Research Update: Direct conversion of h-BN into pure c-BN at ambient temperatures and pressures in air

Journal Article · Mon Feb 01 00:00:00 EST 2016 · APL Materials

DOI:https://doi.org/10.1063/1.4941095· OSTI ID:22499247

Narayan, Jagdish; Bhaumik, Anagh ^[1]

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1. Department of Materials Science and Engineering, Centennial Campus, North Carolina State University, Raleigh, North Carolina 27695-7907 (United States)

We report a direct conversion of hexagonal boron nitride (h-BN) into pure cubic boron nitride (c-BN) by nanosecond laser melting at ambient temperatures and atmospheric pressure in air. According to the phase diagram, the transformation from h-BN into c-BN can occur only at high temperatures and pressures, as the hBN-cBN-Liquid triple point is at 3500 K/9.5 GPa. Using 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 formation of super undercooled BN (Q-BN). The c-BN phase is nucleated from Q-BN depending upon the time allowed for nucleation and growth.

• OSTI ID: 22499247
• Journal Information: APL Materials, Vol. 4, Issue 2; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 2166-532X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AMBIENT TEMPERATURE
BORON NITRIDES
LIQUIDS
MELTING
NUCLEATION
PHASE DIAGRAMS
QUENCHING