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Author Narayan, Jagdish ♦ Bhaumik, Anagh ♦ Xu, Weizong
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS ♦ 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
Abstract 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.
ISSN 00218979
Educational Use Research
Learning Resource Type Article
Publisher Date 2016-05-14
Publisher Place United States
Journal Journal of Applied Physics
Volume Number 119
Issue Number 18


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