Elodie Petit

• University of Clermont Auvergne

Transition metal oxides (TMOs) occupy an increasing share in the search for new electrode materials for Li-Ion batteries. Despite promising electrochemical performances (up to 1000 mAh g⁻¹ in the case of conversion), these materials have poor cyclability linked primarily to hysteresis phenomena. To improve their electrochemical performance, one str...

The use of neutron reflectors is an effective method for improving the quality of neutron sources and neutron delivery systems. In this work, we further develop the method based on the Bragg scattering of neutrons in crystals with large interplanar distances. We compare samples of differently prepared fluorine intercalated graphites by measuring th...

The use of neutron reflectors is an effective method for improving the quality of neutron sources and neutron delivery systems. In this work, we further develop the method based on Bragg scattering of neutrons in crystals with large inter-planar distances. We compare samples of differently prepared fluorine intercalated graphites by measuring the t...

Sub-fluorinated carbon nanofibers (F-CNFs) can be described as a non-fluorinated core surrounded by a fluorocarbon lattice. The core ensures the electron flux in the cathode during the electrochemical discharge in the primary lithium battery, which allows a high-power density to be reached. The ball-milling in an inert gas (Ar) of these F-CNFs adds...

Sulphur-doped graphene was fluorinated using molecular fluorine (F2). First, the fluorination conditions were adapted in order to be mild enough to maintain S in the carbon lattice and form S-F bonds. An unusually weakened C-F bonding for an F/C ratio of 0.71 was then achieved, which allowed enhanced performances when used as a cathode in primary l...

In order to synthesize chemical filters for the selective removal of volatile fluorides, commercial magnesium fluoride MgF2 with high specific surface area (HSA) was investigated. The amount of -OH groups substituting fluorine is not negligible, partly due to the high surface area, but also due to the synthesis route. These hydroxyl groups induce a...

Medical devices (MD) are often made of plasticized polyvinylchloride (PVC). However, plasticizers may leach out into infused solutions and expose the patients to a toxic risk. The aim of the present work is to fluorinate plasticized PVC tubular MDs to create a barrier layer on their internal surface, and to study the impact of such a chemical treat...

In this study, the goal was to compatibilize flax natural fibers (which are inherently polar) with mostly dispersive polymers, while proposing a way to recover greenhouse gases or refrigerants such as CF4 or C2F5H. Such gases exhibit a high global warming potentials (GWPs) and their recovery at the end of their lifecycle is difficult. Therefore, th...

Knowing that carbon fibre reinforced polymers are sensitive to moisture through their interphases, carbon fibres sized with Bisphenol A diglycidyl ether were fluorinated under a N2/F2 atmosphere, which confers them a hydrophobic behaviour, as highlighted by wettability measurements. Low fluorination temperatures (< 230°C) lead to a sizing perfluori...

Pure model geopolymers present a promising potential for high-temperature binders for structural or coating applications. However, their well-known chemical stability, which can reach 1400°C in the case of K-activated geopolymer, is accompanied by deleterious dimensional behavior, with significant shrinkage on heating. The work in the present paper...

Natural fibers are frequently used as alternatives of glass fibers as polymer matrix reinforcement to form composite materials. However, their natural hydrophilicity prevents them from being easily compatible with hydrophobic polymers, which represent the majority of matrices. To solve this, direct fluorination of sized natural fibers (flax fibers...

The thermal behavior of a model MK based K‐geopolymer (Si/Al = 1.38 and K/Al = 0.68; obtained by alkaline activation of a very pure metakaolin) was investigated between room temperature and 1400°C in order to evaluate its potentiality for high‐temperature applications. The purpose of our study was to monitor the behavior of a geopolymer during a te...

The thermal behavior of a model MK‐based K‐geopolymer was investigated between room temperature and 1400°C in order to evaluate its potentiality for high‐temperature applications. The purpose of our study was to monitor the behavior of a geopolymer during a temperature rise in order to better understand its variations with respect to temperature. T...

Following recent works on gas/solid fluorination applied to massive wood that sustainably increased its hydrophobicity thanks to the substitution of OH groups by covalent fluorine atoms, the present paper demonstrates that torrefaction may replace the step of the removal of HF. Because of the strength of covalent CF bonds, torrefaction does not r...

Exfoliation appears as a promising way to decrease the friction coefficient of carbon materials. Although there is massive defluorination during exfoliation, the friction coefficient is not increased and an exfoliated structure facilitates the formation of a homogeneous and stable tribofilm. The weakening of the interparticle interactions due to th...

This study describes the behavior of potential slow-release fertilizers (SRF), prepared by the mechanochemical activation of calcined Mg2Al-CO3 or Mg2Fe-CO3 layered double hydroxides (LDH) mixed with dipotassium hydrogen phosphate (K2HPO4). The effects of LDH thermal treatment on P/K release behavior were investigated. Characterizations of the inor...

Low Density Polyethylene (LDPE) films are treated by a combination of plasma treatment followed by direct fluorination. Plasma treatment is carried out either with ion bombardment or reactive conditions according to the gas(es) used. The properties of samples prepared by the two combinations (i) ion bombardment/fluorination; and (ii) reactive plasm...

A combination of original, powerful characterization techniques was used to make a thorough description of solid geopolymers and of the associated effect of varying the alkali cation source - NaOH, KOH, or CsOH - and aging for up to several years. More specifically, the local and pore structures were progressively determined from atomic local scale...

Before considering their combination on commercial packaging films, two surface treatments processes were investigated. Indeed, direct fluorination and plasma processes are currently recognized as effective processes to improve polymer surface properties. The aim of this first work is to elucidate mechanisms that occur on the treated surface. The m...

Two synthesis ways were applied to fluorination of a novel nano-sized graphitized carbon black: (i) direct fluorination (under a flux of pure molecular fluorine) and (ii) controlled fluorination by TbF4 thermal decomposition. The thermal, electrochemical and tribologic properties of the various fluorinated nanocarbons obtained have been investigate...

High aspect ratio, rod-like and single crystal phase GaAs nanowires (NWs) were grown by gold catalyst-assisted hydride vapor phase epitaxy (HVPE). High resolution transmission electron microscopy and micro-Raman spectroscopy revealed polytypism-free zinc blende (ZB) NWs over lengths of several tens of micrometers for a mean diameter of 50 nm. Micro...

Hydride Vapor Phase Epitaxy (HVPE) makes use of chloride III-Cl and hydride V-H3 gaseous growth precursors. It is known as a near-equilibrium process, providing the widest range of growth rates from 1 to more than 100 μm/h. When it comes to metal catalyst-assisted VLS (vapor-liquid-solid) growth, the physics of HVPE growth is maintained: high dechl...

High aspect ratio, rod-like and single crystal phase GaAs nanowires (NWs) were grown by gold catalyst-assisted hydride vapor phase epitaxy (HVPE). High resolution transmission electron microscopy (HRTEM) and micro-Raman spectroscopy revealed polytypism-free zinc blende NWs over lengths of several tens of micrometers for diameters ranging between 50...

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Carbon product is observed during the study of radiative properties of a titanlike atmosphere plasma generated by an inductively coupled plasma torch. Deposition of carbon is observed not only on the quartz tube outside the inductor but also on the ceramic protection of the torch injector. It appears two types of morphology more or less dense and i...

Single-wall carbon nanotubes (SWCNTs) are fluorinated around 200 °C with mol. fluorine (F2) and xenon difluoride (XeF2) as fluorination agents. In this latter case, fluorination is carried out by at. fluorine F· generated by the thermal decompn. of gaseous XeF2 on the nanotube surface. XeF2 treatment results in stoichiometries from CF0.05 to CF0.32...

In this article, carbon nanotube (CNT)-based sensors have been prepared using dispersion techniques. Sensors are obtained from a dispersion of CNTs using either chloroform as a solvent or sodium dodecylbenzene sulfonate as a surfactant. These sensors are prepared by drop-cast deposition of the solutions on interdigitated electrodes. The organic sol...

This paper describes the preparation of the CNTs-based gas sensors, which are achieved by the utilisation of aqueous dispersions of carbon nanotubes (CNTs) using NaDDBS as a surfactant. The sensors are made of IDEs (Interdigitated electrodes) on which the CNTs dispersion are dropcast deposited. The sensing layers are characterized by Raman and IR s...

Fluorination of single walled carbon nanotubes was carried out at low temperature in the −191/25 °C range under 1 atm pure fluorine gas. In such conditions, the resulting C–F bonding is significantly weaker than for samples fluorinated at 280 °C. If the fluorination is performed at low temperature, fluorine atoms can be then removed from the host s...

Solid state NMR measurements using 13C, 1H and 19F nuclei (MAS, CP-MAS) underline the surface chemistry of nanodiamonds from different synthesis (detonation, high pressure high temperature and shock compression). The comparison of the spin-lattice relaxation times T1 and physicochemical characterization (spin densities of dangling bonds, specific s...

The reactivity with pure fluorine gas of a mixture of carbon nanodiscs and nanocones was investigated. The starting materials were the as-prepared mixture, which results from cracking of heavy oils, and the sample post-treated at 2700 °C in argon atmosphere in order to increase the graphitization degree. The effect of this graphitization on the res...

Nanodiamonds obtained by the detonation method have been investigated by means of solid-state magnetic nuclear resonance (NMR) and electron paramagnetic resonance. 13C and 1H magic angle spinning (MAS) NMR and 13C MAS NMR with 1H to 13C cross-polarization allow the determination of surface-hydrogenated groups (CH, CH2, and COH) and the quasi-absenc...

The adsorption kinetics of gelatin to the air/water interface is still not fully understood. We investigated two samples of gelatin having different gel strength (65 Bloom and 280 Bloom), named, respectively gelatin 65B and 280B. The gelatin samples in solution were characterised by viscosimetric methods. We evidence a chain expansion of gelatin up...

The science and technology of hydrocolloids used in food and related systems has seen many new developments and advances over recent years. This book presents the latest research from leading experts in the field. Some of the topics covered within this book include biochemical characterisation, the use of antibodies, immunostaining and enzyme hydro...