类石墨烯结构二维氮化硼材料:结构特性、合成方法、性能及应用

石墨烯的发现和成功制备引起了人们对二维材料的研究热潮。六方氮化硼(h-BN)薄膜作为类石墨烯结构的二维层状材料,也是当前的研究热点。介绍了h-BN及其相应的低维纳米结构,并概述了近期对二维BN纳米材料的形貌、合成、性能和应用的研究进展。目前对一维和二维纳米材料的研究表明,BN纳米材料具有诸多优异性能,包括高温稳定性、低介电常数、高力学性能、高热导率、高硬度和高耐腐蚀性,BN纳米材料系统已成为最具前景的非碳纳米系统,在不远的将来将有广泛的应用。     

Hexagonal boron nitride (h-BN) nanoparticles decorated multi-walled carbon nanotubes (MWCNT) for hydrogen storage

Hydrogen is considered as the most promising clean energy carrier because of its abundance, environmental friendliness and high conversion efficiency. However, developing safe, compact, light weight and cost-effective hydrogen storage materials is one of the most technically challenging barriers to the widespread use of hydrogen as fuel. The present work reports the hydrogen storage performance of multi-walled carbon nanotubes (MWCNT)/hexagonal boron nitride (h-BN) nanocomposites (MWCNT/h-BN), where ultrasonication method is adopted for the synthesis of the MWCNT/h-BN nanocomposites. Hydrogenation process was carried out using Seiverts-like hydrogenation setup. Characterization techniques such as X-ray Diffraction (XRD), Micro-Raman Spectroscopy, Fourier Transform Infrared (FTIR) Spectroscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDX), Nitrogen adsorption–desorption isothermal studies (BET), CHN-elemental analysis and Thermogravimetric Analysis (TGA) were used to analyze the samples at various stages of the experiment. A maximum of 2.3 wt% hydrogen storage is achieved in the case of acid treated MWCNTs (A-MWCNT) with 5 wt% of h-BN nanoparticles compared to pure MWCNTs that could store 0.15 wt% only. Moreover the calculated binding energy (0.42 eV) of stored hydrogen of A-MWCNT with 5 wt% of h-BN nanocomposite lies in the recommended range of binding energy (0.2–0.6 eV) for fuel cell applications. The TG study shows that 100% desorption is achieved at the temperature range of 120–410 °C and confirms that the prepared hydrogen storage medium will serve effectively in the realm of hydrogen fuel economy in near future.     

Effect of N, C and B interstitial atoms on local bonding structure in mechanically activated TiH2/h-BN, TiH2/C, and TiH2/B mixtures

Mechanically activated TiH₂/h-BN, TiH₂/C and TiH₂/B mixtures was studied by temperature-programmed desorption, X-ray diffraction, transmission electron microscopy and X-ray emission spectroscopy. Ball milling in the presence of additives results in a modification of hydrogen occupation sites. Additional Ti-N, Ti-C or Ti-B bonds from chemical bonding of Ti with interstitial N, C and B atoms, are formed in TiH₂ due to contact of TiH₂ nanoparticles with the respective additive matrix materials. Mixed configurations around Ti atoms with proportional combination of local Ti-H and Ti-N, Ti-C or Ti-B bonds significantly decrease the thermal stability of TiH₂. The effect is most pronounced when boron is the additive.     

板带钢乳化液摩擦学性能与轧制工艺特征

采用不同的基础油及添加剂配制板带钢轧制乳化液后,通过四球摩擦磨损试验机考察了基础油及添加剂对乳化液摩擦学性能的影响,并通过冷轧实验对各乳化液的轧制工艺润滑效果进行了实际验证.结果表明:运动黏度和皂化值是根据实际的润滑需求选择基础油的主要参数,且基础油的选择影响添加剂的分散与稳定;极压抗磨剂对轧制乳化液的摩擦学性能有显著的提高作用;纳米六方氮化硼(h-BN)作为新型纳米润滑添加剂,不但自身具有优异的摩擦学性能,而且与传统添加剂有良好的协同提高作用;在使用含纳米氮化硼的乳化液进行润滑的冷轧过程中,各轧制工艺特征参数(轧制力、轧制功率等)有显著的降低,初步体现了良好的纳米润滑效应.     

Modified Molten Salt Assisted Exfoliation of Large-Size 2D Materials

2D materials hold great promise for numerous applications, and the physical properties of individual 2D materials depend strongly on their thickness and lateral size. Currently, there is a lack of a straightforward method to produce 2D materials with both high-quality and ultra-high aspect ratios. Herein, a modified molten salt-assisted exfoliation (MMSAE) strategy is proposed to prepare high-quality 2D materials with large sizes and controllable thickness. The MMSAE approach involves using high-frequency disturbance to create a shear force that peels off the layers of the intercalated material (e.g., graphene, MoS₂, WS₂, and clays), resulting in the successful and efficient exfoliation of 2D material. Taking h-BN for example, the MMSAE approach achieves the preparation of 2D h-BN with an average lateral size of 6.30 µm, thickness of 2.34 nm, and a high aspect ratio of 2692.     

六方氮化硼在二维晶体微电子器件中的应用与进展

六方氮化硼(h-BN)因其优异的性能和潜在的应用前景而受到广泛关注.着眼于h-BN在微电子器件领域中的发展与应用,总结了近年来国内外通过化学气相沉积(CVD)方法实现h-BN的高质量、大规模可控制备及图形化的代表性工作.围绕h-BN的高介电常数、原子级平滑表面、高导热性和高稳定性,重点介绍了h-BN在二维晶体介电衬底、...     

Synthesis of vertically aligned flower-like morphologies of BNNTs with the help of nucleation sites in Co–Ni alloy

A Co–Ni alloy deposited at the top of Si substrate produces nucleation sites when etches with ammonia. The as-produced nucleation sites are used as a pattern to grow flower-like morphologies of vertically aligned Boron nitride nanotubes (BNNTs) in the present study. HR-TEM micrographs show black-blur like morphology on the outer part of the BNNTs. The sample contains BNNTs with and without internal bamboo like structures. XPS survey shows B 1s and N 1s peaks at ~191 eV and ~398 eV that indicate the presence of Boron and Nitrogen components in the synthesized sample. Raman spectrum shows a major peak at 1370 cm⁻¹ that corresponds to E_2g mode of h-BN. The as-synthesized BNNTs can be used for its potential applications without any further purification.     

Recent advances in preparation,properties and device applications of two-dimensional h-BN and its vertical heterostructures

Two-dimensional (2D) layered materials, such as graphene, hexagonal boron nitride (h-BN), molybdenum disulfide (MoS₂), have attracted tremendous interest due to their atom-thickness structures and excellent physical properties. h-BN has predominant advantages as the dielectric substrate in FET devices due to its outstanding properties such as chemically inert surface, being free of dangling bonds and surface charge traps, especially the large-band-gap insulativity. h-BN involved vertical heterostructures have been widely exploited during the past few years. Such heterostructures adopting h-BN as dielectric layers exhibit enhanced electronic performance, and provide further possibilities for device engineering. Besides, a series of intriguing physical phenomena are observed in certain vertical heterostructures, such as superlattice potential induced replication of Dirac points, band gap tuning, Hofstadter butterfly states, gate-dependent pseudospin mixing. Herein we focus on the rapid developments of h-BN synthesis and fabrication of vertical heterostructures devices based on h-BN, and review the novel properties as well as the potential applications of the heterostructures composed of h-BN.     

导热氮化硼复合绝缘纸的制备与性能研究

为解决纸基绝缘材料散热不足的问题,本研究利用3-氨丙基三乙氧基硅烷（APTES）对六方氮化硼（h-BN）填料进行表面改性处理后,添加到纸浆纤维中制备具有良好热传导性能和绝缘性能的导热氮化硼复合绝缘纸。研究结果表明,APTES对h-BN改性成功且改性h-BN导热填料热稳定性略有下降;当混合尺寸改性h-BN导热填料添加量为40 wt%时,绝缘纸的导热系数和体积电阻率分别为0.682 W/（m·K）和4.72×1014 Ω·cm,比原纸分别提高了387%和84.4%。     

Effects of cross-scale h-BN grains and orientation degree on the mechanical and thermal properties of BN-matrix textured ceramics

h-BN is a two-dimensional ceramic material with a lamellar structure, known for its typical orientation characteristics on mechanical and thermal properties. By optimizing the size and arrangement of h-BN grains in the matrix, the anisotropic characteristics of h-BN ceramics can be fully utilized to obtain ceramic materials with high thermal conductivity or high strength. In order to study the effect of grain orientation distribution on the mechanical and thermal properties of materials, the index of orientation distribution (IOP) was used to quantitatively characterize the orientation degree of h-BN grains and analyzed the effect of h-BN grain size on material properties. The results show when the initial h-BN size is 13.50 μm, the ceramic has the highest orientation degree/-507, and the mechanical and thermal properties show obvious anisotropy. While the related properties of BN-YAG ceramics varies significantly with the decrease of initial h-BN grain size.