X-ray diffraction study of Be to megabar pressure

Powder x-ray diffraction experiments on a low- Z element, Be, were performed at pressures up to 171 GPa using the synchrotron radiation source at SPring-8. All profiles were assigned to the hcp structure of the ambient phase, and the theoretically predicted hcp–bcc phase transition was not observed. The previously proposed hcp–hexagonal phase transition around 14.5 GPa was also not confirmed. The equation of state of hcp-Be was determined by a least mean squares fitting to the Birch–Murnaghan equation from these diffraction data. Calculated values of K 0 and K 0 ′ were 97.2 ± 2.5 GPa and 3.61 ± 0.07, respectively.