Efficient production of NV colour centres in nanodiamonds using high-energy electron irradiation

Nanodiamond powders with an average size of 50 nm have been irradiated using high-energy electron beam. After annealing and chemical treatment, nanodiamond colloidal solutions were obtained and deposited on silica coverslips by spin-coating. The fluorescence of nanodiamonds was studied by confocal microscopy together with atomic force microscopy. We evaluated the proportion of luminescent nanodiamonds as a function of the irradiation duration and showed that large quantities, exceeding hundreds of mg, of luminescent nanodiamonds can be produced within 1 h of electron irradiation.     

Synthesis,properties, and applications of fractionated nanodiamonds

The methods for dispersing nanodiamond powders of different purity grades and preparing nanodiamond powder suspensions suitable for fractionation are analyzed. The main physicochemical properties of fractions separated from the synthesis products (blends) and purified nanodiamonds are investigated. It is found that the size distribution of nanodiamonds in the blend is inhomogeneous: an increase in the particle size leads to a decrease in the fraction of these particles. The advantages of nanodiamonds fractionated in size are demonstrated for different applications.     

Protective silicon coating for nanodiamonds using atomic layer deposition

Ultrathin silicon coating was deposited on nanodiamonds using atomic layer deposition (ALD) from gaseous monosilane (SiH₄). The coating was performed by sequential reaction of SiH₄ saturated adsorption and in situ decomposition. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were utilized to investigate the structural and morphological properties of the coating. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to compare the thermal stability of nanodiamonds before and after silicon coating. The results confirmed that the deposited cubic phase silicon coating was even and continuous. The protective silicon coating could effectively improve the oxidation resistance of nanodiamonds in air flow, which facilitates the applications of nanodiamonds that are commonly hampered by their poor thermal stability.     

Improving the performance of conventional glass fiber epoxy matrix composites by incorporating nanodiamonds

Multiscale glass fiber epoxy matrix composites containing nanodiamonds were fabricated using vacuum bagging technique. Three different loadings of nanodiamonds were incorporated in epoxy resin after their functionalization through ozone-treatment, i.e., 0.1, 0.3 and 0.5 wt%. The functionalization of nanodiamonds was confirmed by infrared spectroscopy, which improved the dispersion of nanodiamond in epoxy resin thus improving the mechanical properties. Tensile, compression, flexural and interlaminar shear properties of the composites were improved. The tensile, compression and flexural strengths improved up to 36, 56 and 30% by the addition of 0.5 wt% nanodiamonds while the corresponding moduli increased to 30, 125 and 46%, respectively. An improvement of 38% in interlaminar shear strength was observed. The microscopy of the composites was performed using optical and electron microscopy and proper impregnation of glass fibers and the absence of the agglomerates of nanodiamonds were ensured. The homogeneous dispersion of nanodiamonds and their adhering role at fiber/matrix interface improved the mechanical properties of the composites. The developed composites are ideal candidate materials for engineering applications demanding high specific mechanical properties.     

Carbon‐Dot‐Decorated Nanodiamonds

The synthesis of a new class of fluorescent carbon nanomaterials, carbon‐dot‐decorated nanodiamonds (CDD‐ND), is reported. These CDD‐NDs are produced by specific acid treatment of detonation soot, forming tiny rounded sp² carbon species (carbon dots), 1–2 atomic layers thick and 1–2 nm in size, covalently attached to the surface of the detonation diamond nanoparticles. A combination of nanodiamonds bonded with a graphitic phase as a starting material and the application of graphite intercalated acids for oxidation of the graphitic carbon is necessary for the successful production of CDD‐ND. The CDD‐ND photoluminescence (PL) is stable, 20 times more intense than the intrinsic PL of well‐purified NDs and can be tailored by changing the oxidation process parameters. Carbon‐dot‐decorated DNDs are shown to be excellent probes for bioimaging applications and inexpensive additives for PL nanocomposites.     

Small-angle neutron scattering by fractal clusters in aqueous dispersions of nanodiamonds

We considered how the choice of a model affects the treatment of data of small-angle neutron scattering by aqueous dispersions of detonation nanodiamonds. The scattering curves were analyzed using a general approach that combines the structure of nanodiamonds, the fractal organization of their clusters, and the interaction of clusters. The effect of the interaction between clusters on scattering was treated within the Guinier approximation.     

Surface chemistry of nanodiamonds

The experimental data available in the literature and the results obtained by the author in research into the structure of nanodiamonds and the physicochemical and chemical properties of their surface are generalized. An account is given of the problems concerning the chemical state and modification of the nanodiamond surface in gaseous and liquid media and the infiuence of modification on the sorption and catalytic properties of nanodiamonds, their compactibility, and sintering. The similarity and difference in the behavior of nanodiamonds and diamond macrocrystals in oxidation processes are discussed. The activation energies of oxidation of nanodiamonds by different reagents are determined in the absence and presence of catalysts.     

Synthesis,Characterization, Properties,and Novel Applications of Fluorescent Nanodiamonds

In the last few years, fluorescent nanodiamonds (FNDs)  have been developed significantly as a new member in the nanocarbon family. The surface of FNDs is embedded with some crystallographic defects containing color centres which surmount the properties of other fluorochromes including up conversion and down conversion nanoparticles, quantum dots, nano tubes, fullerenes, organic dyes, silica etc. Some of the intriguing properties like inevitable photostability, inherent bio-compatibility, outstanding optical and robust mechanical properties, excellent magnetic field, and electric field sensing potentiality make FNDs appealing to some benevolent applications in numerous fields like bio-imaging, delivering drugs, fighting cancer, spin electronics, imaging of magnetic structure at nanoscale and as promising nanometric temperature sensor. The structure of FNDs has certain point defects on the surface among which negatively charged nitrogen vacancy centre (NV^?) is the most investigated color centre. The production of NV^? fluorescence nanodiamonds is the most challenging task as substitution of carbon atoms is required to create vacancies by causing irradiation from an electron beam which is followed by high temperature annealing. Thus, this review points out the relative advantages of FNDs containing negatively charged nitrogen vacancy centres produced from HPHT method or CVD method with those nanodiamonds produced through detonation process or pulsed laser ablation (PLA) method. The steps involved in the fabrication of FNDs are described along with the major challenges and struggles underwent during the process in this review. This review also summarizes the recent developments made in the functionalization and applications predominantly made in the field of biological science and it is understood that depending on the defect color centres they can exhibit different emitted wavelengths ranging from UV–visible to near infrared with broad or narrow bandwidths. This review also highlights some of the fluorescent NDs that emit stable and strong red or green photoluminescence from the defect centers of NV^? which are implanted in the crystal lattice. This critical and extensive review will be useful for the further progress in this futuristic field of FNDs.

     

Not All Fluorescent Nanodiamonds Are Created Equal: A Comparative Study

Fluorescent nanodiamonds (FNDs) are vital to many emerging nanotechnological applications, from bioimaging and sensing to quantum nanophotonics. Yet, understanding and engineering the properties of fluorescent defects in nanodiamonds remain challenging. The most comprehensive study to date is presented, of the optical and physical properties of five different nanodiamond samples, in which fluorescent nitrogen‐vacancy (NV) centers are created using different fabrication techniques. The FNDs' fluorescence spectra, lifetime, and spin relaxation time (T₁) are investigated via single‐particle confocal fluorescence microscopy and in ensemble measurements in solution (T₁ excepted). Particle sizes and shapes are determined using scanning electron microscopy and correlated with the optical results. Statistical tests are used to explore correlations between the properties of individual particles and also analyze average results to directly compare different fabrication techniques. Spectral unmixing is used to quantify the relative NV charge‐state (NV^? and NV⁰) contributions to the overall fluorescence. A strong variation is found and quantified in the properties of individual particles within all analyzed samples and significant differences between the different particle types. This study is an important contribution toward understanding the properties of NV centers in nanodiamonds. It motivates new approaches to the improved engineering of NV‐containing nanodiamonds for future applications.     

以模拟计算的制造成品率为最终评价指标的光学薄膜自动设计

本文提出了一种自动设计思想,即在多层膜设计过程中考虑监控误差对多层膜光学特性的影响。在自动设计的评价函数中不仅包含了膜系的光学特性,而且还包含了计算机模拟的制备成品率,并以最高的生产成品率作为最终的优化目标。用这种方法设计出的膜系不仅满足光学特性要求,而且具有较大的制造允差,便于最经济地组织生产。以宽带减反射膜,可见光加1.06μm的双波段减反射膜为例进行了自动设计,设计结果是令人满意的。     

Selective inhibition of the oxidation of nanodiamonds for their cleaning

The effect of selective inhibition of nanodiamond oxidation upon heating of detonation carbon in air is used to extract nanodiamonds from the detonation products. The methods for cleaning nanodiamonds from nondiamond carbon modifications are described depending on the synthesis conditions.     

Currently available methods of industrial nanodiamond synthesis

The main theoretical aspects of detonation decomposition of powerful mixed explosives with a negative oxygen balance accompanied by the formation of nanodiamonds (ultrafine-dispersed diamonds, UDDs) are described. The basic UDD synthesis parameters are considered, and the expediency of using trotyl-hexogen alloys is shown. The conditions of diamond phase conservation in the detonation products are specified. Various versions of industrial detonation synthesis of UDDs are considered. The most efficient technology of chemical cleaning of UDDs (with nitric acid at high temperatures and pressures) for producing UDDs with the highest purity is described.

     

Nanodiamonds for biological investigations

Nanoparticles with a modified surface are prepared from nanodiamonds produced in Russia. The properties of modified nanodiamonds and their hydrosols and organosols are investigated by biophysicists with the aim of preparing nanoparticles with controlled properties for solving biological problems.     

Characterization of nanodiamonds for metamaterial applications

Several different types of nanodiamonds were characterized in order to find the best sample to be used in further experiments with metamaterials. In this work we present the results of optical analysis of aqueous suspensions containing nanodiamonds, SEM analysis of diamond particles dispersed on silicon substrates and measurements of photoluminescence from defects in nanodiamonds.     

Diamond nanocrystals hosting single nitrogen-vacancy color centers sorted by photon-correlation near-field microscopy

Diamond nanocrystals containing highly photoluminescent color centers are attractive, nonclassical, and near-field light sources. For near-field applications, the size of the nanocrystal is crucial, since it defines the optical resolution. Nitrogen-vacancy (NV) color centers are efficiently created by proton irradiation and annealing of a nanodiamond powder. Using near-field microscopy and photon statistics measurements, we show that nanodiamonds with sizes down to 25 nm can hold a single NV color center with bright and stable photoluminescence.     

Model of formation of three-dimensional polyurethane films modified by detonation nanodiamonds

The possibility of increasing the strain resistance of three-dimensional polyurethane films modified by detonation nanodiamonds is analyzed. It is found that the physicomechanical characteristics of polyurethane foams modified by nanodiamonds at a content of several thousandths of a weight percent change significantly. Models of the hardening of polyurethane films are proposed.     

A Review on Effects of Lubricant Formulations on Tribological Performance and Boundary Lubrication Mechanisms of Non-Doped DLC/DLC Contacts

Tribological efficiency of industrial applications involving boundary lubrication regime can be improved to an appreciable extent by the deposition of hard coatings on interacting surfaces. Among such coatings, diamond-like carbon (DLC) coatings are considered to be one of the most suitable ones for the said role. DLC coatings possess a unique combination of physical, chemical, and material properties due to which they can help in minimizing friction-induced energy and material losses even under starved lubrication conditions. Since commercial lubricants are optimized for steel surfaces, therefore, a lot of experimental investigations were carried out to analyze the tribological compatibility of these lubricants with various DLC coatings. However, there is still a lack of understanding about how DLC coatings interact with conventional lubricant additives. Some researchers reported tribologically beneficial interactions between DLC coatings and formulated lubricants while others observed no such behavior. To address these inconsistencies, there is a need to rearrange the published data in a more apprehensible and organized manner with a special emphasis on the mechanisms responsible for a particular tribological behavior. In this way, it can be determined whether synergistic or antagonistic correlation exists between a particular DLC-lubricant combination and research on DLC coatings can be continued in a logical way. In this article, most widely investigated non-doped DLC coatings (ta-C, a-C:H, a-C, and ta-C:H) are tribologically analyzed. Average values of friction and wear coefficients are calculated for various DLC-lubricant combinations using already published data and compared to quantify the effectiveness of a particular lubricant additive in enhancing tribological characteristics of symmetrical non-doped DLC contacts. Moreover, tribological performance parameters of non-doped DLC coatings are compared with those of doped-DLC coatings to understand differences in their tribological behavior in combination with additives.     

Structure of nanodiamonds prepared by laser synthesis

A study is reported of nanodiamonds obtained by a new method—pulsed laser ablation of a specially prepared carbon target. In the mechanism employed to produce a diamond phase, this method is similar to that of detonation synthesis of nanodiamonds. The main structural characteristics of the material have been determined and compared with the corresponding characteristics of detonation nanodiamonds.     

Investigation of an ejector scheme for forming heterogeneous supersonic flows under cold gas-dynamic spraying conditions

An ejector scheme intended for forming supersonic heterogeneous flows is experimentally examined as applied to conditions typical of cold gas-dynamic spraying. Pressure and temperature distributions in the supersonic part of the nozzle are reported, and critical operating regimes of the nozzle are identified. Specific features and advantages demonstrated by this scheme in practical applications are considered. Results of preliminary tests on the application of coatings with the use of the nozzle unit under study are presented. This work was financially supported by the Russian Foundation for Basic Research (Grants Nos. 06-08-00302 and 05-07-90172).     

Industrial applications of Mössbauer Spectroscopy

A review of the industrial applications of Mössbauer Spectroscopy is presented underlining the powerfulness and usefulness of the technique in the control and optimization of the production processes. A few examples are reported concerning the developments of thin protective coatings for structural parts and media for the magnetic recording field.