Optimization of parameters for silicon planar source of modulated infrared radiation

We report on the performance of planar silicon diodes operating in the double injection mode and emitting modulated infrared radiation at temperature range above 300 K. Results present theoretical analysis and experimental verification of an optimization aimed at maximal difference between emissivity of this structure for cases with and without forward bias applied to p-n junction. Several advantages of the structures were shown: wide emission spectrum (3÷12 μm), short rise-fall time (300 μs), high operating temperature (≈400 K). These planar photonic sources can be used as easily controlled sources of modulated infrared radiation in wide spectral range, image simulators, e.g. dynamic scene simulation devices with frame frequencies well above 200 Hz and for measurements of thermovision camera dynamic parameters.     

Radiation characteristics of gas infrared heaters in radiant heating systems

Results of an experimental study of the radiation characteristics of commercial models of gas infrared heaters are presented. An analytic expression is obtained for the distribution of irradiance over a flat object at various distances from the heater.     

Heat generation properties of Ga doped ZnO thin films prepared by rf-magnetron sputtering for transparent heaters

Ga doped ZnO (GZO) thin films were prepared by rf-magnetron sputtering on glass substrate for window heater applications. Electrical and optical properties of these films were analyzed in order to investigate on substrate temperature and rf power dependencies. High quality GZO films with a resistivity of 1.30 × 10^− 4 Ω cm and a transparency above 90% in the visible range were able to be formed. GZO films have been patterned on glass substrate as a line heater. This GZO line heater showed the rapid heat radiation property from room temperature to 90 °C for 22 s at the applied voltage of 42 V. These results could provide a possibility to use GZO as effective transparent heaters.     

Relaxation of stresses in polystyrene–carbon microcomposite resistive layers

This paper presents the investigation results on thermoresistive elements made with a styrene–butadiene–styrene (SBS) modified polystyrene binder and carbon filler. Resistive layers were deposited by screen-printing method onto a polyethylene terephthalate (PET) foil. The temperature–resistance dependence of the examined layers was observed. The carbon filler content was precisely selected to obtain high values of TCR, such as 70,000 ppm/°C, for resistive layers with a SBS-modified polystyrene binder in the temperature range from 24 to 100 °C. Because of high TCR the influence of mechanical stresses, which is unfavorable feature of the examined layers, may be omitted. The highest TCR value and stability of electrical parameters during operation were observed for layers containing 42.9% of carbon filler by mass content. The measurements were carried out with the aid of an infrared camera and an oscilloscope because of very fast changes of resistive elements parameters. The analysis of the obtained results allows to draw conclusions about the carbon layer properties and to determine the stress–relaxation rate of the polymer structures.     

ZnO nanowire growth by electric current heating method: A study on the effect of substrate temperature

In this study, we report the growth of ZnO nanowire on quartz glass substrates with Au-catalyst assistance by electric current heating of ZnO ceramic bar. The effect of substrate temperature on the properties of ZnO nanostructures has been investigated systematically. Structural analysis indicates that the grown ZnO crystals belong to hexagonal phase with preferential growth along (0 0 2) orientation. Scanning electron microscopic studies reveal the aligned ZnO nanowires were grown at 800 °C. The typical length and diameter of nanowires are in the uniform ranges of 4–20 μm and 20–100 nm, respectively, showing their high aspect ratio of about 1000. We have made an attempt to discuss about the change in ZnO nanostructures with different substrate temperatures and the possible mechanism for the growth of nanowires. Optical reflectance studies show the infrared reflectivity was controlled through the substrate temperature.     

Radiative properties characterization of ZrB2–SiC-based ultrahigh temperature ceramic at high temperature

Experimental investigations of radiative property on pre-oxidized ZrB₂–SiC–15 vol.%–C ultrahigh temperature ceramic (ZSC UHTC) at high temperature range of 1100–1800 °C were performed. By Fourier transform infrared radiant (FT-IR) spectrometer, spectral emissivity was measured in the wavelength region between 3 and 18 μm. Total normal emissivity was calculated using spectral emissivity data via theoretical formula. It has been found that high emissivity for all the testing specimens was presented, and the total normal emissivity is between 0.65 and 0.92 with temperature range from 1100 to 1800 °C. Moreover, the total normal emissivity of pre-oxidized ZSC ceramic decreased non-monotonously as the temperature increased. The total normal emissivity decreased as the testing temperature increased from 1100 to 1800 °C, whereas the total normal emissivity at the testing temperature of 1600 °C was higher than that of 1400 and 1800 °C. Macroscopical surface morphology and microstructure were carried out before and after the testing.     

Ultrafine PZT based ceramics synthesized by auto-ignition of metal–polymer gel: Enhanced sinterablity and higher remnant polarization

PbZr_0.53Ti_0.47O₃ (PZT) nanoparticles within the size range 1–8 nm were synthesized by auto-ignition of metal–polymer gel in single step without any calcination. The auto ignitable gel was obtained by adjustment of nitrate/polymer molar ratio. The amount of the carbonaceous residue in the as-ignited powder was negligible. The as-ignited ultrafine PZT powders showed excellent sinterability and were sintered directly to about 96% of the theoretical density at 1000 °C without any further calcination. Dielectric loss of the sintered PZT sample at room temperature was very low and increased very slowly up to 300 °C, which is advantageous for dielectric application point of view. The measured value of remnant polarization of the 1100 °C-sintered sample was 54.2 μC/cm², which is considerably higher than the value reported in the literature for the same composition.     

Design of laser micromachined single crystal 6H–SiC diaphragms for high-temperature micro-electro-mechanical-system pressure sensors

A 248-nm, 23-ns pulsed excimer laser was used to micromachine 50 μm thick diaphragms in 6H–SiC wafers. The diaphragms were then subjected to high-pressure (0.7–7 MPa) and high temperature (500 K) tests to obtain the pressure-deflection curves. A finite element model was used to predict the stresses and displacements as a function of temperature and pressure. Model data is in good agreement with experiments. The stresses, strains and displacements were determined in order to facilitate the design of high-temperature micro-electro-mechanical-system pressure sensors.     

Thermo-mechanical correlations to erosion performance of short carbon fibre reinforced vinyl ester resin composites

Thermo-mechanical properties and erosion performance of short carbon fibre reinforced vinyl ester resin based isotropic polymer composites with four different fibre weight fractions have been investigated. The storage, loss and damping characteristics were analysed to assess the energy absorption/viscous recoverable energy dissipation and reinforcement efficiency of the composites as a function of fibre content in the temperature range of 0–140 °C. The composite with 30 wt.% of short carbon fibres has been observed to exhibit superior thermo-mechanical response with highest energy dissipation/damping ability accompanied with a constant storage modulus without any substantial decay till 60 °C. The erosion rates (Er) of these composites are evaluated at different impingement angles (30–90°), fibre loadings (20–50 wt.%), impact velocities (43–76 m/s), stand-off distances (55–85 mm) and erodent sizes (250–600 μm) following the erosion test schedule in an air jet type test rig. An optimal parameter combination is determined and subsequently validated for erosion rate minimization following Taguchi method and by conducting confirmation experiments. A correlation between the loss-modulus inverse and the erosion rate has been observed which conceptually establishes a possible mechanistic equivalence between erosion and dynamic mechanical loading modes. The morphologies of eroded surface are examined by the scanning electron microscopy to investigate the nature of wear-craters, material damage mode and other qualitative attributes responsible for promoting erosion.     

Transparent heaters based on solution-processed indium tin oxide nanoparticles

We demonstrate transparent heaters constructed on glass substrates using solution-processed indium tin oxide (ITO) nanoparticles (NPs) and their heating capability. The heat-generating characteristics of the heaters depended significantly on the sintering temperature at which the ITO NPs deposited on a glass substrate by spin-coating were transformed thermally into a solid film. The steady-state temperature of the ITO NP film sintered at 400 °C was 163 °C at a bias voltage of 20 V, and the defrosting capability of the film was confirmed by using dry-ice.     

Efficient 1.53 μm emission and energy transfer in Si/Er-Si-O multilayer structure

Strong 1.53 μm light emission has been achieved in Si/Er-Si-O multilayer structure grown by sputtering method and annealing process. The luminescence intensity at 1.53 μm increases with annealing temperature, reaching maximum at about 800 °C, and decreases at higher temperatures. It is found that the amorphous Si well layer can sensitize and enhance Er³⁺ luminescence in Er-Si-O sublayer through carrier-mediated processes. Moreover, the Si/Er-Si-O multilayer exhibits much low temperature- and carrier-induced quenching of Er³⁺ luminescence, with the photoluminescence intensity at 1.53 μm decreased about a factor of only 1.4 from 80 K to 300 K. The new Si nanostructure material reported here may open the route towards the realization of electrically pumped Si-based light source.     

Structural,optical, and electrical properties of Schottky diodes based on undoped and cobalt-doped ZnO nanorods prepared by RF-magnetron sputtering

Cobalt-doped ZnO nanorods were successfully synthesized on Si/SiO₂ substrate using RF-magnetron sputtering at room temperature. The undoped and Co-doped ZnO nanostructures were characterized by XRD, FE-SEM, AFM, and PL spectra. The results showed that Co²⁺ replaced Zn²⁺ in the ZnO lattice without changing the wurtzite structure. The ZnO structure became high crystallite and was gradually converted into nanorods without extra phases as increased cobalt doping levels to 3 at.% and 4 at.%. The as-synthesized nanorod arrays were dense and vertically grew on the substrate with lengths of approximately 341 and 382.3 nm for 3 at.% and 4 at.% CO, respectively. PL analysis revealed that the ultraviolet (UV) emission intensity decreased and exhibited a blue shift with increased Co atomic percentage. This result was consistent with the energy bandgap values (3.26–3.3 eV) obtained from UV–vis spectra. The I–V characteristics revealed that the Shottky diodes based on Co-doped ZnO nanostructure with Pd electrodes have high barrier height (0.715–0.797 eV) and low saturation current (0.035–0.841 μA). The barrier height decreased after annealing the diodes at 500 °C for 2 h. To the best of our knowledge, Schottky diodes based on Co-doped ZnO nanorods prepared by RF-magnetron sputtering have not yet been reported.     

Porous nanostructured ZnO films deposited by picosecond laser ablation

Porous nanostructured polycrystalline ZnO films, free of large particulates, were deposited by picosecond laser ablation. Using a Zn target, zinc oxide films were deposited on indium tin oxide (ITO) substrates using a picosecond Nd:YVO₄ laser (8 ps, 50 kHz, 532 nm, 0.17 J/cm²) in an oxygen atmosphere at room temperature (RT). The morpho-structural characteristics of ZnO films deposited at different oxygen pressures (150–900 mTorr) and gas flow rates (0.25 and 10 sccm) were studied. The post-deposition influence of annealing (250–550 °C) in oxygen on the film characteristics was also investigated. At RT, a mixture of Zn and ZnO formed. At substrate temperatures above 350 °C, the films were completely oxidized, containing a ZnO wurtzite phase with crystallite sizes of 12.2–40.1 nm. At pressures of up to 450 mTorr, the porous films consisted of well-distinguished primary nanoparticles with average sizes of 45–58 nm, while at higher pressures, larger clusters (3.1–14.7 μm) were dominant, leading to thicker films; higher flow rates favored clustering.     

A study on the electrical properties of Pb(Zr, Ti)O3 thin films crystallized by the electrical resistive heating of Pt thin film

The electrical properties of Pb(Zr, Ti)O₃ thin films annealed by Pt thin film heater were investigated. By the thin film heater, we successfully crystallized Pb(Zr, Ti)O₃ thin films at a high temperature above 750 °C in a few seconds. The thin film heater has some advantages, such as a low thermal budget, little Pb-loss and enhanced surface morphology compared with the conventional furnace because it has a fast heating rate. The electrical properties of the Pb(Zr, Ti)O₃ thin film crystallized by thin film heater improved considerably comparing to those crystallized in conventional furnace. The remanent polarization, breakdown field, and leakage current density measured to be 22.7 μC/cm², 853 kV/cm, and 6.93 × 10⁻⁷ A/cm², respectively.     

The influence of Ni nanoparticles and Ni (II) on the growth of Ag dendrites immobilized on the chelating copolymer membrane

Preparation of Ag dendrites on the surface of chelating copolymer membranes (PBAGI), which was synthesized by using the soap-free emulsion copolymerization of n-butylacrylate (BA) and acrylonitrile (AN), as well as 2-methacrylic acid 3-(bis-carboxymethylamino)-2-hydroxy-propyl ester (GMA-IDA) that was used as a chelating group, is presented in this study. The characteristics of polymer membranes were investigated by Fourier transform infrared (FTIR) spectroscopy and elementary analysis (EA). The weight fraction of GMA-IDA in the polymer was 4.2 wt% as revealed by elemental analysis. The chelating group, –N(CH₂COO⁻Na⁺)₂ on the polymer was used to coordinate different amounts of Ni(II), controlled by different chelating times and subsequently reduced to Ni nanoparticles, as templates for growing Ag nanocrystals from 1.67 wt% AgNO₃ aqueous solution with 55.7 ppm poly(vinyl pyrrolidone) (PVP) added. In addition, the effect of Ni²⁺ concentration on the growth of the Ag dendrites was studied. Crystallinity and morphology of Ag dendrites were examined with X-ray diffraction (XRD) and scanning electronic microscopy (SEM), respectively. Amount of Ag dendrites increased with the increasing of Ni nanoparticles on the PBAGI membrane or the dose of Ni²⁺ present in the aqueous solution. Notable, under higher amount of Ni nanoparticles (over 200 mmol Ni²⁺/g PBAGI membrane), Ag dendrites could be successful grown on the membrane. However, higher dose of Ni²⁺ (over 41.3 ppm) might inhibit the growth of Ag dendrites.     

Electromechanical response of semiconducting carbon–polyimide nanocomposite thin films

Electromechanically responsive polymer nanocomposite thin films can provide embedded microscale sensing elements for unobtrusive monitoring of strain, torque and pressure particularly for composite structures. Thin nanocomposite carbon–polyimide films with thicknesses up to 90 μm were produced with carbon contents that yield semiconducting behaviour attributable to distance dependent electron hopping between isolated nanoparticles. The tensile modulus and the strain at break indicated minimum interaction between polymer and nanoparticle surfaces. A decreasing storage modulus with increasing temperature indicated increasing free volume inducing polymer chain motions.     

A study on the plasma polymer thin film surface modification for DNA alignment by using high energy electron beam irradiation

The plasma polymer thin films were deposited on Si(100) substrate by PECVD (plasma enhanced chemical vapor deposition) method. Liquid cyclohexene was used as single organic precursor. It was heated up to 60 °C and bubbled up by hydrogen gas, which flow rate was 50 sccm (standard cubic centimeters per min). Deposition temperature was room temperature. Plasma was ignited by a radio frequency (RF; 13.56 MHz) of 10 W.As-deposited plasma polymer thin films were treated by e-beam of 300 keV with various adsorption radiation doses. The plasma polymer films, which were treated by high energy e-beam (HEEB), were investigated by FT-IR (Fourier Transform Infrared), XPS (X-ray Photoelectron Spectroscopy), AFM (Atomic Force Microscopy), and the water contact angles.From IR spectra, the intensity of OH functional group is increased by increasing electron dose rate. XPS results also show that the intensity of O_1s peak is increased by increasing electron dose rate. C_1s peak shows that oxygen bonded at carbon site. The water contact angles are decreased by increasing electron dose rate. From the AFM analysis, we observed the formation of λ-DNA (deoxyribonucleic acid) array on plasma polymer film, which was treated by HEEB with 14 kGy of adsorption radiation dose.     

Beam-spot temperature monitoring on the production target at the BigRIPS separator

Since 2007, a water-cooled high-power rotating disk target has been in operation at the in-flight radioactive-isotope beam separator (BigRIPS), RIKEN. The target should withstand a goal beam intensity of 1 particle μA (pμA) ²³⁸U-beam at 350 AMeV with a spot size of 1 mm in diameter, resulting in a heat deposit of 22 kW in the target.A beam-spot temperature monitoring system using infrared devices in high-radiation environment was elaborately developed. The beam-spot temperature on a beryllium (Be) fixed target and on a rotating Be and tungsten (W) disk target was measured with the most intense beams presently available at our facility. The heat deposit achieved was 0.6 kW, that is 1/37 of the goal value. At the present beam intensity, the result supports our estimation that a water-cooled rotating disk target of 30 cm diameter can withstand an approximately tenfold beam intensity compared to a water-cooled fixed target.     

Synthesis,characterization and flocculation activity of novel Fe(OH)3–polyacrylamide hybrid polymer

A novel Fe(OH)₃–polyacrylamide inorganic–organic hybrid polymer (FHPAM) was synthesized via free radical solution polymerization initiated by a redox initiation system ((NH₄)₂S₂O₈–NaHSO₃) in an aqueous medium. Reaction parameters influencing the intrinsic viscosity and the yield of the hybrid polymer, such as initiator concentration, monomer mass fraction, temperature and reaction time were investigated and optimized. The results show that the maximum intrinsic viscosity and up to 94% yields of the hybrid polymer can be achieved using initiator concentration of 0.3% with acrylamide monomer mass fraction of 20% under solution polymerization at 40 °C for 7 h. The physicochemical properties of this hybrid flocculant were characterized with TEM, FTIR spectra, TGA, and conductivity. It was found that a chemical bond exists between Fe(OH)₃ colloid and polyacrylamide chains in the FHPAM. The application of the hybrid polymer for the treatment of 2.5 g L⁻¹ kaolin suspension indicates that it had an excellent flocculation capacity and its flocculation efficiency was much better than that of commercial available polyacrylamide (PAM) and polymeric ferric sulfate (PFS). The optimal conditions for the flocculation treatment of kaolin suspension were the FHPAM dosage of 40 mg L⁻¹ at pH 7.0. The thermodynamic parameters for the flocculation process were calculated based on a statistical model. Interpretation of the results was given.     

Compatibilized Polypropylene/Ethylene–Propylene–Diene-Monomer/Polyamide6 ternary blends: Effect of twin screw extruder processing parameters

Polypropylene (PP)/Polyamide6 (PA6)/Ethylene–Propylene–Diene-Monomer (EPDM) (70/15/15) ternary polymer blends compatibilized with Maleic-anhydride grafted EPDM (EPDM-g-MA) were prepared by melt blending using a twin screw extruder (TSE). Effect of TSE processing parameters including barrel temperature, screw speed and blending sequence on the mechanical properties of ternary polymer blends was investigated by application of Taguchi experimental design methodology. Three different levels of barrel temperature (220 °C, 230 °C, 240 °C), screw speed (90 rpm, 120 rpm, 150 rpm) and blending sequence (nominated as: S1, S2 and S3) were selected. The response variables were tensile properties and impact strength of the prepared samples which are directly affected by the blend microstructure. Investigation of the statistical–mathematical analysis results performed by the software depicted that the optimum processing conditions for the ternary blends investigated here, to achieve balanced tensile and impact properties, are 220 °C, 150 rpm and S2 blending sequence.