Simple-cubic–simple-hexagonal transition in phosphorus under pressure

By using an angle dispersive powder x-ray-diffraction technique with a synchrotron radiation source at the SPring-8, lattice compression of the simple cubic (sc) structure of phosphorus and its phase stability have been studied up to 151 GPa. A phase transition from the sc to the simple hexagonal (sh) structure was observed at 137 GPa via an intermediate phase. In spite of the low packing fraction of atoms, the sc structure was stable over a wide pressure range from 10 to 103 GPa at 300 K and the equation of state of the phase was precisely determined.