• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.255-255
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• 2013

최근 그래핀 연구와 더불어 2차원 구조의 나노소재에 대한 관심이 급증하면서 육각형의 질화붕소(hexagonal boron nitride; h-BN) 박막(nanosheet)이나 붕소 탄화질화물(boron caronitride; BCN) 박막과 같은 2차원 구조체에 대한 연구가 활발히 진행되고 있다. 그 중 BCN은 반금속(semimetal)인 흑연(graphite)과 절연체인 h-BN이 결합된 박막으로 원소의 구성 비율에 따라 전기적 특성을 제어할 수 있다는 장점이 있다. 따라서 다양한 나노소자로의 응용을 위한 연구가 활발히 진행되고 있다. 본 연구에서는 폴리스틸렌(polystyrene, PS)과 보레인 암모니아(borane ammonia)를 고체 소스로 이용하여 열화학 기상증착법을 이용하여 BCN 박막를 SiO2 기판 위에 직접 합성하였다. SEM과 AFM 관측을 통해 합성된 BCN 박막을 확인하였으며, RMS roughness가 0.5~2.6 nm로 매우 낮은 것을 확인하였다. 합성과정에서 PS의 양을 조절하여 BCN 박막의 탄소의 밀도를 성공적으로 제어하였으며, 이에 따라 전기적인 특성이 제어되는 양상을 확인하였다. 또한 합성온도 변화에 따른 BCN 박막의 전기적인 특성이 제어되는 양상을 확인하였다. 추가적으로 같은 방법을 이용하여 BCN 박막을 Ni 위에서 합성하여 SiO2 기판위에 전사 하였다. 합성된 BCN 박막의 구조적 특징과 화학적 조성 및 결합 상태를 투과전자현미경(transmission electron microscopy), X-선 광전자 분광법(X-ray photoelectron spectroscopy)을 통해 조사하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1999.05a
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• pp.47-48
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• 1999

• Korean Journal of Materials Research
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• v.8 no.4
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• pp.293-298
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• 1998

The fracture behavior of $Si_3N_4N$, coated $Si_3N_4N$-BN composite was studied by the Hertzian indentation technique. New types of contact-induced cracks were found, and it was confirmed that these cracks have cone crack geometry. Contact damage was distributed in the substrate layer, which can absorb energy, as well as in the coating layer, so the propagation of initiated cracks in the coating layer were suppressed.

• Composites Research
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• v.37 no.3
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• pp.155-161
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• 2024

Boron nitride nanotubes and carbon nanotubes are the most representative one-dimensional nanostructures, and have received great attention as reinforcement for multifunctional composites for their excellent physical properties. The two nanotubes have similar excellent mechanical stiffness, strength, and heat conduction properties. Therefore, the reinforcing effect of these two nanotubes is greatly influenced by the properties of their interface with the polymer matrix. In this paper, recent comparative studies on the reinforcing effect of boron nitride nanotubes and carbon nanotubes through experimental pull-out test and in-silico simulation are summarized. In addition, the conflicting aspect of the two different nanotubes with structural defects in their side wall is discussed on the viscoelastic damping performance of nanocomposites.

• Composites Research
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• v.37 no.4
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• pp.350-355
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• 2024

Boron nitride nanotubes (BNNT) are materials of significant interest in next-generation technological fields due to their outstanding physicochemical properties, including excellent chemical and thermal stability. However, for effective utilization, dispersion of BNNT is essential. Unfortunately, BNNT exhibit hydrophobic surfaces and strong van der Waals forces, making their dispersion challenging. Current dispersion methods include the addition of surfactants and surface functionalization, but these chemical treatments often damage BNNT and involve cumbersome processes. In this study, we dispersed BNNT in water under various tip ultrasonication conditions and identified conditions that do not affect BNNT using FT-IR spectroscopy, Raman spectroscopy, and X-ray diffraction analysis. Subsequently, enhanced dispersibility was confirmed through turbidity measurements, and the solubility range in 15 different solvents was evaluated using the Hansen solubility parameter.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.288-288
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• 2016

본 실험에서는 미래에 지향하는 플렉서블한 소자 제작에 기존의 소자는 한계를 지니고 있기 때문에 기존 소자 제작에 쓰이는 물질보다 투명하고 유연한 성질을 지닌 그래핀(Graphene), 질화붕소(h-BN)와 황화몰리브덴(MoS2)을 이용하여 소자를 제작하였다. 2차원 물질만을 이용한 소자를 제작함으로써 기존 실리콘 기반의 소자가 가질 수 없었던 투명함과 유연성을 보여주었다. 또한 높은 수준의 on/off ratio를 보여줌으로써 2차원 물질에 기반한 플렉서블 소자 제작의 가능성을 확인할 수 있었다.

• Journal of the Korean Vacuum Society
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• v.14 no.1
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• pp.40-48
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• 2005

Bucky shuttle memory systems were investigated by the classical molecular dynamics(MD) simulations. Energetics and operating response of the shuttle-memory-elements u?ere examined by MD simulations of the C/sub 60/ shuttle in the nanomemory systems under various external force fields. Single-nanopeapod type was consisting of three fullerenes encapsulated in (10, 10) boron-nitride nanotube and filled Cu electrode. Studied systems could be applied to nonvolatile memory. MD simulation results showed that the stable bit flops could be achieved from the external force fields of 0.1 eV/Å for single-nanopeapod type.

• Tribology and Lubricants
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• v.35 no.6
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• pp.343-349
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• 2019

According to a report in 2011, hexagonal boron nitride demonstrated good solubility in pure water, even without surfactants or organic functionalization. Hexagonal boron nitride nanosheets are an effective lubricant additive, and their solubility in pure water has motivated lubrication engineers to utilize aqueous solutions containing these nanosheets as water-based lubricants. In this study, we measure the width and height of the hexagonal boron nitride nanosheets dispersed in pure water by using the Zetasizer and atomic force microscopy. Without surfactants or functionalization, aqueous solutions containing 0.10, 0.07, 0.05, and 0.01 wt% of hexagonal boron nitride nanosheets are synthesized via sonication-assisted hydrolysis. The Zetasizer provides only a one-dimensional size of approximately 410 nm, regardless of the concentration of the solution. Thus, it does not allow the estimation of the shape of the nanosheet. To acquire the three-dimensional size of the nanosheets, atomic force microscopy is employed. The aqueous solutions containing 0.10, 0.07, 0.05, and 0.01 wt% of the hexagonal boron nitride nanosheets show average values of 740, 450, 700, and 610 nm in width, and 37, 26, 33, and 32 nm in thickness, respectively. No significant trend is observed between the concentration of the solution and size of the nanosheets. Therefore, when preparing a water-based lubricant, it may be appropriate to adjust conditions such as ultrasonication time rather than the concentration.

• Composites Research
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• v.32 no.6
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• pp.319-326
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• 2019

To address tremendous needs for developing efficiently heat dissipating material with lightweights, a new class of polymer possessing recyclable and malleable characteristics was synthesized for incorporating model functional hexagonal boron nitride (h-BN) filler. A good interfacial affinity between the polymer matrix and the filler along with shear force generated upon manufacturing the composite yielded the final product bearing highly aligned filler via simple hot pressing method. For this reason, the composite exhibited a high thermal conductivity of 13.8 W/mK. Moreover, it was possible to recover the h-BN from the composite without physical/chemical denaturation of the filler by chemically depolymerizing the matrix, thus the recovered filler can be re-used in the future. We believe this polymer could be beneficial as matrix for incorporating many other functional fillers, thus they may find applications in various polymeric composite related fields.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.7
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• pp.455-461
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• 2018

Boron nitride (BN) nanofibers were fabricated using BN nanoparticles (70 nm) by electrospinning. Morphologies such as the diameter and density of the BN nanofibers are strongly influenced by the viscosity and dispersion state of the precursor solution. In this study, the precursor solution was prepared by ball milling BN nanoparticles and polyvinylpyrrolidone (PVP, Mw~1,300,000) in ethanol, which was electrospun and then calcined to produce BN fibers. High-quality BN nanofibers were well fabricated at a BN concentration of 15 wt% with their diameters in the range of 500 nm to 800 nm; the viscosity of the precursor solution was $400mPa{\cdot}S$. The calcination of the as-electrospun BN fibers seemed to be completed by holding them at $350^{\circ}C$ for 2 h considering the TGA data. The morphologies and phases of the BN fibers were investigated by scanning electron microscopy (SEM) and X-ray diffractometry (XRD), respectively; Fourier transform infrared (FT-IR) was also used for structure analysis.