When carbon impurities trigger the synthesis of alpha boron at high pressure and high temperature

Title data

Chakraborti, Amrita ; Cho, Yeonsoo ; Sjakste, Jelena ; Baptiste, Benoit ; Henry, Laura ; Guignot, Nicolas ; Le Godec, Yann ; Vast, Nathalie:
When carbon impurities trigger the synthesis of alpha boron at high pressure and high temperature.
In: Acta Materialia. Vol. 249 (2023) . - p. 118820.
ISSN 1359-6454
DOI: https://doi.org/10.1016/j.actamat.2023.118820

Official URL:

Abstract in another language

The role of carbon in the formation of α boron at high pressure and high temperature (HPHT) has been investigated by combining HPHT experiments and density functional theory (DFT) calculations. Starting from β rhombohedral or amorphous boron and amorphous carbon at 5 GPa, the α boron phase has been repeatedly observed between 1373 K and 2273 K, at temperatures that are much higher than those reported in the phase diagram of boron. The DFT investigation of the effect of carbon insertion into the α rhombohedral boron atomic structure on the formation enthalpy, volume and optical properties shows that the (B11C) substituted icosahedron defect accounts for the slight volume contraction observed in α boron, is compatible with the observed red colour of α boron crystals, and consistently has a very low formation energy. Our calculations turn out to provide a calibration means to evaluate the concentration of carbon in our samples. Finally, the synthesis temperature is found to be an easy means to control the carbon concentration on demand.

Further data

Item Type:	Article in a journal
Refereed:	Yes
Keywords:	Alpha boron; High pressure high temperature synthesis; Boron phase diagram; Carbon impurities
Institutions of the University:	Research Institutions > Central research institutes > Bavarian Research Institute of Experimental Geochemistry and Geophysics - BGI
Result of work at the UBT:	Yes
DDC Subjects:	500 Science > 550 Earth sciences, geology
Date Deposited:	11 Oct 2024 10:20
Last Modified:	11 Oct 2024 10:20
URI:	https://eref.uni-bayreuth.de/id/eprint/90639