Direct conversion of h-BN into c-BN and formation of epitaxial c-BN/diamond heterostructures
- Department of Materials Science and Engineering, Centennial Campus North Carolina State University, Raleigh, North Carolina 27695-7907 (United States)
We have created a new state of BN (named Q-BN) through rapid melting and super undercooling and quenching by using nanosecond laser pulses. Phase pure c-BN is formed either by direct quenching of super undercooled liquid or by nucleation and growth from Q-BN. Thus, a direct conversion of hexagonal boron nitride (h-BN) into phase-pure cubic boron nitride (c-BN) is achieved by nanosecond pulsed laser melting at ambient temperatures and atmospheric pressure in air. According to the P-T phase diagram, the transformation from h-BN into c-BN under equilibrium processing can occur only at high temperatures and pressures, as the hBN-cBN-Liquid triple point is at 3500 K/9.5 GPa or 3700 K/7.0 GPa with a recent theoretical refinement. Using nonequilibrium nanosecond laser melting, we have created super undercooled state and shifted this triple point to as low as 2800 K and atmospheric pressure. The rapid quenching from super undercooled state leads to the formation of a new phase, named as Q-BN. We present detailed characterization of Q-BN and c-BN layers by using Raman spectroscopy, high-resolution scanning electron microscopy, electron-back-scatter diffraction, high-resolution TEM, and electron energy loss spectroscopy, and discuss the mechanism of formation of nanodots, nanoneedles, microneedles, and single-crystal c-BN on sapphire substrate. We have also deposited diamond by pulsed laser deposition of carbon on c-BN and created c-BN/diamond heterostructures, where c-BN acts as a template for epitaxial diamond growth. We discuss the mechanism of epitaxial c-BN and diamond growth on lattice matching c-BN template under pulsed laser evaporation of amorphous carbon, and the impact of this discovery on a variety of applications.
- OSTI ID:
- 22596973
- Journal Information:
- Journal of Applied Physics, Vol. 119, Issue 18; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Research Update: Direct conversion of h-BN into pure c-BN at ambient temperatures and pressures in air
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Related Subjects
GENERAL PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BORON NITRIDES
DIAMONDS
ELECTRONS
ENERGY BEAM DEPOSITION
ENERGY-LOSS SPECTROSCOPY
EPITAXY
LASER RADIATION
LASERS
LIQUIDS
MELTING
MONOCRYSTALS
PHASE DIAGRAMS
PRESSURE RANGE GIGA PA
PULSED IRRADIATION
PULSES
QUANTUM DOTS
RAMAN SPECTROSCOPY
SAPPHIRE
SCANNING ELECTRON MICROSCOPY
TRANSMISSION ELECTRON MICROSCOPY