Clément Hébert (a), Davy Carole (c), Franck Omnes (a), Etienne Gheeraert (a)

International audienceNanopores in insulating solid state membranes have recently emerged as potential candidates for sorting, probing and manipulating biopolymers, such as DNA, RNA and proteins in their native environment. Here a simple, fast and cost-effective etching technique to create nanopores in diamond membrane by self-assembled Ni nanoparticles is proposed. In this process, a diamond film is annealed with thin Ni layers at 800-850 degrees C in hydrogen atmosphere. Carbon from the diamond-metal interface is removed as methane by the help of Ni nanoparticles as catalyst and consequently, the nanoparticles enter the crystal volume. In order to optimize the etching process and understand the mechanism the annealed polycrystalline and nanocrystalline diamond films were analyzed by X-ray photoelectron spectroscopy (XPS), and the gas composition during the process was investigated by quadrupole mass spectrometer. With this technique, nanopores with lateral size in the range of 15-225 nm and as deep as about 550 nm in diamond membrane were produced without any need for lithography process. A model for etching diamond with Ni explaining the mechanism is discussed

Surface Area of Carbon Nanoparticles: A Dose Metric for a More Realistic Ecotoxicological Assessment

Engineered nanoparticles such as graphenes, nanodiamonds, and carbon nanotubes correspond to different allotropes of carbon and are among the best candidates for applications in fast-growing nanotechnology. It is thus likely that they may get into the environment at each step of their life cycle: production, use, and disposal. The aquatic compartment concentrates pollutants and is expected to be especially impacted. The toxicity of a compound is conventionally evaluated using mass concentration as a quantitative measure of exposure. However, several studies have highlighted that such a metric is not the best descriptor at the nanoscale. Here we compare the inhibition of Xenopus laevis larvae growth after in vivo exposure to different carbon nanoparticles for 12 days using different dose metrics and clearly show that surface area is the most relevant descriptor of toxicity for different types of carbon allotropes

Fabrication Process Independent And Robust Aggregation Of Detonation Nanodiamonds In Aqueous Media

In the past detonation nanodiamonds (DNDs), sized 3–5 nm, have been praised for their colloidal stability in aqueous media, thereby attracting vast interest in a wide range of applications including nanomedicine. More recent studies have challenged the consensus that DNDs are monodispersed after their fabrication process, with their aggregate formation dynamics poorly understood. Here we reveal that DNDs in aqueous solution, regardless of their post-synthesis de-agglomeration and purification methods, exhibit hierarchical aggregation structures consisting of chain-like and cluster aggregate morphologies. With a novel characterization approach combining machine learning with direct cryo-transmission electron microscopy and with X-ray scattering and vibrational spectroscopy, we show that their aggregate morphologies of chain and cluster ratios and the corresponding size and fractal dimension distributions vary with the post-synthesis treatment methods. In particular DNDs with positive ζ-potential form to a hierarchical structure that assembles aggregates into large networks. DNDs purified with the gas phase annealing and oxidation tend to have more chain-like aggregates. Our findings provide important contribution in understanding the DND interparticle interactions to control the size, polydispersity and aggregation of DNDs for their desired applications

From Magnetic to Bioactive Materials: presents electronic, magnetic, biomedical, carbon- and sulfur-based materials and ceramics.: “Carbon Materials”

International audienceMany elements and inorganic compounds play an extraordinary role in daily life for numerous applications, e. g., construction materials, inorganic pigments, inorganic coatings, steel, glass, technical gases, energy storage and conversion materials, fertilizers, homogeneous and heterogeneous catalysts, photofunctional materials, semiconductors, superconductors, soft- and hard magnets, technical ceramics, hard materials, or biomedical and bioactive materials. The present work is written by experienced authors who give a comprehensive overview on the many chemical and physico-chemical aspects related to application of inorganic compounds and materials in order to introduce senior undergraduate and postgraduate students (chemists, physicists, materials scientists, engineers) into this broad field

De l'épitaxie du diamant aux nanodiamants

International audienceLe diamant monocristallin est le semiconducteur ultime pour les dispositifs de puissance ou les détecteurs de rayonnement [1, 2]. Un tel matériau peut être synthétisé par haute pression haute température (HPHT) ou par dépôt chimique en phase vapeur (CVD). En CVD, deux approches sont actuellement utilisées : l'une consiste à déposer des films sur des substrats de diamant (homoépitaxie), la seconde s'applique à des substrats de nature différente (hétéroépitaxie). Dans la première partie de cet exposé, je ferai une synthèse des travaux que nous avons menés au CEA sur l'hétéroépitaxie du diamant sur des substrats multicouches Ir/SrTiO 3 /Si (001) [3]. Les nanoparticules de diamant (nanodiamants) suscitent un intérêt croissant du fait de leurs nombreuses propriétés en partie héritées du diamant massif [4]. Ces nanoparticules sont aujourd'hui utilisées pour la nanomédecine, la catalyse et les applications quantiques (centres colorés). Elles entrent aussi dans la formulation de composites et de lubrifiants avancés. Pour toutes ces applications, la chimie de surface est un paramètre central. Dans une seconde partie, je présenterai les différentes études menées actuellement sur les nanodiamants au laboratoire du CEA NIMBE

Nanodiamonds: From synthesis to applications

International audienceSince a decade, nanodiamond is the object of a growing interest from researchers, engineers, and companies. Its outstanding properties inhered from bulk diamond are completed by new ones conferred at the nanoscale. Consequences on chemicophysical properties of diamond at the nanoscale are discussed in this chapter. It reviews the last progresses in nanodiamond synthesis and in advanced characterization tools. A particular focus is provided on photoluminescent color centers that can be hosted in nanodiamond core. Lastly, the three main application fields of nanodiamonds such as bioapplications, quantum technologies based on spin properties of color centers, and energy applications are discussed. The main challenges for future developments of ND field are lastly presented

X-ray Photoemission Spectroscopy applied to nanodiamonds: From surface chemistry to in situ reactivity

International audienceThe surface chemistry governs most of the physical and chemical properties of nanodiamonds (NDs). X-ray Photoemission Spectroscopy is a method of choice to characterize the surface of NDs. The present paper reviews on XPS studies focusing on modifications of surface terminations or grafting of biomolecules and polymers on NDs. The second part illustrates studies in which XPS can even be used as a specific tool to investigate in situ the reactivity and the stability of NDs toward various atmospheres like plasma or UHV annealing

Surface modifications of nanodiamonds and current issues for their biomedical applications

International audienceCombining numerous unique assets, nanodiamonds are promising nanoparticles for biomedical applications. The present chapter focuses on the current knowledge of their properties. It shows how the control of their surface chemistry governs their colloidal behavior. This allows a fine tuning of their surface charge. Developments of bioapplications using nanodiamonds are summarized and further promising challenges for biomedicine are discussed

Diamond Nucleation and Seeding Techniques: Two Complementary Strategies for the Growth of Ultra-thin Diamond Films

International audienceThe controlled growth of ultra-thin diamond layers on a diversity of substrates is a major challenge for many technological applications (heat spreaders, electromechanical systems, etc.). This explains the huge effort produced during the last two decades to master the early stages of diamond formation. Two main pathways have been investigated in the literature. The nucleation pathway aims to produce diamond nuclei, i.e., the smallest thermodynamically stable diamond islands, at the substrate surface. This is mainly performed by in situ treatments preceding diamond chemical vapor deposition (CVD) growth, such as bias enhanced nucleation (BEN). The second approach consists of skipping the nucleation stage by covering, ex situ, the substrate with diamond nanoparticles, which act as seeds for diamond CVD growth. The present chapter is a review of these pathways. Their respective benefits and drawbacks are discussed. Finally, these two approaches appear very complementary. Seeding allows the growth of ultra-thin diamond layers on large non-conductive substrates with micrometric patterns. On the other hand, the BEN in situ nucleation treatment remains the favored technique to achieve well-adherent diamond films and diamond heteroepitaxy

Synthesis and Applications of Nanocarbons

International audienc