Intermediate 4fbonding structure for samarium under pressure

The crystal structure of the low-symmetry phase Sm(V) was studied by synchrotron x-ray diffraction under isothermal compression at room temperature up to 77 GPa (volume fraction=0.45). Measured lattice spacings and diffraction intensities for Sm(V) in the pressure range beyond the phase mixing show that this phase can be identified as a prototype structure with 3 atoms in the hexagonal unit cell. The occurrence of this low-symmetry structure gives strong evidence for a rapid increase of 4f-electron bonding in Sm in the pressure range above 37 GPa.