In situ study of the formation of rhenium borides from the elements at high-(p, T) conditions: Extreme incompressibility of Re7B3 and formation of new phases

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, Re7B3 was found to be extremely incompressible, with BRe7B3=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 Re3B, BRe3B=320(15)GPa, and have confirmed earlier reports of the bulk modulus of ReB2, BReB2BReB2 = 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.

Schematic p–T field of the phases observed during the reaction of rhenium and boron from the elements in a laser heated diamond anvil cell. The formation of at least two new phase (called phase A and phase B) was observed. The lines are only guides to the eye.Figure optionsDownload as PowerPoint slide