Grain boundaries are observed and characterized in chemical vapor deposition-grown sheets of hexagonal boron nitride (h-BN) via ultra-high-resolution transmission electron microscopy at elevated temperature. Five- and seven-fold defects are readily observed along the grain boundary. Dynamics of strained regions and grain boundary defects are resolved. The defect structures and the resulting out-of-plane warping are consistent with recent theoretical model predictions for grain boundaries in h-BN.

Boron nitride nanoribbons (BNNRs), the boron nitride structural equivalent of graphene nanoribbons (GNRs), are predicted to possess unique electronic and magnetic properties. We report the synthesis of BNNRs through the potassium-intercalation-induced longitudinal splitting of boron nitride nanotubes (BNNTs). This facile, scalable synthesis results in narrow (down to 20 nm), few sheet (typically 2-10), high crystallinity BNNRs with very uniform widths. The BNNRs are at least 1 μm in length with minimal defects within the ribbon plane and along the ribbon edges.

The atomic structure, stability, and dynamics of defects in hexagonal boron nitride (h-BN) are investigated using an aberration-corrected transmission electron microscope operated at 80 kV between room temperature and 1000 °C. At temperatures above 700 °C, parallelogram- and hexagon-shaped defects with zigzag edges become prominent, in contrast to the triangular defects typically observed at lower temperatures. The appearance of 120° corners at defect vertices indicates the coexistence of both N- and B-terminated zigzag edges in the same defect. In situ dynamics studies show that the hexagonal holes grow by electron-induced sputtering of B-N chains, and that at high temperatures these chains can migrate from one defect corner to another. We complement the experiments with first-principles calculation which consider the thermal equilibrium formation energy of different defect configurations. It is shown that, below a critical defect size, hexagonal defects have the lowest formation energy and therefore are the more-stable configuration, and triangular defects are energetically metastable but can be "frozen in" under experimental conditions. We also discuss the possible contributions of several dynamic processes to the temperature-dependent defect formation.

Chemical patterns prepared by self-assembly, combined with soft lithography or photolithography, are directly compared. Pattern fidelity can be controlled in both cases but patterning at the low densities necessary for small-molecule probe capture of large biomolecule targets is better accomplished using microcontact insertion printing (μCIP). Surfaces patterned by μCIP are used to capture biomolecule binding partners for the small molecules dopamine and biotin.

Boron nitride nanoribbons (BNNRs) are theorized to have interesting electronic and magnetic properties, but their high-yield synthesis remains challenging. Here we demonstrate that potassium-induced splitting of BN nanotubes (BNNTs) is an effective high-yield method to obtain bulk quantities of high-quality BNNRs if a proper precursor material is chosen. The resulting BNNRs are crystalline; many of them have a high aspect ratio and straight parallel edges. We have observed numerous few-layer and monolayer BNNRs; the multilayered ribbons predominantly have an AA' stacking. We present a detailed microscopy study of BNNRs that provides important insights into the mechanism of the formation of BNNRs from BNNTs. We also demonstrate that the BNNTs prepared by different synthetic approaches could exhibit dramatically different reactivities in the potassium splitting reaction, which highlights the need for future comparison studies of BN nanomaterials prepared using different methods to better understand their preparation-dependent physical and chemical properties.

The two-dimensional sp 2 -bonded material hexagonal boron nitride (h-BN) has unique electronic, thermal, mechanical, and chemical properties. It has recently found use as an ideal substrate for graphene-based electronic devices. We here describe synthesis of mono-to few-layer h-BN films using low pressure chemical vapor deposition (LPCVD) from borazine, with nickel, copper and platinum employed as catalytic substrates, and transfer of some of these films using a non-polymer method. Characterization of the films via Raman spectroscopy and transmission electron microscopy (TEM) is performed.Chemical vapor deposition synthesis of hexagonal boron nitride from borazine using metallic substrates.

We demonstrate cuprous oxide (Cu2O) based metal insulator semiconductor Schottky (MIS-Schottky) solar cells with efficiency exceeding 3%. A unique direct growth technique is employed in the fabrication, and hexagonal boron nitride (h-BN) serves simultaneously as a passivation and insulation layer on the active Cu2O layer. The devices are the most efficient of any Cu2O based MIS-Schottky solar cells reported to date.

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