Search results for "Interfaces"
showing 10 items of 1258 documents
ReaxFF molecular dynamics simulation study of nanoelectrode lithography oxidation process on silicon (100) surface
2019
Abstract The nanoelectrode lithography has been strengthened in recent years as one of the most promising methods due to its high reproducibility, low cost and ability to manufacture nano-sized structures. In this work, the mechanism and the parametric influence in nanoelectrode lithography have been studied qualitatively in atomic scale using ReaxFF MD simulation. This approach was originally developed by van Duin and co-workers to investigate hydrocarbon chemistry. We have investigated the water adsorption and dissociation processes on Si (100) surface as well as the characteristics (structure, chemical composition, morphology, charge distribution, etc.) of the oxide growth. The simulatio…
Effects of electrolyte doping on electrodeposited nanostructured manganese oxide and chromium oxide
2020
Abstract Electrolyte additions are used to control the functionality of a nanostructured oxide. Dopant ions affect the size and shape of deposit crystallites and modify the host structure. Such ions can be incorporated into the deposit or form a separate oxide phase. The manganese dioxide family of polymorphs with ion-molecular sieve properties represents the additional possibilities of “template” effects of dopant ions on the phase composition, heterovalent substitution in the cationic sublattice, changes in morphology and alteration of nanocrystallite size during electrocrystallisation. The effects of electrolyte doping in electrodeposited, non-stoichiometric manganese dioxide (NH4+, Li+ …
Laser heating and ablation at high repetition rate in thermal confinement regime
2006
International audience; Laser heating and ablation of materials with low absorption and thermal conductivity (paint and cement) were under experimental and theoretical investigations. The experiments were made with a high repetition rate Q-switched Nd:YAG laser (10 kHz, 90 ns pulse duration and l = 532 nm). High repetition rate laser heating resulted in pulse per pulse heat accumulation. A theoretical model of laser heating was developed and demonstrated a good agreement between the experimental temperatures measured with the infrared pyrometer and the calculated ones. With the fixed wavelength and laser pulse duration, the ablation threshold fluence of paint was found to depend on the repe…
Optical modeling of nickel-base alloys oxidized in pressurized water reactor
2012
International audience; The knowledge of the aging process involved in the primary water of pressurized water reactor entails investigating a mixed growth mechanism in the corrosion of nickel-base alloys. A mixed growth induces an anionic inner oxide and a cationic diffusion parallel to a dissolution-precipitation process forms the outer zone. The in situ monitoring of the oxidation kinetics requires the modeling of the oxide layer stratification with the full knowledge of the optical constants related to each component. Here, we report the dielectric constants of the alloys 600 and 690 measured by spectroscopic ellipsometry and fitted to a Drude-Lorentz model. A robust optical stratificati…
Laser densification of organic coating: Effects of laser wavelength, operating parameters and substrate properties
2012
International audience; Mechanical bonding and interface behaviour play a key role for any materials deposited on different substrates. Usually, a post-spray heat treatment is required to improve the coating morphology and to enhance mechanical properties of thermal-sprayed polymeric coating. The effects of YAG, CO2 and diode laser radiations on as-sprayed PEEK coating deposited on stainless steel and aluminum substrates were investigated. The results revealed a good coating densification and interface behavior. A correlation between coating and substrate absorption coefficients, their thermophysical properties and laser operating parameters was shown. Besides, the finite element modeling b…
Optical properties of lithium gallium oxide
2017
Abstract The optical dielectric function tensor of orthorhombic single-crystal LiGaO 2 was determined for polarizations along a , b , and c crystal-axis in the photon energy range from 0.04 eV to 6.5 eV by the generalized spectroscopic ellipsometry. In the far-infrared spectral range from 12.4 meV to 40 meV, the dielectric function was determined from conventional polarized transmittance and polarized reflectance measurements. Lineshape analysis of the dielectric function tensor major components allowed for a determination of the long-wavelength optical phonon characteristics, refractive indices dispersion, and parameters of interband and excitonic optical transitions.
Structure and chemical bonds in reactively sputtered black Ti–C–N–O thin films
2011
The evolution of the nanoscale structure and the chemical bonds formed in Ti–C–N–O films grown by reactive sputtering were studied as a function of the composition of the reactive atmosphere by increasing the partial pressure of an O2+N2 gas mixture from 0 up to 0.4 Pa, while that of acetylene (carbon source) was constant. The amorphisation of the films observed by transmission electron microscopy was confirmed by micro- Raman spectroscopy, but it was not the only effect associated to the increase of the O2+N2 partial pressure. The chemical environment of titanium and carbon, analysed by X-ray photoemission spectroscopy, also changes due to the higher affinity of Ti towards oxygen and nitro…
Enhanced optical response of InSe nanosheet devices decorated with CsPbX3 (X = I, Br) perovskite nanocrystals
2021
Abstract The combination of several two-dimensional materials opens the door for the creation of cooperative nanodevices with functionalities that complement to each other and even compensate the weaknesses of the individual components. Two-dimensional indium selenide (InSe) shows one of the largest tunability bandgap found in two-dimensional materials with application in optoelectronics. However, the intrinsic out-of-plane luminescent dipolar nature limits its implementation in devices operating in vertical configuration. All-inorganic CsPbX3 (X = Br, I) cubic nanoparticles offer high absorption and emission quantum yields and great integrability with two-dimensional materials. Combining t…
X-RAY PHOTOEMISSION ELECTRON MICROSCOPE DETERMINATION OF ORIGINS OF ROOM TEMPERATURE FERROMAGNETISM AND PHOTOLUMINESCENCE IN HIGHCo-CONTENTCoxZn1-xOF…
2014
In this paper, we reported on the X-ray photoemission electron microscope (XPEEM) determination of magnetic and luminescence origins for two CoxZn1-xO films. The cobalt fraction x of radio frequency co-sputtered samples were 0.86(2) and 0.92(2), respectively. Films were ferromagnetic and semiconductive. Unique narrow green color lines beside the ZnO intrinsic emissions were found with a decay time in microsecond range at room temperature. Origins of magnetic and luminescence properties were determined with XPEEM. The X-ray absorption near edge structure at the Co L3-edge denoted that Co was partially oxidized, and phase-contrast images together with chemical composition identification furt…
Properties of ZnO coatings obtained by mechanoactivated oxidation
2009
In this work a new method based on the mechanoactivated oxidation has been applied for obtaining thin nanostructured transparent ZnO coatings on glass. Zn has been transferred onto a glass substrate at room temperature using a quickly rotating steel wire brush. Afterwards by subsequent annealing it is modified into a transparent ZnO coating. The temperature range in which formation of the needle-like (whiskers) structure and transition to the fine-grained structure occurs has been determined. The interrelation between physical properties and the change of microstructure of the ZnO coatings has been shown.