Jump to main content
Jump to site search


Formation and characterization of nano- and microstructures of twinned cubic boron nitride

Author affiliations

Abstract

Nano- and microstructures of phase-pure cubic boron nitride (c-BN) are synthesized by employing nanosecond pulsed-laser annealing techniques at room temperature and atmospheric pressure. In a highly non-equilibrium synthesis process, nanocrystalline h-BN is directly converted into phase-pure twinned c-BN from a highly undercooled melt state of BN. By changing nucleation and growth rates, we have synthesized a wide range of sizes (90 nm to 25 μm) of c-BN. The electron diffraction patterns show the formation of twinned c-BN with [1[1 with combining macron]1] as the twin axis. The twinning density in c-BN can be controlled by the degree of undercooling and quenching rates. The formation of twins predominantly occurs prior to the formation of amorphous quenched BN (Q-BN). Therefore, the defect density in nano c-BN formed under higher undercooling conditions is considerably larger than that in micro c-BN, which is formed under lower undercooling conditions. The temperature-dependent Raman studies show a considerable blue-shift of ∼6 cm−1 with a decrease in temperature from 300 to 78 K in nano c-BN as compared to micro c-BN. The size-effects of c-BN crystals in Raman spectra are modeled using spatial correlation theory, which can be used to calculate the correlation length and twin density in c-BN. It has also been found that the Raman blue-shift in nano c-BN is caused by anharmonic effects, and the decrease in Raman linewidth with decreasing temperature (300 to 78 K) is caused by three- and four-phonon decay processes. The bonding characteristics and crystalline nature of the synthesized c-BN are also demonstrated by using electron energy-loss spectroscopy and electron backscatter diffraction, respectively. We envisage that the controlled growth of phase-pure nano and microstructures of twinned c-BN and their temperature-dependent Raman-active vibrational mode studies will have a tremendous impact on low-temperature solid-state electrical and mechanical devices.

Graphical abstract: Formation and characterization of nano- and microstructures of twinned cubic boron nitride

Back to tab navigation

Publication details

The article was received on 19 Jul 2018, accepted on 16 Sep 2018 and first published on 17 Sep 2018


Article type: Paper
DOI: 10.1039/C8CP04592E
Citation: Phys. Chem. Chem. Phys., 2019, Advance Article
  •   Request permissions

    Formation and characterization of nano- and microstructures of twinned cubic boron nitride

    A. Bhaumik and J. Narayan, Phys. Chem. Chem. Phys., 2019, Advance Article , DOI: 10.1039/C8CP04592E

Search articles by author

Spotlight

Advertisements