Strength measurement of boron suboxide B₆O at high pressure and temperature using in situ synchrotron X-ray diffraction

Abstract

The strength of boron suboxide (B₆O) was measured at high pressure and temperature up to 8 GPa and 800°C using diffraction peak broadening analysis. The sample was synthesized at 6 GPa and 1750°C. In situ energy dispersive X-ray diffraction was conducted at the X17B2 beamline of the National Synchrotron Light Source. The differential stress in the powdered sample was derived through deconvolution of peak broadening of diffraction lines (0 2 1) and (1 1 3) during the compression and heating. The sample shows anisotropic yielding along the two orientations. The (0 2 1) orientation does not show yielding within the investigated pressure range (8 GPa) whereas the (1 1 3) orientation yields at 5 GPa. Upon heating, significant weakening (yielding) was observed at temperatures above 400°C. The yield temperature of boron suboxide is much lower than that of diamond, 1200°C, but similar to that observed in moissanite (SiC).

Keywords:

• boron suboxide
• strength
• high pressure and temperature
• X-ray diffraction
• anisotropy

Acknowledgements

This research was conducted at the beamline partially supported by COMPRES, the Consortium for Materials Properties Research in Earth Sciences under NSF Cooperative Agreement EAR 06-49658. Use of the NSLS, Brookhaven National Laboratory, was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract no. DE-AC02-98CH10886. J.C. would like to thank the support from DOE (grant no. DE-FG02-07ER46461) and NSF (Award EAR-0711321), Y.Z. and J.Z. would like to thank the support from Los Alamos National Laboratory, which is operated by Los Alamos National Security LLC under DOE Contract DE-AC52-06NA25396.