Boron nitride nanotube (BNNT) has similar tubular nanostructure as carbon nanotube (CNT) in which boron and nitrogen atoms arranged in a hexagonal network. Owing to the unique atomic structure, BNNT has numerous excellent intrinsic properties such as superior mechanical strength , high thermal conductivity, electrically insulating behavior, piezoelectric property, neutron shielding capability, and oxidation resistance. Since BNNT was first synthesized in 1995, developing efficient BNNT production route has been a significant issue due to low yield and poor quality in comparison with CNT, thus limiting its practical uses. However, many great successes in BNNT synthesis have been achieved in recent years, enabling access to this material and paving the way for the development of promising applications. In this article, we discussed current progress in the production of boron nitride nanotube, focusing on the most common and effective methods that have been well established so far. In addition, we presented various applications of BNNT including polymer composite reinforcement, thermal management packages, piezo actuators, and neutron shielding nanomaterial.

We report spatially resolved Raman scattering results of polycrystalline monolayer graphene films to study the effects of defects, strains, and strain fluctuations on the electrical performance of graphene. Two-dimensional Raman images of the integrated intensities of the G and D peaks (I_G and I_D) were used to identify the graphene domain boundaries. The domain boundaries were also identified using Raman images of I_D/I_G and I_2D/I_G ratios and 2D spectral widths. Interestingly, the I_D maps showed that the defects within individual domains significantly increased for the graphene with large domain size. The correlation analysis between the G and 2D peak energies showed that biaxial tensile strain was more developed in the graphene with large domain size than in the graphene with small domain size. Furthermore, spatial variations in the spectral widths of the 2D peaks over the graphene layer showed that strain fluctuations were more pronounced in the graphene with large domain size. It was observed that the mobility (sheet resistance) was decreased (increased) for the graphene with large domain size. The degradation of the electrical transport properties of the graphene with large domain size is mainly due to the defects, tensile strains, and local strain fluctuations within the individual domains.

Boron nitride nanotubes (BNNTs) are emerging nanomaterials with analogous structures and similarly impressive mechanical properties to carbon nanotubes (CNTs), but unique chemistry and complimentary multifunctional properties, including higher thermal stability, electrical insulation, optical transparency, neutron absorption capability, and piezoelectricity. Over the past decade, advances in synthesis have made BNNTs more broadly accessible to the nanomaterials and other research communities, removing a major barrier to their utilization and research. Therefore, the field is poised to grow rapidly and see the emergence of BNNT applications ranging from electronics to aerospace materials. A key challenge, that is being gradually overcome, is the development of manufacturing processes to make “neat” BNNT materials. This overview highlights the history and current status of the field, providing both an introduction to this Focus Issue—BNNTs: Synthesis to Applications—as well as a perspective on advances, challenges, and opportunities for this emerging material. Graphical abstract