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 synchrotron X-ray diffraction. The b.c.c.-f.c.c. transition has been observed 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 agreement is found between calculated pressure-volume relations and the experimental data. At twofold compression the calculated repulsion is too strong. We have observed that pure Li, if in direct contact with diamond anvils, develops a corrosive effect on the anvils at pressures above 20 Gpa. (C) 1999 Elsevier Science Ltd. All rights reserved.