Search results for "material"
showing 10 items of 32550 documents
Direct observation of elemental segregation in InGaN nanowires by X-ray nanoprobe
2011
Using synchrotron radiation nanoprobe, this work reports on the elemental distribution in single Inx Ga1–xN nanowires (NWs) grown by molecular beam epitaxy directly on Si(111) substrates. Single NWs dispersed on Al covered sapphire were characterized by nano-X-ray fluorescence, Raman scattering and photoluminescence spectroscopy. Both Ga and In maps reveal an inhomogeneous axial distribution inside sin- gle NWs. The analysis of NWs from the same sample but with different dimensions suggests a decrease of In segregation with the reduction of NW diameter, while Ga distribution seems to remain unaltered. Photoluminescence and Raman scattering measurements carried out on ensembles of NWs exhibi…
Composition dependence ofSi1−xGexsputter yield
2005
Sputtering yields have been measured for unstrained ${\mathrm{Si}}_{1\ensuremath{-}x}{\mathrm{Ge}}_{x}$ $(x=0--1)$ alloys when bombarded with ${\mathrm{Ar}}^{+}$ ions within the linear cascade regime. Nonlinear S-shape dependence of the sputter yield as a function of the alloy composition has been revealed. The dependence is analyzed within the frameworks of the cascade theory conventionally accepted to be the most systematic to date theoretical approach in sputtering. In view of a linear composition dependence predicted for the sputter yield by the cascade theory adapted for polyatomic substrates, the nonlinearity observed in our experiments is shown to be related to the alloying effect on…
Atomic layer deposition of aluminum oxide on modified steel substrates
2016
Abstract Al 2 O 3 thin films were grown by atomic layer deposition to thicknesses ranging from 10 to 90 nm on flexible steel substrates at 300 °C using Al(CH 3 ) 3 and H 2 O as precursors. The films grown to thicknesses 9–90 nm covered the rough steel surfaces uniformly, allowing reliable evaluation of their dielectric permittivity and electrical current densities with appreciable contact yield. Mechanical behavior of the coatings was evaluated by nanoindentation. The maximum hardness values of the Al 2 O 3 films on steel reached 12 GPa and the elastic modulus exceeded 280 GPa.
Normal and relaxor ferroelectric behavior in the Ba1−xPbx(Ti1−yZry)O3 solid solutions
2017
Abstract Polycrystalline samples of Ba 1−x Pb x (Ti 1−y Zr y )O 3 (BPTZ) with x = 0.025 & 0.1 and 0.10 ≤ y ≤ 0.50 have been synthesized by high-temperature solid-state reaction technique. X-ray diffraction reveals the formation of single phase with tetragonal or cubic structure. Dielectric investigations were carried out in the temperature range from 80 to 445 K with frequencies range from 10 2 to 10 6 Hz. A broad dielectric anomaly coupled with the shift of dielectric maxima toward a higher temperature with increasing frequency indicates either a diffuse phase transition or relaxor behavior in some of these ceramics. Whatever lead content, when zirconium is substituted by titanium, T C an…
Spark Plasma Sintering of Metallic Glasses
2019
Spark plasma sintering (SPS) of metallic glasses (MG) can be quite different from sintering crystalline metallic alloys. Indeed, MG behave differently with increasing temperature, as they encounter a glass transition and devitrification. Their shaping can thus be compared to what can be performed on thermoplastic polymers. SPS is a promising way to prepare bulk parts from amorphous powders, since it allows very fast heating and cooling rates. It gives an advantage to avoid or limit devitrification of the amorphous phase upon the thermal cycle. However, diffusion mechanisms, which generally control densification, are activated at temperatures that are not compatible with MG structural integr…
Production of dense nanostructured materials using FAPAS and SPS techniques
2011
International audience
Stealth dicing with ultrafast Bessel beams with engineered transverse profiles
2017
International audience; We investigate high-speed glass cleaving with ultrafast laser beams with engineered transverse intensity profile. We achieve accuracy of ~ 1 µm at 25 mm/s and drastically enhance cleavability compared to standard Bessel beams.
The role of radio frequency scattering in high-energy electron losses from minimum-B ECR ion source
2021
Abstract The measurement of the axially lost electron energy distribution escaping from a minimum-B electron cyclotron resonance ion source in the range of 4–800 keV is reported. The experiments have revealed the existence of a hump at 150–300 keV energy, containing up to 15% of the lost electrons and carrying up to 30% of the measured energy losses. The mean energy of the hump is independent of the microwave power, frequency and neutral gas pressure but increases with the magnetic field strength, most importantly with the value of the minimum-B field. Experiments in pulsed operation mode have indicated the presence of the hump only when microwave power is applied, confirming that the origi…
Very Long Term Stabilization of a 2D Magnet down to the Monolayer for Device Integration
2020
2D materials have recently demonstrated a strong potential for spintronic applications. This has been further reinforced by the discovery of ferromagnetic 2D layers. Nevertheless, the fragility of ...
The biased disc of an electron cyclotron resonance ion source as a probe of instability-induced electron and ion losses
2019
International audience; Electron Cyclotron Resonance Ion Source (ECRIS) plasmas are prone to kinetic instabilities resulting in loss of electron and ion confinement. It is demonstrated that the biased disk of an ECRIS can be used as a probe to quantify such instability-induced electron and ion losses occurring in less than 10 µs. The qualitative interpretation of the data is supported by the measurement of the energy spread of the extracted ion beams implying a transient plasma potential >1.5 kV during the instability. A parametric study of the electron losses combined with electron tracking simulations allows for estimating the fraction of electrons expelled in each instability event to be…