Boron Carbonitride Research Articles

Synthesis of Hexagonal Boron Carbonitride without Nitrogen Void Defects

The synthesis and structure of hexagonal boron carbonitride (h-BCN) film on polycrystalline diamond surface were reported. Polycrystalline diamond and/or diamond-like carbon were first fabricated on Si (100) and then diamond like carbon was used as substrate. The deposition was performed by radio frequency plasma enhanced chemical vapor deposition. In order to reduce the content of nitrogen void defects, the deposition was performed at the high temperature of 950°C under the working pressure of 2.6 Pa. The typical sample with atomic composition of B31 C37 N26 O6 in the h-BCN lattice was characterized by X-ray photoelectron spectroscopy. The fine structure of the film was studied by near-edge X-ray absorption fine structure (NEXAFS) measurements. The B K-edge and N K-edge of NEXAFS spectra revealed that the synthesized h-BCN film had the ideal honeycomb- like BN3 configuration without nitrogen void defects.

Interstitial boron doping effects on the electronic and magnetic properties of graphitic carbon nitride materials

Using first-principles calculations based on density functional theory, we explore the interstitial boron doping effects on the geometrical and electronic structures of graphitic carbon nitrides (g-C3N4 and g-C4N3) and reveal the favorable interstitial boron doping configurations. By analyzing the formation energies of boron-doped systems, we show that boron atoms can be easily doped in g-C4N3 rather than in g-C3N4. Boron doping significantly changes the electronic structure of g-C4N3 from half-metallic to metallic system and from magnetism to non-magnetism after different degrees of doping. Analysis of the density of states and the spatial distribution of spin-polarized electron densities provides an insight into the mechanism underlying such changes. The conclusions obtained in this study are helpful for future studies of two dimensional carbon nitride or boron carbonitride materials.

BCN nanotubes as highly sensitive torsional electromechanical transducers.

Owing to their mechanically tunable electronic properties, carbon nanotubes (CNTs) have been widely studied as potential components for nanoelectromechanical systems (NEMS); however, the mechanical properties of multiwall CNTs are often limited by the weak shear interactions between the graphitic layers. Boron nitride nanotubes (BNNTs) exhibit a strong interlayer mechanical coupling, but their high electrical resistance limits their use as electromechanical transducers. Can the outstanding mechanical properties of BNNTs be combined with the electromechanical properties of CNTs in one hybrid structure? Here, we report the first experimental study of boron carbonitride nanotube (BCNNT) mechanics and electromechanics. We found that the hybrid BCNNTs are up to five times torsionally stiffer and stronger than CNTs, thereby retaining to a large extent the ultrahigh torsional stiffness of BNNTs. At the same time, we show that the electrical response of BCNNTs to torsion is 1 to 2 orders of magnitude higher than that of CNTs. These results demonstrate that BCNNTs could be especially attractive building blocks for NEMS.

Optical and electrical characteristics of plasma enhanced chemical vapor deposition boron carbonitride thin films derived from N-trimethylborazine precursor

Thin BCxNy films have been obtained by plasma enhanced chemical vapor deposition using N-trimethylborazine as a precursor. The films were deposited on Si(100) and fused silica substrates. The grown films were characterized by ellipsometry, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray energy dispersive spectroscopy, X-ray photoelectron spectroscopy, spectrophotometry, capacitance–voltage and current–voltage measurements. The deposition parameters, such as substrate temperature (373–973K) and gas phase composition were varied. Low temperature BCxNy films were found to be high optical transparent layers in the range of 300–2000nm, the transmittance as high as 93% has been achieved. BCxNy layers are dielectrics with dielectric constant k=2.2–8.9 depending on the synthesis conditions.

Analysis features of elemental composition of boron carbonitride films by EDS

Features of the analysis of elemental composition of thin boron carbonitride films by energy dispersive X-ray spectroscopy are discussed. The films are also studied by IR spectroscopy and scanning electron microscopy in order to obtain data on their elemental composition, types of chemical bonds, and surface morphology. The effect of film thickness and electron beam energy on the results of energy dispersive X-ray spectroscopy is also investigated.

Direct chemical conversion of graphene to boron- and nitrogen- and carbon-containing atomic layers

Graphene and hexagonal boron nitride are typical conductor and insulator, respectively, while their hybrids hexagonal boron carbonitride are promising as a semiconductor. Here we demonstrate a direct chemical conversion reaction, which systematically converts the hexagonal carbon lattice of graphene to boron nitride, making it possible to produce uniform boron nitride and boron carbonitride structures without disrupting the structural integrity of the original graphene templates. We synthesize high-quality atomic layer films with boron-, nitrogen- and carbon-containing atomic layers with full range of compositions. Using this approach, the electrical resistance, carrier mobilities and bandgaps of these atomic layers can be tuned from conductor to semiconductor to insulator. Combining this technique with lithography, local conversion could be realized at the nanometre scale, enabling the fabrication of in-plane atomic layer structures consisting of graphene, boron nitride and boron carbonitride. This is a step towards scalable synthesis of atomically thin two-dimensional integrated circuits.

A polarization rule on atomic arrangements of graphite-like boron carbonitride

B and N K-edge near-edge X-ray absorption fine structure (NEXAFS) spectra of boron carbonitride (B–C–N) films prepared by ion beam deposition are interpreted by molecular orbital calculations with the core–hole effect. Model clusters with different atomic arrangements are compared in terms of photoabsorption cross section (PACS) and net charge, and they are classified into two groups, i.e., polarization and non-polarization types. PACS of π∗ peaks near the lowest unoccupied molecular orbital (LUMO) state increase at B K-edge and decrease at N K-edge for polarization type and vice versa for non-polarization type. Based on a comparison between experimental and theoretical results, we propose a rule for atomic arrangements of boron, carbon, and nitrogen atoms in graphite-like B–C–N. Finally, the relationship between the rule and structural stability is discussed.

Direct synthesis of electrical-conductivity-controlled boron-carbonitride films on SiO2 substrates

In this study, electrical-conductivity-controlled boron-carbonitride (BCN) films were synthesized directly on SiO2 substrates by using thermal chemical vapor deposition (TCVD) with solid mixtures containing polystyrene (PS) and ammonia borane. The BCN films had atomically smooth surfaces. The carbon content of the BCN films was simply controlled by modulating the weight of PS in the precursor mixture, which allowed the electrical conductivity of the BCN film to be controlled. In addition, we found that selection of an appropriate growth temperature determined the resulting semiconducting or metallic behavior of the BCN film.

PECVD synthesis and optical properties of BCXNY films obtained from N-triethylborazine as a single-source precursor

Thin films of boron carbonitride BCxNy were synthesized by plasma enhanced chemical vapor deposition using N-triethylborazine as a B-C-N-forming single source precursor. In this work, we investigated the effect of additional gases and temperature synthesis on the chemical composition of the BCxNy films. The plasma was activated via 40.68MHz radio frequency. It was found by FTIR spectroscopy that the low temperature films (Tdep<400°C) are hydrogenated boron carbonitride BCxNy:H. It was shown by Raman spectroscopy that the films synthesized at high temperature (Tdep≥600°C) contain an additional phase of disordered carbon. The refractive index of the BCxNy films increased from 1.5 to 2.8 with increasing temperature of the synthesis. Low temperature films exhibit high transmittance values in the region from 400 to 3200nm (transparency up to 93%). The optical band gap energy ranged from 1.2 to 4.9eV for the films deposited under considered synthesis conditions.

Hexagonal Nano-Crystalline BCN Films Grown on Si (100) Substrate Studied by X-Ray Absorption Spectroscopy

Hexagonal nano-crystalline boron carbonitride (h-BCN) films grown on Si (100) substrate have been precisely investigated. The films were synthesized by radio frequency plasma enhanced chemical vapor deposition using tris-dimethylamino borane as a single-source molecular precursor. The deposition was performed by setting RF power at 400 - 800 W. The reaction pressure was at 2.6 Pa and the substrate temperature was recorded at 700°C - 800°C. Formation of the nano-crystalline h-BCN compound has been confirmed by X-ray diffraction analysis. The diffraction peaks at 26.3° together with a small unknown peak at 29.2° were elucidated due to the formation of an h-BCN structure. The films composed of B, C, and N atoms with different B-N, B-C, C-N chemical bonds in forming the sp2-BCN atomic configuration studied by X-ray photoelectron spectroscopy. Orientation and local structures of the h-BCN hybrid were studied by near-edge X-ray absorption fine structure (NEXAFS) measurements. The dominant presence of p* and s* resonance peaks of the sp2-hybrid orbitals in the B K-edge NEXAFS spectra revealed the formation of the sp2-BCN configuration around B atoms like-BN3 in h-BN. The orientation was suggested on the basis of the polarization dependence of B K-edge and N K-edge of the NEXAFS spectra.

Effect of Y2O3 and SiO2 additions on the phase formation and properties of the hot-pressed boron carbonitride composite

The dependence of phase composition and properties of the BCN composite with additions of Y2O3 and SiO2 (quartz glass) on hot-pressing temperature is studied. It is established that new strengthening phases form with the composite during reaction pressure sintering. The optimum conditions for producing the BCN composite are found. The BCN composite has high thermal strength, oxidation resistance, and electrical insulating properties.

A novel hyperbranched polyborazine and its reactive blend with benzoxazine thermosets

Boron carbonitride polymers have been arising abiding interest due to their excellent thermal and mechanical properties. In this study, a novel kind of hyperbranched polymer based on boron carbonitride skeleton, polyborazine, has been synthesized by a convenient A2+B3 approach. The chemical structure of polyborazine was confirmed by Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), and size exclusion chromatography (SEC). FT-IR and X-ray diffraction (XRD) pattern exhibited that the boron carbonitride compound formed during the pyrolysis process contributed to the improved thermal property of polyborazine. Nevertheless, the polyborazine can catalyze the cure process of benzoxazine thermosets, and enhance the thermal stability of benzoxazine thermosets owning to the presence of the preceramic compound. The approach for fabricating reactive ceramic precursor polymer with prepolymer blend system reveals promising results for thermosets that demanding remarkable thermal stability and oxidation resistance. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

X-ray spectroscopic study of the electronic structure of boron carbonitride films obtained by chemical vapor deposition on Co/Si and CoO x /Si substrates

Boron carbonitride films are synthesized by chemical vapor deposition from a mixture of triethylamine borane and ammonia on a metallic or oxidized cobalt sublayer sprayed over Si(100) substrates. Scanning electron microscopy shows that the surface of a BCxNy/Co/Si sample has a homogeneous fine-grained structure; filamentous entities are found on the surface of the BCxNy/CoOx/Si sample. The electronic structure of the films is investigated by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure spectroscopy (NEXAFS). An analysis of the spectra shows that BCxNy films are composed of graphite and hexagonal boron nitride (h-BN) regions and complex BCxNyOz components with B-C, N-C, B-O, N-O, and C-O bonds. The deposition of the BCxNy film on the oxidized Co sublayer results in an increase in the number of C-O, N-O, B-O, and C-N bonds and a decrease of the graphite and h-BN components and in the number of C-B bonds. The XPS data are used to estimate the surface elemental composition of the BCxNy/CoOx/Si sample. It is found that the film consists of 66 at.% graphite component and 3 at.% h-BN; the proportion of complex C0.46B0.11N0.05O0.38 components is 31 at.%.

First‐principles study of oxidized BC2N nanotubes

AbstractSpin‐polarized density functional theory and norm conserving fully separable pseudopotentials are used to study the structural and electronic properties of atomic oxygen defects (substitution and adsorbed) as well as the O2 adsorption in (3,3) and (5,0) BC2N nanotubes. For the adsorbed molecules, detailed calculations are performed by introducing the van der Waals interactions through the B97‐D functional proposed by Grimme. The most stable configuration for the adsorbed oxygen atom is in the interstitial site binding with boron and carbon atoms (BOCI configuration), and for the substitutional doping, the most stable configuration occurs when the oxygen substitutes the nitrogen atom (ON). For these two defects, the calculated formation energies are −1.67 and 0.62 eV, respectively. The calculated electronic band structures show that the ON defect leads the system to exhibit a p‐type semiconductor character, whereas the interstitial oxygen atom does not introduce any significant changes in the electronic states near the band gap region. The interaction between the nanotubes and the O2 molecule is investigated by the adsorption of the molecule in the inner and outer surfaces of the nanotubes. The calculated binding energies show that the molecule in the triplet state is physically adsorbed in the inner surface with the molecular axis perpendicular to the nanotube axis. For the molecule in the singlet state, the most stable configuration occurs when the molecule interact with the outer surface and bind (weakly) with a boron atom. We also observe spin transference between the molecule and the tube leading the boron carbonitrides (BCN) nanostructures as candidate to storage and detect the O2 molecules. © 2012 Wiley Periodicals, Inc.

Chemical interactions in the layered system BC x N y /Ni(Cu)/Si, produced by CVD at high temperature

Layered samples Si(100)/C/Ni/BC(x)N(y) and Si(100)/C/Cu/BC(x)N(y) were produced by physical vapor deposition of a metal (Ni, Cu, resp.) and low-pressure chemical vapor deposition of the boron carbonitride on a Si(100) substrate. Between the Si and the Ni (Cu) and on the surface of the Ni (Cu) layer, thin carbon layers were deposited, as a diffusion barrier or as a protection against oxidation, respectively. Afterwards, the surface carbon layer was removed. As precursor, trimethylamine borane and, as an auxiliary gas, H(2) and NH(3) were used, respectively. The chemical compositions of the layers and of the interfaces in between were characterized by total-reflection X-ray fluorescence spectrometry combined with near-edge X-ray absorption fine-structure spectroscopy, X-ray photoelectron spectroscopy, and secondary ion mass spectrometry. The application of H(2) yielded the BC(x)N(y) compound whereas the use of NH(3) led to a mixture of h-BN and graphitic carbon. At the BC(x)N(y)/metal interface, metal borides could be identified. At the relatively high synthesis temperature of 700 °C, broad regions of Cu or Ni and Si were observed between the metal layer and the substrate Si.

Converting Graphene Oxide Monolayers into Boron Carbonitride Nanosheets by Substitutional Doping

To realize graphene-based electronics, bandgap opening of graphene has become one of the most important issues that urgently need to be addressed. Recent theoretical and experimental studies show that intentional doping of graphene with boron and nitrogen atoms is a promising route to open the bandgap, and the doped graphene might exhibit properties complementary to those of graphene and hexagonal boron nitride (h-BN), largely extending the applications of these materials in the areas of electronics and optics. This work demonstrates the conversion of graphene oxide nanosheets into boron carbonitride (BCN) nanosheets by reacting them with B(2) O(3) and ammonia at 900 to 1100 °C, by which the boron and nitrogen atoms are incorporated into the graphene lattice in randomly distributed BN nanodomains. The content of BN in BN-doped graphene nanosheets can be tuned by changing the reaction temperature, which in turn affects the optical bandgap of these nanosheets. Electrical measurements show that the BN-doped graphene nanosheet exhibits an ambipolar semiconductor behavior and the electrical bandgap is estimated to be ≈25.8 meV. This study provides a novel and simple route to synthesize BN-doped graphene nanosheets that may be useful for various optoelectronic applications.

Optical characteristics of nickel and boron carbonitride films in Si(100)/Ni/BC x N y structures

The optical characteristics of nickel films deposited on Si(100) substrates by vacuum thermal evaporation have been studied. The thickness and optical constants of the films are determined using monochromatic zero ellipsometry, while the inverse problems are solved within the three-layer optical model of the samples. It is shown that thermal annealing leads to a change in the optical constants of nickel films in the heating-temperature range of 500–900°C. Boron carbonitride layers deposited on silicon substrates with a nickel sublayer are analyzed within multilayer optical models, which make it possible to determine the refractive index and absorption coefficient distributions along the thickness of the synthesized Si(100)/Ni/BC x N y structure.

Few-atomic-layered boron carbonitride nanosheets prepared by chemical vapor deposition

Few-atomic-layered boron carbonitride (BCN) nanosheets have been grown on Si substrate by microwave plasma chemical vapor deposition from a gas mixture of CH(4)-N(2)-H(2)-BF(3). The grown BCN nanosheets are oriented with their base planes perpendicular to the substrate surface. Ultrathin BCN nanosheets with thickness from 2 to a few atomic layers account for a considerable portion of the products, although many of them have more than 10 layers. Photoluminescence is measured for the BCN nanosheets and intense emission at 3.27 eV with very weak defect-related emission is observed for the nanosheets with the composition of B(0.38)C(0.27)N(0.35). The present BCN nanosheets are promising for applications in nanoelectronics, catalyst supports, gas adsorption, etc.

Synthesis and Characterization of Hexagonal Boron Carbonitride Compounds Prepared by Solvothermal Method

A solvothermal method has successfully applied to prepare hexagonal boron carbonitride from CH3CN, NaN3 and NaBF4 in benzene at 400 . °C The synthesized product was characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), select area electron diffraction (SAED), X-ray energy-dispersive spectroscopy (EDS), and electron energy loss spectroscopy (EELS). XRD and SAED indicated that the synthesized product are h-BCN with the lattice constants of a=0.2678 nm and c=0.6639 nm. TEM images reveal that the products mainly consist of nanorods and quartet prism-like nanostructure. The results of EELS and EDS suggested that the product was composed of elements of B, C and N, and the chemical formula was B0.23C0.60N0.17. FTIR exhibited that the product had C—N, B—C and B—N bonds, indicating that an atomic-level hybrid of the three elements was synthesized.

Theoretical study of atomic arrangement in BXCYNZ nanotubular structures

Abstract A theoretical approach was used to study the atomic arrangements of boron carbonitride nanotubes with diameters from 4 to 16 The role played by nitrogen and boron doping in the structural stabilization of these molecular systems was evaluated, and the geometry of carbon and boron carbonitride nanotubes was investigated using quantum chemical methods. The atomic arrangements and chemical compositions of B-C-N tubular structures proposed in the literature (BCN, B 3 C 2 N 3 , and BC 2 N) were analyzed. The results showed that the energy associated with boron and nitrogen incorporation depends strongly on tube diameter and the B-C-N atomic distribution in the tubular structures.