X-ray diffraction study of B4C under high pressure

The high pressure X-ray diffraction study of B₄C was carried out by using the synchrotron radiation source. The ambient crystal structure remained stable to the highest pressure 126 GPa, and the pressure induced amorphization did not occurs. The c/a ratio decreased with increasing pressure that means the apex angle of the rhombohedron increases with increasing pressure. The bulk modulus was determined by the Birch-Murnaghan's equation to be 305.8 GPa.