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

The strength of boron suboxide (B6O) was measured at high pressure and temperature up to 8GPa and 800 degrees C using diffraction peak broadening analysis. The sample was synthesized at 6GPa and 1750 degrees 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 degrees C. The yield temperature of boron suboxide is much lower than that of diamond, 1200 degrees C, but similar to that observed in moissanite (SiC).