Search results for "nanoparticle"
showing 10 items of 2198 documents
Flash microwave synthesis and sintering of nanosized La0.75Sr0.25Cr0.93Ru0.07o3–δ for fuel cell application.
2009
International audience; Perovskite-oxide nanocrystals of La0.75Sr0.25Cr0.93Ru0.07O3–δ with a mean size around 10 nm were prepared by microwave flash synthesis. This reaction was performed in alcoholic solution using metallic salts, sodium ethoxide and microwave autoclave. The obtained powder was characterised after purification by energy dispersive X-ray analysis (EDX), X-ray powder diffraction (XRD), BET adsorption technique, photon correlation spectroscopy (PCS) and transmission electron microscopy (TEM). The results show that integrated perovskite-type phase and uniform particle size were obtained in the microwave treated samples. At last the synthesised powder was directly used in a sin…
Syntheses of TiO2 anatase nanocrystals with controlled size distribution. Influence of the crystallites size on the Raman spectrum and investigation …
2006
The determination of the size and the size distribution of anatase TiO2 nanopowders using Raman spectroscopy is presented. Several synthesis methods (soft chemistry, water-in-oil microemulsion, continuous hydrothermal synthesis) are used in order to control the size (from 3 to 20 nm), shape, phase and size distribution. The shift and width of the anatase Eg peak are often used to obtain the nanoparticles size. Homever, this peak is also sensitive to nonstoichiometry and others parameters. Low-frequency Raman scattering does not suffer from this problem. Size distibutions obtained by Raman spectroscopy and MET micrographs are compared. Finally, in situ Raman spectroscopy is used to study the…
MRI-visible nanoparticles from hydrophobic gadolinium poly(ε-caprolactone) conjugates
2015
International audience; In this work we report on the synthesis of two hydrophobic and degradable gadolinium poly(ε-caprolactone) conjugates and their use for the preparation of MRI-visible nanoparticles intended for diagnosis applications. Advantage has been taken from functional poly(ε-caprolactone)s (PCL) bearing propargyl (PCL-yne) or amine groups (P(CL-co-NH2VL)) to yield conjugates by following two strategies. In a first approach, an azido-chelate of gadolinium (Gd(III)) has been conjugated by CuAAC to PCL-yne to yield a polymeric chelate containing 2.6 wt% of Gd(III). In a second approach, a dianhydride Gd(III)-ligand was reacted with P(CL-co-NH2VL) to yield, after complexation with …
Étude des propriétés optiques et spectroscopiques de nanorods dopés au lanthanide pour des applications de nanosondes en champ proche
2022
Lanthanide-doped nanoparticles constitute a versatile family of photoluminescent local nanoprobes. In this work, we study the photoluminescence of Eu3+-doped NaYF4 nanorods characterized by highly polarized spectra. We develop a full theoretical model and paraxial approximation for nanorod dipole emission. We measure the photoluminescence of individual nanorods by fluorescence confocal microscopy and determine some of their intrinsic optical properties. We also determine the nature (electric or magnetic) and orientations of dipoles moments of the optical transitions used for nanoprobing in the visible range.In addition to the full theoretical model and the paraxial approximation, Fourier mi…
Swarming of micron-sized hematite cubes in a rotating magnetic field -- Experiments
2020
Energy input by under-field rotation of particles drives the systems to emergent non-equilibrium states. Here we investigate the suspension of rotating magnetic cubes. Micron-sized hematite cubes are synthesized and observed microscopically. When exposed to a rotating magnetic field, they form rotating swarms that interact with each other like liquid droplets. We describe the swarming behaviour and its limits and characterize swarm size and angular velocity dependence on magnetic field strength and frequency. A quantitative agreement with a theoretical model is found for the angular velocity of swarms as a function of field frequency. It is interesting to note that hematite particles with p…
Temperature rise during laser-induced self-organization of nanoparticle gratings revealed by Raman microspectroscopy and electron microscopy
2016
International audience
Particle Size Determination in Electrical Arcs with Ag and AgSnO2 Electrodes using X-Ray Scattering
2015
International audience; This article discusses recent synchrotron radiation based measurements of nanoparticle formation between arcing contacts. The studied material is typical in contact applications, Ag and AgSnO2
Contact laws between nanoparticles: the elasticity of a nanopowder
2018
International audience; Studies of the mechanical contact between nanometer-scale particles provide fundamental insights into the mechanical properties of materials and the validity of contact laws at the nanoscale which are still under debate for contact surfaces approaching atomic dimensions. Using in situ Brillouin light scattering under high pressure, we show that effective medium theories successfully predict the macroscopic sound velocities in nanopowders if one takes into account the cementation of the contacts Our measurements suggest the relevance of the continuum approach and effective medium theories to describe the contact between nanoparticles of diameters as small as 4 nm, i.e…
Radiolabeling for long term biodistribution of ultrasmall nanoparticles designed for radiotherapy guided by MRI
2016
International audience
Microstructuration des dépôts imprimés par jet d'encre de la coalescence des nanoparticules d'argent vers la réalisation d'interconnexions de composa…
2012
Several challenges are still holding back the technological transfer of printed electronics to industry in spite of recent progresses. In this thesis work, the printing method of inks based on silver nanoparticles (=25 nm) was optimized according to its rheology and to the fluid/substrate interactions for the fabrication of electrical interconnections with a thickness of 500 nm. These lines were printed on silicon or flexible substrates and annealed either by conventional (oven or infrared) or selective methods (microwave) at temperatures comprised between 100 and 300 °C.A better understanding of the relationship between process and microstructure of these printed thin films, based on sever…