The purpose of this paper is to propose the enhancement of device detectors based on p-n junction in 4H-SiC for nuclear instrumentation. Particular emphasis is placed on the interest on using Boron isotope 10 as a Neutron Converter Layer in order to detect thermal neutrons. Here, we present the main results obtained during several irradiation tests performed in the Belgian Reactor 1 (BR1). We show the capability of our detectors by means of first results of the detector response at different reverse voltage biases and at different reactor power.

Phosphorus is incorporated into single crystal diamond during epitaxial growth at higher concentrations on the (111) crystallographic surface than on the (001) crystallographic surface. To form n+-type regions in diamond for semiconductor devices it is beneficial to deposit on the (111) surface. However, diamond deposition is faster and of higher quality on the (001) surface. A preferential etch method is described that forms inverted pyramids on the (001) surface of a substrate diamond crystal, which opens (111) faces for improved phosphorus incorporation. The preferential etching occurs on the surface in regions where a nickel film is deposited. The etching is performed in a microwave generated hydrogen plasma operating at 160 Torr with the substrate temperature in the range of 800-950 °C. The epitaxial growth of diamond with high phosphorus concentrations exceeding 1020 cm-3 is performed using a microwave plasma-assisted chemical vapor deposition process. Successful growth conditions were achieved with a feedgas mixture of 0.25% methane, 500 ppm phosphine and hydrogen at a pressure of 160 Torr and a substrate temperature of 950-1000°C. The room temperature resistivity of the phosphorus-doped diamond is 120-150 Ω-cm and the activation energy is 0.027 eV.

This study deals with evaluation of mechanical properties (tensile, flexural and impact strength), that verified reinforcing potential of nanofibres in polymeric composites and their applicability in dependence on the filler content of nanofibres of natural and synthetic origin. Considering the hydrophilic nature of natural nanofibres and hydrophobic polypropylene matrix was applied chemical modification that ensures effective interlock of nanofibres with the matrix, namely maleic anhydride grafted polypropylene and ionic modifier. Polymeric nanocomposites were prepared by twin screw extrusion that made possible mixing of all three components together. After cooling in water bath the composites were cut on pellets and dried for further injection moulding. The specimens were made of two- or three-phase component systems that included PP matrix, coupling agent in the volume of 4 wt.% and reinforcing nanofillers in the volume of 2, 4 and 6 wt.%. The presence of nanoparticles and coupling agents had not unambiguous impact on analysed mechanical properties. Coupling agent presence was dominant for impact strength, however, flexural and tensile properties were influenced mainly by the nanofiller type and origin. The dispersed phase and compatibilizer improved flexural modulus but tensile modulus of pure PP were not achieved by three-phase composite, not even with the highest analysed nanoparticle load. Cellulose fibres proved as more proper than the synthetic ones not only for their biodegradability and renewability but for their better toughness as well.

Transport properties have been measured transverse to the plane of sheared and un-sheared thin-film nanocomposites of isotactic Polypropylene (iPP) and multiwall carbon nanotubes (MWCNTs) at various MWCNT concentrations. The sheared samples were processed in the melt at 200 0C at 1 Hz in a Linkan microscope shearing hot stage. The thermal and electrical conductivity measurements were performed on the same cell arrangement with the transport perpendicular to the thin-film plane using a DC method. The thermal and electrical conductivity perpendicular to the surface of the films are higher for the un-sheared as compared to the sheared samples. Interestingly, the percolation threshold appears smeared in both conductivity measurements likely due to pressing and shear treatment of the films, or the spacing between the data points. Important for electronics packaging and materials for which those anisotropic properties are highly desired this work presents important advances in understanding the structure-transport property relations.

High-brightness green phosphorescent hybrid inorganic-organic light-emitting diodes (HyLEDs) and inverted HyLEDs (IHyLEDs) have been demonstrated. The devices comprised a transparent and conductive WO3 layer deposited by thermal evaporation, which improved both hole injection and transport, and led to more balanced charge injection and significant performance enhancement. At 20 mA/cm2, the HyLEDs had a low operation voltage of 6.1 V, 0.8 V lower than that of OLEDs with an organic hole transport layer. With an optimized layer structure, the HyLEDs reached 104 cd/m2 brightness at 7.3 V. At this brightness level, the current efficiency was 55.2 cd/A, 57% higher than that of the OLEDs. In the IHyLEDs, facile hole injection and transport through WO3 was balanced by electron injection from the indium-tin-oxide (ITO) cathode overcoated with nanometer-thick Ca, leading to a low turn-on voltage of ∼6 V. Brightness of 8133 cd/m2 was reached at 20 mA/cm2 and the corresponding current efficiency was 40 cd/A. The hybrid devices also exhibited markedly improved stability under constant-current stressing due to the robust WO3 hole transport layer.

A novel and fundamental method was reported to judge states of lithium ion batteries (LIBs) using the capacitance and the voltage of the cells that were estimated from the real-time currents and voltage characteristics of the cells. We measured the differential capacitance, that is, dQ/dV or delta Q/ delta V that is equal to the currents (I) divided by differential voltages (dV/dt) calculated from the current and the voltage characteristics of the cell during the charging/ discharging, where Q is the charge that flows through the cell, V is the voltage of the cell and t is time. It is thought that the capacitance decrease with the degradation of the cell because the effective area of the electrodes is decreasing due to formation of undesirable compounds. The differential capacitance in some specific voltage range for the LIBs was approximately directly proportional to the state of the degradation of the cell. Therefore, it is concluded that the novel method is very useful to judge the state of the LIBs.

Absorption, scattering and fluorescent properties of several different types of nanodiamond samples are measured to characterize them for various applications. Two different methods, spectrophotometry and photothermal spectroscopy were used to measure absorption properties of nanodiamonds suspended in aqueous solutions. Photothermal spectroscopy provides the advantage of measuring absorption of photoactive nanodiamonds with high-sensitivity. Spectral fluorescence properties of nanodiamond samples were studied using a commercial spectrofluorometer and a home-built inverted microscope integrated with a light-sensitive imaging spectrograph. Characteristic fluorescence spectrum of nitrogen-vacancy defects in single diamond nanocrystals was obtained using the light-sensitive instrument.

Traditional methods of quantifying cell movement in response to a chemotactic factors provide either a binary count of cell migration in response to a known concentration of the factor of interest in solution, as in Boyden chamber assays, or a method of tracking cells to determine velocities across a solubilized protein gradient where exact concentrations vary over time and are difficult to define, as in the Ibidi chemotaxis gradient assay. Using a silane self-assembling monolayer (SAM)-based procedure pioneered by V Hlady and associates, we have developed an assay capable of covalently binding a wide variety of proteins to an optically transparent surface in a 2D pattern via amine linkages. The pattern was then verified by contact angle and Raman and X-ray photoelectron spectroscopy. This new assay provides greater control of protein concentration and gradient intensity than when using only solubilized proteins.

TiO2-supported bimetallic Au-Rh and Au-Pd nanocrystals were synthesized using both impregnation and colloidal approaches employing HAuCl4 and RhCl3 as precursors. The as-obtained bimetallic catalysts were then supported onto TiO2 rutile nanorods in order to provide catalytic systems with well-defined metal-support interactions for HRTEM characterization. The results revealed the superiority of the colloidal approach over the impregnation technique to obtain bimetallic nanoparticles (4 nm in size) with tunable composition. However, for Au-Rh/TiO2, optimization of the procedure of the sol immobilization onto the TiO2 support was required to avoid possible Rh re-dissolution. Preparation of Au-Pd/TiO2 followed the same procedure but with more acidic conditions necessary to perform immobilization on the support. UV-vis spectroscopy and XRD results suggest formation of a Rh-rich shell over an Au core center for Au-Rh NPs, while Au-Pd NPs present a pure alloy structure. Au-Rh/TiO2 was used for performing the high-pressure hydroconversion of tetralin in the presence or not of H2S. The results indicate a strong thioresistance induced by the addition of Au to Rh.

3D scaffolds with different pore sizes, using single-walled carbon nanotubes (SWCNTs) and nanoparticles of different size were constructed. Biotinylated glucose oxidase (GOX-B) and anti-cholera toxin (anti-CT) were immobilized onto the one and two level nanoscaffolds, functionalized with pyrene-β-cyclodextrin for the construction of glucose based enzyme sensors and immunosensors, respectively. For enzyme sensors, highest current density and sensitivity (41.72 μA cm-2, 3 mA M-1 cm-2) were obtained with two level scaffolds made with 100 nm nanoparticles. In contrast to this, for immunosensors, highest current density and sensitivity (11.71 μA cm-2, 116.2 μA M-1 cm-2) were obtained with two level scaffolds made with 500 nm nanoparticles, indicating that the pore sizes can be adjusted using different size of nanoparticles for the respective applications.

The contamination of water by a large variety of molecules is a major environmental issue that will require the use of efficient and versatile materials to purify hydrological systems from source to point-of-use. The present study describes the aqueous-phase adsorption of heavy metal ions and multiple organic compounds at environmentally relevant concentrations onto graphene-single-walled carbon nanotube free-standing hybrid papers. Optical absorption spectroscopy results clearly showed that the hybrid nanocomposites exhibit superior adsorption properties compared to activated carbon, the most widely used adsorbent to date.

We investigated electronic structure of one-dimensional biradical molecular chain which is constructed by exploiting the covalency between organic molecules of a diphenyl derivative of s-indacenodiphenalene (Ph2-IDPL). To control the crystallinity, we used gas deposition method. Ultraviolet photoelectron spectroscopy (UPS) revealed developed band structure with wide dispersion of the one-dimensional biradical molecular chain.

The distribution of alloying elements in the constituent phases of a C-containing γ-TiAl based alloy has been characterized locally by atom probe tomography. The major elements of the alloy under consideration – Ti, Al, Nb, and Mo – are distributed uniformly within each of the constituent phases. Furthermore, Mo is preferentially dissolved in the βo-phase, whereas Nb content is similar in all phases. The selected C concentration of the alloy is below the overall solubility limit as no precipitates have been observed. Therefore, C is enriched in the α2-phase, whereas the βo-phase is depleted of C. In addition, βo/γ-interfaces have been prepared by site specific sample preparation and characterized by atom probe tomography. Segregation of Mo and C into the interfaces and their close vicinity was observed.

The paper deals with the problems of mechanical properties of structural steels used for load-carrying structures of civil engineering constructions. The attention is mainly paid to the values of yield strength from the viewpoint of the design concept of European Standards, i.e. Eurocode 3 for the design of steel structures, with respect to the structural reliability given by the failure probability. In the case of other materials, concrete or timber for example, characteristic and design values of strength given by the corresponding failure probability are used in the design procedures, where the partial safety factor of material is γ M > 1.0. However, in the case of steel, the nominal values instead of characteristic values of steel yield strength are utilized in the structural design procedure, with the partial safety factor for material of γ M = 1.0. These values have been derived based on the statistical and probabilistic evaluation of the data sets of actual material properties obtained from various recent steel producers. The paper presents the brief information on the results of the study oriented to the influence of the nominal or characteristic value of yield strength on the design resistance, which is shown on the examples of the member subjected to tension and bending moment, respectively. The influence mentioned is shown using the examples of structural steels used in constructions of the age of about 40 and 100 years.

Among the transition metal oxides, manganese oxides have been widely studied for electrochemical capacitors and batteries, because of their high energy density, low cost, natural abundance and environmentally friendliness. However, the poor electrical conductivity of manganese dioxide (MnO2) limits its capacitive response. Polyaniline becomes a unique and promising conducting polymer with a great potential application in supercapacitors due to easy synthesis and good conductivity of the conducting material. Combine the two properties can prepare nanocomposite materials in order to improve the conductivity and capacitive performance of the MnO2. MnO2 coated with polyaniline as the coaxial nanowires were prepared in this report. The polyaniline was synthesized via in situ polymerization and we got a controllable thin coating on the well-dispersed MnO2 nanowires. This hybrid nanostructure enhances the conductivity and capacitive performance of the supercapacitor electrode. The specific capacitance of MnO2/PANI composites is as high as 426 F g-1 at 1 A g-1, which is twice much higher than pure MnO2 (188 F g-1) .

A novel SiC optical detector that produces optical signal in contrast to the electric signal generated by conventional electrical detectors. The optical detector is a remote sensor providing response to incident photons from a distant object. The incident photons modify the refractive index and, consequently, the reflectance of the doped SiC by altering the electron densities in the valence band and the acceptor energy levels. This variation in the refractive index or reflectance represents the optical signal as the sensor response, which can be determined with a probe laser such as a He-Ne laser or a light-emitting diode. The sensor can be applied to numerous remote sensing applications including high-temperature or harsh environments due to the optical read-out of the detector response with a probe laser. The effects of different dopants on the detector response for sensing different chemical species, or equivalently imaging in different MWIR wavelengths, have been studied and the dopant concentration has been found to affect the optical signal. These results indicate that a new class of SiC detectorsclassified as optical detectors can be produced for a variety of wavelengths using different dopants for numerous applications.

Five historical full-size wood structural beams of Picea abies were tested with ultrasound. The speed of ultrasound, the modulus of elasticity, the moisture content and the wood density were measured for each specimen. The speed of the ultrasound waves in the radial, tangential and longitudinal directions was 1,769 m/s, 1,599 and 5,713 m/s respectively. The modulus of elasticity in the radial, tangential and longitudinal directions was 1,353 MPa, 1,069 MPa and 13,863 MPa respectively. The moisture content was on average 11.92% and the density was on average 422 kg/m3. Wood parameters such as density and orthotropic directions had influence in ultrasound measurements. In spite of local weakness in the beams, they had enough strength to be considered full structural members.

In this paper an integrated wavelength optical filter and photodetector for Visible Light Communication (VLC) is used. The proposed application uses indoor warm light lamps lighting accomplished by ultra-bright light-emitting diodes (LEDs) pulsed at frequencies higher than the ones perceived by the human eye. The system was analyzed at two different wavelengths in the visible spectrum, one in the blue (430 nm) and the other in the red (626 nm) regions, driven at different currents in order to change their optical intensities. The signals were transmitted into free space and measured using a pin-pin photodetector based on a-SiC:H/a-Si:H. This detector behaves as an optical filter with controlled wavelength sensitivity through the use of adequate optical biasing light. The output photocurrent was measured for different optical intensities of the transmitted optical signal and the extent of each signal was tested. An electrical model was used to support the physical operation of the device.

Because of its large direct band gap of 3.37 eV and high exciton binding energy (∼60 meV), which can lead to efficient excitonic emission at room temperature and above, ZnO nanostructures in the würtzite polymorph are an ideal choice for electronic and optoelectronic applications. Some of the important parameters in this regard are free carrier concentration, doping compensation, minority carrier lifetime, and luminescence efficiency, which are directly or indirectly related to the defects that, in turn, depend on the method of synthesis. We report the synthesis of undoped ZnO nanorods through microwave irradiation of an aqueous solution of zinc acetate dehydrate [Zn(CH3COO)2. 2H2O] and KOH, with zinc acetate dihydrate acting as both the precursor to ZnO and as a self-capping agent. Upon exposure of the solution to microwaves in a domestic oven, ZnO nanorods 1.5 µm -3 µm and 80 nm in diameter are formed in minutes. The ZnO structures have been characterised in detail by X-ray diffraction (XRD), selective area electron diffraction (SAED) and high-resolution scanning and transmission microscopy, which reveal that each nanorod is single-crystalline. Optical characteristics of the nanorods were investigated through photoluminescence (PL) and cathodoluminescence (CL). These measurements reveal that defect state-induced emission is prominent, with a broad greenish yellow emission. CL measurements made on a number of individual nanorods at different accelerating voltages for the electrons show CL intensity increases with increasing accelerating voltage. A red shift is observed in the CL spectra as the accelerating voltage is raised, implying that emission due to oxygen vacancies dominates under these conditions and that interstitial sites can be controlled with the accelerating voltage of the electron beam. Time-resolved fluorescence (TRFL) measurements yield a life time (τ) of 9.9 picoseconds, indicating that ZnO nanorods synthesized by the present process are excellent candidates for optoelectronic devices.

We present a comparative study of the anomalous Nernst effect (ANE), measured at room temperature for magnetite thin films deposited on different substrates in order to study the effects induced by the substrate, compressive or tensile strain and structural defects as anti-phase boundaries (APB), on the observed ANE. From our preliminary results we have observed an increase of the measured ANE in the case of compressive strain compared with the tensile one. Moreover our results also suggest that the density of APBs also play an important role in the ANE values.