Amorphization and a polymorphic transformation of boron stimulated by high dynamic pressures

Structural transformations of polycrystalline boron have been studied under megabar multiple-shock compression. Shock-wave experiments on the compression and subsequent recovery of polycrystalline samples of $\beta$-rhombohedral boron $\beta$-B$_{106}$ have been performed. Thermodynamic states of boron under the conditions of the performed experiments have been calculated. According to these calculations, the maximum pressure in the samples is 115 GPa. X-ray diffraction analysis of the stored boron samples has been performed. It has been shown that the dynamic compression of polycrystalline $\beta$-B$_{106}$ to 115 GPa results in its partial amorphization and transformation to the tetragonal modification of boron T-B$_{192}$.