Nanoconfined 2LiBH4eMgH2eTiCl3 in carbon aerogel scaffold for reversible hydrogen storage

Nanoconfinement of 2LiBH4–MgH2–TiCl3 in resorcinol–formaldehyde carbon aerogel scaffold (RF–CAS) for reversible hydrogen storage applications is proposed. RF–CAS is encapsulated with approximately 1.6 wt. % TiCl3 by solution impregnation technique, and it is further nanoconfined with bulk 2LiBH4–MgH2 via melt infiltration. Faster dehydrogenation kinetics is obtained after TiCl3 impregnation, for example, nanoconfined 2LiBH4–MgH2–TiCl3 requires ∼1 and 4.5 h, respectively, to release 95% of the total hydrogen content during the 1st and 2nd cycles, while nanoconfined 2LiBH4–MgH2 (∼2.5 and 7 h, respectively) and bulk material (∼23 and 22 h, respectively) take considerably longer. Moreover, 95–98.6% of the theoretical H2 storage capacity (3.6–3.75 wt. % H2) is reproduced after four hydrogen release and uptake cycles of the nanoconfined 2LiBH4–MgH2–TiCl3. The reversibility of this hydrogen storage material is confirmed by the formation of LiBH4 and MgH2 after rehydrogenation using FTIR and SR-PXD techniques, respectively.Fil: Gosalawit Utke, Rapee. Helmholtz-Zentrum Geesthacht; Alemania. Suranaree University of Technology; TailandiaFil: Milanese, Chiara. Università degli studi di Pavia; ItaliaFil: Javadian, Payam. University Aarhus; DinamarcaFil: Jepsen, Julian. Helmholtz-Zentrum Geesthacht; AlemaniaFil: Laipple, Daniel. Helmholtz-Zentrum Geesthacht; AlemaniaFil: Karmi, Fahim. Helmholtz-Zentrum Geesthacht; AlemaniaFil: Puszkiel, Julián Atilio. Helmholtz-Zentrum Geesthacht; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Jensen, Torben R.. University Aarhus; DinamarcaFil: Marini, Amedeo. Università degli studi di Pavia; ItaliaFil: Klassen, Thomas. Helmholtz-Zentrum Geesthacht; AlemaniaFil: Dornheim, Martin. Helmholtz-Zentrum Geesthacht; Alemani

Determination of the packing fraction in photonic glass using synchrotron radiation nanotomography

Photonic glass is a material class that can be used as photonic broadband reflectors, for example in the infrared regime as thermal barrier coating films. Photonic properties such as the reflectivity depend on the ordering and material packing fraction over the complete film thickness of up to 100 μm. Nanotomography allows acquiring these key parameters throughout the sample volume at the required resolution in a non-destructive way. By performing a nanotomography measurement at the PETRA III beamline P05 on a photonic glass film, the packing fraction throughout the complete sample thickness was analyzed. The results showed a packing fraction significantly smaller than the expected random close packing giving important information for improving the fabrication and processing methods of photonic glass material in the future

Microstructure of Ti-45Al-5Nb and Ti-45Al-10Nb Powders

Gas-atomised spherical powders of Ti-45Al-5Nb and Ti-45Al-10Nb alloys were produced using the plasma melting induction guided gas atomisation (PIGA) technique. The phase composition was determined by X-ray diffraction at the synchrotron beamline HEMS at PETRA III (DESY), as well as by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), two dimensional and focused ion beam (FIB) based three dimensional electron back scatter diffraction (EBSD) measurements. Due to the high cooling rates the alloy composition of both alloys consists of hexagonal-close-packed α- and body-centred-cubic β-phase. The α-phase is dominant in the larger powder size fractions. Considerable amounts of the β phase were only found in the powder particle size fractions smaller than 32 μm for the Ti-45Al-5Nballoy and smaller than 45 μm for the Ti-45Al-10Nb. A pronounced dendritic cauliflower-like structure was observed in bigger powder particles of the Ti-45Al-10Nb alloy. This gives proof that diffusion took place during the initial β-grain formation, even though there is no orientation relation between the final grain and the dendrite structure in the powder particles. The presence of dendritic structures showed that the cooling rate during powder atomization was still too low to reach the critical growth rate for a planar solidification. The absence of preferred misorientation angles between α-grains indicates that α-grains are not formed out of already solidified β-grains by a solid state phase transformation

The Degradation Interface of Magnesium Based Alloys in Direct Contact with Human Primary Osteoblast Cells.

Magnesium alloys have been identified as a new generation material of orthopaedic implants. In vitro setups mimicking physiological conditions are promising for material / degradation analysis prior to in vivo studies however the direct influence of cell on the degradation mechanism has never been investigated. For the first time, the direct, active, influence of human primary osteoblasts on magnesium-based materials (pure magnesium, Mg-2Ag and Mg-10Gd alloys) is studied for up to 14 days. Several parameters such as composition of the degradation interface (directly beneath the cells) are analysed with a scanning electron microscope equipped with energy dispersive X-ray and focused ion beam. Furthermore, influence of the materials on cell metabolism is examined via different parameters like active mineralisation process. The results are highlighting the influences of the selected alloying element on the initial cells metabolic activity

On radiation damage in FIB-prepared softwood samples measured by scanning X-ray diffraction

The high flux density encountered in scanning X-ray nanodiffraction experiments can lead to severe radiation damage to biological samples. However, this technique is a suitable tool for investigating samples to high spatial resolution. The layered cell wall structure of softwood tracheids is an interesting system which has been extensively studied using this method. The tracheid cell has a complex geometry, which requires the sample to be prepared by cutting it perpendicularly to the cell wall axis. Focused ion beam (FIB) milling in combination with scanning electron microscopy allows precise alignment and cutting without splintering. Here, results of a scanning X-ray diffraction experiment performed on a biological sample prepared with a focused ion beam of gallium atoms are reported for the first time. It is shown that samples prepared and measured in this way suffer from the incorporation of gallium atoms up to a surprisingly large depth of 1 µm

Microstructure of gas atomised γ-TiAl based alloy powders

Due to the rapid development of advanced additive manufacturing production routes in recent years, the demand of high-quality alloy powders is significantly increased. We studied gas-atomised spherical powders of several Nb-bearing γ-TiAl based alloys, Ti-45Al-10Nb and Ti-45Al-5Nb-xC in at.% (x = 0, 0.5, 0.75, and 1), which were produced using the plasma melting induction guided gas atomization (PIGA) technique. The phase constitution of different powder fractions was determined by synchrotron high-energy X-ray diffraction at the HEMS beamline DESY (Germany), as well as by SEM, EDX and EBSD measurements. Due to the high cooling rates in the range of 10$^5$5 K/s, the powder particles mainly consist of hexagonal close packed α-Ti(Al) and body centred cubic β-Ti(Al)-phase. As the cooling rate depends on the particle size, considerable amounts of the β-phase were only found in the small powder fractions (< 45 μm). The total β-phase amount was generally higher in the alloy with a higher Nb content, and also the effect of carbon as a $\alpha_2$-stabilizer was observed. Dendritic cauliflower-like structures are more pronounced in bigger powder particles due to the slower solidification and thus a higher Nb depletion in the remaining melt

Improvement of thermal stability and reduction of LiBH4/polymer host interaction of nanoconfined LiBH4 for reversible hydrogen storage

Addition of multi-wall carbon nanotube (MWCNT) and NaAlH4 into nanoconfined LiBH4 ePcB (poly (methyl methacrylate)ecoebutyl methacrylate) for improving thermal stability and reducing LiBH4/PcB interaction is proposed. The greater the amount of gases desorbed due to polymer (PcB) degradation, the less the thermal stability of polymer host. During dehydrogenation of nanoconfined LiBH4ePcB, combination of gases due to PcB degradation is 64.3% with respect to H2 content, while those of nanoconfined samples doped with MWCNT and NaAlH4 are only 9 and 7.9%, respectively. The LiBH4/PcB (i.e., B/OCH3) interaction is quantitatively evaluated by FTIR technique. The more the ratio of peak area between y(BeH) (from LiBH4) and y(C]O) (from PcB), the lower the LiBH4/PcB interaction. It is found that by adding small amount of MWCNT and NaAlH4, this ratio significantly increases up to 78%. This is in agreement with B 1s XPS results, where the relative amount of BxOy (x/y = 3) to LiBH4 decreases after adding MWCNT and NaAlH4 into nanoconfined LiBH4 ePcB. It should be remarked that significant improvement of thermal stability and decrease of LiBH4/PcB interaction after adding MWCNT and NaAlH4 into nanoconfined LiBH4-PcB result in considerable amount of hydrogen release and uptake as well as hydrogen reproducibility during cycling. However, the dispersion of MWCNT is still one of the most critical factors to be concerned due to probably its hindrance for hydrogen diffusion

OB cells metabolism in direct contact with pure Mg, Mg-2Ag, and Mg-10Gd.

<p>a): Cell viability by Live/Dead staining. Control is cells on tissue culture plates. b): SEM images of cell morphology and coverage. Arrows refer to blebs on the cell surface. c): LDH release from cells induced by the degradation. The measurement was performed after 1, 2, 3, 7, and 14 days of immersion. LDH values at 7 and 14 days (not shown) were approximately 0%. Scale bars in white, grey, and black represent 500, 100, and 50 μm; respectively.</p

Degradation parameters after 4 and 14 days of immersion with and without cells.

<p>a): Mean degradation rate [mm/year] according to the weight loss method for pure Mg, Mg-2Ag and Mg-10Gd discs. Significant differences between the Mg-10Gd and pure Mg were detected using a one way analysis of variance (ANOVA) on ranks with Dunn’s multiple comparison post hoc test at a significance level of p < 0.05. Differences between the conditions of Mg-2Ag were analysed with an ANOVA and the Holm-Sidak post hoc test at a significance level of p < 0.001 (*). b) Online pH measurements during 14 days of immersion. i): controls on tissue culture plastic, ii): pure Mg, iii): Mg-2Ag, and iv): Mg-10Gd. Arrows in the Fig refer to medium exchange and the end point of the immersion test. c): Osmolality changes [Osmole/Kg] during immersion with pure Mg, Mg-2Ag, and Mg-10Gd.</p

The chemical composition of the studied materials.

<p>The chemical composition of the studied materials.</p