300-K equation of state of rhombohedral boron subnitride,

Quasi-hydrostatic compression of rhombohedral boron subnitride has been studied up to 30 GPa at room temperature using angle-dispersive X-ray diffraction with synchrotron radiation. The α -rhombohedral boron type R 3 ̄ m structure of B13N2 is stable in the whole pressure range under study. A fit of the experimental p – V data to the Birch equation of state yields the values of the bulk modulus, B 0 , of 200(15) GPa with fixed first pressure derivative of the bulk modulus, B 0 ′ , of 4.0. The compression is found to be slightly anisotropic with higher compressibility along c -axis.