In situ study of the formation of rhenium borides from the elements at high-(p, T) conditions: Extreme incompressibility of Re_7B_3 and formation of new phases

摘要

Based on in situ synchrotron X-ray diffraction experiments employing laser heated diamond anvil cells to investigate the reaction of rhenium and boron from the elements at high-(p, T) conditions, Re_7B_3 was found to be extremely incompressible, with B_(Re_7B_3) = 435(14) GPa, making it one of the least compressible binary compounds known to date. We also have determined the previously unknown bulk modulus of Re_3B,B_(Re_3B) = 320(15) GPa, and have confirmed earlier reports of the bulk modulus of ReB_2, B_(ReB_2) = 360(18) GPa. The experimental findings were supported by density functional theory calculations, which were also employed to compute elastic stiffness coefficients and estimates for the hardness. At different high-(p, T) conditions the formation of new phases were observed.