Nicholas P Blanchard

Claude Bernard University Lyon 1 | UCBL · Institut lumière matière

Optimizing the synthesis of carbon nanotubes (CNTs) for applications like field emission (FE) sources requires a fundamental understanding of the growth kinetics of individual CNTs. In this article, we explore how applying electric fields during CNT synthesis influences the as-grown nanotubes and their FE performance. We observe growth and undertak...

FeRh alloys in the CsCl-type (B2) chemically ordered phase present an antiferromagnetic to ferromagnetic order transition around 370 K observed in bulk and continuous films but absent in nanoclusters. In...

Hafnium zirconium oxide (HZO) is an ideal candidate for the implementation of ferroelectric memristive devices, due to its compatibility with the complementary metal‐oxide‐semiconductor technology. Ferroelectricity in HZO films is significantly influenced by the properties of electrode/HZO interfaces. Here, the impact of the interfacial microstruct...

Synthesis of high quality colloidal Cerium(III) doped yttrium aluminum garnet (Y3Al5O12:Ce³⁺, “YAG:Ce”) nanoparticles (NPs) meeting simultaneously both ultra‐small size and high photoluminescence (PL) performance is challenging, as generally a particle size/PL trade‐off has been observed for this type of nanomaterials. The glycothermal route is cap...

Carbon thin film depositions were carried out with femtosecond laser ablation from two different sp2-bonded carbon targets, namely highly oriented pyrolytic graphite (HOPG) and glassy carbon (GC). Femtosecond laser deposition is generally known as a means of generating nanoparticles. To our knowledge, Raman spectroscopy is not able to directly disc...

In this study, the atomic and chemical structure and the optical response of A x B 1-x bimetallic nanoparticles (BNPs) combining gold or silver (A) with aluminium or indium (B) were investigated for...

Bimetallic nanoparticles (BNPs) are promising candidates for fundamental research and applications as their physico-chemical properties can in many cases be tuned continuously or enhanced with respect to the mono-metallic particles. Here we investigate the possibility of fabricating silver-indium and silver-aluminium BNPs in the range of 4-5 nm dia...

In this paper, we present some specific chemical and magnetic order results obtained on bimetallic FeRh nanoparticles prepared under non-equilibrium conditions using mass-selected Low Energy Cluster Beam Deposition. Clusters around 7 nm incident diameter are in-situ sandwiched between amorphous carbon films before transfer in air, with different su...

The accurate control of the crystal phase in III-V semiconductor nanowires (NWs) is an important milestone for device applications. Although cubic zinc-blende (ZB) GaAs is a well-established material in microelectronics, the controlled growth of hexagonal wurtzite (WZ) GaAs has thus far not been achieved successfully. Specifically, the prospect of...

Sintering under pressure by means of the spark plasma sintering (SPS) technique is a common route to reduce the sintering temperature and to achieve ceramics with a fine-grained microstructure. In this work, high-density bulk TiO2 was sintered by high pressure SPS. It is shown that by applying high pressure during the SPS process (76 to 400 MPa), d...

The accurate control of the crystal phase in III-V semiconductor nanowires (NWs) is an important milestone for device applications. In this work, we present a method to select and maintain the wurtzite (WZ) crystal phase in self-assisted NWs. By choosing a specific regime where the NW growth process is a self-regulated system, the main experimental...

Glassy carbon (GC) is a chemically stable form of fully sp2-bonded carbon with locally ordered domains. GC is the intermediate material between graphite and diamond combining various properties such as high temperature resistance, hardness, good electrical conductivity, low density, low gases and liquids permeability, and excellent resistance to a...

Silver-based bimetallic nanoalloys are of great interest in plasmonics because their optical absorption is dominated by a strong Localized Surface Plasmon Resonance (LSPR) that not only depends on their size, shape and environment, but also on their composition and chemical order. As a consequence, their optical properties can be modified through t...

Ceramics and their composites are in general brittle materials because they are predominantly made up of ionic and covalent bonds that avoid dislocation motion at room temperature. However, a remarkable ductile behavior has been observed on newly developed 11 mol.% ceria-stabilized zirconia (11Ce-TZP) composite containing fine alumina (8 vol.% Al2O...

In this work we present a new epitaxial lift-off (ELO) approach based on the use of a strained AlAs/InAlAs superlattice (SL) as sacrificial layer for InP related materials. Such an ELO process enables the fabrication and transfer of a thin active III-V heterostructure via its separation from its III-V parent substrate using selective chemical etchi...

Systematic tensile tests were performed on single defect-free 〈110〉 Au nanowires grown by physical vapor deposition while simultaneously recording three-dimensional Bragg peaks using coherent X-rays. The trajectory of three-dimensional Bragg peaks in reciprocal space during tensile testing allowed for measurements of the evolution of strains and ro...

We report on the influence of silver-silica core-shell nanoparticles (Ag@SiO(2)NPs) and bare silver nanoparticles (Ag NPs) on the photoelectric current of plasmonic inverted organic solar cells. The synthesized Ag@SiO(2)NPs are deposited on a zinc oxide layer. The optimized plasmonic devices concern the Ag@SiO(2)NPs with 5 nm shell thickness and pr...

The Kyropoulos technique allows growing large diameter Ti-doped sapphire for Chirped Pulse Amplification CPA laser. A scattering defect particular to Kyropoulos grown crystal is presented. This defect is characterized by different techniques: luminescence, absorption measurement, X-ray rocking curve, Transmission electron microscopy measurements. T...

We report on the fabrication and characterization of Resistive Random Access Memory (RRAM) devices based on nanoparticles in MIM structures. Our approach is based on the use of indium oxide (In2O3) nanoparticles embedded in a dielectric matrix using CMOS-full-compatible fabrication processes in view of back-end-off-line integration for non-volatile...

In the last years new composite materials made of a metallic glass matrix with embedded nanocrystals have arisen as a promising alternative to the metallic glasses, due to their higher hardness. Although the effects of a partial nano-crystallization onto mechanical and magnetic properties have been widely investigated, nothing is known about therma...

This work presents a new and simple procedure for the shape selective purification of gold nanorods from a mixture of rods and spheres. Previously reported methods were time-consuming and revealed several drawbacks such as low yields and difficulty to recover the purified nanoparticles. Additionally, they were mostly applied to high aspect ratio (A...

We propose an arsenic-capping/decapping method, allowing the growth of an epitaxial shell around the GaAs nanowire (NW) core which is exposed to an ambient atmosphere, and without the introduction of impurities. Self-catalyzed GaAs NW arrays were firstly grown on Si(111) substrates by solid-source molecular beam epitaxy. Aiming for protecting the a...

The elaboration and characterization of hydrophobic melamine-based sponges are presented. Sponges were obtained by single-step carbonization of commercial melamine foam having a 3D interconnected network. We show that optimized sponges can be elaborated from a simple pyrolysis treatment with rather low temperatures of 500–600 °C. These materials ex...

We have studied the growth of a SrTiO3 shell on self-catalyzed GaAs nanowires grown by vapor-liquid-solid assisted molecular beam epitaxy on Si(111) substrates. To control the growth of the SrTiO3 shell, the GaAs nanowires were protected using an arsenic capping/decapping procedure in order to prevent uncontrolled oxidation and/or contamination of...

We demonstrate field evaporation of insulating materials, specifically BN nanotubes and undoped Si nanowires, assisted by a convergent electron beam. Electron irradiation leads to positive charging at the nano-object's apex and to an important increase of the local electric field thus inducing field evaporation. Experiments performed both in a...

The coupling between Eu3+ rare earth emitters and Al has been investigated in multilayer structures, which consist of an Eu:Y2O3 phosphor film deposited between percolated and continuous Al films. Passive buffer Y2O3 layers were deposited between phosphor and Al films with different thicknesses to analyze the role of the Eu–Al distance on the nanos...

Understanding and controlling the structural properties of Ge nanowires are important for their current and future use in technological applications. In this study, the initial stages of the heteroepitaxial growth of Ge nanowires on Si(001) via the Au catalyzed vapor-liquid-solid (VLS) method are investigated. We observe a Ge island located at the...

The main goal of this work is to conjugate, what is rare, two independent techniques of TEM-EDX and optical spectroscopy for the localization of Yb3+ and Er3+ rare earth ions and Co2+ transition metal ions as dopants in a compact self-Q-switched microchip laser glass ceramics composed of MgAl2O4 spinel nano-crystals of 10-20 nm size embedded in SiO...

A great number of studies focus their interest on the photophysical properties of fluorescent hybrid gold nanoparticles for potential applications in biotechnologies such as imaging and/or treatment. Spherical gold nanoparticles are known to quench a chromophore fluorescent signal, when moieties are located in their close vicinity. The use of a pol...

Silicon nanoparticles (Si NPs) with a diameter size ranging from 4 to 8 nm were successfully fabricated. They exhibit a visible photoluminescence (PL) due to the quantum confinement effect. Chemical functionalization of these Si NPs with alkyl groups allowed to homogeneously disperse them in nonpolar liquids (NPLs). In comparison to most of literat...

In this chapter we briefly review the techniques available to researchers in the nanofluidic domain to fabricate nanopores and nanochannels. In this context the focused ion beam (FIB) technique will be introduced as a useful and versatile tool for nanofluidics. We illustrate it with two specific examples involving nanopores as building blocks for n...

The photoluminescence properties of silicon nanoparticles ‘’Si NPs’’ have their application as fluorophore in the field of biology . Their use as probes in lubricated contacts is very promising because of their resistance to mechanical stresses and harsh environment. A top-down technology, electrochemical anodization, is used for the development of...

Germanium (Ge) nanoclusters are grown by a molecular-beam epitaxy technique on the chemically oxidized Si(1 0 0) surface at 700 °C. X-ray diffraction and photocurrent spectroscopy demonstrate that the nanoclusters have the local structure of body-centred-tetragonal Ge, exhibiting an optical adsorption edge at 0.48 eV at 50 K. Deposition of silicon...

A great number of works have focused their research on the synthesis, design and optical properties of gold nanoparticles for potential biological applications (bioimaging, biosensing). For this kind of application, sharp gold nanostructures appear to exhibit the more interesting features since their surface plasmon bands are very sensitive to the...

Germanium (Ge) nanoclusters are grown by the molecular-beam epitaxy technique on a chemically oxidized Si(100) surface at 700C. X-ray diffraction and photocurrent spectroscopy demonstrate that the nanoclusters have the local structure of body centered-tetragonal Ge, which exhibits an optical adsorption edge at 0.48 eV at 50 K. Deposition of silicon...

a b s t r a c t InP/Gd 2 O 3 heterostructures have been prepared by molecular beam epitaxy of Gd 2 O 3 on InP nanowires grown on silicon substrates by molecular beam epitaxy assisted with the vapor–liquid–solid method. Transmission electron microscopy showed Gd 2 O 3 nanocrystals, having diameters between 3 and 7 nm, decorating the sidewalls of InP...

The authors present studies on the field emission (FE) mechanism and the FE-induced transformation of individual anatase TiO2 nanowires (NWs). The NWs were synthesized by electrospinning followed by calcination at 500 °C which produces polycrystalline anatase nanofibers as determined by Raman spectroscopy and transmission electron microscopy (TEM)...

In this work, we use a controlled oxidation of a mesoporous silicon substrate as a tool for extending and adjusting the Si lattice parameter to other materials such as SixGe1-x. Our approach involves four steps. First, a seed film is epitaxially grown on a single-crystal Si(100) wafer by Molecular Beam Epitaxy(MBE). Second, porosification is perfor...

We report on the fabrication and characterization of ultrathin (down to 50 nm) tensile strained SiGe films on mesoporous Si substrates. Low temperature oxidation of the porous substrate relaxes the compressive strain in the as grown monocrystalline (mc) SiGe. Applying this method to a 50 nm thick mc-Si(0.72)Ge(0.28) film, a tensile strain >0.78% ca...

The optical properties of thiolate/Cu�110� and S/Cu�110� surfaces created by the adsorption of methanethiol and L-cysteine are investigated using reflection anisotropy spectroscopy �RAS�. We find that characteristic optical signatures are obtained from these systems. The experimental RAS profiles are simulated using a four-phase model consisting of...

High purity single crystal C-60 rods with uniform dimensions are synthesized by a rapid and facile approach which can be completed over a timescale of typically a few minutes. The morphology of the fullerene product has been characterized in detail by scanning electron microscopy, scanning transmission electron microscopy, and atomic force microsco...

Highly tensile strained (up to 2.2%) thin monocrystalline silicon (mc-Si) films were fabricated by a simple and low-cost method based on the in-plane expansion of meso-porous silicon (PS) substrates upon low temperature oxidation. To control the film thickness below 100 nm, an original "two wafer" technique was employed during the porosification pr...

For efficient hole-extraction in solution processed organic solar cells the transparent indium-tin oxide (ITO) electrode is invariably pre-coated with a thin layer of the high work function conducting polymer poly(3,4-ethylenedioxythiophene) doped with poly(styrene-sulfonate). Herein we show that thin films of partially oxidised multi-wall and sing...

We report measurements of the optical reflectance anisotropy RA of the Ag110 surface as a function of temperature and we find evidence for contributions to the RA spectrum from bulk band transitions that are modified by the anisotropic 110 surface. A comparison is made between temperature-induced shifts in the energy of RA peaks and thermovariation...

We report a detailed study of the interaction between surface-oxidized multiwall carbon nanotubes (o-MWCNTs) and the molecular semiconductor tetrasulfonate copper phthalocyanine (TS-CuPc). Concentrated dispersions of o-MWCNT in aqueous solutions of TS-CuPc are stable toward nanotube flocculation and exhibit spontaneous nanostructuring upon rapid dr...

Amorphous carbon-nickel composite films, which constitute a homogeneously mixed phase of carbon and 10% nickel, are prepared by UV pulsed laser ablation. From the low temperature conductivity study of these films, a nearly activated conduction followed by conductivity saturation below a temperature of 25 K has been identified. This is very differen...

Ag-SiO2 nanocomposite layers are synthesized by pulsed laser ablation at room temperature. The synthesized materials are characterized using XPS, RBS, SEM and TEM and the field emission properties are investigated

A water-soluble composite of oxidised multi-wall carbon nanotubes and sulphonic acid sodium salt derivatised copper phthalocyanine for application in bi-layer organic solar cells is reported. Measurements of the topography of thin films of this novel material and of the valence electronic structure of its two components are used to rationalise the...

We report a large reduction in the work function of acid oxidised multi-wall carbon nanotubes upon exchange of protons associated with acidic surface groups with the alkali metal cations Li+, Na+ and K+ measured using ultra-violet photoelectron spectroscopy. X-ray photoelectron spectroscopy provides compelling evidence for the preferential uptake o...

A homogeneously mixed phase of carbon and 10% nickel yielding amorphous carbon-nickel composite (a-C-Ni) films is prepared. by an excimer UV pulsed laser ablation. Conductivity study of these films shows a nearly activated conduction. Also a saturation of conductivity below a temperature of 25 K explains the presence of an additional density of sta...

We compare the RAS of the Au(110)1x2 surface and the RAS of surfaces formed by depositing and then annealing two monolayers of Pd deposited on the Au(110)1x2 surface. The similarities and differences between the RAS of the Au(110) 1x2 surface and the annealed Pd/Au(110) surface are consistent with the view that annealing gives rise to the formation...