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WOS: 000552397100019 Calcite, being the most abundant mineral on earth crust, have wide application areas especially in polymer industry as a micronized functional filler material. It is hydrophilic in natural form, and made hydrophobic after surface modification to meet the requirements of polymer industry: the incompatibility between high energetic hydrophilic surface of calcite and the low-energy surface of hydrophobic polymers is a major problem. Treatment of micronized calcite with fatty acids is one of the most common method to obtain modified mineral surface. In present study, oleic acid (OA), fatty acid type surface modifying agent was used for the surface characterization of OA coated marble dust. Fine tailings of slab cutting unit of a marble processing plant was supplied. The sample was subjected to wet classification process to obtain micronized calcite fraction for experimental works. Surface modification of finely sized fraction was performed in a laboratory type flotation unit. Thermogravimetric analysis (TGA) and Transmission Electron Microscopy (TEM) were used as characterization techniques.

In this work, 16 nm indium nitride (InN) nanoparticles (NPs) are used to increase the performance of thin-film c-Si HIT solar cells. InN NPs were spin-coated on top of an ITO layer of c-Si HIT solar cells. The c-Si HIT cell is a stack of 2 mu m p type c-Si, 4-5 nmn type a-Si, 15 nm n(+) type a-Si and 80 nm ITO grown on a p(+) type Si substrate. On average, short circuit current density (J(sc)) increases from 19.64 mA cm(-2) to 21.54 mA cm(-2) with a relative improvement of 9.67% and efficiency increases from 6.09% to 7.09% with a relative improvement of 16.42% due to the presence of InN NPs. Reflectance and internal/external quantum efficiency (IQE/EQE) of the devices were also measured. Peak EQE was found to increase from 74.1% to 81.3% and peak IQE increased from 93% to 98.6% for InN NPs coated c-Si HIT cells. Lower reflection of light due to light scattering is responsible for performance enhancement between 400-620 nm while downshifted photons are responsible for performance enhancement from 620 nm onwards.

We have investigated structural, magnetic, and magnetocaloric properties of monovalent Ag-doped La1−x Ag x MnO3 (0.05 ≤ x ≤ 0.25) compounds. The materials were prepared by the sol–gel method and then characterized by X-ray diffraction (XRD). The XRD results indicated that all the samples have a single phase of hexagonal (rhombohedral) structure with the $R\overline {\text {3}} c$ space group. The morphology and particle size distributions were investigated using scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS). The SEM images showed that the grain sizes are smaller than 1 μm and remain the same with increasing Ag concentrations. The magnetic properties were studied by measuring magnetization and varying temperature (M(T)) and external magnetic field (M(H)). The M(T) measurements show that with decreasing temperature all samples exhibit a paramagnetic-to-ferromagnetic phase transition. The Curie temperature, T C, increases from 200 to 290 K as Ag doping increases from 0.05 to 0.25. The magnetic entropy change (|−SM|) is obtained in all samples near the Curie temperatures at a magnetic field change of 3 T. Furthermore, their maximum relative cooling power (RCP) values were found to be 82.492, 82.614, and 127.375 J/kg for x = 0.10, 0.15, and 0.25.

CeMn2Ge2 nanopowders have been obtained by high-energy ball milling for 5 and 10 hours from bulk compound to investigate the effect of milling time on magnetic and magnetocaloric properties. CeMn2Ge2 nanopowders have been characterized by X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy, transmission electron microscopy, and magnetization measurements. The average grain size of the nanoparticles from XRD measurements is about 12.2 and 8 nm for 5-hour and 10-hour ball-milled samples, respectively. The investigations reveal that magnetic entropy change (∆S m) can be altered by changing the particle size of the compound. Maximum ∆S m is −2.45 and −1.30 J kg−1 K−1 for the 5- and 10-hour ball-milled nanopowders, respectively.

In this work, we present a hybrid indium nitride particle/polycrystalline silicon solar cell based on 230 nm size indium nitride particles (InN-Ps) obtained through laser ablation. The solar cell performance measurements indicate that there is an absolute 1.5% increase (Δη) in the overall solar cell efficiency due to the presence of InN-Ps. Within the spectral range 300-1100 nm, improvements of up to 8.26% are observed in the external quantum efficiency (EQE) and increases of up to 8.75% are observed in the internal quantum efficiency (IQE) values of the corresponding solar cell. The enhancement in power performance is due to the down-shifting properties of the InN-Ps. The electrical measurements are supplemented by TEM, Raman, UV/VIS and PL spectroscopy of the InN-Ps. © 2015 IOP Publishing Ltd.

International audience; We investigate experimentally and numerically the nonlinear propagation of intense Bessel–Gauss vortices in transparent solids. We show that nonlinear Bessel–Gauss vortices preserve all properties of nonlinear Bessel–Gauss beams while their helicity provides an additional control parameter for single-shot precision micro structuring of transparent solids. For sufficiently large cone angle, a stable hollow tube of intense light is formed, generating a plasma channel whose radius and density are increasing with helicity and cone angle, respectively. We assess the potential of intense Bessel vortices for applications based on the generation of hollow plasma channels.

We present a new method to form liquid-core optofluidic waveguides inside hydrophobic silica aerogels. Due to their unique material properties, aerogels are very attractive for a wide variety of applications; however, it is very challenging to process them with traditional methods such as milling, drilling, or cutting because of their fragile structure. Therefore, there is a need to develop alternative processes for formation of complex structures within the aerogels without damaging the material. In our study, we used focused femtosecond laser pulses for high-precision ablation of hydrophobic silica aerogels. During the ablation, we directed the laser beam with a galvo-mirror system and, subsequently, focused the beam through a scanning lens on the surface of bulk aerogel which was placed on a three-axis translation stage. We succeeded in obtaining high-quality linear microchannels inside aerogel monoliths by synchronizing the motion of the galvo-mirror scanner and the translation stage. Upon ablation, we created multimode liquid-core optical waveguides by filling the empty channels inside low-refractive index aerogel blocks with high-refractive index ethylene glycol. In order to demonstrate light guiding and measure optical attenuation of these waveguides, we coupled light into the waveguides with an optical fiber and measured the intensity of transmitted light as a function of the propagation distance inside the channel. The measured propagation losses of 9.9 dB/cm demonstrate the potential of aerogel-based waveguides for efficient routing of light in optofluidic lightwave circuits., NA

3rd International Congress on Advances in Applied Physics and Materials Science - APR 24-28, 2013 - Antalya, TURKEY WOS: 000339825400067 Recently, so-called "phenol-formaldehyde-urea resins", which are generally made only by mechanical blending of UF resin and alkaline type PF resins, have been used as adhesives for the manufacturing of wood products. Faster curing PF resins can be also prepared by the addition of urea during or after the resin synthesis to yield co-condensed phenol-urea-formaldehyde (PUF) resins. In this study, resin/clay composites were prepared by in situ polymerization of phenol(18.2%)-urea(36.3%)-formaldehyde(45.5%) (PUF) with the various ratios of organoclay (7.69-45.45%) and colored organoclay (3.22-20.0%). The objective of our work is the investigation of the effect of addition of both organoclay and colored organoclay at different ratios on the textural characteristics. The composites are characterized by X-ray diffraction, Fourier transform infrared spectroscopy techniques and using high resolution transmission electron microscopy images of the samples. It was found that clay layers exfoliated in the resin matrix. Doga Nanobiotech Inc, Mega Technol Serv Inc

Martensitic transitions in shape memory Ni-Mn-Ga Heusler alloys take place between a high temperature austenite and a low temperature martensite phase. However, intermartensitic transformations have also been encountered that occur from one martensite phase to another. To examine intermartensitic transitions in magnetic shape memory alloys in detail, we carried out temperature dependent magnetization, resistivity, and x-ray diffraction measurements to investigate the intermartensitic transition in Ni50Mn50-xGax in the composition range 12 x 25 at. %. Rietveld refined x-ray diffraction results are found to be consistent with magnetization and resistivity data. Depending on composition, we observe that intermartensitic transitions occur in the sequences 7M ! L10; 5M ! 7M, and 5M ! 7M ! L10 with decreasing temperature. The L10 non-modulated structure is most stable at low temperature.

International audience; We study in detail the compression of high-energy ultrashort laser pulses to the few-cycle regime in gas-filled planar hollow waveguides. In this scheme, the laser beam is guided in only one transverse dimension, whereas the other dimension is free to adjust, allowing scalability to high pulse energies. We report on various practical aspects of the planar hollow waveguide compression scheme and characterize the dependence of the performance of the method on several experimental parameters: (i) we evaluate different materials for the construction of planar waveguides; (ii) we investigate the dependence of the pulse duration on gas type and pressure; (iii) we measure the spatial intensity and phase; (iv) we characterize the pulse duration along the transverse beam direction; and (v) we investigate the focusability. An output pulse energy of 10.6 mJ at a duration of 10.1 fs (FWHM) in the beam center after compression is demonstrated. A careful estimation reveals that the radiation should be focusable to a relativistic intensity exceeding 10^19 W.cm−2 in the few-cycle regime. The experimental results are supported by numerical modeling of nonlinear pulse propagation inside planar hollow waveguides. We discuss energy up-scalability exceeding the 100 mJ level.

International audience; We demonstrate compression of high-energy ultrashort laser pulses by nonlinear propagation inside gas-filled planar hollow waveguides. We adjust the input beam size along the nonguided dimension of the planar waveguide to restrain the intensity below photoionization, while the relatively long range guided propagation yields significant self-phase modulation and spectral broadening. We compare the compression in different noble gases and obtain 13.6 fs duration with output pulse energy of 8.1 mJ in argon and 11.5 fs duration with 7.6 mJ energy in krypton. The broadened spectra at the output of the waveguide are uniform over more than 70% of the total pulse energy. Shorter duration could be obtained at the expense of the introduction of spatial structure in the beam (and eventual formation of filaments) resulting from small-scale self-focusing in the nonguided direction.

International audience; We report on numerical simulations and experiments of pulse self-compression by filamentation. Spectral and temporal evolution during ultrashort-pulse laser filamentation can be intuitively represented using spectrograms, which display spectra at different time delays of a gate pulse. This representation makes evident the features of self-compression by filamentation, namely spectral broadening and pulse shortening. In addition, it allows for an analysis of the spectral phase during the nonlinear propagation. In our simulations we observe occurrence of negative chirp over a few cm before the shortest pulse is obtained during filamentation; this provides an important basis for the understanding of the mechanisms leading to self-compressed filaments. We attribute the negative chirp to spatio-temporal reshaping due to the competition between self-phase modulation and group velocity dispersion. We show that the plasma induced dispersion plays a minor role in establishing the negative chirp.

International audience; We show that axicon-focusing of ultrashort laser pulses facilitates the generation of filaments with specific spatial profiles in the form of nonlinear Bessel beams. For conditions ensuring that the energy arriving from each Bessel ring is in quasi equilibrium with that absorbed by multiphoton processes, these Bessel filaments generate meter long plasma channels whereas the same pulses focused by a standard lenses generate plasma channels which do not exceed a few centimeters long. Measurements with different lasers show that the length and the homogeneity of the plasma channels are enhanced by the use of large beams and sharp-tip (ideal) axicons whereas blunt-tip axicons induce a lens effect leading to oscillations of the plasma density along the propagation axis.

International audience; We present a theoretical and experimental study of the intensity distribution of a laser beam, after its propagation through a real axicon. We show that, while an ideal axicon generates Bessel-like radial intensity profile and smooth on-axis intensity around the focal region, in practice, the bluntness of the tip of the axicon causes significant deviations from these profiles. In particular, strong oscillations occur on the on-axis intensity. The input beam size also plays a strong role; for small beams the axicon acts more like a conventional lens, while for the large ones, it exhibits two focal regions. We also propose scheme for apodization. In all cases, the experiments match closely with the calculations. Our results show that axicons cannot be assumed to always generate smooth on-axis intensities and the structures coming from the real profiles should be taken into account for most applications.

International audience; We present a single-shot frequency-resolved optical gating setup for measurements of ultrashort pulse intensity and phase down to single-optical-cycle durations. Several issues stemming from short durations and extreme bandwidths are addressed. We show that after using spectral response correction, the regular FROG algorithm yields reliable pulse retrievals. We demonstrate measurement of pulse widths down to 4.9 fs.

International audience; A transition–Cherenkov electromagnetic emission by a femtosecond laser pulse propagating in a self-induced plasma channel in air has been very recently proposed as mechanism for production of terahertz (THz) radiation in the forward direction. In this paper, we study in detail the theory of the transition–Cherenkov process. The theoretical model is developed and compared with recent experimental results for several gases.

International audience; A new terahertz (THz) source in air based on the bifilamentation of femtosecond laser pulses is reported. This THz radiation is 1 order of magnitude more intense than the transition-Cherenkov THz emission from femtosecond laser filaments reported recently and shows different angular and polarization properties. We attribute it to the emission from a bimodal transmission line created by two plasma filaments.