Issue |
Europhys. Lett.
Volume 68, Number 4, November 2004
|
|
---|---|---|
Page(s) | 550 - 556 | |
Section | Condensed matter: structure, mechanical and thermal properties | |
DOI | https://doi.org/10.1209/epl/i2004-10235-1 | |
Published online | 29 October 2004 |
Strain-induced disorder and phase transformation in hexagonal boron nitride under quasi-homogeneous pressure: In situ X-ray study in a rotational diamond anvil cell
Texas Tech University, Center for Mechanochemistry and Synthesis of New Materials, Department of Mechanical Engineering Lubbock, TX 79409-1021, USA
Received:
26
January
2004
Accepted:
17
September
2004
One of the challenges in characterization of strain-induced
transformations is to create uniform pressure. In this letter,
conditions for nearly homogeneous pressure distribution are
predicted and achieved experimentally. Compared to hydrostatic
loading, plastic shear generally reduces the transformation
pressure significantly. We observed, however, an unexpected
phenomenon: the transformation of hexagonal to superhard
wurtzitic BN under pressure and shear initiated at a pressure
comparable to that in hydrostatic compression ().
In situ X-ray diffraction revealed that plastic shear
increases the disorder, while hydrostatic compression does not.
This increase neutralizes the transition pressure reduction
caused by shear. For the same disorder, shear reduced the
transformation pressure significantly, and caused a complete,
irreversible transformation.
PACS: 64.60.-i – General studies of phase transitions / 64.70.Kb – Solid-solid transitions
© EDP Sciences, 2004
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