for the degradation of rhodamine B under visible light illumination ({lambda}>420 nm). The enhancement of the photocatalytic activity of the Bi{sub 2}O{sub 3}/Bi{sub 2}WO{sub 6} heterojunction catalysts can be ascribed to their improved light absorption property and the reduced recombination of the photoexcited electrons and holes during the photocatalytic reaction. The effect of loading amount of Bi{sub 2}O{sub 3} on the catalytic performance of the heterojunction catalysts was also investigated and the optimal content of Bi{sub 2}O{sub 3} is 3 wt%. The Bi{sub 2}O{sub 3}/Bi{sub 2}WO{sub 6} heterojunction photocatalysts are essentially stable during the photocatalytic process. - Graphical abstract: The Bi{sub 2}O{sub 3}/Bi{sub 2}WO{sub 6} heterojunction catalysts were constructured with improved photocatalytic activity, which can be ascribed to their improved light absorption property and the reduced recombination rate between photoexcited electrons and holes. Highlights: > Bi{sub 2}O{sub 3}/Bi{sub 2}WO{sub 6} heterojunction photocatalysts. > Effective separation of photoexcited electrons and holes. > High visible light photocatalytic activity.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2011

Oriented SrFe{sub 12}O{sub 19} thin films prepared by chemical solution deposition

Thin films of SrFe{sub 12}O{sub 19} (SrM) were prepared from a solution of iron and strontium alkoxides through the chemical solution deposition method on both amorphous (glassy SiO{sub 2}), and single crystal substrates (Si(100), Si(111), Ag(111), Al{sub 2}O{sub 3}(001), MgO(111), MgAl{sub 2}O{sub 4}(111), SrTiO{sub 3}(111)) substrates. The process of crystallization was investigated by means of powder diffraction, atomic force microscopy and scanning electron microscopy. Magnetization measurements, ferromagnetic and nuclear magnetic resonance were used for evaluation of anisotropy in the films. Whilst amorphous substrates enabled growth of randomly oriented SrM phase, use of single crystal substrates resulted in samples with different degree of oriented growth. The most pronounced oriented growth was observed on SrTiO{sub 3}(111). A detailed inspection revealed that growth of SrM phase starts through the breakup of initially continuous film into isolated grains with expressive shape anisotropy and hexagonal habit. A continuous film with epitaxial relations to the substrate was produced by repeating recoating and annealing. - Graphical Abstract: XRD and AFM patterns of SrFe{sub 12}O{sub 19} thin film epitaxially grown on SrTiO{sub 3}(111) single crystal using seeding layer templating. Highlights: > Single phase SrFe{sub 12}O{sub 19} thin films prepared by chemical solution deposition. > Epitaxial growth on SrTiO{sub 3}(111) with (00l)SrM//(111)SrTiO{sub 3}, <110>SrM//<110>SrTiO{sub 3}). > Seed layer breaks into isolated single crystal islands and serves as a template. > Larger seed grains grow by consuming the grains within the bulk of recoated film.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2011

Study of the surface chemistry and morphology of single walled carbon nanotube-magnetite composites

The study of the morphologies of the single walled carbon nanotube (SWCNT), magnetite nanoparticles (MNP), and the composite based on them was carried with combined X-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). These techniques together with thermogravimetric analyses (TGA) and diffuse reflectance infrared transform spectroscopy (DRIFTS) confirmed the production of pure single phases, and that the composite material consisted of MNP attached to the outer surface of the SWCNT. The Moessbauer spectroscopy (MS) research showed the presence of a large quantity of Lewis acid sites in the highly dispersed magnetite particles supported on the SWCNT outer surface. The DRIFTS carbon dioxide adsorption study of the composites revealed significant adsorption of carbon dioxide, fundamentally in the Lewis acid sites. Then, the Lewis acid sites were observed to be catalytically active. Further, the electron exchange between the Lewis acid sites and the basic or amphoteric adsorbed molecules could influence the magnetic properties of the magnetite. Consequently, together with this first ever use of MS in the study of Lewis acid sites, this investigation revealed the potential of the composites for catalytic and sensors applications. -- Graphical abstract: A large amount of Lewis acid sites were found in the highly dispersed magnetite which is supported on the SWCNT outer surface. Display Omitted Research highlights: {yields} The obtained materials were completely characterized with XRD, Raman and SEM-TEM. {yields} DRIFT, TGA and adsorption of the composites allowed understand the material formation. {yields} This is the first report of a study of Lewis sites by Moessbauer spectroscopy.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2011

Evolutionary determination of experimental parameters for ptychographical imaging

The Ptychographical Iterative Engine (PIE) algorithm is a recently developed novel method of Coherent Diffractive Imaging (CDI) that uses multiple overlapping diffraction patterns to reconstruct an image. This method has successfully produced high quality reconstructions at both optical and X-ray wavelengths but the need for accurate knowledge of the probe positions is currently a limiting factor in the production of high resolution reconstructions at electron wavelengths. This paper examines the shape of the search landscape for producing optimal image reconstructions in the specific case of electron microscopy and then shows how evolutionary search methods can be used to reliably determine experimental parameters in the electron microscopy case (such as the spherical aberration in the probe and the probe positions).

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2011

Magnetic properties of Fe{sub 62}Co{sub 19}Ga{sub 19} films deposited on Si(100) substrates

Fe{sub 81-X}Co{sub X}Ga{sub 19} films, with x = 0-23 atom % Co, were deposited on Si(100) substrates, respectively, by the dc magnetron sputtering method. Film thickness (t{sub f}) ranged from 30 to 400 nm. We have done the following experiments on those films: saturation magnetostriction ({lambda}{sub S}), high-temperature magnetic hysteresis, x-ray diffraction (XRD), atomic force microscopy, Auger-depth profile analysis, and plane-view and/or cross-section transmission electron microscopy. Our main finding is that if x increases from 0 to 19 atom % Co, {lambda}{sub S} increases from 56 to 152 ppm, and if x continues to increase from 19 to 23 atom % Co, {lambda}{sub S} decreases. These results indicate that the addition of Co in the Fe{sub 81}Ga{sub 19} alloy is advantageous in enhancing {lambda}{sub S}, if x is the correct value. From XRD, the Fe{sub 62}Co{sub 19}Ga{sub 19}/Si(100) film comprises the A2 and B2 phases. The mechanism for large enhancement of {lambda}{sub S} in Fe{sub 62}Co{sub 19}Ga{sub 19}/Si(100) is related to an intrinsic origin. The t{sub f} dependence of {lambda}{sub S} for the Fe{sub 62}Co{sub 19}Ga{sub 19} films is that: [1] in the range of 110 {<=} t{sub f} {<=} 400 nm, {lambda}{sub S} increases as t{sub f} decreases; [2] in the range of 30 {<=} t{sub f} {<=} 110 nm, {lambda}{sub S} decreases as t{sub f} continues to decrease. The {lambda}{sub S} behavior in the regions [1] and [2] is explained based on the modified Neel model. Other physical properties of the Fe{sub 62}Co{sub 19}Ga{sub 19} films include the following: saturation magnetization 4{pi}M{sub S} = 1.8 - 2.0 T, coercivity H{sub C} = 35 - 64 Oe, Curie temperature T{sub C} = 597 deg. C, planar (mean) grain size D{sub P} = 29.6 nm, and columnar grain size D{sub L} {approx_equal} t{sub f}.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Phase stability and property evolution of biphasic Ti-Ni-Sn alloys for use in thermoelectric applications

Thermoelectric properties and phase evolution have been studied in biphasic Ti–Ni–Sn materials containing full-Heusler TiNi 2 Sn embedded within half-Heusler thermoelectric TiNiSn. Materials, prepared by levitation induction melting followed by annealing, were of the nominal starting composition of TiNi 1+x Sn, with x between 0.00 and 0.25. Phases and microstructure were determined using synchrotron X-ray diffraction and optical and electron microscopy. The full-Heusler phase is observed to be semi-coherent with the half-Heusler majority phase. Differential thermal analysis was performed to determine melting temperatures of the end-member compounds. The thermal conductivity is reduced with the introduction of a dispersed, full-Heusler phase within the half-Heusler material. This leads to an increased thermoelectric figure of merit, ZT, from 0.35 for the stoichiometric compound to 0.44 for TiNi 1.15 Sn. Beyond x = 0.15 ZT decreases due to a rise in thermal conductivity. Density functional theory calculations using hybrid functionals were performed to determine band alignments between the half- and full-Heusler compounds, as well as comparative energies of formation. The hybrid functional band structure of TiNiSn is presented as well.

Douglas, Jason E.↗
DOE OSTI2011

Interaction between BaCO{sub 3} and OPC/BFS composite cements at 20 {sup o}C and 60 {sup o}C

A BaCO{sub 3} slurry, containing radioactive {sup 14}C, is produced during the reprocessing of spent nuclear fuel. This slurry is encapsulated in a Portland-blastfurnace slag composite cement. The effect of BaCO{sub 3} on the hydration of OPC and Portland-blastfurnace slag cements has been studied in this work. Samples containing a simulant BaCO{sub 3} slurry were cured for up to 720 days at 20 and 60 {sup o}C and analysed by XRD, SEM(EDX) and ICC. BaCO{sub 3} reacted with OPC to precipitate BaSO{sub 4} from a reaction between soluble sulfate and BaCO{sub 3}. Calcium monocarboaluminate subsequently formed from the carbonate released. The monocarboaluminate precipitated as crystals in voids formed during hydration. At 60 {sup o}C in OPC, it was not identified by XRD, suggesting the phase is unstable in this system around this temperature. In the Portland-blastfurnace slag cements containing BaCO{sub 3}, less monocarboaluminate and BaSO{sub 4} were formed, but the hydration of BFS was promoted and monocarboaluminate was stable up to 60 {sup o}C.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2010

Exchange interaction at the interface of Fe-NiO nanocomposites

Fe-NiO nanocomposites with Fe to NiO ratio 20:80, 30:70 and 50:50 were prepared by a chemical route. X-ray diffraction and TEM measurements showed the presence of {alpha}-Fe and NiO phases in the prepared nanocomposites having an average crystallite size 17 nm. HRTEM image showed a structurally disordered phase at the Fe-NiO interface. Moessbauer spectra of the nanocomposites consist of a doublet along with a sextet corresponding to relaxed and blocked {alpha}-Fe phases, respectively. The dc magnetization measurements in field-cooled condition show a shift of hysteresis loop and an enhancement of coercive field at low temperature confirming the presence of exchange bias at Fe-NiO interfaces. The irreversibility observed in the FC and ZFC magnetization measurements also points to exchange bias effect. -- Graphical abstract: Fe-NiO nanocomposites exhibited some structural disordered region at the interface as revealed by HRTEM. A prominent shift in the hysteresis loops in field cooled condition confirmed the presence of exchange bias at Fe-NiO interfaces. The irreversibility observed in M-T measurements also points to exchange bias effect. Display Omitted

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2011

Tuning the aspect ratio of hydrothermally grown ZnO by choice of precursor

Variable aspect ratio (length/diameter), one dimensional ZnO nanostructures are synthesized by reacting Zn{sup 2+} precursor derived from Zn.Ac{sub 2}, Zn.Cl{sub 2} and Zn.(NO{sub 3}){sub 2} under hydrothermal treatment. The growth mechanism illustrating the formation of self-assembling from individual ZnO nanoparticles to rod-like form is explained briefly. XRD reveals that the ZnO obtained from various zinc salts are pure, wurtzite structure, with crystalline hexagonal phase. The qualitative analysis of ZnO formation and morphology of ZnO nanoparticles are estimated from FESEM and TEM micrographs. Strong UV absorption corresponding to the recombination of electron-hole pair is observed and the blue shift absorption obeys the size confinement effect. The extent of absorption relatively varies when the morphology is changed from nano-bundles to individual rod-like ZnO. When electrons are excited at wavelength of 240 nm, a strong near band edge (NBE) emission and surface defects emission are observed in the PL spectra. The broader emission situated in the blue-green region of the visible spectrum, originating from surface oxygen defects, is not observed in ZnO derived from Zn.Ac{sub 2}. -- Graphical abstract: The study investigates the effect of Zn{sup 2+} ions derived from various zinc sources (Zn.Ac{sub 2}, Zn.Cl{sub 2} and Zn.(NO{sub 3}){sub 2}) on the formation of one dimensional ZnO nanostructures with tunable aspect ratio. Display Omitted

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2011

Novel alkylimidazolium/vanadium pentoxide intercalation compounds with excellent adsorption performance for methylene blue

Novel alkylimidazolium-intercalated V{sub 2}O{sub 5} compounds were synthesized by a redox reaction between iodide ion and V{sub 2}O{sub 5}. The X-ray photoelectron spectroscopy and the diffuse reflectance UV-vis spectrometry experiments reveal that the vanadium in the intercalated V{sub 2}O{sub 5} products was partially reduced by an iodide ion and the resultant iodine can be removed in the final products. The transmission electron microscope observation and X-ray diffraction analysis testify that the prepared alkylimidazolium/V{sub 2}O{sub 5} intercalation compounds have typical lamellar structure with different d{sub 100} interlayer spacing values and the special straw-like nanofiber morphology with the length of 0.5-10 {mu}m. Systematic investigation indicates that new intercalation compounds possess the extraordinary adsorption performance for methylene blue in an aqueous solution. -- Graphical abstract: The alkylimidazolium-intercalated V{sub 2}O{sub 5} compounds with special straw-like nanofiber morphology were synthesized by a redox reaction between iodide ion and V{sub 2}O{sub 5}, which show the excellent adsorption performance for methylene blue in an aqueous medium. Display Omitted Research highlights: {yields} Novel alkylimidazolium-intercalated V{sub 2}O{sub 5} compounds. {yields} A simple preparation method by a redox reaction between iodide ion in ionic liquid and V{sub 2}O{sub 5}. {yields} The excellent adsorption performance for methylene blue in an aqueous medium.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2011

Preparation and photocatalytic activity of Sb{sub 2}S{sub 3}/Bi{sub 2}S{sub 3} doped TiO{sub 2} from complex precursor via gel-hydrothermal treatment

Sb{sub 2}S{sub 3}/Bi{sub 2}S{sub 3} doped TiO{sub 2} were prepared with the coordination compounds [M(S{sub 2}CNEt){sub 3}] (M=Sb, Bi; S{sub 2}CNEt=pyrrolidinedithiocarbamate) as precursors via gel-hydrothermal techniques. The doped TiO{sub 2} were characterized by XRD, SEM, XPS and UV-vis diffuse reflectance means. The photocatalyst based on doped TiO{sub 2} for photodecolorization of 4-nitrophenol (4-NP) was examined. The optimal Bi{sub 2}S{sub 3}/Sb{sub 2}S{sub 3} content, pH and different doped techniques have been investigated. Photocatalytic tests reveal that M{sub 2}S{sub 3} doped TiO{sub 2} via the gel-hydrothermal route performs better photocatalytic activity for photodegradation reaction of 4-nitrophenol (4-NP). -- Graphical abstract: Sb{sub 2}S{sub 3}/Bi{sub 2}S{sub 3} doped TiO{sub 2} were prepared using [M(S{sub 2}COEt){sub 3}] (M=Sb, Bi; S{sub 2}COEt=pyrrdidine-1-dithiocarbamaate) as precursors via gel-hydrothermal techniques. M{sub 2}S{sub 3} doped TiO{sub 2} performs better photocatalytic activity for photodegradation reaction of 4-nitrophenol. Display Omitted Highlights: {yields} The coordination compounds [M(S{sub 2}CNEt){sub 3}] (M=Sb, Bi; S{sub 2}CNEt=pyrrolidinedithiocarbamate) as precursors to prepare Sb{sub 2}S{sub 3}/Bi{sub 2}S{sub 3} doped TiO{sub 2}. {yields} The sol-hydrothermal, sol-gel and gel-hydrothermal processes for photocatalysis fabrication were employed and compared. {yields} Sb{sub 2}S{sub 3}/Bi{sub 2}S{sub 3} doped TiO{sub 2} obtained via the gel-hydrothermal process showed better performance for photodecolorization test of 4-nitrophenol (4-NP).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2010

Contribution to the Study of Ferrite Nanobeads: Synthesis, Characterization and Investigation of Horizontal Low Gradient Magnetophoresis Behaviour

In this work we investigate the possibilities of the use of Horizontal Low Gradient Magnetic Field (HLGMF)(<100 T/m) for filtration, control and separation of the synthesized magnetic particles, considering, the characteristics of the suspension, the size and the type of nanoparticles (NPs) and focusing on the process scale up. Reversible aggregation is considered in the different steps of magnetic nanobeads synthesis. For these purpose, we synthesized Fe{sub 2}O{sub 3}-silica core-shell nanobeads by co-precipitation, monodispersion and silica coating. SQUID, TEM, XRD, and Zeta potential techniques were used to characterize the synthesized nanobeads. An extensive magnetophoresis study was performed at different magnetophoretic conditions. Different reversible aggregation times were observed at different HLGMF, at each step of the synthesis route: Several orders of magnitude differences where observed when comparing citric acid (CA) suspension with silicon coated beads. Reversible aggregation times are correlated with the properties of the NPs at different steps of synthesis.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Experimental Investigations on Pulsed Nd:YAG Laser Welding of C17300 Copper-Beryllium and 49Ni-Fe Soft Magnetic Alloys

Copper-beryllium and soft magnetic alloys must be joined in electrical and electro-mechanical applications. There is a high difference in melting temperatures of these alloys which cause to make the joining process very difficult. In addition, copper-beryllium alloys are of age hardenable alloys and precipitations can brittle the weld. 49Ni-Fe alloy is very hot crack sensitive. Moreover, these alloys have different heat transfer coefficients and reflection of laser beam in laser welding process. Therefore, the control of welding parameters on the formation of adequate weld puddle composition is very difficult. Laser welding is an advanced technique for joining of dissimilar materials since it can precisely control and adjust the welding parameters. In this study, a 100W Nd:YAG pulsed laser machine was used for joining 49Ni-Fe soft magnetic to C17300 copper-beryllium alloys. Welding of samples was carried out autogenously by changing the pulse duration, diameter of beam, welding speed, voltage and frequency. The spacing between samples was set to almost zero. The ample were butt welded. It was required to apply high voltage in this study due to high reflection coefficient of copper alloys. Metallography, SEM analysis, XRD and microhardness measurement was used for survey of results. The results show that the weld strength depends upon the chemical composition of the joints. To change the wells composition and heat input of the welds, it was attempted to deviate the laser focus away from the weld centerline. The best strength was achieved by deviation of the laser beam away about 0.1mm from the weld centerline. The result shows no intermetallic compounds if the laser beam is deviated away from the joint.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Surface nanostructuring of laser ablated copper in ambient gas atmosphere and a magnetic field

A comprehensive study on deposition of copper nanoclusters back on to the laser ablated target in combined ambient of gas and a magnetic field is reported. The characteristics and mechanism of the inverse plume deposition are investigated by characterizing the laser ablated plasma plume using time resolved imaging and optical emission of the plume. The morphology of the deposited particles in presence of magnetic field depends on the nature of the ambient gas used; the elliptical shape of reverse deposited particles changes to spherical with the increase in mass of the ambient gas. The structural, morphological, and optical properties of the deposited nanoclusters were studied by using x-ray diffraction, scanning electron microscope and photoluminescence spectra respectively. The possibility of enhanced deposition rates in combined ambient gas and a magnetic field has potentials of industrial applications of the process.

36 MATERIALS SCIENCE↗
DOE OSTI2011

XRD and IR Studies of Yb{sup 3+} Doped Tellurite Glass

Ytterbium doped sodium-tellurite glasses having composition of (80-x) TeO{sub 2}-20Na{sub 2}O-(x)Yb{sub 2}O{sub 3}(where x = 0.0-2.0 mol%) are prepared by melt quenching technique. The crystallinity of the glass has been examined using X-ray diffraction technique. All glass are found to be amorphous in nature. Meanwhile the transmission spectroscopy is determine by using Infrared Spectroscopy. It is found that the absorption vibrational spectra occurs at range 3405-3423 cm{sup -1}, 1632-1643 cm{sup -1}, 1377-1382 cm{sup -1}, 721-732 cm{sup -1} and 589-606 cm{sup -1} peaks. The predominant peaks around 700 cm{sup -1} is due to the Te-O-Te vibration while peak at 600 cm{sup -1} is due to the vibration of Yb{sup 3+} ions.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Use of Justified Constraints in Coherent Diffractive Imaging

We demonstrate the use of physically justified object constraints in x-ray Fresnel coherent diffractive imaging on a sample of nanoporous gold prepared by dealloying. Use of these constraints in the reconstruction algorithm enabled highly reliable imaging of the sample's shape and quantification of the 23- to 52-nm pore structure within it without use of a tight object support constraint.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Probing Fundamental Mechanisms of Plastic Deformation with High Energy X-rays (Final Progress Report)

Overall, substantial progress was made on developing BCDI techniques in the direction of imaging defects in multi-crystal samples. Section 2.1 describes a new method to reconstruct the 3D atomic displacement field within a grain from multiple coherently resolved diffraction peaks. The key development is the ability to recover a best fit to the grain shape at the same time as the internal displacement (strain) variation with no prior knowledge of the microstructure. This is complemented by the development of a method, Sec. 2.2, to separate out sets of Laue reflections that belong to a single grain (and thus be able to index its orientation) in the commonly encountered situation in which the beam illuminates several grains in a given location. This is essential for enabling collection of coherent diffraction data (at APS 34-ID-C) from neighboring grains. All experiments depend on the quality of samples used. Although good progress has been made with thin film samples, we are working with a broader range of geometries. A new sample design uses a high-Z metal (e.g., Pt) deposited in a sub-micron trench in a low-Z metal (e.g., Al) so that the grain size is prevented from exceeding the current limit for BCDI. We also report in section 3.1 on successfully applying NF-HEDM to a fine-grain Mg sample that would normally be considered out of scope for the method. This represents progress towards being able to map out polycrystalline samples in 3D before performing BCDI on individual grains. We further report in section 3.2 on preliminary NF-HEDM characterization of a sample of UO2 that has sub-micron grains; the data imply the capability of mapping fine-grain polycrystals at 1-ID-E, again for the purposes of BCDI in the bulk. Lastly, our plan is to load grains in polycrystalline samples by inducing thermal stress. We also report the experimental measurements of the Ti- 6Al-4V alloy obtained at the European Synchrotron Radiation Facility (ESRF), which had been indexed and mapped via HEDM at APS in section 9. As discussed below, however, technique development pre-occupied the team throughout the project which meant that we did not make any significant progress towards answering the original hypotheses as stated in the proposal. In summary, we assert that we have made good progress in methods and samples and future work taking advantage of this progress is likely to obtain and analyze BCDI data from multiple adjacent grains in 3D polycrystals. Obtaining such data depends on re-gaining access to the Advanced Photon Source, which is anticipated in late summer or the Fall. In all cases, work has involved close collaboration with faculty, staff, postdocs and students from Brigham Young University (BYU), the Los Alamos National Laboratory and APS beamlines 1-ID and 34-ID.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Simultaneous pore enlargement and introduction of highly dispersed Fe active sites in MSNs for enhanced catalytic activity

An effective post-hydrothermal treatment strategy has been developed to dope highly dispersed iron catalytical centers into the framework of mesoporous silica, to keep the particle size in nanometric scale, and in the meanwhile, to expand the pore size of the synthesized mesoporous silica nanoparticles (MSNs). Characterization techniques such as XRD, BET, SEM and TEM support that the synthesized samples are long period ordered with particles size about 100 nm and a relatively large pore size of ca. 3.5 nm. UV-vis, XPS and EPR measurements demonstrate that the introduced iron active centers are highly dispersed in a coordinatively unsaturated status. NH{sub 3}-TPD verifies that the acid amount of iron-doped MSNs is quite high. The synthesized nanocatalysts show an excellent catalytic performance for benzylation of benzene by benzyl chloride, and they present relatively higher yield and selectivity to diphenylmethane with a lower iron content and much shorter reaction time. - Graphical abstract: Uniform MSNs with iron active centers and large pore size have been prepared by a newly developed strategy, which demonstrates enhanced catalytic performance for benzylation of benzene by benzyl chloride. Highlights: Black-Right-Pointing-Pointer Iron species were introduced into the framework of mesoporous silica nanoparticles with uniform dispersion. Black-Right-Pointing-Pointer The pore sizes of the synthesized nanocatalysts were expanded. Black-Right-Pointing-Pointer The acidic site quantities were quite high and the acidic centers were accessible. Black-Right-Pointing-Pointer The nanocatalysts presented higher yield and selectivity to diphenylmethane with significantly lower Fe content.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗