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Silica nanosheets (SN) derived from natural vermiculite (Verm) were successfully incorporated into polyethersulfone–polyvinylpyrrolidone (PES–PVP) polymer to fabricate high–temperature proton exchange membranes (HT–PEMs). The content of SN filler was varied (0.1–0.75 wt%) to study its influence on proton conductivity, power density and durability. Benefiting from the hydroxyl groups of SN that enable the formation of additional proton–transferring pathways, the inorganic–organic membrane displayed enhanced proton conductivity of 48.2 mS/cm and power density of 495 mW/cm2 at 150 °C without humidification when the content of SN is 0.25 wt%. Furthermore, exfoliated SN (E–SN) and sulfonated SN (S–SN), which were fabricated by a liquid–phase exfoliation method and silane condensation, respectively, were embedded in PES–PVP polymer matrix by a simple blending method. Due to the significant contribution from sulfonic groups in S–SN, the membrane with 0.25 wt% S–SN reached the highest proton conductivity of 51.5 mS/cm and peak power density of 546 mW/cm2 at 150 °C, 48% higher than the pristine PES–PVP membranes. Compared to unaltered PES–PVP membrane, SN added hybrid composite membrane demonstrated excellent durability for the fuel cell at 150 °C. Using a facile method to prepare 2D SN from natural clay minerals, the strategy of exfoliation and functionalization of SN can be potentially used in the production of HT–PEMs.

Challenging space missions include those at very low altitudes, where the atmosphere is source of aerodynamicdrag on the spacecraft. To extend such missions lifetime, an efficient propulsion system is required. Onesolution is Atmosphere-Breathing Electric Propulsion (ABEP). It collects atmospheric particles to be usedas propellant for an electric thruster. The system would minimize the requirement of limited propellantavailability and can also be applied to any planet with atmosphere, enabling new mission at low altituderanges for longer times. Challenging is also the presence of reactive chemical species, such as atomic oxygenin Earth orbit. Such species cause erosion of (not only) propulsion system components, i.e. acceleration grids,electrodes, and discharge channels of conventional EP systems. IRS is developing within the DISCOVERERproject, an intake and a thruster for an ABEP system. The paper describes the design and implementationof the RF helicon-based inductive plasma thruster (IPT). This paper deals in particular with the design andimplementation of a novel antenna called the birdcage antenna, a device well known in magnetic resonanceimaging (MRI), and also lately employed for helicon-wave based plasma sources in fusion research. This isaided by the numerical tool XFdtd®. The IPT is based on RF electrodeless operation aided by an externallyapplied static magnetic field. The IPT is composed by an antenna, a discharge channel, a movable injector,and a solenoid. By changing the operational parameters along with the novel antenna design, the aim is tominimize losses in the RF circuit, and accelerate a quasi-neutral plasma plume. This is also to be aided by theformation of helicon waves within the plasma that are to improve the overall efficiency and achieve higherexhaust velocities. Finally, the designed IPT with a particular focus on the birdcage antenna design procedureis presented This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 737183

Cold sintering is a promising technology for preparing electronic materials, enabling densification at low temperature, but rarely employed for thermoelectrics. Herein, high-quality Ca2.7Bi0.3Co3.92O9+δ ceramics were synthesised by a combination of cold sintering and annealing processes. Stoichiometric mixtures of raw materials were calcined once or twice at 1203 K for 12 h in air, and then cold sintered at 673 K for 60 min under a pressure of 85 MPa, followed by annealing at 1203 K for 12 h or 24 h in air. The effects of the calcination processes and annealing conditions on the thermoelectric performance of cold sintered samples were investigated. By optimising heat-treatment, the formation of secondary phases, texture development and porosity were controlled, leading to enhanced electrical conductivity and reduced thermal conductivity. Consequently, at 800 K there was 85% increase in power factor and 35% increase in ZT (value of 0.15) compared to previous studies.

This work studies the impact of adding 0.5 wt.% Si on the formation of Al3(Sc,Zr) L12 precipitates in a lean Al-Sc-Zr alloy. Precipitation kinetics are significantly accelerated when ageing at 300 and 375 °C in the presence of Si. At 375 °C, peak hardness occurs in a few minutes and is maintained up to 200 h at 375 °C . High resolution TEM reveals the presence of very fine core-shell L12 dispersoids ~5 nm in size that remain stable for up to 200 h at 375 °C. Using high-resolution energy dispersive X-ray spectroscopy (EDX) and atom probe tomography (APT), the presence of Si and Fe is detected in the core of the dispersoids, where their content decreases as a function of ageing time. Similar Si and Fe compositions were observed inside the dispersoids for both alloys regardless of bulk Si content. Both Si and Fe are found to have preference for the Al site in the L12 structure, which is supported by density functional theory (DFT) calculations. DFT also explains the decrease of Si and Fe over time, showing that there is no thermodynamic driving force for either Si or Fe to be present in the L12. Instead Si and Fe are found to play a crucial role at the early stages of clustering, but are expelled from the particles when they stabilise into L12 structures.

Reduced electrochemically exfoliated graphene oxide (rEGO) is combined with carbon black (CB) as a hybrid support material to improve platinum (Pt) catalyst electrochemical activity and durability. Pt/rEGO2-CB3 (rEGO/CB ratio 2/3) retains 71% of initial electrochemical surface area (ECSA) and maintains higher oxygen reduction reaction (ORR) activity compared to Pt/CB after 30000 cycles of the accelerated stress test (AST). In addition, Pt/rEGO2-CB3 shows a 1.8 times improvement in the hydrogen fuel cell performance compared with Pt/CB and is more stable after 24 h at a continuous 0.60 V. The Pt/rEGO2-CB3 promotes the 4e− reaction pathway demonstrated by linear sweep voltammetry (LSV), which leads to greater ORR activity. In addition, the combination of rEGO and CB leads to both enhanced transport properties and improved stability. The Pt particles on both CB and rEGO are less likely to agglomerate in the composite support than in either of the two carbon supports when used alone.

The effect of silica-promotion on the reduction of iron oxides in hydrogen was investigated using in situ X-ray diffraction and aberration-corrected transmission electron microscopy to understand the mechanism of reduction and the identity of the iron(II) silicate phase that has historically been designated as the cause of the iron-silica interaction in such materials. In the absence of a silica promoter the reduction of hematite to {\alpha}-Fe proceeds via magnetite. Silica promoted amorphous iron oxide is reduced to {\alpha}-Fe via stable magnetite and w\"ustite phases. During reduction of silica-promoted iron oxide, Fe0 diffuses out of the amorphous silica-promoted iron oxide matrix upon reduction from Fe2+ and coexists with an amorphous Fe-O-Si matrix. Certain portions of w\"ustite remain difficult to reduce to {\alpha}-Fe owing to the formation of a protective silica-containing layer covering the remaining iron oxide regions. Given sufficient energy, this amorphous Fe-O-Si material forms ordered, crystalline fayalite., Comment: 8 figures

We have used advanced analytical electron microscopy to characterise the local structure and chemistry at the interface between nm-thick TiO precipitates and the V-based matrix in a V-4Ti-4Cr alloy. Our results reveal the presence of an intergrowth between the fcc TiO and bcc vanadium structures, with a repeat lattice distance that equals 2.5 times the vanadium lattice parameter along the c-axis. Our atomic resolution analysis of the interface will impact the mechanistic understanding of its interaction with interstitials and radiation-induced latticedefects, and consequently trigger the development of improved alloy structures with interfaces engineered for enhanced radiation tolerance.

The early stages of nano-particulate formation in mechanically alloyed and annealed, precursor powders used to manufacture the legacy commercial oxide dispersion strengthened alloy PM2000, formerly produced by Plansee GmbH, have been investigated. Powders were analysed in both the as-mechanically-alloyed condition and after annealing over the temperature range 923–1423 K. The nucleation and growth of coherent nano-particles in the partially recovered, fine grained, ferritic matrix of powders annealed at temperatures as low as 923 K has been confirmed. Powders annealed for 1 h at temperatures of 1123 K and 1223 K were partially recrystallised and contained high number densities ( N V > 10 23 m −3 ) of coherent 2 nm yttrium–aluminium–oxygen rich nano-particles. The identification of particle free zones in recrystallised grains, adjacent to recrystallising interfaces, plus the identical orientation relationships between nano-particles and the matrices in both unrecrystallised and recrystallised grains, indicates that the Y–Al–O nano-particles, first formed in fine grained regions, are dissolved during recrystallisation and re-precipitated subsequently in recrystallised grains.

Barrier-type, nanocrystalline anodic films have been formed on a ZE41 magnesium alloy under a constant current density of 5 mA cm-2 in a glycerol/fluoride electrolyte, containing 5 vol.% of added water, at 293 K. The films contain magnesium, fluorine and oxygen as the major species, and lower amounts of alloying element species. The films grow at an efficiency of ∼0.8 to 0.9, with a formation ratio in the range of ∼1.2 to 1.4 nm V -1 at the matrix regions and with a ratio of ∼1.8 nm V -1 at Mg-Zn-RE second phase. At the former regions, rare earth species are enriched at the film surface and zinc is enriched in the alloy. A carbon- and oxygen-rich band within the film suggests that the films grow at the metal/film and film/electrolyte interfaces. © 2014 The Authors. Published by Elsevier Ltd.

Graphitic materials and graphite composites experience dimensional change when exposed to\ud radiation-induced atomic displacements. This has major implications for current and future\ud technological ranging from nuclear fission reactors to the processing of graphene-silicon\ud hybrid devices. Dimensional change in nuclear graphites is a complex problem involving the\ud filler, binder, porosity, cracks and atomic-level effects all interacting within the polygranular\ud structure. An improved understanding of the atomistic mechanisms which drive dimensional\ud change within individual graphitic crystals is required to feed into the multiscale modelling of\ud this system.\ud In this study, micromechanically exfoliated samples of highly oriented pyrolytic graphite\ud have been ion irradiated and studied in situ using transmission electron microscopy (TEM) in\ud order to gain insights into the response of single graphitic crystals to displacing radiation.\ud Under continuous ion bombardment, a complex dynamic sequence of deformation evolves\ud featuring several distinct stages from the inducement of strain, the creation of dislocations\ud leading to dislocation arrays, the formation of kink band networks and localised doming of the sample. Observing these ion irradiation-induced processes using in situ TEM reveals\ud previously unknown details of the sequence of microstructural developments and physics\ud driving these phenomena. A mechanistic model consistent with the microstructural changes\ud observed is presented.