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The insulation material of high voltage motors and generators is a polymer composite which is composed of mica, which is inorganic silica (SiO 2 ), and organic polymer materials. In this section, concept of the electrical insulation design of the machines is introduced and the importance of partial discharge endurance is explained. Then, historical basic research on nano‐composite materials is reviewed in terms of partial discharge characteristics. Finally, recent progress in the development of nano‐composite application to high voltage generators is described. As another topic of polymer composite in generators and motors, stress grading system for coil end termination is briefly mentioned.

We have designed a fully automated optical microscope running at high-speed and achieving a very high spatial resolution. In order to overcome the resolution limit of optical microscopes, it exploits the localized surface plasmon resonance phenomenon. The customized setup using a polarization analyzer, based on liquid crystals, produces no vibrations and it is capable of probing isolated nanoparticles. We tested its performance with an automated readout using a fine-grained nuclear emulsion sample exposed to 60 keV carbon ion beam and, for the first time, successfully reconstructed the directional information from ultra-short tracks produced by such low-energetic ions using a solid-state tracking detector.

Calcium carbonate-based bone substitutes derived from natural coral exoskeleton (aragonite) are resorbed and remodeled faster than calcium phosphate-based substitutes. However, coral species with structures appropriate for use as bone substitutes are very limited. Therefore, it is important to evaluate potential of artificial calcium carbonate ceramics as a bone substitute. In this study, calcium carbonate granules with various porosities and pore sizes were prepared by sintering a highly pure (>99.98%) calcium carbonate powder (calcite), and their resorption properties and bone formation abilities were examined in vivo for the first time. The sintered calcium carbonate was resorbed faster than β-tricalcium phosphate, which has a similar structure. However, sintered calcium carbonate did not promote new bone formation during long-term implantation. Furthermore, both resorption and new bone formation were affected by the pore structure. The optimal structures of the artificially sintered calcium carbonate bone substitute were also discussed.

This study investigates the time to breakdown of epoxy/TiO 2 nanocomposites with a void defect. In the tests, partial discharge (PD) is continuously monitored to clarify the degradation of the nanocomposites. In evaluating the dependence of the maximum agglomerate size and the volume fractions of the TiO 2 particles, it is found that the agglomerate size, rather than the volume fractions, dominates the electrical insulation lifetime of the nanocomposites. Furthermore, the lifetime increases drastically when the agglomerate size exceeds a critical value. The continuous PD signal monitoring reveals that the lifetime extension of the nanocomposites is achieved due to delaying the electrical tree propagation in the nanocomposite, rather than extensions of the times required for the transition from the void discharges to the tree initiation.

This study investigates the relationship between void size and insulation lifetime due to partial discharges (PDs) in internal voids. Experimental results clearly show that the larger the void size, the shorter the insulation lifetime, which decreases the lifetime n-value index of the voltage-time characteristics. The results also show a clear relationship between the insulation lifetime of a solid insulator having void defects and the PD energy generated in the void, which is related to the cumulative PD energy density per cycle. Therefore, we propose estimating the insulation lifetime of an insulator with voids by calculating the cumulative PD energy density per cycle.

In this study, TiO 2 /epoxy nanocomposites are evaluated for impulse and AC breakdown strength when agglomerations of TiO 2 nanofillers are removed by centrifugation. It is found that the nanocomposites with micrometric agglomerates exhibit lower breakdown strengths than that of unfilled epoxy resin. However, with the removal of agglomerates larger than 0.5 µm for 0.4 vol% filler concentration, the breakdown strengths are higher than that of unfilled epoxy resin. Micrometric agglomerates of TiO 2 nanoparticles behave as defects, thus lowering the breakdown strength of the nanocomposites. When such agglomerates are removed prior to curing, an improvement of the breakdown strengths is observed with very low filler concentration.

Exploring the simple fabrication process to prepare CNC@HAp for biological tissues is still a challenging subject considering the wide applications of the composites for bio tissues. In this work, aiming for the fabrication of CNC@HAp composites via a simple and environment-friendly process and materials, we propose the neutralization titration in the presence of CNCs in the suspension. Core–shell structured composite of cellulose nanocrystal (CNC) and hydroxyapatite (HAp) (CNC@HAp) was successfully synthesized via simple aqueous neutralization titration. The method studied successfully hybridizes CNCs with a certain amount of HAps and easily controls the coating amounts of HAps from 9 wt% to 17 wt%. In particular, CNC@HAp pellets were easily prepared by simple compression molding from the powder of hybridized CNCs and HAps and the pellets showed high mechanical strength of over 500 N with a low strain of less than 5%. Both the process and the product of the study were environmental-friendly, no toxicity, simple and pure therefore the CNC@HAp can be easily applied to tissue engineering and medical purposes.

Owing to their excellent photoluminescence (PL) properties in a narrow linewidth below 30 nm and high photoluminescence quantum yield (PLQY), organometal halide perovskite nanocrystals (PeNCs) are ...

Polymer electrolyte fuel cells (PEFC) are expected as next energy generation systems, and their performance is strongly dependent upon the polymer electrolyte membrane (PEM). We have suggested a ne...

Silicon carbide particle-loaded semi-conductive materials with electric field-dependent conductivity have been used for end-turn stress grading (SG) systems of high voltage rotating electrical machines for decades. Particularly, high voltage class turbogenerators use double-layer SG systems, at which two SG materials with different conductivities are applied, to reduce power dissipations within the SG materials. To prevent the excessive local heating of the SG material and resulting flashover, the field-dependent conductivities of the two SG materials, as well as length of the SG layer in the longitudinal direction along a coil, were optimized, by a nonlinear transient electrical field and thermal coupled analysis. The field-dependent conductivities of the SG materials were adjusted to the suitable ones by changing the average diameter of silicon carbide particles. Then, the appropriate length of the SG layer was selected to minimize the temperature rise in the system. As a result, the newly optimized double-layer SG system showed a 20% lower temperature rise, and more than 15% higher flashover voltage than the conventional ones. Therefore, the effectiveness of the optimized double-layer SG system is successfully confirmed.

The main objective of this article is to establish which of the many dicing tapes used in the semiconductor industry would be most suitable for use in plasma dicing. Tape design over the past 40 years has continually evolved through advancements in both dicing technologies and the incessant revision of integrated circuit packaging. Die singulation has traditionally been accomplished using a diamond saw, laser-based technology, or a combination of both. The stress on dicing tape was, therefore, limited to fatigue through the physical nature of saw dicing or heat energies induced during laser dicing. These processes do not expose dicing tape to either a high vacuum or a variety of plasma chemistries. This investigative work is a continuation of studies examining the dicing tape behavior when used in plasma dicing. Results show that polyolefin (PO) UV tape with low-to-medium adhesion strength exhibits the greatest resilience under harsh plasma etch conditions and that efficient photoinitiated cross linking (or curing) of the adhesive is triggered if directly exposed to the photonic energies present in a pure SF6 plasma or full plasma dicing process. However, the postplasma dice, post-UV cure adhesive strength can still be minimized if the tape manufacturers recommended time limitations between which the tape mount, plasma dice, and die pickup process are adhered to.

Here we present an ab initio prediction of an order-disorder transition (ODT) from a $I\overline{4}2d$-type to ${\mathrm{Th}}_{3}{\mathrm{P}}_{4}$-type phase in the cation sublattices of ${\mathrm{Mg}}_{2}\mathrm{Ge}{\mathrm{O}}_{4}$, a post-post-perovskite phase. This uncommon type of prediction is achieved by carrying out a high-throughput sampling of atomic configurations in a 56-atom supercell followed by a Boltzmann ensemble statistics calculation. ${\mathrm{Mg}}_{2}\mathrm{Ge}{\mathrm{O}}_{4}$ is a low-pressure analog of $I\overline{4}2d$-type ${\mathrm{Mg}}_{2}\mathrm{Si}{\mathrm{O}}_{4}$, a predicted major planet-forming phase of super-Earths' mantles. Therefore, a similar ODT is anticipated in $I\overline{4}2d$-type ${\mathrm{Mg}}_{2}\mathrm{Si}{\mathrm{O}}_{4}$ as well, which should impact the internal structure and dynamics of these planets. The prediction of this ${\mathrm{Th}}_{3}{\mathrm{P}}_{4}$-type phase in ${\mathrm{Mg}}_{2}\mathrm{Ge}{\mathrm{O}}_{4}$ further enhances the relationship between the crystal structures of Earth/planet-forming silicates and oxides at extreme pressures and those of rare-earth sesquisulfides at low pressures.

This work aims to reveal the tensile characteristics of Glass Fibre fabrics based single face corrugated Structure Sheet (GFSS) by developing a pressure-adjustable fixture in the machine producing direction of GFSS. In order to set the fixture quick-ready and stable, the effects of several set-up conditions on the tensile behavior of GFSS were investigated. As the set-up condition, a wavy aluminum block fitted to the surface trace, insertion of multiple flexible pins into wave holes, and double-sided tapes attached on the upper/lower surfaces were discussed by changing the number of pins N, and also a few of instant adhesives was dipped on the clamped/pressured zone of GFSS (the reinforced model). Through this study, the followings were revealed. To use multiple polystyrene pins and several pieces of double-sided tapes in the proposed fixture contributes to make the tensile line force stable (as the simple model: without any instant adhesives on the clamped zone). To perform the breakage of liner and wave layers in the area of the gauge span, the reinforced model is usable when choosing N > 1. Investigating the tensile response, the strength (peak maximum line force) and the elongation limit of the liner and wave layers were revealed, respectively. By dipping instant adhesives on the clamping zone when N > 6, the combination resistance of liner and wave braiding structure was actualized.

In this work, the tensile characteristics of a 0.2-mm-thick polypropylene (PP) sheet subjected to indentation with virgin and blunt knives (apex angle, α=42◦; tip thickness, w=6 and 20 μm, respectively), were experimentally investigated. To determine the effect of mechanical condition, such as the notched depth and the profile of the root surface, on the breaking behavior of the half-cut PP specimen, the tensile testing of the half-cut specimen was carried out by varying the indentation depth and tensile velocity. By the experiments, the breakage behavior of the scored (half-cut) zone was determined by varying the indentation depth, tip thickness of the blade, and elongation rate. A kind of crazing or cracking by the blunt knife decreased the tensile resistance and burr elongation for an indentation depth larger than 0.9, whereas the work hardening by the blunt knife increased these properties for an indentation depth less than 0.8. When a blunt knife was used at a high elongation rate larger than 0.01 s-1, the half-cut zone of the PP sheet exhibited brittle fracture, i.e., the tensile resistance and burr elongation decreased.

Charge-transfer complex crystals have been extensively studied because of their metallic conductivity, photoconductivity, ambipolar charge transport, and high career mobility. Numerous studies of their applications for organic electric devices such as organic field effect transistors and solar cells have reported. However, bulky single crystals of charge-transfer complexes are difficult to handle, specifically to be made into a form of a thin film. Recently, nano/micro crystallization of charge-transfer crystal is attracted to realize thin film applications. In this paper, charge transfer complex nanorods composed of dibenzotetrathiafulvalene-tetracyanoquinodimethane (DBTTF-TCNQ) were prepared by the reprecipitation method. The as-formed nanorods possess a kinetically metastable crystal structure different from the thermodynamically stable bulk crystal prepared by slow evaporation of the solvent. From photoconductive measurement, nanorod stacks show a significant photosensitivity (354.57 μA/W) on par with bulk crystal (417.14 μA/W). These results suggest dibenzotetrathiafulvalene-tetracyanoquinodimethane (DBTTF-TCNQ) nanorods have a favorable crystal structure for carrier transport due to the difference of molecular stacking assembly.

This paper proposes a novel method for measuring the potential distribution along the stress grading system of a model stator bar whose voltage is over several tens kV. The technique uses a Pockels field vector sensor by introducing an inverse calculation process from the measured field profile to the potential profile on the measured stator bar. With this system, a potential distribution along a model bar under 50 kVp, 50 Hz voltage is successfully measured. In principle, it is possible to estimate the potential either by measuring the horizontal or vertical component of the field. The utilization of the vertical component is preferable in measuring a model bar due to robustness against optical alignment errors. Through the potential distribution measurement of the model bar, although the maximum value of the electric field increases slightly with the applied voltage, it is confirmed that the electric field grading function was working due to the non-linear resistive material.

For fabricating semiconductor devices and for microelectromechanical systems, photoresists are important materials supporting photolithography processes. However, photoresists must be removed for subsequent processes. An earlier study demonstrated that adding a small amount of oxygen gas to the atmosphere in which hydrogen radicals are produced increased the decomposition rate of a positive-tone novolac photoresist. For this study, we prepared polymers with different side chain structures based on poly(vinyl phenol) (PVP). We examined the effects of added oxygen and the oxygen-added hydrogen radicals on the decomposition rates of PVP-based polymers. Hydroxyl groups of PVP are partly substituted with tert-butoxycarbonyl groups in order to use for base polymer of KrF photoresist. Results show that oxygen addition can be useful for KrF photoresist removal.

Degradation of the electrical insulation within power transformers by partial discharge (PD) may lead to catastrophic failure of the apparatus, hence PD should be detected at an early stage. Ultra-high frequency (UHF) measurement method, i.e. detecting electromagnetic (EM) waves in the UHF range radiated from PD, has recently received attention for its various advantages, such as the robustness against external noises and its capability of localisation of the PD position. However, the EM waves suffer attenuation while propagating within transformers, in some cases, which results in undesirable low detection sensitivity. To evaluate the propagation and attenuation characteristics of the EM waves quantitatively, the simulation technique of the EM wave propagation is of importance. In this study, at first, the EM waveforms as well as attenuation properties of their amplitudes and cumulative energies while propagating through transformer windings in an oil-filled tank were experimentally investigated. Next, the detailed conditions for simulating the EM wave propagation based on time-domain finite integration technique were described. Then, the simulated results were compared with the experimentally obtained ones. These simulation and measurement results showed good agreement with each other, therefore the authors have successfully validated the newly developed simulation of the EM wave propagation.

Phase diagram of Au–Si binary alloy system shows a large drop in melting temperature of about 1000K compared with that of Si at a composition of Au:Si = 81:19, where the melting temperature is about 636K. Mixing of Au and Si below the melting temperature was observed by transmission electron microscopy experiment, and it was found that the mixed region shows a diffraction pattern of a diffuse ring intensity indicating an amorphous structure of the mixed area. Si L-emission spectra, which reflect the energy state of bonding electrons of Si atom, of molten Au81Si19 alloy were measured for the first time to investigate the energy state of valence electrons of Si. The Si L-emission spectrum showed a characteristic loss of L1 peak, which is related to sp3 directional bonding in crystalline Si. The intensity profile is also different from that of molten Si reported. This suggests a characteristic atomic arrangement that exists in the molten state. The intensity profile also indicated a small density of state in the molten state at Fermi energy. The obtained spectrum was compared with the calculated density of state of possible crystal structures reported. The comparison suggested that Si atoms are surrounded by eight Au atoms in the molten state of Au81Si19 alloy. The formation of this local atomic arrangement can be an origin of a large drop of melting temperature at about Au:Si = 81:19.

In this work, dynamic creasing characteristics of liquid-container-purpose paperboard of basis weight 313 g/m2 (a thickness of t = 0.47 mm) were investigated, when varying the holding time of two creasing knives (a round edge and/or a flat edge) at an indentation depth of d = 0.8 mm. In a scoring process, the relationship between the time-dependent behavior of reaction force f and the permanent scored depth das was approximately linearized with a logarithmic function of the elapsed holding time tep = 0-60 s. When using the paperboard scored with the specified indentation depth and varying the tracking holding time Tep, the relationship of the bending moment M and the rotation angle θ was investigated. The effects of the tracking holding time at the scoring process on the bending moment resistance (as the maximum strength) M90(0) at θ = 90° and the initial gradient C1 = \(\partial M/\partial \theta \)(θ = 0–5°) were characterized with a logarithmic function of Tep, and also an explicit expression of C1 with M90(0) was revealed. Namely, a time-dependent relaxation of scoring reactional force f and the time-dependent relaxation of C1 (and/or M90(0)) in a folding process has occurred with a logarithmic term of the holding time.

Devolatilization is an important process for separating and removing unnecessary residual volatile substances or solvents during the production of polymers using twin-screw extruders. Latinen proposed a surface renewal model to determine the concentration of volatile components in the extrudate of a single-screw extruder. When a twin-screw extruder is used to calculate the concentration, it is necessary to use the exposed surface area of the resin in the starved region of Latinen&rsquo, s model, which, however, is difficult to estimate. In our previous work, we numerically determined resin profiles of the screws using the 2.5D Hele&ndash, Shaw flow model and the finite element method, which helps in estimating the surface area of devolatilization. In this study, we numerically analyzed the volatile concentration of the extrudate in a self-wiping corotating twin-screw extruder using Latinen&rsquo, s surface renewal model along with our resin profile calculation method. The experimental results of the concentrations of the volatile component (toluene) in the extrudate of polypropylene agreed well with its numerical calculation with a relative error of 6.5% (except for the data of the lowest rotational speed). Our results also showed that decreasing the flow rate and increasing the pump capacity were effective for removing the volatile component. The screw pitch of a full-flight screw was not affected by the devolatilization efficiency with a fixed flow rate and screw speed.

Electric tree is a phenomenon of local dielectric breakdown with partial discharge (PD). It is also the final stage of insulation deterioration. The electrical treeing has been discussed by using conventional PD parameters such as the generation phase, charge amount and so on. Since the obtained PD waveforms were processed by an analog filter designed according to the frequency characteristics of the measurement instrument such as an oscilloscope, its waveform is a convolution of the original PD waveform and the transfer function of the measurement system. However, the feature values such as a rise time, fall time and frequency spectrum in the original PD waveform should show the behavior of electrons and ions in the discharge space. In this paper, the original PD waveforms generated in micro-silica/epoxy composite with the electrical tree were acquired, and the feature values of the original PD waveform were analyzed. In addition, the behavior of the electric charges in the discharge space was assessed from the change of the feature values.

Mica epoxy insulation as used for generator stator windings is required to be improved as regards withstand electrical stress and heat dissipation. Replacement of epoxy resins by epoxy nanocomposites is a useful method to fulfil a purpose of such improvement. This paper is aimed to evaluate PD-initiated breakdown (BD) performances as one of the most crucial characteristics using simulated model specimens. Two constituent materials, i.e. mica tapes and resin layers were set as about 40 and 10 µm in thickness, respectively. EDX analysis shows that the model specimens include silica nanofillers properly dispersed in narrow nanocomposite regions and are suitable for PD initiated BD experiments. It was found that PD initiated BD lifetime was 2.8 times in nanocomposites than in neat epoxy under a rather high electric stress condition.

Polymer nanocomposites have attracted attention for various superior insulation performances. However, the effect of nanocomposites on the insulation lifetime with an enclosed void defect is unclear. Also, the insulation lifetime extension mechanism has rarely been reported. This paper experimentally investigates the lifetime extension mechanism of epoxy/TiO 2 nanocomposites with the void defect. Centrifugation and dilution procedures are used to control the dispersion state of TiO 2 nanofillers. Time evolutions of partial discharge (PD) current are also recorded to investigate the insulation degradation procedure. Consequently, it is clarified that the lifetime becomes longer with increasing the maximum agglomerate size of the TiO 2 nanofillers. Results of the PD current monitoring suggest that the lifetime extension of the nanocomposite is achieved due to delaying the electrical tree propagation in the sample.

Epoxy nanocomposites (NCs) are known to have advantages when used in the electrical insulation of power equipment. Agglomerates of nanoparticles, which inevitably form during the fabrication process, can affect the insulating properties of the resultant nanocomposites. Our previous research has clarified that the impulse breakdown strength of the solid part, rather than the surface, of epoxy–TiO 2 NCs with agglomerates removed was higher than that of unfilled epoxy resin. Here, we investigated the dependence of the TiO 2 filler volume fraction on the AC breakdown strength of NCs whose agglomerate size was controlled. The volume fraction and the maximum agglomerate size were controlled using a simple dilution procedure and a centrifugation technique. The AC breakdown strength of the NCs was found to increase with decreasing volume fraction of TiO 2 nanoparticles when the maximum agglomerate size was controlled at the same level. The variation of the AC breakdown strength of the NCs decreased with decreasing maximum agglomerate size, suggesting that the existence of agglomerates larger than a critical size could affect the breakdown.

Agglomerates of nanoparticles which inevitably occur in the fabrication process of epoxy nanocomposite can affect the insulation properties of epoxy nanocomposite. This paper presents an attempt to clarify the effect of agglomerate size on two important insulation properties of epoxy/TiO 2 nanocomposite (NC). One is intrinsic AC breakdown strength and the other is long-term partial discharge lifetime. We used a centrifugation technique to control the maximum size of the agglomerates in the range from 5 μm down to 0.05 μm in each sample. As the results, AC intrinsic breakdown strength was increased with decreasing the maximum agglomerate size and became even higher than the neat epoxy resin when the maximum size is less than around 0.05um. On the other hand, partial discharge lifetime decreased with decreasing the maximum agglomerate size. It should be noted that the PD lifetime distinctively decreased when the agglomerate size is less than around 0.2 um indicating the existence of a critical agglomerate size which contribute to the suppression of partial discharge development resulting in the extension of the partial discharge lifetime.

SiC-based nonlinear conductive stress grading tape (SGT) has been used at an end-turn stress grading system of a form-wound rotating machine. Although previous researches reported that high-frequency repetitive pulses cause electric field enhancement and local heating at the SG system, few paper deals with the detailed electrical and thermal behaviors under pulse width modulation (PWM) waveforms, which contain not only the repetitive high-frequency, i.e., the carrier frequency, component but also the fundamental frequency component. In this study, the surface potential, the electric field, the time-averaged power densities as well as the resulting temperature rise under the 3-level PWM waveforms were investigated by the transient electric field and thermal coupled FEM simulation. Furthermore, the behavior of the accumulated charges within the SGT was analyzed, based on the simulation results. Consequently, it has been revealed that the charge behavior and the power densities by the carrier-frequency component and those by the fundamental frequency component could be separated individually.

Electric field grading system (SG system) is introduced to prevent partial discharge at the stator coil end of a rotating machine. The SG system consists of corona armor tape (CAT) and stress grading tape/paint (SGT/SGP). The CAT is a carbon-loaded highly-conductive tape and is wound over the main insulation. A SGT/SGP is a silicon carbide powder-loaded tape/paint with field-dependent conductivity and is wound over partially the end of CAT. In general, the conductivity of SGT/SGP also has temperature dependence, but has little field-dependence under higher temperature condition. The coil temperature under operating condition exceeds 100°C and this means the electric field on the coil end may increase due to the less non-linearity of SGT/SGP. When the temperature is high, the density of air decreases and surface discharge may occur easily even under the same field distribution. To examine this issue, light emission of partial discharge (PD) on a model bar system under 1-kHz AC voltage was observed by a photomultiplier tube and a digital camera equipped with an image intensifier. The temperature on SG system was set to 30, 70, and 100°C. Unexpectedly, light emission from PD became weaker and the light emission area became smaller as the temperature increased. Some reasonable explanations for this are as follows: the change in the occurrence phase of PD: and the amount of water contained in the vicinity of SG system surface. Although further investigation is required, but the unexpected increase in the PD pulses has not been observed so far within the measured range.

We report a simple method to control the end shape of silver nanowires by adding pure water in the conventional polyol synthesis. The use of 0.2-0.4% (v/v) water in ethylene glycol as a solvent provides pencil-like silver nanowires with sharp ends in a high yield. We have demonstrated remote excitation of SHG on the sharp nanowires, promising a point light source for super resolution microscopy. ispartof: CHEMICAL COMMUNICATIONS vol:55 issue:77 pages:11630-11633 ispartof: location:England status: published

In the second part of our presentations we discuss the results of diffraction experiments from nanodiamond-polymer composite gratings performed with slow neutrons, i.e., at wavelengths longer than a nanometer. One goal of our investigations is to develop flexible, handy, low cost neutron diffractive optical elements (gratings) which can be tailored to serve as mirrors, two-port beamsplitters, multiport beamsplitters, polarizing beamsplitters or even can be assembled to form an interferometer. Basically three adjustable multiplicative parameters are decisive for the performance, i.e., the reflectivity or diffraction efficiency, of such gratings: the wavelength of the neutrons, the thickness and the neutron scattering density modulation of the grating. While the _rst is solely determined by the application one has in mind, the second parameter can be adjusted during the production process of the sample or by tilting the grating about an axis parallel to the grating vector, thus increasing the effective thickness. The third parameter, however, can only be tuned via the production process of the gratings but offers an enormous flexibility due to a variety of nanoparticles and the polymeric host materials at hand. For neutrons the important criteria are to design gratings having high coherent scattering length density modulation while avoiding incoherent scattering and absorption at the same time. For interferometric purposes an ideal grating will have high reflectivity and low angular selectivity. Here, we show first results obtained with nanodiamond-polymer composite gratings and outline potential ways to improvements.

We demonstrate for the first time the use of nanodiamond in constructing holographic nanoparticle-polymer composite transmission gratings with large saturated refractive index modulation amplitudes at both optical and slow-neutron wavelengths, resulting in efficient control of light and slow-neutron beams. This is so because nanodiamond possesses a high refractive index at optical wavelengths and large coherent and small incoherent scattering cross sections with low absorption at slow-neutron wavelengths. In the first part of the work we describe the synthesis of nanodiamond, the preparation of photopolymerizable nanodiamond-polymer composite films, the construction of transmission gratings in nanodiamond-polymer composite films and light optical diffraction experiments. Experiments of slow-neutron diffraction from such gratings will be described in the second part.

We examined the crystal structure of FeHX (X~1) (FeH hereafter) at high pressure and temperature by X-ray diffraction up to 137 GPa. Results show that FeH adopts a face-centered cubic (fcc) structure at pressures of 43 to 137 GPa and temperatures of ~1000 to 2000 K. Our study revises a phase diagram of stoichiometric FeH in which fcc has a wider-than-expected stability field at high pressure and temperature. Based on our findings, the FeH end-member of the Fe-FeH system is expected to be stable in the fcc structure at the P-T conditions of the Earth's core, rather than in the double-hexagonal close packed (dhcp) structure as previously reported. We compared the experimentally determined unit-cell volumes of FeH with those from ab initio calculations. Additionally, we observed a change in compressibility at ~60 GPa, which could be attributed to a magnetic transition—an interpretation supported by our ab initio computations.