Nanodiamond Powder Research Articles

Optically detected magnetic resonance study of thermal effects due to absorbing environment around nitrogen-vacancy-nanodiamond powders

We implanted Fe+ ions in nanodiamond (ND) powder containing negatively charged nitrogen-vacancy (NV−) centers and studied their Raman spectra and optically detected magnetic resonance (ODMR) in various applied magnetic fields with green light (532 nm) excitation. In Raman spectra, we observed a blue shift of the NV− peak associated with the conversion of the electronic sp3 configuration to the disordered sp2 one typical for the carbon/graphite structure. In the ODMR spectra, we observed a red shift of the resonance position caused by local heating by an absorptive environment that recovers after annealing. To reveal the red shift mechanism in ODMR, we created a controlled absorptive environment around ND by adding iron-based Fe2O3 and graphitic sp2 powders to the ND suspension. This admixture caused a substantial increase in the observed shift proportional to the applied laser power, corresponding to an increase in the local temperature by 150–180 K. This surprisingly large shift is absent in non-irradiated NV-ND powders, is associated only with the modification of the local temperature by the absorptive environment of NV-NDs, and can be studied using ODMR signals of NV−.

Determination of non-combustible impurities in detonation nanodiamond powder

The study of the physicochemical (including adsorption) properties of nanodiamond requires the possibility of reproducible generation of the carbon surface of an individual particle without metal impurities of unknown composition. This kind of surface can be obtained through an additional deep cleaning of a commercially available sample. This article is dedicated to the study of the composition of non-combustible impurities of detonation nanodiamond powder. Using inductively coupled plasma mass spectrometry, iron and titanium were identified as the main metal components of the unburned residue, and the presence of Cr, Ni, Zr, As, and Sb was qualitatively established. The expected composition of the main molecular ions formed on the surface of the unburned residue in the course of laser desorption/ionisation mass spectrometry was presented. Based on the results of mass spectrometry analysis, a method of two-stage chemical treatment of detonation nanodiamond powder was proposed, which allowed reducing the mass fraction of non-combustible impurities during annealing in air from 2.0 to 0.1%.

Powders of Diamond Nanoparticles as a Promising Material for Reflectors of Very Cold and Cold Neutrons.

More than 15 years ago, the study of nanodiamond (ND) powders as a material for designing reflectors of very cold neutrons (VCNs) and cold neutrons (CNs) began. Such reflectors can significantly increase the efficiency of using such neutrons and expand the scope of their application for solving applied and fundamental problems. This review considers the principle of operation of VCN and CN reflectors based on ND powders and their advantages. Information is presented on the performed experimental and theoretical studies of the effect of the size, structure, and composition of NDs on the efficiency of reflectors. Methods of chemical and mechanical treatments of powders in order to modify their chemical composition and structure are discussed. The aim is to avoid, or at least to decrease, the neutron inelastic scatterers and absorbers (mainly hydrogen atoms but also metallic impurities and nitrogen) as well as to enhance coherent elastic scattering (to destroy ND clusters and sp2 carbon shells on the ND surface that result from the preparation of NDs). Issues requiring further study are identified. They include deeper purification of NDs from impurities that can be activated in high radiation fluxes, the stability of NDs in high radiation fluxes, and upscaling methods for producing larger quantities of ND powders. Possible ways of solving these problems are proposed.

ЭКСПЕРИМЕНТ ПО НИЗКОТЕМПЕРАТУРНОМУ ОБЛУЧЕНИЮ ПОРОШКА ФТОРИРОВАННЫХ ДЕТОНАЦИОННЫХ НАНОАЛМАЗОВ В РЕАКТОРЕ ВВР-К: УСЛОВИЯ И ПЕРВИЧНАЯ ХАРАКТЕРИЗАЦИЯ ОБРАЗЦОВ

Fluorine-doped detonation nanodiamond (DND) powders are considered as a new class of neutron reflectors and can significantly improve the performance of very cold and ultracold neutron sources, which in turn will lead to new types of experiments at a qualitative level. These improvements are achieved due to such properties of DNDas high diffusion and quasi-mirror reflection. The high reflectivity improves the neutron delivery efficiency and, consequently, the neutron fluxes at neutron facilities. On this basis, fluorinated DNDs are considered as a potential neutron reflector material for the designed very cold and ultracold neutron source at the WWR-K reactor. However, to date, experimental data on the behaviour of fluorinated DND in the neutron field are insufficient, and therefore, in order to study the radiation resistance of DND at the WWR-K reactor, work has been started on their irradiation and further study. For this purpose, an optimal irradiation capsule design was developed and comprehensive calculations were performed to justify the conditions and limits of reactor irradiation. This paper describes the irradiated samples and reactor experiment, the methodology and conditions for irradiating the samples, and the results of their initial characterisation after irradiation.

Silicon-Nanodiamond-Based Anode for a Lithium-Ion Battery.

Maintaining the physical integrity of a silicon-based anode, which suffers from damage caused by severe volume changes during cycling, is a top priority in its practical applications. The performance of silicon-flake-based anodes has been significantly improved by mixing nanodiamond powders with silicon flakes for the fabrication of anodes for lithium-ion batteries (LIBs). Nanodiamonds adhere to the surfaces of silicon flakes and are distributed in the binder between flakes. A consistent and robust solid electrolyte interphase (SEI) is promoted by the aid of abundant reactive surface-linked functional groups and exposed dangling bonds of nanodiamonds, leading to enhanced physical integrity of the silicon flakes and the anode. The battery's high-rate discharge capabilities and cycle life are thus improved. SEM, Raman spectroscopy, and XRD were applied to examine the structure and morphology of the anode. Electrochemical performance was evaluated to demonstrate a capacity retention of nearly 75% after 200 cycles, with the final specific capacity exceeding 1000 mAh/g at a test current of 4 mA/cm2. This is attributed to the improved stability of the solid electrolyte interphase (SEI) structure that was achieved by integrating nanodiamonds with silicon flakes in the anode, leading to enhanced cycling stability and rapid charge-discharge performance. The results from this study present an effective strategy of achieving high-cycling-performance by adding nanodiamonds to silicon-flake-based anodes.

Understanding continuous wave laser-induced chemical reactions at micro- and nano-diamond-glass interface under infrared excitation

This work addresses the issue of laser-induced white light generation by nano- and micro-diamond powder and the accompanying redox processes occurring at the surface of the particles. The broadband white light is generated by near infra-red continuous wave laser (975 nm) on micro and nano-diamond powders sealed in lightbulb-like devices. It is shown that the emission from diamond samples is a highly nonlinear process with apparent saturation close to 1 W of the optical excitation power. Multiband mechanism and mixed hybridization at particle surface are further discussed as a possible origin of the white light emission. Changes in the sp2/sp3 ratio upon the laser excitation are here discussed in terms of molecular dynamics simulations. Observed surface changes related to diamond graphitization are considered further as possible pathways for chemical reactions at the interface of the glass and diamond samples. Obtained results bring relevant physical premises according to the possible mechanism responsible for the white emission from diamond-like carbon materials, its mechanisms, and an essential figure of merit considering the diverse applicability of this phenomenon in various electronic devices.

Progress in coupling MPGD-based photon detectors with nanodiamond photocathodes

The next generation of gaseous photon detectors is requested to overcome the limitations of the available technology, in terms of resolution and robustness. The quest for a novel photocathode, sensitive in the far vacuum ultra violet wavelength range and more robust than present ones, motivated an R&D programme to explore nanodiamond based photoconverters, which represent the most promising alternative to cesium iodine. A procedure for producing the novel photocathodes has been defined and applied on THGEMs samples. Systematic measurements of the photo emission in different Ar/CH4 and Ar/CO2 gas mixtures with various types of nanodiamond powders have been performed. A comparative study of the response of THGEMs before and after coating demonstrated their full compatibility with the novel photocathodes.

Effect of diamond seeds size on the adhesion of CVD diamond coatings on WC-Co instrument

In this study, we investigated the effect of the size of diamond seeds on the adhesion of multilayered polycrystalline diamond (PCD) films, grown by microwave plasma-assisted chemical vapor deposition (MPCVD). For that, identical WC-Co substrates were separately seeded by a set of diamond powders with various average particle sizes from water-based suspensions using similar seeding procedures. This investigation included powders with a difference in particle sizes of nearly 3 orders of magnitude: from 5 nm up to 2-4 μm. Seeded substrates were used to grow 8-10 μm thick multilayered PCD films using MPCVD with time-limited cycling injections of N2 gas. The Raman spectra and scanning electron microscopy (SEM) studies showed the similarity of microstructure and phase composition of all grown films, which confirmed that all films were grown in similar conditions. The performed scratch tests revealed sufficient differences in the adhesion of the films seeded with different diamond particles. The PCD film grown on 250-500 nm particles delaminated even before any mechanical investigations. The substrates seeded with 50 nm particles allowed the formation of the stable PCD film, but it started flaking under a load as small as 15 N. The 2-4 μm powder allowed the formation of PCD film with decent adhesion, which had local flaking under scratch test, which can be explained by the inhomogeneity of seeds distribution. Detonation nanodiamond (DND) powders allowed the formation of continuous diamond films with decent adhesion, however, powders with positive zeta potential were superior due to a much lower agglomeration of separate particles.

Air Oxidation Disaggregates the Nanodiamond Powder

Air Oxidation Disaggregates the Nanodiamond Powder

Nanodiamond-promoted white light emission in Eu, Dy, and Cu-containing phosphate glass: quantitative analysis and colorimetric study.

A thorough analysis of glass containing Eu2 O3 and Dy2 O3 , or Eu2 O3 , Dy2 O3 , and CuO melted together with nanodiamond powder was pursued based on measurements of optical absorption, photoluminescence (PL) emission and excitation spectra, and colorimetry. Nanodiamond facilitated the stabilization of Cu+ and Eu2+ ions with blue-emitting characteristics that, along with yellow-emitting Dy3+ and red-emitting Eu3+ led to the white light-emitting glass. Novel intensity notations implemented in intensity-based spectral ratios, and difference intensity correlation analysis were proposed for the assessment of PL properties. The chromaticity and correlated colour temperature of the emission were ultimately investigated as a two-parametric problem based on: (1) the different ionic components; and (2) the various excitation wavelengths employed. The optical analysis approach adds to the characterization methods to further fundamental understanding and provide helpful analytical tools for designing materials for tunable white light-emitting devices.

Effect of Nanodiamond Sizes on the Efficiency of the Quasi-Specular Reflection of Cold Neutrons.

Nanomaterials can intensively scatter and/or reflect radiation. Such processes and materials are of theoretical and practical interest. Here, we study the quasi-specular reflections (QSRs) of cold neutrons (CNs) and the reflections of very cold neutrons (VCNs) from nanodiamond (ND) powders. The fluorination of ND increased its efficiency by removing/replacing hydrogen, which is otherwise the dominant cause of neutron loss due to incoherent scattering. The probability of the diffuse reflection of VCNs increased for certain neutron wavelengths by using appropriate ND sizes. Based on model concepts of the interaction of CNs with ND, and in reference to our previous work, we assume that the angular distribution of quasi-specularly reflected CNs is narrower, and that the probability of QSRs of longer wavelength neutrons increases if we increase the characteristic sizes of NDs compared to standard detonation nanodiamonds (DNDs). However, the probability of QSRs of CNs with wavelengths below the cutoff of ~4.12 Å decreases due to diffraction scattering on the ND crystal lattice. We experimentally compared the QSRs of CNs from ~4.3 nm and ~15.0 nm ND. Our qualitative conclusions and numerical estimates can help optimize the parameters of ND for specific practical applications based on the QSRs of CNs.

Study of nanodiamond photocathodes for MPGD-based detectors of single photons

The proposed new Electron–Ion Collider poses a technical and intellectual challenge for the detector design to accommodate the long-term diverse physics goals envisaged by the program. This requires a 4π detector system capable of reconstructing the energy and momentum of final state particles with high precision. The Electron-Ion Collider also requires identification of particles of different masses over a wide momentum range.A diverse spectrum of Particle IDentification detectors has been proposed. Of the four types of detectors for hadron identification, three are based on Ring Imaging Cherenkov Counter technologies, and one is realized by the Time of Flight method. The quest for a novel photocathode, sensitive in the far vacuum ultraviolet wavelength range and more robust than cesium iodide, motivated an R&D programme to explore nano-diamond (ND) based photocathodes, started by a collaboration between INFN and CNR Bari and INFN Trieste. Systematic measurements of the photoemission in different Ar:CH4 and Ar:CO2 gas mixtures with various types of ND powders and Hydrogenated ND (H-ND) powders are reported. A first study of the response of THGEMs coated with different photocathode materials is presented.The progress of this R&D programme and the results obtained so far by these exploratory studies are described.

Enhanced directional extraction of very cold neutrons using a diamond nanoparticle powder reflector.

For more than a decade, detonation nanodiamond (DND) powders have been actively studied as a material for efficient reflectors of very cold neutrons (VCNs) and cold neutrons. In this work, we experimentally demonstrate, for the first time, the possibility of enhanced directional extraction of a VCN beam using a reflector made of fluorinated DND powder. With respect to the theoretical flux calculated from an isotropic source at the bottom of the reflector cavity, the gain in the VCN flux density along the beam axis is ∼10 for the neutron velocities of ∼57 and ∼75m/s. The use of such reflectors for enhanced directional extraction of VCN from neutron sources will make it possible to noticeably increase the neutron fluxes delivered to experiments and expand the scope of VCN applications.

Amorphous Carbon Films with Embedded Well-Dispersed Nanodiamonds: Plasmon-Enhanced Analysis and Possible Antimicrobial Applications

An amorphous carbon film with embedded detonation nanodiamond (DND) particles (a-C:ND) was produced by magnetron sputtering of nanodiamond powder. An Ag film was deposited on the carbon structure by radiofrequency magnetron sputtering. The silver film was irradiated with a 150 eV Ar+ to form plasmonic-active nanoparticles (NP) on the surface of the a-C:ND. The structure of the obtained a-C:ND and a-C:ND/Ag structures were studied by scanning and transmission electron microscopy, electron energy-loss spectroscopy, UV–Visible absorption spectroscopy, Raman spectroscopy, and fluorescence lifetime imaging at two-photon excitation. The analysis revealed 76% of sp3-carbon and a good dispersion of diamond nanoparticles in the a-C. Surface-enhanced Raman scattering (SERS) was applied to investigate the a-C:ND/Ag structure, allowing for the observation of SERS from the sp2-carbon species and the absence of significant a-C:ND damage after Ar+ irradiation of the Ag overlayer. A plasmonic-metal-enhanced luminescence was observed at one- and two-photon excitations, revealing a two- to five-fold intensity increase. The activity of the used DNDs was tested using the agar diffusion method and observed against the bacteria of Bacillus subtilis, Staphylococcus aureus, and Escherichia coli and the fungi of Aspergillus niger, Aspergillus fumigatus, and the yeast of Candida albicans, showing DND activity against all the test strains of fungi.

Nano-Diamond Reinforced Polymer Separators for Energy Dense Lithium-Ion Batteries

Traditional polyolefin separators tend to perform poorly against heat-triggering reactions causing potentially catastrophic issues in lithium-ion batteries (LIBs). In this study, we developed a high temperature resistant, flexible, mechanically robust and highly ionically conductive composite separator made from electrochemically stable polymer encased with nanodiamonds (NDs). We systematically study the effect of ND concentration in the polymer matrix of the membrane to improve the thermal, mechanical and electrochemical properties of the composites. When tested in LIB with high-voltage LiNiMnCoO2 (NMC), these novel separators exhibited substantially superior performance when compared with commercial polyolefin separator membranes. These cells exhibited closed-to-theoretical capacity (200mAhg-1 NCM), excellent rate capability and minimal degradation for over 150 cycles. Our study showcased the capability of ND powder as a nano-sized filler materials for the fabrication of composite membranes with superior properties, and opened up the broad possibilities of composite membrane fabrications by varying the polymer composition, micro-structure, nanoparticle surface chemistry and concentrations.

Physico-chemical analysis of white light-emitting Eu, Dy and Cu tri-doped plasmonic glasses synthesized via nanodiamond

Phosphate glasses containing Eu2O3, Dy2O3 and CuO were melted together with nanodiamond (ND) powder for an assessment of optical and plasmonic properties aiming for the tuning of light-emitting properties towards photonic applications. A thorough evaluation incorporating optical absorption, differential scanning calorimetry, Raman scattering, and photoluminescence (PL) spectroscopy was carried out. The presence of ND allowed for the stabilization of the Cu+ ions with blue-emitting character alongside the yellow-emitting Dy3+ and red-emitting Eu3+ ions thus allowing for attaining the white light-emitting glasses. Further heat treatment within 470–490 °C of the tri-doped glass resulted in the development of the surface plasmon resonance (SPR) characteristic of Cu nanoparticles (NPs). A strong correlation of the optical bandgaps with SPR development is revealed. Further, a novel approach for assessing the activation energy for Cu NP precipitation is proposed linked to the glass transition temperature of the host. Subsequently, the effect of the plasmonic character on the PL properties was evaluated and correlated to the emission color. Correlated color temperature and chromaticity shifts were assessed and analyzed. The study contributes to the fundamental understanding and design of materials for tunable white light-emitting devices and the influence of incorporating plasmonic nanostructures attractive for photonic applications.

Improved beam extraction at compact neutron sources using diamonds nanoparticles and supermirrors

Aimed to investigate potential benefits from mounting reflecting layers of diamond nanoparticles or supermirrors in neutron extraction channels, a conceptual compact neutron source was designed using Geant4 and MCNP. The scattering of low-energy neutrons with nanodiamonds was implemented in Geant4 and validated with existing experimental data. The source design was based on a 13 MeV proton beam hitting a beryllium target, with neutron moderation facilitated by a water premoderator, supplemented by a quasi 1-dimensional parahydrogen moderator, before emission towards a few (2–5) beamlines. In an attempt to increase the neutron flux available for experiments, reflecting layers of diamond nanoparticles or supermirrors were placed in the neutron extraction channel, and results for different implementations were assessed and compared.The results show that the cold neutron flux is increased by using the nanodiamond powder, in particular for large divergence neutrons (greater than 2°), but a significant effect is observed also for low-divergence neutrons, which are of particular interest to neutron scattering experiments. The effect is dependent on the neutron wavelength and the size of nanodiamonds, with larger effects in general obtained for longer wavelengths, and particles of larger size. The same configuration was studied, where instead of nanodiamonds, supermirrors were used. The use of supermirrors at the beam extraction predicts even higher potential gains. These results are very promising to increase the efficiency of compact sources and can be applied to various configurations of such sources.

Obtaining nanocrystalline superhard materials from surface-modified nanodiamond powder

Obtaining nanocrystalline superhard materials from surface-modified nanodiamond powder

Thermal Conductivity of Detonation Nanodiamond Hydrogels and Hydrosols by Direct Heat Flux Measurements.

The methodology and results of thermal conductivity measurements by the heat-flow technique for the detonation nanodiamond suspension gels, sols, and powders of several brands in the range of nanoparticle concentrations of 2–100% w/w are discussed. The conditions of assessing the thermal conductivity of the fluids and gels (a FOX 50 heat-flow meter) with the reproducibility (relative standard deviation) of 1% are proposed. The maximum increase of 13% was recorded for the nanodiamond gels (140 mg mL−1 or 4% v/v) of the RDDM brand, at 0.687 ± 0.005 W m−1 K−1. The thermal conductivity of the nanodiamond powders is estimated as 0.26 ± 0.03 and 0.35 ± 0.04 W m−1 K−1 for the RUDDM and RDDM brands, respectively. The thermal conductivity for the aqueous pastes containing 26% v/v RUDDM is 0.85 ± 0.04 W m−1 K−1. The dignities, shortcomings, and limitations of this approach are discussed and compared with the determining of the thermal conductivity with photothermal-lens spectrometry.

Effect of Particle Sizes on the Efficiency of Fluorinated Nanodiamond Neutron Reflectors.

Over a decade ago, it was confirmed that detonation nanodiamond (DND) powders reflect very cold neutrons (VCNs) diffusively at any incidence angle and that they reflect cold neutrons quasi-specularly at small incidence angles. In the present publication, we report the results of a study on the effect of particle sizes on the overall efficiency of neutron reflectors made of DNDs. To perform this study, we separated, by centrifugation, the fraction of finer DND nanoparticles (which are referred to as S-DNDs here) from a broad initial size distribution and experimentally and theoretically compared the performance of such a neutron reflector with that from deagglomerated fluorinated DNDs (DF-DNDs). Typical commercially available DNDs with the size of ~4.3 nm are close to the optimum for VCNs with a typical velocity of ~50 m/s, while smaller and larger DNDs are more efficient for faster and slower VCN velocities, respectively. Simulations show that, for a realistic reflector geometry, the replacement of DF-DNDs (a reflector with the best achieved performance) by S-DNDs (with smaller size DNDs) increases the neutron albedo in the velocity range above ~60 m/s. This increase in the albedo results in an increase in the density of faster VCNs in such a reflector cavity of up to ~25% as well as an increase in the upper boundary of the velocities of efficient VCN reflection.