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The present study aims to demonstrate the application of sugarcane bagasse as an excellent field emitter. Field emission property of as-pyrolyzed sugarcane bagasse (p-SBg) before and after the plasma treatment has been investigated. It has been observed that electronic nature of p-SBg transformed from semiconducting to metallic after plasma treatment. Maximum current and turn-on field defined at 10 μA/cm2 was found to be 800 μA/cm2 and 2.2 V/μm for as-pyrolyzed sugarcane bagasse (p-SBg) and 25 μA/cm2 and 8.4 V/μm for H2-plasma treated p-SBg. These values are found to be better than the reported values for graphene and activated carbon. In this report, pyrolysis of bagasse has been carried in a thermal chemical vapor deposition (Th-CVD) system in inert argon atmosphere. Scanning electron microscopy (SEM), X-ray Diffraction (XRD), High-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) have been used to study the structure of both pre and post plasma-treated p-SBg bagasse’s sample. HRTEM study reveals that carbonaceous structures such as 3D-nanographene oxide (3D-NGO), graphite nanodots (GNDs), carbon nanotubes (CNTs), and carbon onions are present in both pre-treated and plasma-treated p-SBg. Hence, we envision that the performed study will be a forwarding step to facilitate the application of p-SBg in display devices.

We report the growth of ultrathin diamond nanorods (DNRs) by a microwave plasma assisted chemical vapor deposition method using a mixture gas of nitrogen and methane. DNRs have a diameter as thin as 2.1 nm, which is not only smaller than reported one-dimensional diamond nanostructures (4-300 nm) but also smaller than the theoretical value for energetically stable DNRs. The ultrathin DNR is encapsulated in tapered carbon nanotubes (CNTs) with an orientation relation of (111)(diamond)//(0002)(graphite). Together with diamond nanoclusters and multilayer graphene nanowires/nano-onions, DNRs are self-assembled into isolated electron-emitting spherules and exhibit a low-threshold, high current-density (flat panel display threshold: 10 mA/cm(2) at 2.9 V/mu m) field emission performance, better than that of all other conventional (Mo and Si tips, etc.) and popular nanostructural (ZnO nanostructure and nanodiamond, etc.) field emitters except for oriented CNTs. The forming mechanism of DNRs is suggested based on a heterogeneous self-catalytic vapor-solid process. This novel DNRs-based integrated nanostructure has not only a theoretical significance but also has a potential for use as low-power cold cathodes.

Enhanced field emission is observed in nanocrystalline diamond (NCD) films upon irradiation with 100 MeV Ag9+ ions in the range of fluences from 5 × 1010 to 5 × 1011 ions/cm2. Field emission characteristics monotonically changes with the ion beam fluence, but does not show any correlation with sp2 cluster size induced. Enhancement of field emission is presumed to result from the formation of interconnected sp2 cluster network. The turn-on field (E0) for inducing the electron field emission (EFE) has been lowered from 28 to 3.2 V/μm, whereas the EFE current density has been increased from 1.4 × 10− 6 to 2.086 mA/cm2. Such EFE properties are comparable with those of carbon nanotubes.

Multi-wall nitrogenated carbon nanotubes (N-CNTs) are modified by the chlorine–plasma treatment (N-CNTs:Cl) and hence studied their field emission characteristics. It is observed that the turn-on voltage of N-CNTs is decreased from ~ 1.0 V/µm to ~ 0.875 V/µm on chlorination. The current density is enhanced from 1.3 mA/cm 2 (N-CNTs) to ~ 15 mA/cm 2 (N-CNTs:Cl) at an electric field of 1.9 V/µm. The X-ray absorption near edge structure spectra revels, the formation of different bonding of chlorine with carbon and nitrogen presence in the N-CNTs during the process of chlorine–plasma treatment by the charge transfer (or else) that increase the density of free charge carriers and hence enhanced the field emission characteristics of N-CNTs:Cl.

Different forms of diamond have been shown to have qualities as field emission sources. As a consequence, much effort has been focused on both the synthesis of diamond nanostructures to increase the field enhancement factor and understanding the emission mechanism in these nominally insulating materials. In our recent study, we have grown ultrananocrystalline diamond (UNCD) coated nanocrystalline diamond (NCD) tips on NCD films for field emitters. The films were characterized using field emission scanning electron microscopy and Raman spectroscopy to identify the quality of the films. The fabricated different sizes of pyramid tips and their field emission properties are reported. It has been observed that with increase in tip size, the turn on voltage also increases.

Nitrogen (N) ion implantation induced modification on structural and electron field emission (EFE) properties of ultrananocrystalline diamond (UNCD) films were reported. Low dose ion implantation slightly improved the EFE properties of UNCD films mainly due to the formation of defects and annealing brought the EFE parameters back to original state by eliminating the defects. Conversely, high dose ion implantation markedly enhanced the EFE properties for UNCD films possibly due to the induction of amorphous carbons for the UNCD films. The annealing process converts the amorphous phase into a more stable graphitic one such that the EFE properties persisted even after the annealing process.

Ultra-nanocrystalline diamond (UNCD) films prepared by microwave plasma enhanced chemical vapor deposition were implanted using 0.3 MeV nitrogen ions under a dose of 10 13 , 10 14 , and 10 15 ions cm − 2 . While the surface morphology of the UNCD films was not pronounced modified, the crystallinity of the films was changed appreciably due to ion implantation. The scratch test has been used to study the adhesion of the film to the substrate, which illustrated that the critical load, used as a measure of the adhesive strength, is found to increase with ion dose. Secondary ion mass spectroscopy (SIMS) analyses on the interfacial morphology indicated that the main factor in improving the adhesive strength is the modification on interfacial structure through inter-diffusion between film and substrate.

Single crystal diamond films of varying quality are deposited using microwave plasma chemical vapor deposition (MPCVD) apparatus. Unpolished natural diamond seeds are used as substrates in the temperature (Ts) range 850–1200 °C. The gas mixture of methane (CH4), hydrogen (H2) and oxygen (O2) is used for the deposition of diamond. The deposition pressure is varied in the range 90 to 150 Torr. The films are characterized using scanning electron microscopy (SEM), Atomic force microscopy (AFM) and Raman spectroscopy techniques. The growth morphology of the films is found to be a sensitive function of the deposition parameters. The crystalline nature of the films change from polycrystalline to single crystal as we increase Ts and for a certain set of parameters the filamentary growth of the diamond crystals can be seen. The films are polycrystalline in the range of substrate temperatures 850–900 °C and oriented grains of diamond crystals are evident as the Ts increases. The single crystal diamond growth is observed to proceed via the step growth mechanism with the evidence of bunching of the steps. Our study explores evolution of the growth of single crystal diamond in a wide range of parameters.

Carbon nanotubes (CNTs) filled with ferromagnetic materials have the potentials for use in magnetic scanning probe microscopy and as an assembly of aligned high density magnetic nanocores for future magnetic data storage devices. Highly ordered and uniform Ni-filled CNTs were deposited by chemical vapour deposition. As-grown Ni-filled CNTs were characterized using transmission electron microscopy, Raman spectroscopy and nano-area diffraction. The magnetic properties of Ni-filled CNTs were investigated using superconducting quantum interference device analysis. Magnetisation characterization, performed at temperature 2 K with magnetic field up to 2 T, showed better ferromagnetism compared to the bulk Ni.

The self-supported diamond sheets were deposited at various deposition pressure (Pd) using HFCVD technique. The sheets were characterized using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM). XRD shows the growth of cubic diamond. This is confirmed by Raman spectroscopy showing a sharp line at 1332 cm−1 in all the sheets. The sheets deposited at low pressures show clean sharp facets. The sheets were irradiated with high energy Au and Ag ions of varying energy and dose. The energy range was 100–120 MeV and the dose varied between 1×1012 and 3×1013 ions. Raman spectra showed the reduction in the intensity of diamond line (1332 cm−1) as well as non-diamond band at 1550 cm−1 after irradiation. SEM images of irradiated sheets show a phase transformation on the surface of the crystal. A photoluminescence (PL) signal is observed after the irradiation of the sheets at 2.634 eV., © Elsevier

Self-supported diamond sheets of the thickness ranging from 15 to 30 mum were prepared using hot filament chemical vapor deposition technique. The controlled variation of the deposition parameters resulted in the sheets with varying amount of nondiamond impurities. Routine characterization of the sheets was carried out using scanning electron microscopy, x-ray diffractometry, Raman spectroscopy, Fourier transform infrared spectroscopy, and Positron annihilation spectroscopy techniques. Detailed measurements of room temperature electrical conductivity (sigma (300)), current-voltage (I-V) characteristics, and annealing studies on the sheets deposited with various structural disorder have yielded useful information about the electrical conduction in this interesting material. sigma (300) and I-V characteristic measurements were done in sandwiched configuration taking care off the surface effects. The diamond sheets deposited at low deposition pressure (P-d< 60 Torr) contain negligible nondiamond impurities and show sigma (300)congruent to 10(-6)-10(-7) S.cm(-1). The I-V characteristics in these sheets show space charge limited conduction behavior with I proportional toV(n) and n >1, in high voltage range. In contrast the sheets deposited at higher pressure (60 Torr and higher), containing high concentration of nondiamond impurities, show a sharp reduction in the values of sigma (300). Interestingly, the conduction in these sheets is ohmic with n values nearly equal to unity. Similarly the sheets deposited with nitrogen also show a sharp reduction in sigma (300). Annealing of all types of diamond sheets results in a decrease in sigma (300) values by several orders of magnitude. In the sheets deposited at low P-d, the n values increase sharply with annealing. On the other hand the values of n in the sheets deposited at higher pressure remain constant with annealing. The above results are explained in terms of hydrogen abstraction from the traps and compensation of donor-acceptor pairs. (C) 2001

Nanocrystalline diamond films prepared by microwave plasma enhanced chemical vapor deposition (MPECVD) were implanted using 110 keV nitrogen ions under fluence ranging from 1013–1014 ions/cm2. Scanning Electron Microscopy (SEM) and Raman spectroscopy were used to analyze the changes in the surface of the films before and after ion implantation. Results show that with nitrogen ion implantation in nanocrystalline diamond film cause to decrease in diamond crystallinity. The field emission measurement shows a sharp increase in current density with increase in dose. The ion implantation also alters the turn on field. It is observed that the structural damage caused by ion implantation plays a significant role in emission behaviour of nanocrystalline diamonds.

Diamond windows prepared using hot filament chemical vapor deposition (CVD) were irradiated with Au and Ag ions of energy 100 and 130 MeV, respectively with fluence in the range 1010 to 3 × 1013 ions/cm2. Scanning electron microscopy (SEM) images showed substantial damage at the surface of the windows irradiated with Au+ of energy 100 MeV and fluence of 3 × 1013 ions/cm2. At some locations on the diamond windows deposited at 16 kPa, the surface layer appeared to have melted and flowed like a liquid exposing small crystallites underneath. Raman spectra of windows after irradiation showed i) a decrease in the intensity of the one-phonon line at 1332 cm− 1 along with an increase in its half width; ii) substantial reduction in the intensity of the graphite G band; and, iii) the appearance of a new band at 667 cm− 1. The band at 667 cm− 1 did not have a corresponding Stokes line and was therefore identified as a photoluminescence (PL) band. The ion induced damage and localized melting of CVD diamond windows are discussed in terms of the thermal spike model., © Elsevier

International audience; Multiwalled carbon nanotubes are grown by microwave plasma chemical vapor deposition with CH4 and H2 as precursor gases. Ni and Ni/Pt electroplated layers are used as catalysts for the synthesis of the tubes. We observe that a very efficient filling of the tubes takes place with Ni. In some cases Ni/Pt filling is also observed inside the tubes. High-resolution transmission electron microscopy (HRTEM) studies, coupled with energy-dispersive X-ray analyses of the tubes, indicate Ni nanorods with a highly symmetrical cylindrical structure. The diameter of the cylindrical nanorods is on the order of 40 nm, and their length is 660 nm. The nano area diffraction pattern of the nanorods reveals the cubic structure of nickel, and electron diffraction spots corresponding to (111), (200), (220) planes are evident. The lattice constant of Ni measured from the diffraction spots was found to be 0.347 ± 0.0013 nm. This should be compared with 0.352 nm, the value of "a" in bulk Ni. The decrease in the lattice constant may be due to the strain experienced inside the tubes. Raman spectroscopy shows the typical signature of the tangential breathing mode present in the tubes at 1580 cm-1 that shifts to a new position when the C12 is replaced by 13C. The shift, however, is too small and is difficult to explain on the basis of mass difference. HRTEM experiments indicate the presence of Ni3C in the samples dominantly in the interfacial region.

In this work we demonstrate that the field emission characteristics of disordered Si-doped diamond-like carbon (DLC) thin films depend not only on properties of the conductive clustered sp2 phase and the insulating sp3 matrix (or sp2/sp3 ratio) but also on the presence of Si–H n and C–H n species in the film. The presence of such species reduces the hardness of the film and simultaneously enhances the field emission performance. A turn on electric field (E TOF) of 6.76 V/µm produced a field emission current density of ∼0.2 mA/cm2, when an electric field of ∼20 V/µm was applied. The Fowler–Nordheim (FN) tunneling model is appropriate to explain the field emission mechanism only within limited range of the current density. However, it is found that there is an apparent crossover between space charge limited current (SCLC) and the Frenkel effect due to impurities incorporated during the fabrication of Si-DLC films. This combined effect (SCLC + Frenkel) allows for the emission of electrons from the top of the reduced barriers due to the formation of comparatively soft DLC:Si films. The emission also occurs through tunneling from one conductive cluster (sp2 C=C) to another separated by an insulating matrix (sp3 C–C) after reducing the effective depth of a trap on application of high electric field.

Enhanced electron field emission (EFE) behavior was observed in ultrananocrystalline diamond (UNCD) and microcrystalline diamond (MCD) films upon irradiation with 100 MeV Ag9+-ions in a fluence of 5×1011 ions/cm2. Transmission electron microscopy indicated that while the overall crystallinity of these films remained essentially unaffected, the local microstructure of the materials was tremendously altered due to heavy ion irradiation, which implied that the melting and recrystallization process have occurred along the trajectory of the heavy ions. Such a process induced the formation of interconnected nanocluster networks, facilitating the electron conduction and enhancing the EFE properties for the materials. The enhancement in the EFE is more prominent for MCD films than that for UNCD films, reaching a low turn-on field of E0=3.2 V/μm and large EFE current density of Je=3.04 mA/cm2 for 5×1011 ions/cm2 heavy ion irradiated samples.

With reference to our recent reports [Appl. Phys. Lett. 90, 192107 (2007); Appl. Phys. Lett. 91, 202102 (2007)] about the electronic structure of chlorine treated and oxygen-plasma treated nitrogenatcd carbon nanotubes (N-CNTs), here we studied the electron field emission effects on chlorination (N-CNT:Cl) and oxidation (N-CNT:O) of N-CNT. A high current density (J) of 15.0 mA/cm(2) has been achieved on chlorination, whereas low J of 0.0052 mA/cm(2) is observed on oxidation compared to J=1.3 mA/cm(2) for untreated N-CNT at an applied electric field E-A of similar to 1.9 V/mu m. The turn-on electric field (E-TO) was similar to 0.875. The 1.25 V/mu m was achieved for N-CNT:C1 and N-CNT:O, respectively, with respect to E-TO= 1.0 V/mu n for untreated one. These findings are due to the formation of different bonds with carbon and nitrogen in the N-CNT during the process of chlorine (oxygen)-plasma treatment by the charge transfer, or else that changes the density of free charge carriers and hence enhances (reduces) the field emission properties of N-CNTs:C1 (N-CNTs:O). (C) 2008 American Institute of Physics. [DOI: 10. 1063/1.2981090]

Possibility of Chemical Vapour Deposited (CVD) diamond coating on precision and complex geometry gave an extra edge over PCDs. Diamond-coating challenges are amplified by the fact that the primary market demand is for diamond coating on existing grades of tungsten carbide or steel tools. In this paper, we have reviewed some of the efforts made in the direction of improving quality and adhesion of diamond films to the respective substrates. With the advent of nanodiamond coating with reduced surface roughness and improved hardness, the machining of Metal Matrix Composites was made more economical.