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Boron nitride (BN) has numerous advantageous physical and electrical properties for mechanical and (opto‐)electronic applications, yet growing large single crystals is challenging. The ammonothermal method has demonstrated its suitability for large single‐crystal gallium nitride growth and is investigated for its ability to grow BN. The temperature‐dependent solubility of BN in sodium‐containing supercritical ammonia is previously demonstrated. Herein, the application of a temperature gradient across a baffled autoclave toward the continuous dissolution and crystallization of BN is examined. BN deposits on all wetted surfaces in the lower‐temperature zone, predominantly on the autoclave walls as polycrystalline sheets and to a lesser degree on suspended seeds of cubic BN as oriented, micrometer‐sized, repeated trapezoidal platelet units. Analysis of the grown BN crystals by Raman, X‐ray diffraction, and transmission electron microscopy suggests the growth of sp2‐hybridized BN, predominantly the rhombohedral crystal structure on nitrided NiCr alloy surfaces and rhombohedral and hexagonal crystal structures on the cubic BN seed crystal surfaces. The interfacial relationships between the cBN and the sp2‐hybridized BN phases are examined, where favorable attachment sites are discovered between the dissimilar lattices, further supporting the observed crystal growth.
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Reactivity of Boron Nitride Nanomaterials with Phosphoric Acid and Its Application in the Purification of Boron Nitride Nanotubes
- Award ID(s):
- 2108838
- PAR ID:
- 10575292
- Publisher / Repository:
- American Chemical Society
- Date Published:
- Journal Name:
- Chemistry of Materials
- Volume:
- 36
- Issue:
- 1
- ISSN:
- 0897-4756
- Page Range / eLocation ID:
- 157 to 166
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Due to its excellent chemical/thermal stability and mechanical robustness, hexagonal boron nitride (hBN) is a promising solid matrix material for ionogels. While bulk hBN ionogels have been employed in macroscopic applications such as lithium-ion batteries, hBN ionogel inks that are compatible with high-resolution printing have not yet been realized. Here, we describe aerosol jet-printable ionogels using exfoliated hBN nanoplatelets as the solid matrix. The hBN nanoplatelets are produced from bulk hBN powders by liquid-phase exfoliation, allowing printable hBN ionogel inks to be formulated following the addition of an imidazolium ionic liquid and ethyl lactate. The resulting inks are reliably printed with variable patterns and controllable thicknesses by aerosol jet printing, resulting in hBN ionogels that possess high room-temperature ionic conductivities and storage moduli of >3 mS cm −1 and >1 MPa, respectively. By integrating the hBN ionogel with printed semiconductors and electrical contacts, fully-printed thin-film transistors with operating voltages below 1 V are demonstrated on polyimide films. These devices exhibit desirable electrical performance and robust mechanical tolerance against repeated bending cycles, thus confirming the suitability of hBN ionogels for printed and flexible electronics.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1021/acs.chemmater.3c01424
