Investigation of a novel high pressure phase transition in boron carbide resulting in much improved dynamical strength

Boron carbide is a popular superhard ceramic, with application ranging from abrasives to nuclear power plants. However, it famously, and anomalously, loses its high mechanical strength at impacts beyond 15-17 GPa. Several hypotheses such as amorphisation and point vacancy generation has been proposed to explain this phenomenon. Recently, a carbon rich boron carbide containing C-C chains has been designed from first principles which will not have the fatal structural flaws of conventional B4C, thus preventing the dynamic failure. In fact, we have observed evidence of the synthesis of this material ex-situ at 62 GPa in a laser heated diamond anvil cell. However, we need XRD and Raman characterisation before and after compression, laser heating and decompression using the small beamspot and high intensity of the ESRF synchrotron to analyse this high pressure phase transformation of boron carbide completely.