Equation of state of lithium to 21 GPa

The equation of state of lithium has been measured up to 21 GPa (T = 298 K) using diamond anvil cell techniques and high-resolution angle-dispersive s ynchrotron X-ray diffraction. The b.c.c.-f.c.c. transition has been observe d near 7.5 Gpa. The volume change at the transition amounts to only 0.16(3) %. These results basically confirm earlier diffraction studies up to 10 GPa by Clinger and Shaner. Total energy calculations were performed using the full-potential linearized augmented-plane-wave method. Good overall agreeme nt is found between calculated pressure-volume relations and the experiment al data. At twofold compression the calculated repulsion is too strong. We have observed that pure Li, if in direct contact with diamond anvils, devel ops a corrosive effect on the anvils at pressures above 20 Gpa. (C) 1999 El sevier Science Ltd. All rights reserved.