Effect Of Boron Incorporation Research Articles

Effect of boron incorporation on the structural, morphological, and spectral properties of CdNb2O6:Dy3+ phosphor synthesized by molten salt process

The effect of boron addition on the structural, morphologic and spectral properties was investigated by using xDy3+ (x = 0.5, 3, 6 mol%) doped, and xDy3+, yB3+ (y = 0, 5, 15, 25 mol%) co-doped CdNb2O6 powders produced by molten salt method. X-ray diffractions (XRD) of all Dy3+ doped, and B3+, Dy3+ co-doped samples showed that they retained the single-phase structure. The homogeneous dissolution of the Dy3+ doping without forming an impurity phase in the structure can be attributed to the flux effect of the molten salt process and boron doping. Scanning electron microscopy (SEM) micrographs of the B3+, Dy3+ co-doped grains showed that the effect of boron promotes grain growth and prismatic-like grain shape. Photoluminescence (PL) emissions of the phosphors with the excitation of 351.9 nm were monitored by the 4F9/2→6H15/2, 4F9/2→6H13/2, and 4F9/2→6H11/2 transitions. PL excitations and a broad peak at 275 nm originating from the O2–→Nb5+ band transition were observed with the emission of 577.9 nm. The PL emissions of Dy3+, B3+ co-doped phosphors increased about two fold compared to Dy3+ doped samples. The increase in PL may be related to the increased presence of luminescence centers at or near grain surface due to the decreasing surface area (SA)/volume (V) ratio as the growth of B3+ co-doped grains and the transformation from rod-like to prismatic-like shape. The increased Dy3+ presence led to a decrease in observed lifetime, while the B3+ increase did not cause any change. The study may provide a different perspective for the understanding and controlling of grain morphology and the luminescence relation for RE-doped phosphors.

Correction to: Effect of Boron Incorporation on the Mechanical, and Radiation Shielding Behaviors of Borosilicate Bioactive Glasses

Correction to: Effect of Boron Incorporation on the Mechanical, and Radiation Shielding Behaviors of Borosilicate Bioactive Glasses

Effect of Boron Incorporation on the Mechanical, and Radiation Shielding Behaviors of Borosilicate Bioactive Glasses

Effect of Boron Incorporation on the Mechanical, and Radiation Shielding Behaviors of Borosilicate Bioactive Glasses

Effect of boron incorporation into the carbon-site in Nb2SC MAX phase: Insights from DFT

Inherent and modified characteristics of MAX phase materials are important for technological applications in different fields. From this point of view, the present article gives a brief overview of the physical properties of Nb2SC1-xBx (x = 0.0–1.0) MAX phase solid solutions via the calculations of elastic, electronic, thermal and optical properties using density functional theory (DFT). The substitutional effect of B at the C site on the physical properties of Nb2SC is also discussed. The increase of B-content (x) enhances the elastic constants (except C12 and C13) and moduli (except B), Debye temperature, melting point, and minimum and lattice thermal conductivity of Nb2SC1-xBx. Conversely, the machinability and dry lubricity decrease gradually with the increase of x. The ductility decreases with the increase of x, and when x > 0.2, Nb2SC1-xBx becomes completely brittle and the brittleness increase with further increase of x. All the compositions of Nb2SC1-xBx have potential to be used as thermal barrier coating (TBC) and high temperature structural materials. Moreover, the investigated optical parameters are discussed on the basis of electronic structures. Average reflectivity in the visible light region is more than 45%, which make Nb2SC1-xBx systems capable of reducing the solar heating. It is expected that this study will stimulate the MAX phase research community to further explore the characteristics of these materials via experiment and theory.

Effect of boron incorporation on the bioactivity, structure, and mechanical properties of ordered mesoporous bioactive glasses.

B2O3 doped (0.5-15 mol%) ordered mesoporous bioactive glasses (MBG) with the composition 80% SiO2-15% CaO-5% P2O5 were synthesized via a sol-gel based evaporation-induced self-assembly process using the block-copolymer P123 as a structure directing agent and characterized by biokinetic, mechanical and structural investigations. Nitrogen physisorption isotherms and electron microscopy indicate no detrimental effect of B2O3 on the ordered hexagonal pore structure. Boron incorporation increases both the bulk modulus and hardness of the glasses. In vitro bioactivity tests reveal a rapid initial release of Ca2+ and PO43- ions, followed by formation of hydroxyapatite carbonate within a few hours. Contrary to the tight incorporation of Al in Al-doped MBGs, the rapid release of borate species into simulated-body-fluid suggests loosely bound species localized at the internal surfaces of the mesopores. 29Si, 11B, 31P, and 1H solid state NMR spectroscopy reveal that the majority of the borate is present as anionic BO4/2- species. The need for charge compensation leads to an increase in the average degree of polymerization of the phosphate species for high boron contents. 11B{31P} rotational echo double resonance NMR results reveal the absence of B-O-P linkages. This structural model explains the rapid release of borate and the enhanced dissolution kinetics of the Ca2+ and phosphate species.

Stable Boron-Modified ZSM-22 Zeolite Catalyst for Selective Production of Propylene from Methanol

The effects of boron incorporation on the ZSM-22 particle size, morphology, and acidity were investigated via a microwave-assisted synthesis method (MAHyS). The in situ addition of boron into the TON framework resulted in ZSM-22 zeolite (TON framework) with the same needle-shape morphology but smaller particles size as observed from the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images. The incorporation of boron into ZSM-22 zeolite resulted in enhanced textural properties as indicated by N adsorption-desorption measurements. The temperature-programmed desorption of ammonia (NH-TPD) analysis showed insignificant changes in the acidity properties, while pyridine Fourier-transform infrared (FTIR) analysis showed a slight enhancement in the boron-incorporated ZSM-22 zeolite acidity. The boron-incorporated ZSM-22 zeolite sample showed extended catalytic activity in methanol conversion to light olefins.

Electrical properties of boron-incorporated ultrananocrystalline diamond/hydrogenated amorphous carbon composite films

Boron-incorporated ultrananocrystalline diamond/hydrogenated amorphous carbon composite (UNCD/a-C:H) films were deposited by coaxial arc plasma deposition with boron-blended graphite targets. The effects of boron incorporation on the electrical properties of the films were investigated by hard X-ray photoelectron spectroscopy. Their electrical conductivity increased from 10−7 to 10−1 Ω−1 cm−1 with increasing boron content up to 5 at.%. From the temperature dependence of electrical conductivity, hopping conduction due to localized states produced by boron atoms is predominant in carrier transport. X-ray photoelectron spectra showed the shifts of Fermi levels toward the top of the valence band with increasing boron content. It implies that boron atoms in the films lead to form localized states, which results in enhanced electrical conductivity.

Effect of Boron Incorporation on Structural and Optical Properties of AlN Layers Grown by Metal‐Organic Vapor Phase Epitaxy

To investigate the effect of boron (B) incorporation on the structural and optical properties of aluminum nitride (AlN) layers, B‐doped AlN layers without columnar structures are grown on c‐plane sapphire substrates with an AlN underlayer by metal‐organic vapor phase epitaxy. Triethylboron, trimethylaluminum, and ammonia are used as B, Al, and N precursors, respectively. The B‐doped AlN layers exhibit a homogeneous B concentration of 2.0 × 1021 cm−3 (≈2%) at the macroscale and microscale. However, most of the B atoms segregate in the AlN layer at the nanoscale and do not form BAlN alloys. As a result, high‐density dot‐shaped crystalline defects are induced in the layer. The dot‐shaped crystalline defects align along the facets and form complex inclined defects with high‐density oxygen atoms. These defects result in much worse crystalline quality and optical emission property than those of conventional crystalline defects, e.g., threading dislocations and stacking faults. Therefore, further improvement in the crystalline quality of B‐doped AlN is important to understand the potential properties of BAlN alloy semiconductors.

Effects of Boron-Incorporation in a V-Containing Zr-Based AB2 Metal Hydride Alloy

In this study, boron, a metalloid element commonly used in semiconductor applications, was added in a V-containing Zr-based AB2 metal hydride alloy. In general, as the boron content in the alloy increased, the high-rate dischargeability, surface exchange current, and double-layer capacitance first decreased and then increased whereas charge-transfer resistance and dot product of charge-transfer resistance and double-layer capacitance changed in the opposite direction. Electrochemical and gaseous phase characteristics of two boron-containing alloys, with the same boron content detected by the inductively coupled plasma optical emission spectrometer, showed significant variations in performances due to the difference in phase abundance of a newly formed tetragonal V3B2 phase. This new phase contributes to the increases in electrochemical high-rate dischargeability, surface exchange current, charge-transfer resistances at room, and low temperatures. However, the V3B2 phase does not contribute to the hydrogen storage capacities in either gaseous phase and electrochemical environment.

Effect of boron incorporation on slow interface traps in SiO2/4H-SiC structures

The reason for the effective removal of interface traps in SiO2/4H-SiC (0001) structures by boron (B) incorporation was investigated by employing low-temperature electrical measurements. Low-temperature capacitance–voltage and thermal dielectric relaxation current measurements revealed that the density of electrons captured in slow interface traps in B-incorporated oxide is lower than that in dry and NO-annealed oxides. These results suggest that near-interface traps can be removed by B incorporation, which is considered to be an important reason for the increase in the field-effect mobility of 4H-SiC metal–oxide–semiconductor devices. A model for the passivation mechanism is proposed that takes account of stress relaxation during thermal oxidation.

Effect of boron incorporation on light emission characteristics of UV BAlGaN/AlN quantum well structures

The effect of boron incorporation on the light emission characteristics of UV BxAlyGa1−x−yN/AlN quantum well (QW) structures was investigated. The internal field rapidly decreases with increasing boron composition and becomes zero at critical boron compositions. As a result, the light intensity of the BAlGaN/AlN QW structure is increased by roughly four times at the critical boron composition of x = 0.03 and y = 0.2. Therefore, in the range of Al composition below 0.7, we expect that UV BAlGaN/AlN QW structures can be used as a high-efficiency light source with a strain reduction of 20–30%, relative to conventional AlGaN/AlN QW structures.

Effect of boron incorporation on the phase composition and high-temperature behavior of polymer-derived silicon carbide

Within the present work, boron-containing silicon carbide (SiBC) powders and monoliths were prepared from a polyborocarbosilane. The main aspect addressed here relates to the fate of boron in the prepared SiBC ceramics, which has not been clarified unambiguously so far. X-ray diffraction data, corroborated with XPS, FTIR and Raman spectroscopic results indicate that boron preferably gets incorporated within the segregated carbon phase present in polycarbosilane-derived SiC; thus, the prepared SiBC samples show dispersed boron-containing carbon phases with boron contents from ca. 9 to 18at%. Interestingly, the B-containing carbon phase does not convert into crystalline boron carbide, even upon annealing at very high temperatures and despite the high boron content. Moreover, processing details concerning the pressureless preparation of dense Si(B)C monoliths are considered in the present paper and their high temperature evolution is analyzed.

Sol-gel-derived SiBOC ceramics with highly graphitized free carbon

SiBOC ceramics with highly graphitized free carbon were prepared from sol–gel derived pre-ceramic gels followed by pyrolysis at 1000–1600°C under nitrogen. The effects of boron incorporation on the precursor architecture, microstructure and crystallization of SiBOC ceramics were discussed. The experimental results showed that the incorporation of boron had little effect on the silicon bonding environment in SiBOC precursor and led to a higher ceramic yield of 89%. The crystallization of both β-SiC and free carbon was enhanced in SiBOC ceramics. Raman spectra showed that the intensity ratio of D to G band was very small for the SiBOC ceramics pyrolyzed at 1600°C, indicating the highly ordering and graphitization of free carbon. The clear presence of D׳ band at 1610cm−1 in Raman spectra suggested the partial substitution of C with B atoms in graphite layer, which significantly promoted the graphitization of free carbon. The turbostratic graphite with 10–20 layers graphene was observed by TEM.

Effects of boron incorporation on the structural, optical and electrical properties of sol–gel-derived ZrO2 gate dielectrics

The effect of boron (B) doping on the microstructure, band gap energy and electrical properties of ZrO2 gate dielectrics deposited by sol–gel method at low temperature were systemically investigated. By means of characterization of spectroscopy ellipsometry and ultraviolet–visible spectroscopy, the thicknesses and optical constants of ZrO2 gate dielectrics have been determined precisely. The B incorporation dependent electrical properties of ZrO2 films were determined by capacitance–voltage (C–V) and leakage current density–voltage (J–V) measurements. The dominant conduction mechanisms of Al/B:ZrO2/n-Si MOS structures have been discussed systematically in detail. As a result, the optimized B incorporation content has been obtained to achieve ZrO2 gate dielectrics with high quality.

Effect of boron incorporation on the structure, products selectivities and lifetime of H-ZSM-5 nanocatalyst designed for application in methanol-to-olefins (MTO) reaction

The effect of boron incorporation into H-ZSM-5 nanocatalyst on the stability, product distribution and hydrocarbons selectivity in methanol to olefins (MTO) reaction was investigated. The reference and boron-modified ZSM-5 nanocatalysts were prepared by hydrothermal method. The fresh and used nanocatalysts were characterized using TG–DTA, XRD, FE-SEM, BET, FT-IR, TPH, TPO and NH3-TPD techniques. The performance test runs of the two H-ZSM-5 and [B]-H-ZSM-5 samples were conducted in a fixed-bed reactor at T=480°C, P=1atm, methanol WHSV=0.9h−1 with methanol to water weight ratio of unity in the feed. The results revealed that propylene selectivity does not change significantly with the isomorphous substitution of B in H-ZSM-5 zeolite. However, the lifetime of the modified zeolite (1300h) showed a significant increase compared to that of the reference sample (340h). The considerable enhancement of the lifetime and catalytic stability could be attributed to reduction of strong/mild acid sites ratio as well as small crystal size of the [B]-H-ZSM-5 nanocatalyst. The characterization of the deactivated nanocatalysts showed that incorporation of boron decreased both rates of coke formation and coke-susceptibility of the ZSM-5 nanocatalyst.

Effects of boron incorporation on the strain and photoluminescence properties of GaAsSb/GaAs quantum wells

Boron-containing GaAsSb/GaAs quantum wells (QWs) with different antimony (Sb) mole fractions were grown by low-pressure metal–organic chemical vapor deposition for the first time. The effects of boron incorporation on the performance of GaAsSb/GaAs QWs are discussed. For samples with low compressive strain, injection of triethylboron can enhance the Sb content and increase the compressive strain, although boron incorporation can lead to a reduction in strain. This effect was less for strained GaAsSb/GaAs QWs, so the compressive strain of these QWs did not vary. Room-temperature photoluminescence emission at 1116nm with a full-width at half-maximum (FWHM) value of 56meV was obtained for strained BGaAsSb/GaAs QWs.

The saturation density property of (B)InAs/GaAs quantum dots grown by metal-organic chemical vapor deposition

The density property of InAs/GaAs quantum dots (QDs) grown by metal-organic chemical vapor deposition (MOCVD) was investigated in detail. The saturation density of InAs/GaAs QDs was experimentally demonstrated. The InAs deposition thickness (InAs coverage) when the saturation density reached was also found. Furthermore, we systemically analyzed the influences of growth temperature and growth rate of InAs/GaAs QDs on the saturation density. Finally, BInAs/GaAs QDs with room-temperature photoluminescence (RT-PL) wavelength of 1320nm and full width at half maximum (FWHM) of 40mev were achieved for the first time, and the effects of boron incorporation on InAs/GaAs QDs were studied.

The effect of boron incorporation on the structure and properties of glassy carbon

Boron was introduced into glassy carbon by chemical modification and by irradiating the precursor polymer with boron ions. Using chemical modification, a polymer with uniform distribution of boron in the bulk was obtained, whereas irradiation with B 3+ produced a polymer with boron located in a narrow region under the surface. Following modification with boron, the samples were carbonized at 1273 K and examined using X-ray diffraction, Raman spectroscopy, temperature programmed desorption (TPD) and by hardness measurements. Structural analysis results suggest that boron is mostly substitutionally bonded in the glassy carbon structure regardless of the method used to introduce boron into the polymer precursor. Formation of crosslinks between glassy carbon ribbons during carbonization as a consequence of the recombination of ion beam induced changes in the polymer structure and a high concentration of boron in the subsurface layer is proposed to account for an increase of glassy carbon hardness. An increase in the total amount of surface oxygen groups was observed in the TPD spectra of both boron-modified samples due to an increase in the number of active sites. Results show that the nature of these sites is influenced by the initial distribution of boron in the polymer precursor.

Free-standing boron doped CVD diamond films grown on partially stabilized zirconia substrates

Boron doped diamond films have been grown adhered to silicon substrates by chemical vapor deposition using boron containing gases. In this work it was shown that it is possible to grow free-standing boron doped CVD diamond films on partially stabilized zirconia substrates using boron powder as the source for doping. Results from Raman spectroscopy confirmed the boron incorporation with concentration up to ∼10 20 cm −3. X-ray diffraction and scanning electron microscopy showed that the effect of boron incorporation in the microstructure of the diamond film is negligible. The measurement of the resistivity as a function of temperature confirmed the semiconductor behavior, as expected for p-type diamond.

Effect of boron incorporation on the structure and electrical properties of diamond-like carbon films deposited by femtosecond and nanosecond pulsed laser ablation

The influence of the incorporation of boron in diamond-like carbon (DLC) films on the microstructure of the coatings has been investigated. The boron-containing DLC films (a-C:B) have been deposited by pulsed laser deposition (PLD) at room temperature in high vacuum conditions, by ablating graphite and boron targets either with a femtosecond pulsed laser (800nm, 150fs, fs-DLC) or with a nanosecond pulsed laser (248nm, 20ns, ns-DLC). Alternative ablation of the graphite and boron targets has been carried out to deposit the a-C:B films. The film structure and composition have been highlighted by coupling Field Emission Scanning Electron Microscopy, Electron Energy Loss Spectroscopy and High Resolution Transmission Electron Microscopy. Using the B K-edge, EELS characterization reveals the boron effect on the carbon bonding. Moreover, the plasmon energy reveals a tendency of graphitization associated to the boron doping. Pure boron particles have been characterized by HRTEM and reveal that those particles are amorphous or crystallized. The nanostructures of the boron-doped ns-DLC and the boron-doped fs-DLC are thus compared. In particular, the incorporation of boron in the DLC matrix is highlighted, depending on the laser used for deposition. Electrical measurements show that some of these films have potentialities to be used in low temperature thermometry, considering their conductivity and temperature coefficient of resistance (TCR) estimated within the temperature range 160–300K.